Search

Peri-implantitis is the most common risk factor for dental implant failure. Nanostructured ceria (nano-CeO2) has anti-inflammatory and antibacterial functions, and different shapes of ceria enclosed by specific crystal planes could be an effective approach to enhance intrinsic catalysis. In the present study, the authors developed a novel implant surface-modification strategy by coating different shapes of nano-CeO2 onto titanium (Ti) surfaces to enhance their antibacterial and anti-inflammatory properties. The objectives of the study were to: (1) develop novel Ti surfaces modified with different shapes of nano-CeO2 (nanorod, nanocube and nano-octahedron) for peri-implantitis prevention; (2) investigate and compare the inhibition efficacy of different shapes of CeO2-modified surfaces against biofilms of peri-implantitis-related pathogens; and (3) evaluate the different CeO2-modified surfaces on cell inflammatory response in vitro and in vivo. The results showed that nanorod CeO2-modified Ti had more bacteria attachment of Streptococcus sanguinis in the early stage, compared with other CeO2-modified Ti (p 0.1). Nanocube and nano-octahedron CeO2-modified Ti exerted much better anti-inflammatory effects and ROS-scavenging ability than nanorod CeO2 in vitro (p Statement of Significance Peri-implantitis is the most common risk factor for dental implant failure. Nanostructured ceria (nano-CeO2) has anti-inflammatory and antibacterial functions, and different shapes of ceria enclosed by specific crystal planes could be an effective approach to enhance intrinsic catalysis. In the present study, we developed a novel implant surface-modification strategy by coating different shapes of nano-CeO2 onto titanium surfaces to enhance their antibacterial and anti-inflammatory properties for dental implants. In addition, we found that the nano-octahedron CeO2 coating on titanium would have great therapeutic potential for alleviating and eliminating peri-implantitis.

Objective Secondary caries and micro-cracks are the main limiting factors for dentin bond durability. The objectives of this study were to develop a self-healing adhesive containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the effects of water-aging for 12 months on self-healing, dentin bonding, and antibacterial properties for the first time. Methods Microcapsules were synthesized with poly (urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) and N,N -dihydroxyethyl- p -toluidine (DHEPT). The adhesive contained 7.5% microcapsules, 10% DMAHDM, and 20% NACP (all mass). Specimens were water-aged at 37 °C for 1 day to 12 months. Dentin bond strength was measured using extracted human teeth. A single-edge-V-notched-beam (SEVNB) method was used to measure fracture toughness K IC and self-healing efficiency. A dental plaque microcosm biofilm model was used with human saliva as inoculum. Results The microcapsules + DMAHDM + NACP group showed no decline in dentin bond strength after water-aging for 12 months, which was significantly higher than that of other groups without DMAHDM ( p IC was obtained even after 12 months of water immersion, indicating that the self-healing ability was not lost in water-aging ( p > 0.1). The bacteria-killing ability of this adhesive did not decline from 1 day to 12 months ( p > 0.1), with biofilm CFU reduction by 3–4 orders of magnitude after the resin was water-aged for 12 months, compared to control resin. Significance This novel adhesive with triple merits of self-healing, antibacterial and remineralization functions showed an excellent long-term durability in water-aging for 12 months. This multifunctional adhesive has the potential for dental applications to heal cracks, inhibit bacteria, provide ions for remineralization, and increase the restoration longevity.

Objectives The objective of the present study was to investigate long-term dentin remineralization via the combination of poly(amido amine) (PAMAM) with a novel rechargeable adhesive containing nanoparticles of amorphous calcium phosphate (NACP). Methods The NACP adhesive was immersed in lactic acid at pH 4 to exhaust its calcium (Ca) and phosphate (P) ion release, and then recharged with Ca and P ions. Dentin samples were pre-demineralized with 37% phosphoric acid, and then divided into four groups: (1) dentin control, (2) dentin treated with PAMAM, (3) dentin with recharged NACP adhesive, (4) dentin with PAMAM + recharged NACP adhesive. In group (2) and (4), the PAMAM-coated dentin was immersed in phosphate-buffered saline with vigorous shaking for 77 days to accelerate any detachment of the PAMAM macromolecules from the demineralized dentin. Samples were treated with a cyclic remineralization/demineralization regimen for 21 days. Results After 77 days of fluid flow challenge, the immersed PAMAM still retained its nucleation template function. The recharged NACP adhesive possessed sustained ion re-release and acid-neutralization capability, both of which did not decrease with repeated recharge and re-release cycles. The immersed PAMAM with the recharged NACP adhesive achieved long-term dentin remineralization, and restored dentin hardness to that of healthy dentin. Conclusions The PAMAM + NACP adhesive completely remineralizes pre-demineralized dentin even after long-term fluid challenges and provides long-term remineralization to protect tooth structures. Clinical significance The novel PAMAM + NACP adhesive provides long-term bond protection and caries inhibition to increase the longevity of resin-based restorations.

