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Aim Methodology Results Conclusions To compare the effects of Cervical Access Cavity (CervAC) and Traditional Access Cavity (TradAC) on root canal preparation, root canal filling, and fracture resistance in mandibular incisors.Twenty recently extracted and intact mandibular incisors were initially scanned using a micro‐CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge‐shaped non‐carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double‐faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single‐cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann–Whitney test or the Student's t‐test, with a statistical significance level of 5%.Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008).CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors. [ABSTRACT FROM AUTHOR]

Aim: To compare the efficacy of Enterococcus faecalis biofilm removal using the GentleWave System (GWS) (Sonendo Inc, CA) on non‐instrumented versus minimally instrumented root canal systems. Methodology: Thirty‐four mandibular molars were autoclaved and allocated to four groups: Negative control (n = 5); positive control (n = 5); Group 1: non‐instrumentation + GWS (NI + GWS) (n = 12); and Group 2: minimal instrumentation + GWS (MI + GWS) (n = 12). Of 34 samples, 24 samples with Vertucci type 2 configuration within the mesial root of each sample were allocated to Groups 1 and 2 and then matched based on the working length and root canal configuration. After inoculation of samples with E. faecalis for 3 weeks, the GWS was used on Group 1 without any instrumentation and Group 2 after instrumentation of mesial canals until size 20/06v. CFU and SEM analysis were used. Results: Log10 (CFU/mL) from the positive control, and Group 1 and 2 were 7.41 ± 0.53, 3.41 ± 1.54, and 3.21 ± 1.54, respectively. Both groups showed a statistically significant difference in the reduction of viable E. faecalis cells compared to the positive control (Group 1 [p =.0001] and Group 2 [p <.0001]), whilst showing no significant difference between the two tested groups (p <.05). Conclusion: The use of GWS on the non‐instrumented root canal system could be an effective disinfection protocol in removing the biofilm without dentin debris formation. [ABSTRACT FROM AUTHOR]

Aim: Endodontic irrigants may affect the mechanical and chemical properties of dentine. This study evaluated the effects of various final irrigation protocols including the use of chitosan nanoparticle (CSnp) and cross‐linking with genipin on the (1) mechanical and (2) chemical properties of dentine against enzymatic degradation. Methodology: CSnp was synthesized and characterized considering physiochemical parameters and stability. The root canals of 90 single‐rooted teeth were prepared and irrigated with NaOCl. Dentine discs were obtained and divided into groups according to the following irrigation protocols: Group NaOCl+EDTA, Group NaOCl+CSnp, Group NaOCl+EDTA+CSnp, Group NaOCl+CSnp+Genipin, Group NaOCl+EDTA+CSnp+Genipin and Group distilled water. (1) Mechanical changes were determined by microhardness analysis using Vickers‐tester. (2) Chemical changes were determined by evaluating molecular and elemental compositions of dentine using Fourier transform infrared spectroscopy (FTIR) analysis and scanning electron microscope (SEM)/energy dispersive X‐ray spectroscopy (EDS) analysis, respectively. All analyses were repeated after the discs were kept in collagenase for 24 h. Data were analysed with repeated measures analysis of variance and Bonferroni correction for microhardness analysis, and Kruskal–Wallis and Wilcoxon tests for FTIR and SEM/EDS analyses (p =.05). Results: (1) Collagenase application did not have a negative effect on microhardness only in Group NaOCl+EDTA+CSnp+Genipin when compared with the post‐irrigation values (p >.05). Post‐collagenase microhardness of Group NaOCl+EDTA+CSnp and Group NaOCl+CSnp+Genipin was similar to the initial microhardness (p >.05). (2) After collagenase, Amide III/PO43− ratio presented no change in Group NaOCl+EDTA+CSnp, Group NaOCl+CSnp+Genipin and Group NaOCl+EDTA+CSnp+Genipin (p >.05), while decreased in other groups (p <.05). Collagenase did not affect CO32−/PO43− ratio in the groups (p >.05). There were no changes in the groups in terms of elemental level before and after collagenase application (p >.05). Conclusions: CSnp and genipin positively affected the microhardness and molecular composition of dentine. This effect was more pronounced when CSnp was used after EDTA. [ABSTRACT FROM AUTHOR]

Aim: To develop a new coculture system that allows exposure of dental pulp cells (DPCs) to Streptococcus mutans and dentine matrix proteins (eDMP) to study cellular interactions in dentine caries. Methodology: Dental pulp cells and S. mutans were cocultured with or without eDMP for 72 h. Cell proliferation and viability were assessed by cell counting and MTT assays, while bacterial growth and viability were determined by CFU and LIVE/DEAD staining. Glucose catabolism and lactate excretion were measured photometrically as metabolic indicators. To evaluate the inflammatory response, the release of cytokines and growth factors (IL‐6, IL‐8, TGF‐β1, VEGF) was determined by ELISA. Non‐parametric statistical analyses were performed to compare all groups and time points (Mann–Whitney U test or Kruskal–Wallis test; α =.05). Results: While eDMP and especially S. mutans reduced the number and viability of DPCs (p ≤.0462), neither DPCs nor eDMP affected the growth and viability of S. mutans during coculture (p >.0546). The growth of S. mutans followed a common curve, but the death phase was not reached within 72 h. S. mutans consumed medium glucose in only 30 h, whereas in the absence of S. mutans, cells were able to catabolize glucose throughout 72 h, resulting in the corresponding amount of l‐lactate. No change in medium pH was observed. S. mutans induced IL‐6 production in DPCs (p ≤.0011), whereas eDMP had no discernible effect (p >.7509). No significant changes in IL‐8 were observed (p >.198). TGF‐β1, available from eDMP supplementation, was reduced by DPCs over time. VEGF, on the other hand, was increased in all groups during coculture. Conclusions: The results show that the coculture of DPCs and S. mutans is possible without functional impairment. The bacterially induced stimulation of proinflammatory and regenerative cytokines provides a basis for future investigations and the elucidation of molecular biological relationships in pulp defence against caries. [ABSTRACT FROM AUTHOR]

Aim: Dental pulp is richly innervated by nerve fibres, which are mainly involved in the sensation of pain. Aside from pain sensation, little is known regarding the role of dental innervation in reparative dentine formation. We herein generated a mouse model of experimental dentine injury to examine nerve sprouting within the odontoblast and subodontoblastic layers and investigated the potential effects of this innervation in reparative dentinogenesis. Methodology: Mouse tooth cavity model (bur preparation + etching) was established, and then nerve sprouting, angiogenesis and reparative dentinogenesis were determined by histological and immunofluorescent staining at 1, 3, 7, 14 and 28 days postoperatively. We also established the mouse‐denervated molar models to determine the role of sensory and sympathetic nerves in reparative dentinogenesis, respectively. Finally, we applied calcitonin gene‐related peptide (CGRP) receptor antagonist to analyse the changes in angiogenesis and reparative dentinogenesis. Results: Sequential histological results from dentine‐exposed teeth revealed a significant increase in innervation directly beneath the injured area on the first day after dentine exposure, followed by vascularisation and reparative dentine production at 3 and 7 days, respectively. Intriguingly, abundant type H vessels (CD31+Endomucin+) were present in the innervated area, and their formation precedes the onset of reparative dentine formation. Additionally, we found that sensory denervation led to blunted angiogenesis and impaired dentinogenesis, while sympathetic denervation did not affect dentinogenesis. Moreover, a marked increase in the density of CGRP+ nerve fibres was seen on day 3, which was reduced but remained elevated over the baseline level on day 14, whereas the density of substance P‐positive nerve fibres did not change significantly. CGRP receptor antagonist‐treated mice showed similar results as those with sensory denervation, including impairments in type H angiogenesis, which confirms the importance of CGRP in the formation of type H vessels. Conclusions: Dental pulp sensory nerves act as an essential upstream mediator to promote angiogenesis, including the formation of type H vessels, and reparative dentinogenesis. CGRP signalling governs the nerve‐vessel‐reparative dentine network, which is mostly produced by newly dense sensory nerve fibres within the dental pulp. [ABSTRACT FROM AUTHOR]

Aim: The aim was to develop a standardized curved root canal model in bovine dentine and to assess whether that natural substrate would behave differently from the resin in standard plastic training blocks when prepared chemo‐mechanically. The impact of substrate microhardness on simulated canal transportation was considered. Methodology: High‐precision computer numerical control (CNC) milling was used to recreate a simulated root canal from a resin training block (Endo Training Bloc J‐Shape, size 15) in longitudinally sectioned, dis‐ and re‐assembled bovine incisor roots. Optical overlays obtained from 10 resin blocks were used to identify an average canal and program the CNC milling apparatus accordingly. Resin and dentine microhardness were measured. Simulated root canals in resin training blocks and their bovine counterparts were then instrumented at 37°C using Reciproc R25 instruments (VDW) with water or 17% EDTA (n = 10). Open‐access image processing software was used to superimpose and analyse pre‐ and postoperative images obtained with a digital microscope. Centering ratios were averaged to indicate canal transportation. The effects of substrate and irrigant on canal transportation were assessed by two‐way anova. Results: Superimposed images showed that resin blocks under investigation varied considerably in terms of simulated canal length and curvature, whilst the milled canals were highly similar. The microhardness of dentine was more than three times higher than that of the resin. Conversely, canal transportation was considerably greater in dentine compared to resin, and in dentine had a tendency to be increased by EDTA. There was a strong effect of substrate on canal transportation (p <.001), no overall effect of irrigant, and a marginally significant interaction between irrigant and substrate (p =.077). Conclusions: CNC milling allows to create standardized simulated curved root canals in bovine dentine. These models may be useful to test and compare materials and concepts of chemo‐mechanical root canal instrumentation. Microhardness is a bulk feature that does not predict the response to chemo‐mechanical instrumentation of a composite material such as dentine. [ABSTRACT FROM AUTHOR]