Bulk fracture and secondary caries are the two main problems causing failures and shortening the lifetime of dental resinous restorations. This article reviews recent research on self-healing dental and biomedical materials. This includes the development of self-healing dental resin composites and adhesives, combining self-healing with calcium phosphate nanoparticles in the resins for tooth lesion remineralization, and adding antibacterial monomer into self-healing resins to suppress oral biofilm grows and acid production. Furthermore, since the oral environment experiences saliva and drinks, this paper also reviews research on the self-healing of dental resins while being submerged in an aqueous environment, and the effect of long-term water-aging time from 1 day to 6 months on the self-healing capability. The new class of materials have demonstrated excellent self-healing efficacy in various material systems including bonding agents, composites and cements. They could heal cracks, regain load-bearing ability, inhibit oral pathogens, reduce or eliminate biofilm acids, raise biofilm pH to protect the teeth, and regenerate lost tooth minerals. Furthermore, their effects were indicated to be durable and long-lasting. While most of the recent publications on self-healing dental resins are from our group, this article also reviews publications from other researchers. The novel class of dental materials with triple benefits of self-healing, antibacterial and remineralization capabilities offer the much-needed improvements to address the two main reasons for restoration failures: fracture and secondary caries. They are expected to have potential for a wide range of dental and biomedical applications to overcome the current challenges and prolong the restoration life.

The purpose of this study was to report the clinical efficacy of decompression for 3 cases with large periapical lesions and to review technique details. Three cases with large periapical cystic lesions were treated with decompression after root canal treatment. A traditional decompression technique was used for the first case. After aspiration, mucogingival incision, irrigation, and incisional biopsy, a pediatric endotracheal tube was sutured in place and kept for 3 weeks for lesion debridement. An aspiration/irrigation technique was adopted for the second case. An 18-G needle with a syringe was used to aspirate the cystic lesion. Two needles were then inserted into the lesion; copious saline irrigation was delivered from 1 needle and until clear saline was expressed from the other. For the third case, decompression was accomplished with a surgical catheter that was subsequently replaced with a gutta-percha plug after 1 month. None of the 3 cases underwent complete enucleation and root-end surgery. Healed lesions or lesions in healing were observed after 1 to 2 years. Based on the presented cases and published case reports on decompression, a literature review was provided covering indications, technique details, modification, and prognosis of decompression in endodontics. For large periapical cystic lesions, conservative decompression may be used for certain cases before or in lieu of apical surgery. Decompression enables healing of large, persistent periapical lesions after root canal treatment.

Objectives The present study examined the effect of food medium on the three-body wear behaviour of veneering porcelain derived from porcelain-fused-to-metal crowns. Methods Seventy-four rectangular metal–ceramic specimens were prepared using Ceramco III as the veneering porcelain. After storage in distilled water at 37 °C for 2 days, the specimens were tested with a custom-designed chewing machine with a stainless steel ball as antagonist (350 N loads, 2.4 × 106 cycles). Testing was performed using water, silica beads, poly(methyl) methacrylate beads, millet seed slurry, chicken slurry or celery slurry as abrasive medium. Wear analysis of the veneering porcelain was performed using a 3D profilometer after every 300,000 wear cycles and analysed with one-way analysis of variance and post-hoc pairwise comparison procedures. Worn surfaces were examined with scanning electron microscopy. Results The wear curves of all experimental groups demonstrated three wear stages (running-in, steady wear and severe wear) with characteristic microstructure of worn surfaces. All the three food items selected in the present study (celery, chicken and millet seeds) had lower hardness compared with the veneering porcelain and produced less abrasion of the porcelain than a two-body wear system (water only). Abrasive wear produced with silica particles was the highest for the veneering porcelain. Conclusion The wear process of veneering porcelain in porcelain-fused-to-metal restorations is affected by the type of food consumed during mastication. Clinical significance Excessive abrasion may lead to premature failure of porcelain-fused-to-metal restorations. The importance of the wear behaviour of dental ceramic materials cannot be overstated. Three-body wear is an unavoidable consequence of oral function and occurs daily during eating. Understanding the effect of food particles on the wear behaviour of dental porcelain provides insight into the clinical performance and durability of these restorations.

Currently available drug delivery systems for oral diseases suffer from short retention time and poor local concentrations at the target site. A biodegradable stimulus-responsive hydrogel was synthesized in the present study to evaluate its application as an environmentally sensitive carrier for on-demand intraoral drug delivery. The hydrogel was synthesized from diacrylate-containing polyethylene glycol–based scaffolds and a cysteine-terminated peptide crosslinker (CGPQG↓IWGQC) via a Michael-type addition reaction. Because CGPQG↓IWGQC can be cleaved by matrix metalloproteinase 8 (MMP-8), minocycline hydrochloride, bovine serum albumin, or an antibacterial peptide (KSL) was incorporated into the scaffolds to evaluate the MMP-8-responsive release behavior of the on-demand drug delivery system. Hydrogel characterization and gelation kinetics were examined with gel time, Fourier-transform infrared spectroscopy, scanning electron microscopy, and measurements of rheologic parameters. Degradation behavior and MMP-8-responsive drug release were performed by high-performance liquid chromatography and protein-specific assay. Biocompatibility evaluation indicated that the hydrogels were noncytotoxic. Antibacterial testing demonstrated that the released drugs were able to maintain bioactivity. Taken together, these results suggest that the MMP-8-sensitive hydrogel is a promising candidate for on-demand intraoral localized drug delivery. Because MMP-8 is one of the most important biomarkers for periodontitis, the MMP-8-responsive hydrogel has potential to be used for in situ adaptive degradation in response to chronic periodontitis and peri-implantitis. This notion has to be tested in animal models of periodontal disease.

Objectives Osteoclast differentiation is regulated by transcriptional, post-transcriptional and post-translational mechanisms. Micro-ribonucleic acids (miRNAs) are 20–24 nucleotides long non-coding RNAs involved in post-translational regulation of gene expressions during osteoclast differentiation. The objective of the present study was to investigate the role played by the miRNA, miR-338-3p, in osteoclastogenesis. Methods Osteoclastogenesis was induced in murine RAW264.7 cells using M-CSF and RANKL. The differentiated cells were harvested at designated times for TRAP staining and detection of designated gene expressions. A synthetic miR-338-3p mimic or its inhibitor was transfected into RAW264.7 cells prior to the induction of osteoclastogenesis. The effects of mimic or inhibitor on osteoclastogenesis were examined by qRT-PCR and TRAP staining. Bioinformatic analysis and luciferase activity were performed to identify the relationship between miR-338-3p and the transcription factor MafB. The miR-338-3p mimic and MafB siRNA were co-transfected into RAW264.7 cells to evaluate the cross-talk between miR-338-3p and MafB. Results miR-338-3p was increased significantly during osteoclast differentiation. Overexpression of miR-338-3p promoted osteoclastogenesis while its inhibition had the opposite effect. Bioinformatic analysis and dual luciferase assays indicated that miR-338-3p targeted MafB to repress its gene expression. MafB knockdown by RNA silencing blocked the promotional effect of miR-338-3p on osteoclast differentiation. Conclusion Because miR-338-3p is crucial for osteoclastic differentiation via targeting of the transcription factor MafB, inhibition of this miRNA represents a potential strategy for modulating osteoporosis in an aging population. Clinical significance Understanding the role played by miR-338-3p in osteoclast differentiation bridges the gap between the pathogenesis of osteoporosis and the quest for novel therapeutics to reduce the risk of bone fracture associated with this global disease.

Objectives: The present in vitro study evaluated the effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), a cross-linking agent used as an additional therapeutic primer for luting fiber posts to radicular dentine to prevent hybrid layer degradation. Methods: Root canal treatment was performed on 80 extracted single-rooted human teeth. A 10-mm post space was prepared and pecimens were randomly assigned to four groups (n=20) according to the bonding system: 1) All Bond 3 (Bisco); 2) All Bond 3 + 0.3M EDC; 3) Prime&Bond XP (Dentsply Sirona); 4) Prime&Bond XP + 0.3M EDC. In groups 2 and 4, EDC was applied on phosphoric acid-etched dentine for 1 min. Fiber posts (RelyX Fiber Post, 3M ESPE) were luted with a dual-cured resin cement (Core-X flow, Dentsply Sirona). Slices were prepared for micro push-out test and interfacial nanoleakage evaluation of the coronal and apical region of the canal space after 24 h and 1 year storage in artificial saliva. In-situ zymography was performed to investigate endogenous matrix metalloproteinase activities within the hybrid layer. Results were statistically analysed with three-way ANOVA test or Chi Square test. Statistical significance was set at α=0.05. Results: No significant influence was identified between the two adhesives. The use of EDC significantly improved fiber post bond strength at 1 year but not at 24 h. Application of 0.3 M EDC prior to bonding significantly reduced gelatinolytic activities within the radicular hybrid layers. Conclusions: Carbodiimide was effective in preserving fibre post bond strength over time, through reducing the activities of intra-radicular endogenous proteases. Clinical Significance: Inhibition of matrix metalloproteinases using EDC over radicular dentin could play an important role in bond strength preservation. However, the clinical relevance of these findings needs to be proven.

To evaluate the efficacy of two sonic-powered irrigation systems, EDDY and EndoActivator, in killing intracanal biofilms.Eighty-three instrumented, autoclaved single-rooted human premolars were inoculated with Enterococcus faecalis (ATCC-29212) for 21 days to generate mature, single-species biofilms. The teeth were devided into four groups: irrigation with saline (N = 11); irrigation with 2% NaOCl without agitation (N = 24); irrigation with 2% NaOCl with agitation by the EndoActivaor (N = 24); irrigation with 2% NaOCl with agitation by the EDDY (N = 24). Colony-forming unit (CFU) counts and XTT assay were used to evaluate bacterial load. Additional teeth were split into root-halves for fluorescence staining to examine the percentages of live/dead bacteria in the dentinal tubules present in different canal locations (coronal, mid-root and apical portions).Agitation of 2% NaOCl by EDDY or EndoActivator reduced bacteria load more proficiently than the use of 2%NaOCl without agitation (p0.05). No significant difference was detected between the two sonic-powered irrigant agitation systems (p0.05). Confocal laser scanning microscopy indicated that both devices had better intratubular bacteria killing efficacy than the use of 2% NaOCl only in all parts of the canal space (p0.05), with no significant difference detected between EDDY and EndoActivator (p0.05). Elimination of intracanal and intratubular bacteria were less efficient in the apical portion of the canal space for all experimental groups.The two sonic-powered irrigant activation systems demonstrated comparable intracanal bacteria reduction efficacy when 2% NaOCl was used for disinfecting E. faecalis biofilms in single-rooted teeth.With the use of 2% NaOCl as irrigant, the EDDY and EndoActivator sonic-powered irrigant agitation systems have improved and equivalent intracanal bacteria reduction efficacy but are incapable of completely killing all bacteria that resided within the dentinal tubules of root canals.