Aim: Fat mass and obesity‐associated (FTO) protein, the first discovered N6‐methyladenine (m6A) demethylase, played positive roles in bone formation. In this study, the aim was to investigate the function and potential mechanism of Fto in dentine formation. Methodology: In vivo model, postnatal 12‐day (PN12), 4‐week‐old (4 wk), 6‐week‐old (6 wk) healthy male C57BL/6J were randomly divided into Fto knockout (Fto−/−) mice and wild‐type (WT) littermates according to their genotypes, with 3–5 mice in each group. The mandibles of Fto−/− mice and WT control littermates were isolated for analysis by micro–computed tomography (micro‐CT), 3‐dimensional reconstruction and Haematoxylin–eosin (HE) staining. In vitro, mouse dental papilla cells (mDPCs) and human dental stem pulp cells (hDPSCs) were cultured with odontogenetic medium to evaluate differentiation capacity; expression levels of odontoblastic related genes were evaluated using quantitative real‐time polymerase chain reaction (qRT‐PCR). The inclusion levels of Runt‐related transcription factor 2 (RUNX2) exon 5 in mDPCs and hDPSCs were detected by semiquantitative real‐time polymerase chain reaction (RT‐PCR). The RNA binding motif protein 4 (RBM4) m6A site was verified through m6A methylated RNA immunoprecipitation (MeRIP) and the stability of RBM4 mRNA influenced by FTO knockdown was measured by mRNA stability assay. Differences with p values <.05 were regarded as statistically significant. Results: We discovered that Fto−/− mice showed significant dentine formation defects characterized by widened pulp cavity, enlarged pulp‐tooth volume ratio, thinned dentine and pre‐dentine layer of root (p <.05). Fto−/− mDPCs and FTO‐silencing hDPSCs not only exhibited insufficient mineralization ability and decreased expression levels of odontoblastic mineralization related genes (p <.05), but showed significantly reduced Runx2 exon 5 inclusion level (p <.05). FTO knockdown increased the m6A level of RBM4 and destabilized the mRNA of RBM4, thus contributing to the reduced RBM4 expression level. Moreover, Rbm4 overexpression in Fto−/− mDPCs can partly restore Runx2 exon 5 inclusion level and the differentiation ability disrupted by Fto knockout. Conclusion: Thus, within the limitations of this study, the data suggest that FTO promotes odontoblastic differentiation during dentine formation by stabilizing RBM4 mRNA to promote RUNX2 exon 5 inclusion. [ABSTRACT FROM AUTHOR]

Aim: The primary goal of this study was to investigate the potential effects of A5G81 in inducing reparative dentine (RD) formation both in vitro and in vivo. Methodology: Cell adhesion was observed by crystal violet staining and quantified by Sodium Dodecyl Sulphate (SDS) extraction. Cell proliferation was investigated using Cell Counting Kit‐8 (CCK‐8) assay. Spreading of cytoskeleton was visualized using immunofluorescence staining. Protein expression level of Akt signalling pathway was compared in a human Akt pathway phosphorylation array. Genes that were up or downregulated by A5G81 were identified by RNA sequencing. The mRNA expression of odontoblastic markers was detected by quantitative real‐time polymerase chain reaction (qPCR). Moreover, mineralization of human dental pulp cells (hDPCs) was visualized by alizarin red staining and quantified using cetylpyridinium chloride (CPC). A direct pulp‐capping model was established in SD rats and the RD formation at 2 weeks after operation was observed using HE staining. Results: A5G81 (optimal coating concentration: 0.5 mg/mL) promoted hDPCs adhesion and proliferation to a level that was similar to Type I collagen (COL‐1). Meanwhile, A5G81 activated Akt signalling pathway, albeit to a lesser extent than COL‐1. An inhibition test indicated that A5G81 induced hDPCs adhesion by activating PI3K pathway. A5G81 induced the expression of ECM remodelling genes and odontoblastic genes, which were demonstrated by RNA‐seq and qPCR, respectively. In addition, A5G81 efficiently accelerated the mineralization of hDPCs in both immobilized and soluble forms, a property that makes it more applicable in dental clinic. Finally, the pulp‐capping study in rats suggested that use of A5G81 could successfully induce the formation of RD within 2 weeks. Conclusion: Coating of A5G81 to non‐tissue culture–treated polystyrene facilitates spreading, proliferation and differentiation of hDPCs, resulting in rapid RD formation in artificially exposed pulp. [ABSTRACT FROM AUTHOR]

Aims: Chitosan‐based biomaterials exhibit several properties of biological interest for endodontic treatment. Herein, a low molecular weight chitosan (CH) solution was tested for its antimicrobial activity against Enterococcus faecalis (E. faecalis) and effects on dentine structure. Methodology: The root canal of 27 extracted uniradicular teeth were biomechanically prepared, inoculated with a suspension of E. faecalis and randomly assigned to be irrigated with either 5.25% sodium hypochlorite (NaClO), 0.2% CH or sterile ultrapure water (W). Bacteriologic samples were collected from root canals and quantified for of E. faecalis colony‐forming units (CFUs). The effectiveness of CH over E. faecalis biofilms was further measured using the MBEC Assay®. Additionally, dentine beams and dentine powder were obtained, respectively, from crowns and roots of 20 extracted third molars. Dentine samples were treated or not with 17% EDTA and immersed in either CH or W for 1 min. The effects of CH on dentine structure were evaluated by assessment of the modulus of elasticity, endogenous proteolytic activity and biochemical modifications. Results: The number of E. faecalis CFUs was significantly lower for samples irrigated with CH and NaClO. No significant differences were found between CH and NaClO treatments. Higher modulus of elasticity and lower proteolytic activity were reported for dentine CH‐treated specimens. Chemical interaction between CH and dentine was observed for samples treated or not with EDTA. Conclusions: Present findings suggest that CH could be used as an irrigant during root canal treatment with the triple benefit of reducing bacterial activity, mechanically reinforcing dentine and inhibiting dentine proteolytic activity. [ABSTRACT FROM AUTHOR]

Aim: This study evaluated and compared the shaping ability of four rotary instrument systems in long–oval root canals using microcomputed tomographic (micro‐CT) evaluation. Currently, there is no data available on the canal shaping abilities of BlueShaper and DC Taper instruments. Methodology: Sixty‐four single‐rooted mandibular premolars were matched based on similar root canal morphologic features as determined by (micro‐CT) and randomly assigned to 1 of 4 experimental groups (n = 16) according to the instrument system used: BlueShaper, TruNatomy, DC Taper and HyFlex EDM One File. Changes in the root canal surface and volume, remaining dentine thickness, and number of prepared areas were assessed. Results: No significant differences were found amongst the four instrument systems for the parameters evaluated (p >.05). There was a significant reduction in the number of unprepared areas and the remaining dentine thickness after each increase in size of the instruments tested (p <.05). Conclusions: The four instrument systems perform similarly in long oval root canals. Although none could prepare all canal walls, larger preparations incorporated significantly more surfaces in the final shape. [ABSTRACT FROM AUTHOR]

Aim: Inducing odontogenic differentiation and tubular dentine formation is extremely important in dentine repair and tooth regeneration. Bone morphogenic proteins (BMPs) signalling plays a critical role in dentine development and tertiary dentine formation, whilst how BMPR1A‐mediated signalling affects odontoblastic differentiation of Axin2‐expressing (Axin2+) odontogenic cells and tubular dentine formation remains largely unknown. This study aims to reveal the cellular and molecular mechanisms involved in the formation of secondary dentine. Methodology: Axin2lacZ/+ mice harvested at post‐natal 21 (P21) were used to map Axin2+ mesenchymal cells. Axin2CreERT2/+; R26RtdTomato/+ mice and Axin2CreERT2/+; R26RDTA/+; R26RtdTomato/+ mice were generated to observe the tempo‐spatial distribution pattern of Axin2‐lineage cells and the effect of ablation of Axin2+ cells on dentinogenesis, respectively. A loss‐of‐function model was established with Axin2CreERT2/+; Bmpr1afl/fl; R26RtdTomato/+ (cKO) mice to study the role of BMP signalling in regulating Axin2+ cells. Micro‐computed tomography, histologic and immunostainings, and other approaches were used to examine biological functions, including dentine formation, mineralization and cell differentiation in cKO mice. Results: The results showed rich expression of Axin2 in odontoblasts at P21. Lineage tracing assay confirmed the wide distribution of Axin2 lineage cells in odontoblast layer and dental pulp during secondary dentine formation (P23 to P56), suggesting that Axin2+ cells are important cell source of primary odontoblasts. Ablation of Axin2+ cells (DTA mice) significantly impaired secondary dentine formation characterized with notably reduced dentine thickness (Mean of control: 54.11 μm, Mean of DTA: 27.79 μm, p =.0101). Furthermore, malformed osteo‐dentine replaced the tubular secondary dentine in the absence of Bmpr1a with irregular cell morphology, abnormal cellular process formation and lack of cell–cell tight conjunction. Remarkably increased expression of osteogenic markers like Runx2 and DMP1 was detected, whilst DSP expression was observed in a dispersed manner, indicating an impaired odontogenic cell fate and failure in producing tubular dentine in cKO mice. Conclusions: Axin2+ cells are a critical population of primary odontoblasts which contribute to tubular secondary dentine formation, and BMP signalling pathway plays a vital role in maintaining the odontogenic fate of Axin2+ cells. [ABSTRACT FROM AUTHOR]

Aim: The present study aimed to determine and compare the dentine thickness around the root canals of maxillary molars with fusion using micro‐computed tomography (micro‐CT). Methodology: A total of 120 fused maxillary molars having more than a single canal with distinct canal orifices near the cementoenamel junction were selected from a pool of extracted maxillary molars, which were scanned on a micro‐CT device (SkyScan 1172, Bruker‐microCT). The minimum dentine thickness around the root canals in furcal direction was measured using CTAn software (v.1.18.8 Bruker‐microCT) at each millimetre. The specimens were grouped according to their fusion type, and dentine thickness around the canals was compared. The data were statistically analysed using anova and post hoc Tukey–Kramer tests following an assessment of the normality of their distribution with the Kolmogorov–Smirnov test (p <.05). Results: Dentine thickness showed a statistically significant decrease at 2 mm apical to the orifice level irrespective of fusion type. The minimum dentine thickness values were detected around the second mesiobuccal canal as 0.30 mm at 6 mm below orifice. Dentine thickness around the mesiobuccal canal was significantly greater in fusion type 1 than those of types 2 and 3 (p <.05), while those of distobuccal and palatal canals were significantly thinner in type 3 fusion compared with type 1 or 6 (pDentine thickness showed a statistically significant decrease at 2 mm apical to the orifice level irrespective of fusion type. The minimum dentine thickness values were detected around the second mesiobuccal canal as 0.30 mm at 6 mm below orifice. Dentine thickness around the mesiobuccal canal was significantly greater in fusion type 1 than those of types 2 and 3 (Conclusion: Minimum dentine thickness values at the danger zone of distobuccal and palatal canals change according to the fusion type in fused maxillary second molars. [ABSTRACT FROM AUTHOR]