Commercially available dental adhesives fail to chemically unite the demineralized collagen matrix with resinous materials within the resin-dentin interface. Sub-micron separations between the collagen fibrils and polymerized resin provide the backdrop for bond deterioration. Here, novel isocyanate-terminated urethane methacrylate precursors (UMP) were synthesized with the capacity to bond chemically to dentin collagen via covalent and hydrogen bonds. Collagen grafted with UMP also copolymerized with other methacrylate resin monomers, thereby producing a monoblock of chemically-linked biocomposite. The viscosity, degree of conversion and biocompatibility of UMP are comparable with commercially available resin monomers. An experimental adhesive containing 40% UMP demonstrated co-polymerization capability, good infiltration capacity and achieved higher immediate bond strength to dentin than the control commercially available adhesive. Improvement of dentin bonding by incorporation of UMP into dentin adhesives justifies future evaluation of the potential of these UMP-based adhesives in extending the longevity of resin-dentin bonds. STATEMENT OF SIGNIFICANCE: Composite-adhesive restorations have become an indispensable treatment modality in contemporary restorative dentistry. While the inability of these adhesives to bond chemically with collagen undermines the bond quality. This study describes a novel isocyanate-terminated urethane multi methacrylate precursors (UMP) which can bridge dentinal matrix collagen with adhesive resin by covalent and hydrogen bonds. Furthermore, an experimental UMP-based adhesive shows better co-polymerization capability, good infiltration capacity and higher immediate bond strength than the putatively effective adhesive Single Bond 2. The new chemical bonding mechanism based on UMP would theoretically produce more stable bonding interface that are more resistant to degradation.

Objectives The objectives were to develop a calcium (Ca) and phosphate (P) ion-rechargeable and protein-repellent adhesive containing nanoparticles of amorphous calcium phosphate (NACP) and 2-methacryloyloxyethyl phosphorylcholine (MPC), and investigate the MPC effects on ion recharge and re-releases for the first time. Methods Pyromellitic glycerol dimethacrylate and ethoxylated bisphenol-A dimethacrylate were used to fabricate adhesive PEHB. Six adhesives were tested: (1) Scotchbond (SBMP); (2) PEHB, (3) PEHB + 20%NACP; (4) PEHB + 30%NACP; (5) PEHB + 20%NACP+3%MPC; (6) PEHB + 30%NACP+3%MPC. Dentin shear bond strength, Ca/P ion release, recharge and re-release, and protein adsorption were measured. A microcosm biofilm model was tested for lactic-acid production and colony-forming units (CFU). Results Adding NACP + MPC did not negatively affect dentin bond strength (p > 0.1). With increasing the number of recharge/re-release cycles, the Ca/P ion re-release reached similarly higher levels (p > 0.1), indicating long-term remineralization capability. One recharge enabled the adhesives to have continued re-releases for 21 days. Incorporation of 3% MPC yielded 10-fold decrease in protein adsorption, and 1–2 log decrease in biofilm CFU. Conclusions The new rechargeable adhesive with MPC + 30%NACP greatly reduced protein adsorption, biofilm growth and lactic acid. Incorporation of MPC did not compromise the excellent Ca/P ion release, rechargeability, and dentin bond strength. Clinical significance Novel bioactive adhesive containing MPC + NACP is promising to repel proteins and bacteria, and inhibit secondary caries at the restoration margins. The method of NACP + MPC to combine CaP-recharge and protein-repellency is applicable to the development of a new generation of materials including composites and cements to suppress oral biofilms and plaque formation and protect tooth structures.

The present study examined the effects of irrigant flow rate and simulated intraosseous sinusoidal pressure on the rate of NaOCl extrusion from the apical terminus of a faux root canal.An extrusion setup was designed to enable irrigant extrusion to be opposed by 30 mm Hg simulated intraosseous pressure. The faux canal apex was opposed by atmospheric + 30 mm Hg pressure (experimental) or atmospheric pressure only (control group). Using five irrigant delivery rates (15.6 8.0, 4.0, 3.4 or 3.0 mL/min), the extrusion rates of 2% NaOCl from the faux apex were measured in both groups (n = 16). Data were analysed with two-factor ANOVA and pairwise comparisons at α = 0.05. Correlation between NaOCl delivery rates and extrusion rates in both groups were analysed with the Pearson product-moment procedure.Irrespective of the presence or absence of simulated sinusoidal pressure, NaOCl extrusion rates were positively-correlated with irrigant flow rates. For the factor "irrigant flow rates", significant differences in NaOCl extrusion rates were identified among all flow rates (p 0.05), except for the pairwise comparison between 4.0 and 3.4 mL/min in the control. For all irrigant flow rates, NaOCl extrusion rate was significantly lower in the presence of 30 mm Hg simulated sinusoidal pressure than that obtained in the absence of opposing pressure (p 0.05).In the presence of 30 mm Hg simulated intraosseous pressure, NaOCl delivered via a side-vented needle inserted to 1 mm short of working length may be prevented from extrusion when its flow rate is ≤ 3.0 mL/min.When opposed by intraosseous sinusoidal pressure, NaOCl delivered via a side-vented needle inserted to 1 mm short of working length may be prevented from extrusion when its flow rate is ≤ 3.0 mL/min.

Objectives To evaluate the bonding performance, antibacterial activity, and remineralization effect on enamel of the orthodontic adhesive containing MAE-DB and NACP. Methods Eighty non-carious human premolars were divided into 3 groups: Transbond XT (TB), PEHB + 5% MAE-DB (PD), and PEHB + 40% NACP + 5% MAE-DB (PND). Premolars were bonded with orthodontic brackets, the first subgroup (n = 10) and the second subgroup (n = 10) were subjected to shear bond strength testing after immersed in water for 1 day and in demineralization solution for 28 days respectively and then tested surface roughness, while the third subgroup (n = 6) was used for microhardness evaluation after aged in demineralization solution for 28 days. For each adhesive, fifty disk samples were prepared for antibacterial study. Specimens measuring 12 mm × 2 mm × 2 mm were fabricated for ion release test. Results Bond strengths were in the order TB = PND > PND = PD for “1-day in water”, and in the order TB = PND > PD for “28-days in pH 4 solution”. No significant difference in the ARI scores for the three adhesive. Numerous bacteria adhered to TB surface, while PD and PND had minimal bacterial growth and activity. PND showed high levels of Ca and P ions release and enamel hardness. The surface roughness of enamel in PND was much lower than TB and PD and showed no significant difference with the sound, control enamel. Conclusion PND adhesive with 5% MAE-DB and 40% NACP exhibits antibacterial and remineralizing capabilities, and did not adversely affect bond strength compared to commercial adhesive. Clinical significance Novel adhesive containing quaternary ammonium monomer and nano-amorphous calcium phosphate represents a promising candidate in combating enamel white spot lesions and even dental caries.

Made available in DSpace on 2018-12-11T17:16:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Objectives The objective of the present study was to investigate the long-term effect of 0.01% acrolein (ACR) aqueous solution, employed as an additional primer, on the mechanical durability and enzymatic activity of resin-dentine interfaces created with a simplified etch-and-rinse adhesive. Methods Dentine surfaces were etched with 35% phosphoric acid for 15 s, rinsed and blot-dried. Specimens were then assigned to: Group 1: dentine pre-treated with 0.01% ACR aqueous solution for 1 min and bonded with Adper Scotchbond 1 XT (SB1XT), a 2-step etch-and-rinse adhesive; Group 2: SB1XT was applied on untreated acid-etched dentine (control). Resin composite build-ups were made using Filtek Z250. Microtensile bond strength was tested by stressing sectioned specimens to failure immediately or after 1 year of storage in artificial saliva at 37 °C. Zymography and in-situ zymography assays were performed for examining dentine matrix metalloproteinase (MMP) activities. Results The use of 0.01% ACR as conditioning primer appeared to have contributed better to preservation of bond strength over time without affecting immediate bond strength. Zymography and in-situ zymography showed reduction in MMP activities after the application of ACR. Conclusion Dentine collagen cross-linking produced by an ACR-based primer increases the longevity of resin-dentine bonds by reinforcement of the adhesive interface and reduction of dentine MMP activities. Further studies are required to evaluate the potential in vivo and in vivo cytotoxicity of ACR. Clinical significance The acrolein-based primer is a potentially useful clinical bonding tool because it demonstrates good collagen cross-linking ability within a clinically-acceptable working time. Although a low ACR concentration was employed in the present study, the cytotoxicity of ACR should be tested prior to clinical use. Department of Biomedical and Neuromotor Sciences DIBINEM University of Bologna - Alma Mater Studiorum School of Dentistry Faculty of Medicine University of Novi Sad Department of Restorative Dentistry School of Dentistry University of São Paulo Private Practice Department of Pediatric Dentistry and Orthodontics Araraquara School of Dentistry UNESP – University of Estadual Paulista The Dental College of Georgia Augusta University Department of Pediatric Dentistry and Orthodontics Araraquara School of Dentistry UNESP – University of Estadual Paulista

The medical literature is replete with the maxim ‘primum non nocere’, cautioning health care providers to avoid doing any harm to human subjects in their delivery of medical care. Sodium hypochlorite (NaOCl) is a well-established irrigant for root canal treatment because of its antimicrobial and organic tissue remnant dissolution capability. However, little is known about the deleterious effect of this strong oxidizing agent on the integrity of human mineralized dentin. Iatrogenically-induced loss of dentin integrity may precipitate post-treatment root fracture and has potential medico-legal complications. In the present work, transmission electron microscopy provided evidence for collagen destruction in the surface/subsurface of dentin treated with high NaOCl concentrations and long contact times. Size exclusion chromatography showed that the hypochlorite anion, because of its small size, penetrated the water compartments of apatite-encapsulated collagen fibrils, degraded the collagen molecules and produced a 25–35 µm thick, non-uniform “ghost mineral layer” with enlarged, coalesced dentinal tubules and their lateral branches. Fourier transform-infrared spectroscopy identified increases in apatite/collagen ratio in NaOCl-treated dentin. The apatite-rich, collagen-sparse dentin matrix that remained after NaOCl treatment is more brittle, as shown by the reductions in flexural strength. Understanding the deleterious effects of NaOCl on mineralized dentin enables one to balance the risks and benefits in using high NaOCl concentrations for lengthy periods in root canal debridement. Delineating the mechanism responsible for such a phenomenon enables high molecular weight, polymeric antimicrobial and tissue dissolution irrigants to be designed that abides by the maxim of ‘primum non nocere’ in contemporary medical practices. Statement of Significance The antimicrobial and tissue-dissolution capacities of NaOCl render it a well-accepted agent for root canal debridement. These highly desirable properties, however, appear to be intertwined with the untoward effect of collagen matrix degradation within mineralized dentin. Because of its small size, the hypochlorite anion is capable of infiltrating mineralized collagen and destroying the collagen fibrils, producing a mineral-rich, collagen sparse ghost mineral matrix with reduced flexural strength. Findings from the present work challenge the biosafety of NaOCl when it is used in high concentrations and for lengthy time periods during root canal treatment, and laid the background work for future biomaterials design in debridement of the canal space.