Aim: To investigate the effect of Wnt3a on odonto/osteogenic differentiation of stem cells isolated from human exfoliated deciduous teeth (SHEDs) and reparative dentine formation in a rat model. Methodology: Stem cells isolated from human exfoliated deciduous teeth were cultured in media with Wnt3a (50–200 ng/ml). Wnt activation was confirmed by β‐catenin immunocytochemistry. Colony‐forming unit assay (normalized percentage area), osteogenic gene expression analysis by real‐time polymerase chain reaction and mineralization assays measured by the absorption at 540 nm were performed. Tertiary dentine formation in vivo was evaluated using 8‐week‐old, male Wistar rats. Cavities with pinpoint pulp exposure by a sharp instrument were prepared at the mesial surface of the first molars. Teeth were divided into (n = 6): (1) distilled water (negative control), (2) phosphate‐buffered saline (PBS), (3) lithium chloride in DI (20 μM), and (4) Wnt3a in PBS (200 ng/ml). Collagen sponge was used as a scaffold. The cavity was sealed with glass ionomer restoration. Four weeks later, animals were euthanized by sodium pentobarbital (120 mg/kg body weight). Hard tissue formation was evaluated using micro‐computerized tomography. Sixty consecutive slides from the initial plane were analysed and calculated as bone/dentine volume per total tissue volume. Paraffin sections (2 μm) were stained with haematoxylin and eosin and Masson's trichrome for morphological evaluation. Data are presented as the mean ± standard error. Mann–Whitney U test was used for two‐group comparison. Kruskal Wallis followed by pairwise comparison was employed for three or more group comparisons. Statistical analysis was performed using GraphPad Prism 7. Differences were considered significant at p <.05. Results: Wnt3a decreased SHEDs colony formation and increased OSX, BMP2, and DMP1 expression, corresponding to an increase in mineralization. Additionally, a significant increase in dentine/bone volume per total tissue volume was observed in Wnt3a treated defects. Dentine bridge formation at the exposure sites treated with Wnt3a demonstrated, while fibrous tissues were observed in the control. Conclusions: Wnt3a suppressed proliferation, increased osteogenic differentiation of SHEDs and promotes tertiary dentine formation. Wnt3a could be utilized as biological molecule for vital pulp therapy. [ABSTRACT FROM AUTHOR]

Background: Pulp–dentine complex regeneration via tissue engineering is a developing treatment modality that aims to replace necrotic pulps with newly formed healthy tissue inside the root canal. Designing and fabricating an appropriate scaffold is a crucial step in such a treatment. Objectives: The present study aimed to review recent advances in the design and fabrication of scaffolds for de novo regeneration of pulp–dentine complexes via tissue engineering approaches. Methods: A literature search was conducted using PubMed, Europe PMC, Scopus and Google Scholar databases. To highlight bioengineering techniques for de novo regeneration of pulp–dentine complexes, both in vitro and in vivo studies were included, and clinical studies were excluded. Results: In the present review, four main classes of scaffolds used to engineer pulp–dentine complexes, including bioceramic‐based scaffolds, synthetic polymer‐based scaffolds, natural polymer‐based scaffolds and composite scaffolds, are covered. Additionally, recent advances in the design, fabrication and application of such scaffolds are analysed along with their advantages and limitations. Finally, the importance of vascular network establishment in the success of pulp–dentine complex regeneration and strategies used to create scaffolds to address this challenge are discussed. Discussion: In the tissue engineering platform, scaffolds provide structural support for cells to adhere and proliferate and also regulate cell differentiation and metabolism. Up to now, considerable progress has been achieved in the field of pulp–dentine complex tissue engineering, and a spectrum of scaffolds ranging from bioceramic‐based to naturally derived scaffolds has been fabricated. However, in designing a suitable scaffold for engineering pulp–dentine complexes, a variety of characteristic parameters related to biological, structural, physical and chemical features should be considered. Conclusion: The variety of biomaterials and fabrication techniques provides a great opportunity to address some of the requirements for scaffolds in regenerative endodontics. However, more studies are required to develop an ideal scaffold for use in a clinical setting. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effects of progressive root canal enlargements on the unprepared surface area and remaining dentine thickness of three‐rooted maxillary first premolars with different root configurations. Methodology: Thirty three‐rooted maxillary first premolars with three root configurations (n = 10) were selected and scanned in a micro‐CT device. The root canals were sequentially enlarged with rotary instruments sizes 30.02 (step 1), 30.04 (step 2) and 30.06 (step 3). After each step, a new scan was taken. Analysed parameters included morphometric measurements (length, volume and surface area), number of static voxels and minimal dentine thickness. Statistical analyses were performed with one‐way anovapost hoc Tukey tests and paired sample t‐test at a significance level of 5%. Results: No statistical differences were observed amongst groups regarding the morphometric parameters and static voxels (p >.05). The minimal dentine thickness of the distobuccal root significantly changed depending on the root configuration (p <.05), whilst no differences were observed in the other roots (p >.05). A great variation in the position of the minimal dentine thickness was observed after preparation. Overall, mean percentage reduction in dentine thickness was higher in the buccal roots than in the palatal root (p <.05). In the mesiobuccal and distobuccal root, the number of slices with minimal dentine thickness lower than 0.05 mm increases 2 to 3 times and 3 to 4 times, respectively, from steps 1 to 3. Conclusions: Instruments sizes 30.02 and 30.04 can be safely and effectively used to enlarge the buccal and palatal canals of three‐rooted maxillary first premolars. [ABSTRACT FROM AUTHOR]

This narrative review will focus on a number of contemporary considerations relating to the restoration of root filled teeth and future directions for research. Clinicians are now more than ever, aware of the interdependence of the endodontic and restorative aspects of managing root filled teeth, and how these aspects of treatment are fundamental to obtaining the best long‐term survival. To obtain the optimal outcomes for patients, clinicians carrying out endodontic treatment should have a vested interest in the restorative phase of the treatment process, as well as an appreciation for the structural and biomechanical effects of endodontic‐restorative procedures on restoration and tooth longevity. Furthermore, the currently available research, largely lacks appreciation of occlusal factors in the longevity of root filled teeth, despite surrogate outcomes demonstrating the considerable influence this variable has. Controversies regarding the clinical relevance of minimally invasive endodontic and restorative concepts are largely unanswered with respect to clinical data, and it is therefore, all too easy to dismiss these ideas due to the lack of scientific evidence. However, conceptually, minimally invasive endodontic‐restorative philosophies appear to be valid, and therefore, in the pursuit of improved clinical outcomes, it is important that the efficacies of these treatment protocols are determined. Alongside an increased awareness of the preservation of tooth structure, developments in adhesive bonding, ceramic materials and the inevitable integration of digital dentistry, there is also a need to evaluate the efficacy of new treatment philosophies and techniques with well‐designed prospective clinical studies. [ABSTRACT FROM AUTHOR]

Aim: The use of high‐concentration sodium hypochlorite (NaOCl) as an endodontic irrigant remains controversial because of its potential impact on the fracture strength of endodontically treated teeth. This study evaluated the effects of using different NaOCl concentrations, with 2‐min‐ethylenediaminetetraacetic acid (EDTA) as the final active irrigant, on the biomechanical and structural properties of root dentine. Methodology: A new test method, which is more clinically relevant, was utilized to calculate the fracture strength of root dentine. Bovine incisors were used to obtain root dentine discs. The root canals were enlarged to mean diameter of 2.90 mm with a taper of 0.06. The resulting discs were divided into five groups (n = 20) and treated with different concentrations of NaOCl (5.25%, 2.5%, and 1.3%) for 30 min plus 17% EDTA for 2 min. The discs were then loaded to fracture by a steel rod with the same taper through the central hole. The fractured specimens were examined by scanning electron microscopy to evaluate changes in the dimensions of the remaining intertubular dentine and the tubular radius. Micro‐hardness was also measured with a Knoop diamond indenter along a radius to determine the depth of dentine eroded by the irrigation. Results were analysed by one‐way anova and the Tukey test. The level of significance was set at α = 0.05. Results: The damage by NaOCl increased with its concentration. 5.25% NaOCl greatly reduced the fracture strength of root dentine from 172.10 ± 30.13 MPa to 114.58 ± 26.74 MPa. The corresponding reduction in micro‐hardness at the root canal wall was 34.1%. The damages reached a depth of up to 400 μm (p <.05). Structural changes involved the degradation of the intratubular wall leading to enlarged dentinal tubules and the loss of intertubular dentine. Changes in the microstructural parameters showed positive linear relationships with the fracture strength. Conclusions: With the adjunctive use of EDTA, NaOCl caused destruction to the intratubular surface near the root canal and, consequently, reduced the root dentine's mechanical strength. The higher the concentration of NaOCl, the greater the effect. Therefore, endodontists should avoid using overly high concentration of NaOCl for irrigation to prevent potential root fracture in endodontically treated teeth. [ABSTRACT FROM AUTHOR]

Aim: The aim of the study was to investigate the influence of cavity cleaning and conditioning on marginal integrity of directly placed post‐endodontic composite class‐I‐restorations in vitro. Methodology: A total of 168 fully intact teeth without caries or fillings received pre‐endodontic composite restorations (class‐II) after their extraction. Occlusal endodontic access‐cavities were prepared, and root canals were instrumented and filled with gutta‐percha and an epoxy resin‐based sealer. Prior to post‐endodontic class‐I‐restoration, access cavities were completely contaminated with sealer, cleaned with alcohol and pre‐treated as follows: cleaner only (alcohol), glycine‐polishing, Al2O3 sandblasting, carbide bur (immediate as well as delayed restoration). A positive control (not contaminated with sealer and adhesive used) and negative control (cleaner used but no adhesive) were established. Half of the teeth from each group were subjected to thermocycling and mechanical loading (TCML). Marginal integrity of post‐endodontic restoration was evaluated in oro‐vestibular or mesio‐distal sections after AgNO3 dye penetration (DP) by standardized photomacroscopic imaging and expressed in per cent of margin length along all segments and separately for enamel, dentine and composite, respectively. Results were analysed non‐parametrically (α =.05). Results: No restorations or teeth fractured or debonded completely. Without TCML, the median DP of all segments was significantly higher for the negative control compared with all other groups in oro‐vestibular cutting direction (53%; p =.002) and in mesio‐distal cutting direction (51%; p ≤.041). The other groups without TCML revealed 16%–24% DP (oro‐vestibular) and 12%–24% DP (mesio‐distal). With TCML, the median DP in oro‐vestibular cutting direction for all segments ranged between 48% and 62% for all groups, a significant difference was only observed between glycine‐polishing and carbide bur (p =.041). In mesio‐distal cutting direction, the median DP in negative control was 69% with TCML and significantly higher compared with all other groups (p =.002). For all other groups, the median DP of all segments ranged between 28% and 40% with TCML without significant differences. Error rates method (k = 7) revealed a significant influence of TCML in general on penetration of all segments in both oro‐vestibular and mesio‐distal cutting directions. Conclusion: Additional access cavity pre‐treatment after alcohol cleaning did not improve the marginal integrity of post‐endodontic composite restorations. Thorough cleaning of the access cavity with alcohol seems to assure an acceptable marginal integrity to the tooth and restorative composite. [ABSTRACT FROM AUTHOR]