Microbial infections affect humans worldwide. Many quaternary ammonium compounds have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for preparation of antimicrobial biomaterials. Various polymerization techniques have been employed to prepare antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymerization techniques enable precise control over macromolecular structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technological developments have also been accompanied by potential toxicological and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-containing biomaterials that are based on randomized human clinical trials, the golden standard in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.

Limitations associated with wet-bonding led to the recent development of a selective demineralization strategy in which dentin was etched with a reduced concentration of phosphoric acid to create exclusive extrafibrillar demineralization of the collagen matrix. However, the use of acidic conditioners removes calcium via diffusion of very small hydronium ions into the intrafibrillar collagen water compartments. This defeats the purpose of limiting the conditioner to the extrafibrillar space to create a collagen matrix containing only intrafibrillar minerals to prevent collapse of the collagen matrix. The present work examined the use of polymeric chelators (the sodium salt of polyacrylic acid) of different molecular weights to selectively demineralize extrafibrillar dentin. These polymeric chelators exhibit different affinities for calcium ions (isothermal titration calorimetry), penetrated intrafibrillar dentin collagen to different extents based on their molecular sizes (modified size-exclusion chromatography), and preserve the dynamic mechanical properties of mineralized dentin more favorably compared with completely demineralized phosphoric acid-etched dentin (nanoscopical dynamic mechanical analysis). Scanning and transmission electron microscopy provided evidence for retention of intrafibrillar minerals in dentin surfaces conditioned with polymeric chelators. Microtensile bond strengths to wet-bonded and dry-bonded dentin conditioned with these polymeric chelators showed that the use of sodium salts of polyacrylic acid for chelating dentin prior to bonding did not result in significant decline in resin-dentin bond strength. Taken together, the findings led to the conclusion that a chelate-and-rinse conditioning technique based on extrafibrillar collagen demineralization bridges the gap between wet and dry dentin bonding. Statement of Significance The chelate-and-rinse dental adhesive bonding concept differentiates from previous research in that it is based on the size-exclusion characteristics of fibrillar collagen; molecules larger than 40 kDa are prevented from accessing the intrafibrillar water compartments of the collagen fibrils. Using this chelate-and-rinse extrafibrillar calcium chelation concept, collagen fibrils with retained intrafibrillar minerals will not collapse upon air-drying. This enables adhesive infiltration into the mineral-depleted extrafibrillar spaces without relying on wet-bonding. By bridging the gap between wet and dry dentine bonding, the chelate-and-rinse concept introduces additional insight to the field by preventing exposure of endogenous proteases via preservation of the intrafibrillar minerals within a collagen matrix. If successfully validated, this should help prevent degradation of resin-dentine bonds by collagenolytic enzymes.

Dental resin monomers such as 2-hydroxyethyl methacrylate (HEMA) disturb vital cell functions and induce mitochondrial intrinsic apoptosis via generation of oxidative stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the gene expression of antioxidative enzymes and plays a crucial role in the maintenance of cellular redox equilibrium and mitochondrial homeostasis. The present study investigated the functional significance of Nrf2 in cellular response toward HEMA. It was found that HEMA stimulation promoted nuclear translocation of Nrf2 and increased Nrf2 and heme oxygenase-1 (HO-1) expression, which was further enhanced by Nrf2 activator tert-butylhydroquinone (tBHQ), but suppressed by Nrf2 inhibitor ML385. Pretreatment of primary human dental pulp cells (hDPCs) with tBHQ protected the cells from HEMA-induced oxidative injury (increased reactive oxygen species production and apoptosis) and mitochondrial impairment (morphological alterations, decreased ATP production, suppressed oxidative phosphorylation activity, depolarization of mitochondrial membrane potential, and disrupted electron transport chain). In contrast, pretreatment with ML385 increased cell sensitivity to these injurious processes. This protective effect on mitochondria could be related to peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α)/nuclear respiratory factor 1 (NRF1) pathway. These results contribute to the understanding of the function of Nrf2 and the development of novel therapies to counteract the adverse effects of dental resin monomers.

Objectives Malocclusion may be corrected nonsurgically by mechanical tooth movement. The plasma protein profiles of human subjects receiving the first phase of orthodontic treatment were examined to test the hypothesis that application of mechanical stresses to teeth induces systemic proteomic alterations. Methods Tandem mass tag-based liquid chromatography-mass spectrometry (LC–MS/MS) was used to examine systemic proteomic alterations in subjects undergoing controlled stress application (N = 10) and in volunteers not receiving treatment (N = 7) at 3 time intervals within 24 h. Proteins differentially expressed by the tooth movement group were functionally analyzed with “Gene Ontology” (GO) and “Search Tool to Retrieve Interacting Genes/proteins” (STRING) softwares. Enzyme-Linked Immunosorbent Assay and Western-blot were used to validate the in vivo protein alterations. An in vitro model consisting of human periodontal ligament cells (hPDLCs) under compression was used to validate the force-responsive characteristics of galectin-3 binding protein (LGALS3BP). Results Sixteen out of the 294 proteins identified by LC–MS/MS were differentially expressed in the plasma of subjects receiving controlled mechanical stresses for moving teeth. Those proteins were clustered in biological processes related to acute inflammatory response and vesicle-related transportation. Serotransferrin, fibronectin and LGALS3BP were processed for confirmation in vivo; LGALS3BP was significantly increased in the tooth movement group. In vitro secretion of LGALS3BP in PDLCs was force-responsive. Conclusions Regional application of mechanical stresses stimulates systemic proteomic changes. Because serum LGALS3BP is over-expressed in different systemic diseases, including cancer, further work is needed to examine how systemic up-regulation of LGALS3BP affects the progression of those diseases.

Hong-ye Yang,1 Li-na Niu,2 Jin-long Sun,2 Xue-qing Huang,3 Dan-dan Pei,4 Cui Huang,1 Franklin R Tay5 1The State Key Laboratory Breeding Base of Basic Science of Stomatology, Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei, People’s Republic of China; 2State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an, Shaanxi, People’s Republic of China; 3Department of Prosthodontics, Guanghua School and Hospital of Stomatology, Guangdong Key Laboratory of Stomatology, Yat-sen University, Guangzhou, Guangdong, People’s Republic of China; 4Department of Prosthodontics, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, People’s Republic of China; 5Department of Endodontics, College of Dental Medicine, Augusta University, Augusta, GA, USA Abstract: Scaffold supplements such as nanoparticles, components of the extracellular matrix, or growth factors have been incorporated in conventional scaffold materials to produce smart scaffolds for tissue engineering of damaged hard tissues. Due to increasing concerns on the clinical side effects of using large doses of recombinant bone-morphogenetic protein-2 in bone surgery, it is desirable to develop an alternative nanoscale scaffold supplement that is not only osteoinductive, but is also multifunctional in that it can perform other significant bone regenerative roles apart from stimulation of osteogenic differentiation. Because both amorphous calcium phosphate (ACP) and silica are osteoinductive, a biodegradable, nonfunctionalized, expanded-pore mesoporous silica nanoparticle carrier was developed for loading, storage, and sustained release of a novel, biosilicification-inspired, polyamine-stabilized liquid precursor phase of ACP for collagen biomineralization and for release of orthosilicic acid, both of which are conducive to bone growth. Positively charged poly(allylamine)-stabilized ACP (PAH-ACP) could be effectively loaded and released from nonfunctionalized expanded-pore mesoporous silica nanoparticles (pMSN). The PAH-ACP released from loaded pMSN still retained its ability to infiltrate and mineralize collagen fibrils. Complete degradation of pMSN occurred following unloading of their PAH-ACP cargo. Because PAH-ACP loaded pMSN possesses relatively low cytotoxicity to human bone marrow-derived mesenchymal stem cells, these nanoparticles may be blended with any osteoconductive scaffold with macro- and microporosities as a versatile scaffold supplement to enhance bone regeneration. Keywords: amorphous calcium phosphate, biomineralization, collagen, mesoporous silica, osteoinductive, poly(allylamine)

Objective The present study tested the central hypothesis that selective demineralisation of dentine extrafibrillar minerals by lowering the phosphoric acid concentration improves the quality of the resin-dentine interface. Methods Dentine surfaces were etched with different concentrations of phosphoric acid (1, 5, 10, 20, 30 or 40 wt%). Scanning electron microscopy was used to observe the micromorphology of the etched dentine surfaces. Energy dispersive X-ray analysis was performed to determine the residual Ca-content of the demineralised dentine matrix. Atomic force microscopy-based nanoindentation was used to analyse the nanomechanical properties of the treated dentine surfaces. The influence of H3PO4 concentration on resin-dentine bond strength was evaluated by microtensile bond strength testing. One-way ANOVA was used to compare the residual Ca-content ratio, reduced elastic modulus (Er) of the treated dentine surfaces and microtensile bond strength among groups. Results Collagen fibrils appeared to be wider in diameter after etching with 5% and 10% H3PO4. The partially-demineralized collagen scaffold retained part of its rigidity to maintain an uncollapsed three-dimensional structure. Etching with 1% H3PO4 resulted in the highest residual Ca-content ratio and Er of demineralised dentine matrix, followed by 5% H3PO4. Those values were all significantly higher than values derived from the other groups. Etching with 30% H3PO4 resulted in the lowest Ca-content ratio and Er. Using 5% H3PO4 as etchant resulted in the highest resin-dentine bond strength. Conclusions Selective demineralisation of the dentine matrix may be achieved by lowering the H3PO4 concentration to 5 wt%, to achieve better bonding performance. Clinical relevance By retaining intrafibrillar minerals, more through air-drying of the partially demineralised collagen matrix may be accomplished without the need to worry about collapsing a mineral-free collagen matrix during air-drying. This may result in the elimination of water-wet bonding during the application of etch-and-rinse adhesives.