Aim: The aim of the study was to investigate the effect of dentine conditioning agents on growth factor liberation and settlement of dental pulp progenitor cells (DPSCs) on dentine surfaces. Methodology: The agents used included ethylenediaminetetraacetic acid (EDTA; 10%, pH 7.2), phosphoric acid (37%, pH < 1), citric acid (10%, pH 1.5) and polyacrylic acid (25%, pH 3.9). Human dentine slices were conditioned for exaggerated conditioning times of 5 and 10 min, so that the growth factor liberation reached quantifiable levels above the limit of detection of the laboratory methods employed. Transforming growth factor beta‐1 (TGF‐β1) release and surface exposure were quantified by enzyme‐linked immunosorbent assay (ELISA) and immunogold labelling. Scanning electron microscopy (SEM) was used to assess the morphology of cells and coverage by DPSCs cultured on dentine surfaces for 8 days. Results: After 5‐min conditioning of dentine slices, citric acid was the most effective agent for growth factor release into the aqueous environment as measured by ELISA (Mann–Whitney U with Bonferroni correction, p <.01 compared with phosphoric and polyacrylic acid). As well as this, dentine slices treated with phosphoric acid for the same period, displayed significantly less TGF‐β1 on the surface compared with the other agents used, as measured by immunogold labelling (MWU with Bonferroni correction, p <.05). After 8 days, widespread coverage by DPSCs on dentine surfaces conditioned with citric acid and EDTA were evident under SEM. On dentine surfaces conditioned with phosphoric and polyacrylic acid, respectively, less spread cells and inconsistent cell coverage were observed. Conclusions: Based on the findings of this in vitro study, a desirable biological growth factor‐mediated effect may be gained when conditioning dentine by milder acidic or chelating agents such as citric acid and EDTA. The results must be interpreted in the context that the potential of the applied materials inducing a desirable biological response in DPSCs is only one consideration amongst other important ones in a clinical setting. However, it is crucial to look beyond the mere physical effects of materials and move towards biologically based treatment approaches as far as the restorative management of teeth with viable dental pulps are concerned. [ABSTRACT FROM AUTHOR]

Aim: To assess the interfacial adaptation (gap‐containing areas) of two root canal sealers (EndoSequence BC Sealer and AH Plus) to a conventional gutta‐percha (GP) cone (GP‐sealer interface) in oval‐shaped canals filled using the single cone technique. Methodology: Sixteen teeth with oval‐shaped canals were selected, scanned in a micro‐computed tomographic device, and pair‐matched according to the volume, aspect ratio and configuration of root canals. Root canals were then sequentially prepared with WaveOne Gold Primary and Large instruments, followed by filling with WaveOne Large GP points associated with either the premixed calcium‐silicate EndoSequence BC Sealer or the epoxy resin‐based AH Plus sealer (n = 8 per group) using the single cone technique. After 7 days stored in phosphate‐buffered saline solution at 37°C, the specimens were rescanned and the reconstructed images segmented in order to differentiate the filling materials (sealer and GP cone) to the dentine. A total of 453 cross‐sectional slices were assessed and categorized according to the presence or absence of gaps at the GP‐sealer interface. Mann–Whitney U‐test verified the differences between groups and were considered significant at alpha = 5%. Results: Gaps were non‐homogenously distributed in two‐dimensional axial cross‐section images and none of the specimens showed completely gap‐free areas along the entire GP‐sealer interface. Root canals filled with EndoSequence BC Sealer and AH Plus displayed 171 (37.75%) and 136 (30.02%) slices with gaps in the GP‐sealer interface and these frequencies were statistically significant (p =.000). Conclusions: Although none of the specimens had a gap‐free area along the entire GP‐sealer interface, oval canals filled with AH Plus showed less gaps than the ones filled with EndoSequence BC Sealer. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the role of biomimetic pulp scaffolds derived from the extracellular matrix derived of stem cells from human exfoliated deciduous teeth (SHED-ECM-PS) in promoting pulp-dentine complex regeneration., Methodology: SHED-ECM-PS was prepared through cell aggregation and decellularization techniques. Histological and immunofluorescence analyses, scanning electron microscopy, and DNA quantification assays were used to characterize the SHED-ECM-PS. Additionally, a tooth slice implantation model was established to evaluate the effects of SHED-ECM-PS on regeneration of the pulp-dentine complex in vivo. Extraction medium for SHED-ECM-PS was prepared, and its effect on bone marrow mesenchymal stem cells (BMMSCs) was assessed in vitro. Cell counting kit-8 and Ki-67 staining assays were performed to determine cell proliferation. The rate of apoptosis was evaluated by flow cytometry. Wound healing and transwell assays were conducted to evaluate cell migration. Alizarin red S staining was performed to examine mineralized nodule formation. Western blotting was used to detect the expression of osteogenic and odontogenic markers. The results were analysed using an independent two-tailed Student's t-test. p < .05 was considered statistically significant., Results: SHED-ECM-PS was successfully constructed, exhibiting a striped dental pulp-like shape devoid of nuclear structures or DNA components, and rich in fibronectin, collagen I, DMP1 and DSPP. Notably, SHED-ECM-PS showed no impact on the proliferation or apoptosis of BMMSCs. Histological analysis revealed that dental pulp fibroblasts formed an interwoven mesh in the root canal, and angiogenesis was observed in the SHED-ECM-PS group. Moreover, a continuous, newly formed tubular dentine layer with polarized odontoblast-like cells was observed along the inner wall of the root canal. SHED-ECM-PS promoted the migration, polar alignment and mineralized nodule formation of BMMSCs and specifically elevated the expression levels of odontogenic markers, but not osteogenic markers, compared with the control group in vitro., Conclusion: SHED-ECM-PS exhibited no cytotoxicity and promoted pulp-dentine complex regeneration in vivo as well as cell migration and odontogenic differentiation of BMMSCs in vitro. These findings provide evidence that SHED-ECM-PS, as a novel biological scaffold, has the potential to improve the outcomes of REPs., (© 2024 British Endodontic Society. Published by John Wiley & Sons Ltd.)

Background: The effects of ethylenediaminetetraacetic acid (EDTA) on regenerative endodontic procedures (REPs) are controversial, because, despite releasing growth factors from dentine, some studies show negative effects on cell behaviour. Objectives: The aim of the study was to investigate the influence of the use of EDTA in REP on the growth factors' release, cell behaviour and tissue regeneration. Methods: A systematic search was conducted (PubMed/Medline, Scopus, Cochrane Library, Web of Science, Embase, OpenGrey and reference lists) up to February 2021. Only in vivo and in vitro studies evaluating the effects of EDTA on the biological factors of dentine, pulp/periapical tissues and cell behaviour were eligible. Studies without a control group or available full text were excluded. The growth factors' release was the primary outcome. Risk of bias in the in vitro and in vivo studies was performed according to Joanna Briggs Institute's Checklist and SYRCLE's RoB tool, respectively. Results: Of the 1848 articles retrieved, 36 were selected. Amongst these, 32 were in vitro, three animal studies and one with both models. The EDTA concentrations ranged from 3% to 15%, at different times. Regarding growth factors' release (17 studies), 15 studies found significant transforming growth factor (TGF)‐β release after dentine conditioning with EDTA, and most found no influence on vascular endothelial growth factor release. Regarding cell behaviour (26 studies), eight studies showed no influence of EDTA‐treated dentine on cell viability, whereas, five, nine and six studies showed higher cell migration, adhesion and differentiation respectively. No influence of EDTA conditioning was observed in animal studies. In vitro studies had a low risk of bias, whereas animal studies had high risk of bias. Meta‐analysis was unfeasible. Discussion: This review found that EDTA increased TGF‐β release and improved cell activity. However, well‐designed histological analyses using immature teeth models are needed. Conclusions: High‐quality in vitro evidence suggests that EDTA‐treated dentine positively influences TGF‐β release, cell migration, attachment and differentiation; further research to evaluate its influence on tissue regeneration is necessary due to low methodological quality of the animal studies. [ABSTRACT FROM AUTHOR]

Root canal curvature and calcification introduce factors that increase the risk of procedural accidents during root canal treatment. The inability to achieve patency to the apical third, asymmetrical dentine removal leading to transportation, perforation, and instrument fracture inside the curved trajectories are some of the procedural problems that might jeopardize the management of intraradicular infection and result in poor treatment outcomes. In fact, curved and constricted canals introduce such complexity that total instrumentation concepts and specially designed instruments have been developed to deal with the challenge. This narrative review seeks to provide and consolidate the principles necessary for understanding the dynamics of curved and constricted canal management and to improve the understanding for future developments in this field. [ABSTRACT FROM AUTHOR]

Vertical root fracture (VRF) is a common reason for the extraction of root filled teeth. The accurate diagnosis of VRF may be challenging due to the absence of clinical signs, whilst conventional radiographic assessment is often inconclusive. However, an understanding of the aetiology of VRFs, and more importantly, the key predisposing factors, is crucial in identifying teeth that may be susceptible. Thorough clinical examination with magnification and co‐axial lighting is essential in identifying VRFs, and although CBCT is unable to reliably detect VRFs per se, the pattern of bone loss typically associated with VRF can be fully appreciated, and therefore, increases the probability of correct diagnosis and management. The prevalence of VRFs in root filled teeth is significantly greater than in teeth with vital pulps, demonstrating that the combination of loss of structural integrity, presence of pre‐existing fractures and biochemical effects of loss of vitality is highly relevant. Careful assessment of the occlusal scheme, presence of deflective contacts and identification of parafunctional habits are imperative in both preventing and managing VRFs. Furthermore, anatomical factors such as root canal morphology may predispose certain teeth to VRF. The influence of access cavity design and root canal instrumentation protocols should be considered although the impact of these on the fracture resistance of root filled teeth is not clearly validated. The post‐endodontic restoration of root filled teeth should be expedient and considerate to the residual tooth structure. Posts should be placed 'passively' and excessive 'post‐space' preparation should be avoided. This narrative review aims to present the aetiology, potential predisposing factors, histopathology, diagnosis and management of VRF and present perspectives for future research. Currently, there are limited options other than extraction for the management of VRF, although root resection may be considered in multi‐rooted teeth. Innovative techniques to 'repair' VRFs using both orthograde and surgical approaches require further research and validation. The prevention of VRFs is critical; identifying susceptible teeth, utilizing conservative endodontic procedures, together with expedient and appropriate post‐endodontic restorative procedures is paramount to reducing the incidence of terminal VRFs. [ABSTRACT FROM AUTHOR]

With advances in knowledge and treatment options, pulp regeneration is now a clear objective in clinical dental practice. For this purpose, many methodologies have been developed in attempts to address the putative questions raised both in research and in clinical practice. In the first part of this review, laboratory‐based methods will be presented, analysing the advantages, disadvantages, and benefits of cell culture methodologies and ectopic/semiorthotopic animal studies. This will also demonstrate the need for alignment between two‐dimensional and three‐dimensional laboratory techniques to accomplish the range of objectives in terms of cell responses and tissue differentiation. The second part will cover observations relating to orthotopic animal studies, describing the current models used for this purpose and how they contribute to the translation of regenerative techniques to the clinic. [ABSTRACT FROM AUTHOR]

As a range of materials used in endodontics may cause tooth discolouration, exploration of factors responsible for the darkening of the tooth crown or root is warranted. This narrative review paper discusses the range of technical factors that apply in laboratory studies that assess endodontic discolouration. As an example of how these factors operate, particular examples relating to discolouration caused by endodontic medicaments containing tetracycline antibiotics are used. Following the PRILE 2021 guideline approach, a summary of key variables to be addressed in the methodology for laboratory studies is presented, to inform future work. [ABSTRACT FROM AUTHOR]

In order to ensure predictable decontamination of the root canal system, chemo‐mechanical preparation of the root canal space is sometimes supplemented with the use of intracanal medication. As microbial control of the root canal space is fundamental to the resolution of apical periodontitis, root canal disinfection strategies haven been researched intensively. The use of intracanal medication as a supplementary step to the chemo‐mechanical preparation of the root canal space is one of them. Because of the costs and limitations of clinical research it is relevant and common practice to first evaluate alternative or new root canal disinfection modalities in laboratory studies. This involves the simulation of a root canal infection in a laboratory model, on which different disinfection strategies can be tested. When modelling the infected root canal, different levels of infection can be discriminated: suspended bacteria, microbial biofilms and infected dentine. This review describes the experimental models associated with these infection levels and critically appraises their value and methodological details. Suggestions for relevant research methods and experimental models are given, as well as some good practices for laboratory‐based microbiological studies. [ABSTRACT FROM AUTHOR]

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro‐computed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the influence of traditional and conservative access cavity preparations on the remaining dentine thickness in the coronal third of mesial canals of extracted mandibular molars prepared with reciprocating instruments using micro‐computed tomography as the analytical tool. Methodology: Seventy extracted mandibular molars were scanned at a pixel size of 19 μm. From this initial sample, 20 teeth were selected, pair‐matched and distributed into two groups (n = 10) according to the access cavity preparation: traditional (TradAC) or conservative (ConsAC). The root canals were sequentially enlarged with Reciproc Blue R25 (size 25, 0.08v taper) and R40 (size 40, 0.06v taper) instruments. A new scan was performed and the postoperative stacks were coregistered with their respective preoperative datasets. A colour‐coded cross sections of the roots were created and used to identify and measure the smallest dentine thickness related to both MB and ML canals at 1.0‐mm intervals from the furcation level of up to 5 mm in the apical direction, in both mesial and distal aspects of the roots, before and after preparation. The statistical analyses were performed with paired‐samples t‐test, independent‐samples Student T‐test and Chi‐Square test with a significance level of 5%. Results: At all levels of both groups, dentine thickness before preparation was greater than after preparation (p <.05). No difference in the percentage of dentine reduction was observed between TradAC and ConsAC groups (p >.05), but a significantly greater reduction was observed to the distal aspect of the roots (p <.05). After root canal preparation, dentine thinner than 0.5 mm was observed mostly along the distal aspect of the root (10% to 15%) of the MB and ML canals, with no influence of the access cavity type on its incidence to either mesial (X2 = 1.66; p =.2) or distal (X2 = 0.40; p =.5) directions. In the TradAC group, dentine thickness in most slices was greater than 1.0 mm after preparation (n = 124) whilst, in the ConsAC, it ranged from 0.5 to 1.0 mm (n = 136). Conclusion: Traditional or conservative access cavity preparation in extracted mandibular molars did not influence the remaining dentine thickness in the coronal third of mesial canals enlarged with thermomechanically treated nickel–titanium reciprocating instruments. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the shaping ability of several heat‐treated nickel–titanium systems used to prepare root canals with moderate and severe curvature, in extracted mandibular molars, by micro‐computed tomography, considering their variation in kinematics and design. Methodology: Curved‐mesial roots of mandibular molars were randomly selected and assigned into 4 balanced experimental groups (n = 10), established by determining homogeneous 3D parameters of volume and surface area: R‐Motion (RM) size 30, 0.04 taper (RM; FKG Dentaire), Reciproc Blue (RCB) size 25, 0.08 taper (RCB; VDW GmbH), HyFlex CM (HFX) size 30, 0.04 taper (HFX; Coltène Whaledent) and XP‐endo Shaper size (XPS) 30, 0.01 taper (XPS; FKG Dentaire). The volume of irrigation was established at 10 ml of 2.5% NaOCl. Throughout the entire root canal preparation procedures, the samples were fixed in a vice submerged in a container with water monitored at 37°C. Dimensional cross‐sectional measures of area, perimeter, roundness, major/minor diameters and 3‐dimensional (volume, surface area, structure model index – SMI) parameters as well as the smallest dentine thickness along the cervical and middle root thirds were evaluated by micro‐CT. Data were analysed using analysis of variance and post hoc Tukey tests (α = 5%). Results: Reciproc Blue and XPS had significantly greater mean increases in cross‐sectional area measurements, only in the middle third, when compared with RM and HFX (p <.05). RM, RCB and XPS had a similar increase in measurements of length and width of perimeter (p >.05), and HFX had significantly lower mean increases in perimeter values only when compared with XPS (p <.05). RCB and XPS had significantly greater mean increases in volume when compared with RM and HFX (p <.05). RM had a significantly lower difference in SMI after preparation, compared with RCB, HFX and XPS (p <.05). The smallest dentine thickness was observed after the use of RCB (p <.05), in the danger and safety zones. Conclusions: XP‐endo Shaper and RM had a shaping ability similar to that of instruments with larger tapers, achieved with less dentine removal in danger and safe zones in curved‐mesial canals of extracted molar teeth treated on a laboratory benchtop. [ABSTRACT FROM AUTHOR]

Aim: To assess odontogenic differentiation abilities of porous biomineralizable composite scaffolds comprising eggshell derived nano‐hydroxyapatite (HAnp) and carboxymethyl chitosan (CMC) on cultured human dental pulp stem cells (hDPSCs). Methodology: Nano‐hydroxyapatite was derived from eggshells using a simple combustion method and CMC was prepared from chitosan through a chemical route. Several compositions of HAnp‐CMC (0:5, 5:0, 1:5, 2:5, 3:5, 4:5 and 1:1 w/w%) scaffolds were prepared by magnetic stirring and freeze‐drying methods. HAnp‐CMC scaffolds were characterized using high‐resolution scanning electron microscopy combined with energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and X‐ray diffraction methods. In vitro bioactivity was determined following the interaction in simulated body fluid for 21 days. The optimized composite was then loaded onto hDPSCs to assess cell viability/proliferation, dentine sialophosphoprotein (DSPP) and vascular endothelial growth factor (VEGF) expressions using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay, real‐time quantitative polymerase chain reaction and flow cytometry methods, respectively, following 7, 14 and 21 days. For intergroup and intragroup comparisons, Kruskal–Wallis and Friedman tests were employed, respectively, followed by appropriate post hoc test (Dunn). Significant levels were set at *p <.05 and *p <.01. Results: Synthesized hydroxyapatite (HAp) comprised crystals ranging from 20 to 50 nm (HAnp) with spherulite morphology and calcium/phosphorus (Ca/P) molar ratio of 1.67. The ultrastructure of all the scaffolds revealed a highly interconnected porous microstructure, whilst the chemical characterization displayed specific functional groups of both HAnp and CMC. In vitro bioactivity assessment confirmed the biomineralization potential of all scaffolds with an apatite‐like crystal formation on the surface. The 1:5 HAnp‐CMC revealed a favourable pore size (60–180 µm) that was suitable for cell seeding and was chosen for further experiments. Cell viability/proliferation rates of hDPSCs loaded 1:5 HAnp‐CMC at 21st day was significantly greater than that at 7th day (p <.05). The mean relative quantification of DSPP expression by the scaffold was significantly higher (p <.05) on day 21 (3.16) than on day 7 (1.67). Mean fluorescence intensity of the VEGF expression at day 21 (32.5) was also significantly higher (p <.01) than at day 7 (12.54). Conclusion: hDPSCs on 1:5 HAnp‐CMC scaffolds displayed increased cell viability/proliferation and enhanced DSPP as well as VEGF expressions. The 1:5 HAnp‐CMC composite has the potential to serve as a promising scaffold for dentine regeneration. [ABSTRACT FROM AUTHOR]

Aim: To evaluate in a laboratory setting, the impact of three designs of endodontic access cavities on dentine removal and effectiveness of canal instrumentation in extracted maxillary first molars using micro‐computed tomography (micro‐CT). Methodology: A total of 30 extracted intact maxillary first molars were selected and scanned by micro‐CT with a voxel size of 24 µm and randomly distributed into three groups: the traditional endodontic cavity (TEC) group, the conservative endodontic cavity (CEC) group and the guided endodontic cavity (GEC) group. The pulp chambers of teeth in the groups were accessed accordingly. After root canal preparation, the teeth were rescanned. The volume of dentine removed after canal preparation, the noninstrumented canal areas, canal transportation and centring ratio were analysed. Data were analysed statistically using one‐way analysis of variance. Tukey's post hoc test was used for multiple comparisons. The significance level was set at p <.05. Results: The total volume of dentine removed was significantly greater in the TEC group after root canal preparation (p <.05). No significant differences in the volume of dentine removed occurred between the CEC and GEC groups (p >.05). The volume of dentine removed in the crown, pericervical dentine and coronal third of the canal was significantly lower in CEC and GEC groups when compared to that in the TEC group (p <.05), no difference was observed in the middle third of the canal and apical third of the canal amongst the three groups (p >.05). There was no significant difference in noninstrumented canal area, canal transportation and centring ratio amongst the TEC, CEC and GEC groups (p >.05). Conclusions: In extracted maxillary molars tested in a laboratory setting, CEC and GEC preserved more tooth tissue in the crown, pericervical dentine and coronal third of the canal compared with TEC after root canal preparation. The design of the endodontic access cavity did not impact on the effectiveness of canal instrumentation in terms of noninstrumented canal area, canal transportation and centring ratio. [ABSTRACT FROM AUTHOR]

Cemental tears are an important condition of relevance to Endodontics but are often overlooked. A cemental tear is the partial or complete detachment of the cementum from the cemento‐dentinal junction or along the incremental line within the body of cementum. The limited attention received is most likely due to the limited awareness amongst dental professionals and challenges in accurately diagnosing them, resulting in misdiagnosis and erroneous treatment. The aim of this review is to describe the: (i) epidemiology and predisposing factors; (ii) clinical, radiographic and histological features and (iii) the clinical management and treatment outcomes of cemental tear. The review included 37 articles published in English that comprised eight observational studies and 29 case reports. The prevalence of cemental tears was reported to be lower than 2%; whilst the incidence remains unknown. Internal factors due to the inherent structural weakness of cementum and its interface with the dentine, and external factors that are associated with stress have been proposed as the two mechanisms responsible for the development and propagation of cemental tears. Predisposing factors that have been implicated were tooth type, gender, age, previous root canal treatment, history of dental trauma, occlusal trauma and excessive occlusal force; however, evidence is limited. Common clinical and radiographic manifestations of cemental tears resemble the presentations of primary endodontic diseases, primary periodontal diseases and combined endodontic–periodontal lesions. Clinical management tended to focus on complete removal of the torn fragments and periodontal treatment, often combined with regenerative treatment. In this article, a new classification for cemental tears is developed that consists of classes 0 to 6 and stages A, B, C and D based on the: (i) location and accessibility of the torn cemental fragment; (ii) the pattern and extension of the associated bony defect in relation to the root length and (iii) the number of root surface/s affected by the cemental tear/s and the associated bony defect. Recommendations for treatment strategies are also provided and linked to the classification to aid in streamlining the process of treatment decision making. [ABSTRACT FROM AUTHOR]

Aim: To apply an innovative three‐dimensionally printed tooth model to investigate the efficacy of three ultrasonically activated irrigation (UAI) systems in removing multispecies biofilms from dentine samples. Methodology: Three‐dimensionally printed teeth with a curved root canal were fabricated with a standardized slot in the apical third of the root to achieve precision fit of human root dentine specimens. Multispecies biofilms including Enterococcus faecalis, Streptococcus mitis and Campylobacter rectus were developed in the root canal for 21 days. The canals were allocated to be irrigated with 1% sodium hypochlorite (NaOCl) using a syringe and needle or ultrasonically activated NaOCl with a stainless‐steel file (Irrisafe), a conventional nickel‐titanium (Ni‐Ti) file (CK) or a blue heat‐treated Ni‐Ti file (Endosonic Blue). Infected root canals irrigated with distilled water served as controls. Bacterial reduction was determined by colony‐forming unit (CFU) counting (n = 20), whilst biofilms were analysed using confocal laser scanning microscopy (n = 7) and field emission scanning electron microscopy. For CFU counting, the independent two‐sample t‐test (Welch's t‐test) was examined to compare overall bacterial reduction amongst groups. For CLSM analysis, the data were analysed using one‐way analysis of variance (ANOVA), followed by the Scheffé post hoc test. The p‐values <.05 were considered to indicate statistical significance. Results: All groups in which NaOCl was ultrasonically activated had significantly lower CFU values than the syringe‐and‐needle irrigation and control groups (p <.05). Ultrasonic activation with the stainless‐steel file and blue heat‐treated Ni‐Ti file significantly reduced the biofilm volume compared with other groups (p <.05). Overall, UAI with the blue heat‐treated file resulted in the highest antibacterial and biofilm removal efficacy. Conclusions: UAI with different inserts had differential antibiofilm effects. The blue heat‐treated Ni‐Ti ultrasonic insert resulted in the greatest antibacterial and biofilm removal from dentine in this standardized root canal model. [ABSTRACT FROM AUTHOR]

Aim: To introduce a methodology designed to simultaneously visualize dental ultrastructures, including cellular and soft tissue components, by utilizing phosphotungstic acid (PTA) as a contrast‐enhancement agent. Methodology: Sound third molars were collected from healthy human adults and fixed in 4% buffered paraformaldehyde. To evaluate the impact of PTA in concentrations of 0.3%, 0.7% and 1% on dental soft and hard tissues for CT imaging, cementum and dentine‐pulp sections were cut, dehydrated and stained with immersion periods of 12, 24 h, 2 days or 5 days. The samples were scanned in a high‐resolution nano‐CT device using pixel sizes down to 0.5 µm to examine both the cementum and pulpal regions. Results: Dental cementum and periodontium as well as odontoblasts and predentine were made visible through PTA staining in high‐resolution three‐dimensional nano‐CT scans. Different segments of the tooth required different staining protocols. The thickness of the cementum could be computed over the length of the tooth once it was made visible by the PTA‐enhanced contrast, and the attached soft tissue components of the interior of the tooth could be shown on the dentine‐pulp interface in greater detail. Three‐dimensional illustrations allowed a histology‐like visualization of the sections in all orientations with a single scan and easy sample preparation. The segmentation of the sigmoidal dentinal tubules and the surrounding dentine allowed a three‐dimensional investigation and quantitative of the dentine composition, such as the tubular lumen or the ratio of the tubular lumen area to the dentinal surface. Conclusion: The staining protocol made it possible to visualize hard tissues along with cellular layers and soft tissues in teeth using a laboratory‐based nano‐CT technique. The protocol depended on both tissue type and size. This methodology offers enhanced possibilities for the concomitant visualization of soft and hard dental tissues. [ABSTRACT FROM AUTHOR]

Caries results in the demineralization and destruction of enamel and dentine, and as the disease progresses, irreversible pulpitis can occur. Vital pulp therapy (VPT) is directed towards pulp preservation and the prevention of the progression of inflammation. The outcomes of VPT are not always predictable, and there is often a poor correlation between clinical signs and symptoms, and the events occurring at a molecular level. The inflamed pulp expresses increased levels of cytokines, including tumour necrosis factor (TNF)‐α, interleukin (IL)‐1α, IL‐1β, IL‐4, IL‐6, IL‐8, IL‐17 and IL‐23, which recruit and drive a complex cellular immune response. Chronic inflammation and sustained cytokine release can result in irreversible pulp damage and a decreased capacity for tissue healing. Other chronic inflammatory diseases, such as psoriasis, inflammatory bowel diseases and rheumatoid arthritis, are also characterized by an dysregulated immune response composed of relatively high cytokine levels and increased numbers of immune cells along with microbial and hard–soft tissue destructive pathologies. Whilst anti‐cytokine therapies have been successfully applied in the treatment of these diseases, this approach is yet to be attempted in cases of pulp inflammation. This review therefore focuses on the similarities in the aetiology between chronic inflammatory diseases and pulpitis, and explores how anti‐cytokine therapies could be applied to manage an inflamed pulp and facilitate healing. Further proof‐of‐concept studies and clinical trials are justified to determine the effectiveness of these treatments to enable more predictable outcomes in VPT. [ABSTRACT FROM AUTHOR]

Aim: To assess the chemical and microstructural characteristics of dentine after the use of two irrigation protocols and correlate this with the antimicrobial properties of hydraulic calcium silicate cement (HCSC) sealers and changes to the dentine structure/chemistry after sealer placement. Methodology: Two irrigation protocols – Protocol A using 2% NaOCl used 5 mL/5 min and Protocol B with 2% NaOCl (5 mL/5 min) followed by 17% EDTA (5 mL/3 min) – were used to prepare dentine. The chemical and microstructural changes following irrigation were assessed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT‐IR) spectroscopy (n = 5) on dentine obtained from the mid‐root and coronal parts of extracted human teeth. Four sealers (AH Plus, BioRoot, MTA Fillapex, TotalFill) were characterized by SEM/EDS (n = 3). The ability of the sealers to eradicate intratubular Enterococcus faecalis biofilms was assessed by live/dead dye and confocal laser scanning microscopy to measure the percentage of living cells. The effect of combined irrigation and root filling on dentine was assessed by SEM and EDS analysis (n = 5). Statistical analysis was undertaken using one‐way anova and a number of post hoc tests to detect intergroup differences. The F‐test was used for comparison of variances in the microbiology testing. Results: The use of NaOCl alone left the smear layer intact, with traces of chlorine remaining on dentine. The use of BioRoot sealer restored the calcium levels of dentine which had been depleted by the irrigation with EDTA. BioRoot exhibited antimicrobial properties against intratubular bacteria even in the presence of smear layer (Protocol A). Smear layer removal improved the bactericidal effect of all sealers and Ca2+ leaching. The use of a chelating agent was important for the intratubular sealer penetration for AH Plus but not the other sealers. Conclusion: The removal of smear layer was necessary for penetration of AH Plus into the dentinal tubules. BioRoot was a more effective sealer in reducing the bacterial load in the dentinal tubules than the other materials tested and the presence of smear layer did not affect its activity. [ABSTRACT FROM AUTHOR]

Aim: To explore the proliferation, adhesion and differentiation response and the underlying mechanisms that occur in lipopolysaccharide (LPS)‐induced inflamed dental pulp cells (DPCs) in contact with Biodentine and mineral trioxide aggregate (MTA). Methodology: The DPCs were isolated from three healthy donors and named DPC‐H1 to DPC‐H3. The DPCs were pre‐cultured with 2 or 5 μg mL−1 LPS for 24 h to induce inflammation. The expression of inflammation marker miR‐146a was detected by q‐PCR. The normal and LPS‐induced DPCs were further treated with 0.14 mg mL−1 Biodentine or 0.13 mg mL−1 MTA for 24 h. MTT assay and adhesion assay were used to analyse the changes of cell phenotypes. DSPP, AKT and ERK expressions were detected by Western blotting. The data were analysed by Mann–Whitney test or two‐way anova. Differences were considered statistically significant when P < 0.05. Results: In LPS‐induced DPCs, Biodentine and MTA treatment neither induced nor aggravated LPS‐induced inflammation, but their presence did increase the expression of the odontogenic differentiation marker DSPP. Under 2 or 5 μg mL−1 LPS‐induced inflammation, Biodentine and MTA promoted the proliferation of DPC cells, and significantly in DPC‐H2 (P < 0.0001 for both reagents). With the treatment of 2 μg mL−1 LPS, the cell adhesion of DPCs on the fibronectin‐coated culture plates was increased significantly by Biodentine (P = 0.0413) and MTA (P < 0.0001). Biodentine and MTA regulated cell adhesion on the fibronectin‐coated culture plates (P < 0.0001 for both reagents) and proliferation (P < 0.0001 for both reagents) via the AKT pathway. However, the AKT pathway was not involved in the expression of DSPP induced by Biodentine and MTA. Conclusion: Biodentine and MTA enhanced the proliferation, adhesion and differentiation of LPS‐induced DPCs. The proliferation and adhesion process induced by Biodentine and MTA was via the AKT pathway. However, the cellular differentiation process might not use the same pathway, and this needs to be explored in future studies. [ABSTRACT FROM AUTHOR]

The pulp plays a key role in the treatment of traumatic dental injuries (TDIs) and is strongly associated with the outcome, particularly in severe cases. A correct pulp diagnosis is essential as it forms the basis for developing the appropriate management strategy. However, many TDIs are complex, and their treatment requires a profound knowledge of the physiological and pathological responses of the affected tissues. This comprehensive review will look at the dentine–pulp complex and its interaction with the surrounding tissues following TDIs. The literature up to 2020 was reviewed based on several searches on PubMed and the Cochrane Library using relevant terms. In addition to the recently revised guidelines of the International Association of Dental Traumatology, this article aims to provide background information with a focus on endodontic aspects and to gather evidence on which a clinician can make decisions on the choice of the appropriate endodontic approach for traumatized permanent teeth. [ABSTRACT FROM AUTHOR]

Aim: To investigate the effects of a bioactive glass with a high proportion of phosphorus (BG‐hP) on the repair and regeneration of dental pulps in rats under an inflammatory microenvironment. Methodology: Human dental pulp cells (hDPCs) stimulated with 1 μg mL−1 lipopolysaccharide (LPS) were co‐cultured with 0.1 mg mL−1 BG‐hP. Cell proliferation was detected by 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5 diphenyltetrazolium bromide (MTT) assays. The expression of inflammation‐related genes and odontogenic differentiation‐related genes was determined by real‐time PCR. Alizarin red staining was used to detect the formation of mineralized nodules. Coronal pulp tissues of rat molars were stimulated with 10 mg mL−1 LPS and then treated with BG‐hP. The expression of inflammation‐related genes in pulp tissue was determined by real‐time PCR. Haematoxylin‐eosin staining and Masson staining were performed to observe the inflammatory response and mineralized matrix formation, after subcutaneous implantation in nude mice, at 3 days and 4 weeks, respectively. Analysis of variance was performed to measure statistical significance (P < 0.05). Results: BG‐hP significantly reduced expression of interleukin‐6 (IL‐6) and IL‐8 and significantly upregulated the expression of IL‐10, IL‐4 and transforming growth factor‐β1 of the LPS‐stimulated hDPCs (P < 0.05). BG‐hP significantly inhibited the initial cell number (P < 0.05), but the hDPCs stimulated by LPS and co‐cultured with BG‐hP maintained the same proliferation rate as the untreated hDPCs. BG‐hP significantly promoted the expression of dentine matrix protein‐1 and dentine sialophosphoprotein and the mineralization capacity of the LPS‐stimulated hDPCs (P < 0.05). Furthermore, BG‐hP significantly downregulated the expression of Il‐6 and reduced the inflammatory response of the LPS‐stimulated pulp tissue 3 days after subcutaneous implantation (P < 0.05). Four weeks after subcutaneous implantation, BG‐hP induced the formation of a continuous layer of dentine‐like structure with dentinal tubules and polarizing odontoblast‐like cells aligned along it in the LPS‐stimulated pulp tissue. Conclusion: The present preliminarily results demonstrated that the bioactive glass with a high proportion of phosphorus inhibited the inflammatory response and promoted the formation of a pulp‐dentine complex in a rat experimental model. This study provides a foundation for the construction of materials with the dual functions of exerting anti‐inflammatory effects and promoting tissue regeneration to meet the needs of dental pulp repair and regeneration. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the correlation between the volume of dental hard tissues removed and the fracture resistance of mandibular molar teeth with ultraconservative (UltraAC) or traditional (TradAC) access cavity preparations. Methodology: Sixty recently extracted and intact mandibular first molars were scanned in a microcomputed tomographic (micro‐CT) device, anatomically matched and assigned at random to 2 groups (n = 30), according to the access cavity type: UltraAC or TradAC. After access preparation, mesial and distal canals were prepared using Reciproc instruments and a new scan was taken. The volumes of pulp chamber and dental hard tissues in each specimen were measured before and after the experimental procedures, and the percentage volume reduction of hard tissues calculated for the entire tooth and for the crown separately. Teeth were then root filled, restored and subjected to fracture resistance tests in an universal testing machine. The force required to fracture was recorded in Newtons (N). The adherence of the variables to a Gaussian curve was verified using a Shapiro–Wilk test. Skewed data were analysed with nonparametric Wilcoxon signed rank or Spearman correlation tests, whilst the normally distributed data were analysed with a dependent samples Student t‐test. Level of significance was set at 5%. Results: Pre‐operatively, no difference was observed between groups regarding the volume of pulp canal space or dental hard tissues (P > 0.05). After access preparation, volumes of the removed hard tissues from the entire tooth and from the crown were significantly greater in teeth prepared with TradAC than with UltraAC (P < 0.05). No significant difference was observed in the fracture resistance values between TradAC (902.9 ± 347.8 N) and UltraAC (948.7 ± 405.7 N) groups (P = 0.975). The Spearman test was unable to identify a correlation between fracture resistance and percentage volume of removed dental hard tissues in the entire root (P = 0.525, r = −0.084) or only in the crown (P = 0.152, r = −0.187). Conclusion: The volume of hard dental tissues removed, although greater in teeth with TradAC compared to UltraAC, did not correlate with the fracture resistance results, indicating that a minimally invasive access cavity did not increase the resistance of restored mandibular first molars to fracture. [ABSTRACT FROM AUTHOR]

Aim: To describe the innovative use of intentional replantation for Biodentine root reconstruction of a previously treated immature maxillary central incisor with vertically extended crown root fracture and root detachment. Summary: In the present case, the intentional replantation of a failing, previously treated maxillary central incisor with a vertical crown/root fracture in a 12‐year‐old male patient is reported. The gross extrusion of gutta‐percha points beyond the apex and the pre‐existing extensive, trauma related, distal cervical dentinal detachment justified the intentional replantation treatment plan as an option for tooth retention. After controlling the infection by oral administration of antibiotics, the immature tooth was extracted atraumatically and kept in gauze embedded with tooth replantation medium. The apical third of the immature fractured tooth was treated with ultrasonics and an MTA plug (MTA Angelus White, Londrina, Brazil). The distal cervical dentinal root defect was reconstructed with Biodentine (Septodont, St. Maur‐des‐Fosses, France). The tooth was reinserted and stabilized to the adjacent teeth for 2 weeks. The total extraoral time before replantation was 25 min. In the 10 years since the initial trauma (9 years after the intervention) radiographic and clinical evaluation revealed uneventful healing of the periapical lesion, normal mobility and no detectable signs of external replacement resorption. Key learning points: Intentional replantation may provide a viable treatment alternative in cases of severe complicated crown/ root fracturesBiodentine may be useful in the reconstruction of external root defects in crown root fractured traumatic dental injuries [ABSTRACT FROM AUTHOR]

Aim: To evaluate in a laboratory setting the antimicrobial properties and the potential to inhibit biofilm formation of novel remineralizing polymeric nanoparticles (NPs) when applied to dentine surfaces and to ascertain the effect of the functionalization of these NPs with zinc, calcium or doxycycline. Methodology: The antimicrobial activity and inhibition of biofilm formation of polymeric NPs were analysed on human dentine blocks that were infected with Enterococcus faecalis before or after application of NPs. LIVE/DEAD ® testing under Confocal Laser Scanning Microscopy and bacterial culturing were employed to analyse biofilm biovolume and bacterial viability. Field Emission Scanning Electron Microscopy was also employed to assess biofilm morphology. One‐way anova with Welch's correction and post hoc comparison by the Games–Howell test were performed for comparisons between groups. Results: The un‐functionalized NPs displayed the greatest antimicrobial activity against E. faecalis biofilms as they provided the lowest biovolume (3865.7 ± 2926.97 µm3; P < 0.001) and the highest dead/injured cells percentage (79.93 ± 18.40%; P < 0.001), followed by Dox‐NPs (biovolume: 19,041.55 ± 17,638.23 µm3, dead/injured cells: 45.53 ± 26.50%; P < 0.001). Doxycycline‐loaded NPs had the largest values of inhibition of biofilm formation with the lowest biofilm biovolume (8517.65 ± 7055.81 µm3; P < 0.001) and a high dead/injured bacterial percentage (68.68 ± 12.50%; P < 0.001). Un‐functionalized NPs did not reduce biomass growth (P > 0.05), but attained the largest percentage of compromised cells (93 ± 8.23%; P < 0.001), being able to disrupt biofilm formation. It also produced occlusion of dentinal tubules, potentially interfering with bacterial tubule penetration. Conclusions: A new generation of bioactive nano‐fillers (doxycycline‐functionalized polymeric NPs) had antibacterial activity and occluded dentinal tubules. Incorporating these NPs into endodontic sealers may have the potential to enhance the outcome of root canal treatment. [ABSTRACT FROM AUTHOR]

Aim: To investigate the relationship between radiographically and macroscopically well‐defined carious lesions and the dentine–pulp complex with regard to: (i) level of bacterial penetration; (ii) inflammatory status including the presence of hyperplastic pulp stroma; and (iii) formation of hard and/or ectopic connective tissue. Methodology: The material comprised 68 untreated cavitated permanent teeth divided into well‐defined radiographic categories based on the lesion penetration depth: (i) deep lesions (≥3/4 of the dentine thickness with a radio‐dense zone separating the lesion from the pulp) and (ii) extremely deep lesions (the carious lesion penetrated the entire thickness of the dentine, without a radio‐dense zone). After extraction, the teeth were processed for histology. The material was scored with regard to coronal breakdown, macroscopic variables describing caries activity and histological variables describing the dentine–pulp complex (bacteria, inflammatory infiltrate, partial pulp necrosis, hyperplastic changes and hard tissue/ectopic presence of connective tissue). Interrater agreement was assessed using Cohen's kappa. Associations between variables were assessed using Pearson's chi‐squared or Fisher's exact test. The effect size was reported by odds ratio (OR) and associated 95% confidence interval (CI). Level of significance was set to 5%. Results: There were significant associations between a closed environment (1–2 surfaces involved) and the presence of biofilm, retrograde demineralization and light‐coloured demineralized dentine. Whereas radiographically defined deep lesions tended to have bacteria only in the primary dentine (P < 0.001, OR = 20.55, 95% CI [4.44, 107.89]), extremely deep carious lesions tended to have bacteria in contact with the pulpal tissue (P = 0.007, OR = 6.84, 95% CI [2.00, 62.83]), presence of an inflammatory infiltrate (Fisher's exact; P < 0.001) and partial pulp necrosis. Hyperplastic pulps were seen only in extremely deep lesions. Conclusions: Unlike deep lesions, extremely deep carious lesions were often associated with severe pulp inflammation and infection. A radiographic threshold between deep and extremely deep lesions is suggested as indicator of the bacterial penetration level and the severity of the pulpal response prior to intervention. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the nanohardness reduction and erosion in root canal dentine after application of 17% ethylenediaminetetraacetic acid (EDTA), 9% etidronic acid (HEBP) and 2% peracetic acid (PAA) either alone or combined with sodium hypochlorite (NaOCl). Methodology: One hundred and sixty single‐rooted teeth were decoronated and their root canals were chemomechanically prepared. For the nanohardness evaluation, 80 roots with instrumented canals were split longitudinally into two halves. Dentine blocks with a length of 7 mm were obtained from the middle third of one half of each tooth and were embedded in epoxy resin blocks exposing the root canal walls. Initial nanohardness values of root canal dentine were measured for each specimen using a nanoindenter with a Berkovich tip. The specimens were divided into seven experimental (n = 10) and one control (n = 10) group according to the final irrigation regimens: Group 1: 2.5% NaOCl, Group 2: 17% EDTA, Group 3: 2.5% NaOCl‐17% EDTA, Group 4: 2% PAA, Group 5: 2.5% NaOCl‐2% PAA, Group 6: 9% HEBP, Group 7: 2.5% NaOCl + 9% HEBP and Group 8: Distilled water (control). The measurement of the nanohardness values was repeated for each specimen after being exposed to the irrigants. The nanaohardness reduction of each sample was calculated and recorded. The other 80 instrumented root canals were used for scanning electron microscope (SEM) evaluation. First, they were irrigated with the same protocols stated above and longitudinally split into two halves. One half of each root canal was viewed using SEM for the amount of erosion. The erosion scores were recorded. Data were analysed statistically using Kruskal–Wallis and Bonferroni‐adjusted Mann–Whitney U‐tests with a significance level of 0.05. Results: Use of etidronic acid and NaOCl + HEBP reduced the nanohardness values significantly more than the other experimental solutions (P < 0.05). There was no significant difference between the values for the nanohardness reduction in the samples irrigated with a single chelator and chelator combined with NaOCl (P > 0.05). Peritubular and intertubular erosion were observed in the samples irrigated with HEBP and NaOCl + HEBP. Conclusion: Final irrigation of root canals using etidronic acid alone or combined with NaOCl was associated with structural alterations in root canal dentine of extracted teeth. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effect of Biodentine eluate on cytotoxicity and production of pro‐ and anti‐inflammatory cytokines and osteodestructive/osteoprotective cytokines in cultures of human periapical lesion cells. Methodology: Conditioned Biodentine Medium (CBM) was prepared according to ISO 10993‐12, by incubating Biodentine in RPMI medium (0.2 g mL−1) for 3 days at 37 °C. CBM contained both released microparticles and leachable soluble components. Inflammatory cells were isolated from 22 human periapical lesions after apicectomy or tooth extraction, by collagenase/DNase digestion, and cultured in several dilutions of CBM. The composition of periapical lesion cells was determined by morphological criteria, cytotoxicity was quantified by MTT and flow cytometric apoptosis/necrosis assays, whereas the levels of produced cytokines in cell culture supernatants were measured by flow cytometry and ELISA. Student t‐test and Friedman test with Dunn's post‐test were used for comparison of parametric and nonparametric variables, respectively. Results: Undiluted (100%), 75% and 50% CBM were cytotoxic for periapical lesion cells due to induction of both necrosis (100% CBM) and apoptosis (75% and 50% CBM). Noncytotoxic concentrations of CBM (25%) inhibited the production of pro‐inflammatory cytokines: TNF‐α, (P < 0.005); IL‐1β (P < 0.01); IL‐6 (P < 0.005) and chemokines IL‐8: (P < 0.005); MCP‐1 (P < 0.005), stimulated the production of anti‐inflammatory cytokine (IL‐10; P < 0.005), Th2 cytokines: IL‐4, IL‐5 and IL‐33 (all P < 0.01), and IL‐17A (P < 0.01). The concentration of CBM (12.5%) inhibited the production of IL‐6 (P < 0.05), IL‐8 (P < 0.01) and MCP‐1 (P < 0.005) and augmented the production of IL‐10 (P < 0.05). No significant effects on Th1‐related cytokines (IFN‐γ and IL‐12) and IL‐23 were detected with 25% and 12.5% CBM concentrations. Both CBM concentrations inhibited the production of osteolytic receptor activator of nuclear factor kappa‐Β ligand (RANKL), dose dependently (P < 0.005 and P < 0.01, respectively). Higher CBM concentrations decreased RANKL/osteoprotegerin (OPG) ratio (P < 0.05), without significant influence on the levels of osteoprotective OPG. Conclusion: Biodentine possesses immunomodulatory properties by suppressing pro‐inflammatory and augmenting anti‐inflammatory cytokines. Together with the reduction of osteodestructive mediators, this novel root‐end filling cement could be beneficial for healing and bone reparation after the surgical treatment of periapical lesions. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effects of the prolonged use of various irrigant solutions used during regenerative endodontic procedures on the physical and chemical structure of root canal dentine in extracted human teeth. Methodology: Sixtyroot dentine samples from extracted, single‐rooted, human teeth were assigned to 10 groups. Eight groups were irrigated with 1.5% NaOCl for 5 min, followed by 3%, 10%, 17% EDTA or 10% citric acid (CA) for 5 or 10 min. One group received only NaOCl irrigation, and samples with only distilled water irrigation were used as a control group. The changes in microhardness and flexural strength were determined using Vickers and 3‐point flexural tester, respectively. Molecular and elemental compositions were recorded using FTIR and EDS spectroscopy. Data were analysed using one‐way anova, Kruskal–Wallis and Mann–Whitney U tests. Results: The application of 1.5% NaOCl for 5 min did not affect the mineral content or microhardness of dentine (P > 0.05). However, it significantly decreased the dentine collagen peak values (P < 0.05), which was similar to the control group after the use of chelating agents (EDTA and 10% of CA) (P > 0.05). The effect of EDTA on the inorganic content was not concentration and time dependent (P > 0.05). CA resulted in a significantly greater reduction in the inorganic contents compared with the control and EDTA groups (P < 0.05). Regardless of the time, EDTA and CA significantly decreased dentine microhardness compared to the control (P < 0.05) with the greatest reduction in the CA groups (P < 0.05). NaOCl alone was associated with the lowest flexural strength, while none of the other irrigation regimens significantly decreased the flexural strength compared to the control group (P> 0.05). Conclusions: Use of 1.5% NaOCl for 5 min decreased the collagen content of samples of human dentine from extracted teeth while EDTA and 10% citric acid mostly affected the inorganic content and microhardness of dentine surfaces. None of the irrigant solutions significantly decreased the mechanical properties of the entire dentine specimen. [ABSTRACT FROM AUTHOR]

Aim: To explore a set of inflammatory biomarkers obtained from dentinal fluid (DF) from patients with symptomatic irreversible pulpitis (IP), reversible pulpitis (RP) and normal pulp (NP). Methodology: A cross‐sectional exploratory study was performed, recruiting 64 patients on the basis of their respective pulp condition. DF samples were obtained from all patients (23, from IP patients; 20, from RP patients; and 21, from NP patients). Quantification of biomarkers was performed using a Luminex® MAGPIX platform system and multiplex assay kits. The Kruskal–Wallis test was used for comparisons with regard to pulp state. A simple logistic regression model and the odds ratio (OR) with a 95% level of confidence (P = 0.05) were used to evaluate associations between biomarker levels and pulpal diagnosis. The performance discrimination of the biomarkers was evaluated through the construction of a receiver operating characteristic (ROC) curve by calculating the area under the curve (AUC) for IP versus RP after logistic regression modelling. Youden criteria were used to establish cut‐off points for biomarkers alone with AUC > 70 and P‐value < 0.05, or estimated probabilities from the multivariable logistic model. Results: The biomarkers that had significantly higher values in participants with IP versus RP were IL‐1α, VEGF‐α and FGF acid (P < 0.05). FGF acid (OR: 12.62; P = 0.0085; CI 95% 1.91–83.29) and VEGF‐α (OR: 2.61; P = 0.0252; CI 95% 1.13–6.03) were associated with pulp diagnoses of IP versus RP. The AUC‐ROC curve for FGF acid was 0.79. The model containing FGF acid, IL‐1α, IL‐6 and TIMP‐1 had an AUC‐ROC of 0.92 for IP versus RP with a significant difference from the FGF acid ROC curve (P = 0.0231). Conclusions: Dentinal fluid could be used to assay pulpal mediators in the molecular diagnosis of pulpitis. Despite the limitation of the clinical diagnostics used in the present study, it was possible to detect a difference between irreversible symptomatic pulpitis and reversible pulpitis associated with the following combined biomarkers: FGF acid + IL‐6 + IL‐1α, +TIMP‐1. [ABSTRACT FROM AUTHOR]

Aim: To study the impact of dentine cutting efficiency of rotary instruments on the lateral force they create when instrumenting simulated root canals in bovine dentine. Methodology: Lateral cutting efficiency of austenitic files (ProTaper Universal) was compared to that of counterparts of a reported identical geometrical design with a martensite phase component (ProTaper Gold) in bovine dentine disks (n = 6). Instrument shapes were studied using digital microscopy. The intracanal lateral force exerted by the two systems in simulated premolars (n = 9) made from bovine incisor roots containing a standardized narrow root canal of 16 mm length was monitored using a testing apparatus equipped with a torque‐controlled endodontic motor/handpiece. Data were compared using parametric statistics, alpha error = 0.05. Results: The geometrical design of the two systems under investigation was found to be identical. The martensitic nickel‐titanium rotary files had a significantly (t‐test, P < 0.05) higher lateral cutting efficiency than austenitic counterparts. This difference, however, did not impact the lateral force that was created when instrumenting simulated premolar root canals. Furthermore, lateral force peaks were generated with the progressively tapered instruments under investigation towards the full working length. Even though a glide path was prepared, the first instrument in the full‐length sequence (S1) created the highest lateral force (anova/Tukey's HSD, P < 0.05). Conclusions: The current experimental set‐up allows the study of the lateral force generated during root canal instrumentation. This force was not influenced by the dentine cutting efficiency of the instruments under investigation, but rather by their geometrical design. [ABSTRACT FROM AUTHOR]

Aim: To establish whether irrigant activation techniques, namely manual dynamic activation (MDA), passive ultrasonic irrigation (PUI) and sonic irrigation (SI), improve the tubular penetration of sodium hypochlorite (NaOCl) into root dentine when compared with conventional needle irrigation (CNI). Secondly, investigate if increasing NaOCl concentration and/or contact time improves the performance of these techniques. Methodology: A total of 83 extracted human maxillary permanent canines were decoronated to 15 mm, and root canals prepared to a size 40,.10 taper. Root dentine was stained with crystal violet for 72 h and embedded in silicone. Eighty specimens were randomly distributed into 16 groups (n = 5) according to the irrigant activation technique, NaOCl concentration (2%; 5.25%) and irrigant contact time (10 min; 20 min). All activation techniques were used for 60 s in the last minute of irrigation. Additionally, three teeth were not exposed to NaOCl to confirm adequate dentine staining had occurred (i.e. negative control). All specimens were subsequently dissected, observed under a light microscope and NaOCl penetration depth (µm) determined by measuring the average width of bleached dentine using ImageJ software. Statistical comparisons were made with paired and unpaired t‐tests, anovas followed by post hoc Tukey's and Dunnett's tests, and a general linear model (α < 0.05). Results: Overall, NaOCl penetration ranged from 38.8 to 411.0 µm with MDA, PUI and SI consistently resulting in significantly greater tubular infiltration than CNI (P < 0.05). The deepest measurements in the coronal, middle and apical segments were all recorded in the MDA; 5.25%; 20 min group and the least in the CNI; 2%; 10 min group. Increasing either irrigant concentration or contact time resulted in significantly greater NaOCl penetration depths for all techniques and segments of the canal (P < 0.05). However, when irrigant concentration and contact time were increased together, a significant interaction effect between these two independent variables was observed on overall NaOCl penetration (P < 0.05). Conclusions: Agitating irrigants with MDA, PUI or SI, as well as using greater irrigant concentrations or contact times, potentiated NaOCl penetration into root dentine. However, longer durations of NaOCl exposure at lower concentrations resulted in similar depths of tubular penetration as those achieved at higher concentrations. [ABSTRACT FROM AUTHOR]