Biomineralization in vertebrates is a ubiquitous and tightly regulated process which creates hierarchical structures for the skeleton. Because of the lack of understanding and applicability of cell-based or biological systems to achieve intrafibrillar mineralization, scientists adopted various in vitro methods to elucidate the mechanism of intrafibrillar mineralization. In this article, biomimetic intrafibrillar mineralization of collagen in its wide ramifications is reviewed. It is intriguing how prevailing intrafibrillar mineralization mechanisms derived from two potentially discordant crystallization philosophies were equally adept, depending on the experimental context, at theorizing the formation of calcium phosphate within a fibrillar template. This complementarity is not unique to biomineralization and has precedence in other fundamental physical interpretations. A new intrafibrillar mineralization process based on the use of polycationic process-directing agent added uncertainty to the use of existing mechanisms in accounting for the observations.

Objectives To evaluate the bonding of resin-cement to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) via silica coating followed by silanization, and three one-bottle universal adhesives, with or without prior conditioning using a zirconia primer. Methods Y-TZP specimens (n = 160) were conditioned by tribochemical silica coating and silanization (CS), or alumina sandblasting with one of the following MDP containing adhesives or primers: Z-Prime Plus™ (zirconia primer, ZP), Single Bond Universal™ (SU), Clearfil Universal Bond™ (CU) or All-Bond Universal™ (AU). Additionally, some specimens (ZPSU, ZPCU and ZPAU) received Z-Prime Plus™ followed by one of the three adhesives. After 24 h water storage and “aging” (20,000 thermocycles plus additional 40-day water storage), shear bond strength (SBS) was measured. Fourier-transform infrared spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) were employed for characterization of the chemical bonds between the primer/adhesives and the zirconia. Thermodynamic calculations were used to examine the hydrolytic stability between the MDP-zirconia chemical bonds and the SiO2-silane chemical bonds. Results The CS and ZPCU groups showed higher SBS than the other six groups. There were no significant pairwise differences amongst ZP, SU and ZPSU, or amongst ZP, AU and ZPAU. Aging led to significantly decreased SBS for all groups except CS and ZPCU. There was no statistically significant interaction between surface treatment and aging. XPS determined the chemical bonds between MDP and zirconia. FTIR showed similar shifts in characteristic phosphate peaks for all the primer and/or adhesive groups. Result of thermodynamic calculation showed that equilibrium constant of SiO2-silane system is much larger than the one of MDP-tetragonal phase zirconia system. Significance The application of one-bottle universal adhesives after alumina sandblasting is an alternative to tribochemical silica coating with silanization for bonding to zirconia, while bonding between resin and Y-TZP is more susceptible to hydrolysis when zirconia primer or one-bottle universal adhesive is used.

During development of mineralized collagenous tissues, intrafibrillar mineralization is achieved by preventing mineralization precursor inhibitors that are larger than 40 kDa from entering the collagen fibrils. Such a property is incorporated in the design of a calcium chelator for dentin bonding in the etch-and-rinse technique that selectively demineralizes extrafibrillar apatite while leaving the intrafibrillar minerals intact. This strategy prevents complete demineralization of collagen fibrils, avoids collapse of collagen that blocks resin infiltration after air-drying, and protects the completely demineralized fibrils from bacteria colonization and degradation by endogenous proteases after resin bonding. In the present study, a water-soluble glycol chitosan-EDTA (GCE) conditioner was synthesized by conjugation of EDTA, an effective calcium chelator, to high molecular weight glycol chitosan, which exhibits weak chelation property. The GCE conjugate was purified, characterized by FTIR, 1H NMR, isothermal titration calorimetry and ICP-AES, and subjected to size exclusion dialysis to recover molecules that are >40 kDa. The optimal concentration and application time for etching dentin were determined by bond strength testing to ensure that the dentin bonding results were comparable to phosphoric acid etching, and maintained equivalent bond strength after air-drying of the conditioned collagen matrix. Extrafibrillar demineralization was validated with transmission electron microscopy. Inhibition of endogenous dentin proteases was confirmed using in-situ zymography. The water-soluble GCE dentin conditioner was non-cytotoxic and possessed antibacterial activities against planktonic and single-species biofilms, supporting its ongoing development as a dentin conditioner with air-drying, anti-proteolytic and antibacterial properties to enhance the durability of bonds created using the etch-and-rinse bonding technique. Statement of Significance The current state-of-the-art techniques for filling decayed teeth with plastic tooth-colored materials require conditioning the mineralized, biofilm-covered, decayed dentin with acids or acid resin monomers to create a surface layer of completely- or partially-demineralized collagen matrix for the infiltration of adhesive resin monomers. Nevertheless, fillings prepared using these strategies are not as durable as consumers have anticipated. Conjugation of polymeric glycol chitosan with EDTA produces a new conditioner for dentin bonding that demineralizes only extrafibrillar dentin, reduces endogenous protease activities and kills biofilm bacteria. The high molecular weight glycol chitosan-EDTA is non-cytotoxic to the key regenerative players within the dentin-pulp complex. This advance permits dry bonding and the use of hydrophobic resins.

Collagen-bound nucleation inhibitor ameliorates mineralization via caching of prenucleation clusters., Contemporary models of intrafibrillar mineralization mechanisms are established using collagen fibrils as templates without considering the contribution from collagen-bound apatite nucleation inhibitors. However, collagen matrices destined for mineralization in vertebrates contain bound matrix proteins for intrafibrillar mineralization. Negatively charged, high–molecular weight polycarboxylic acid is cross-linked to reconstituted collagen to create a model for examining the contribution of collagen-ligand interaction to intrafibrillar mineralization. Cryogenic electron microscopy and molecular dynamics simulation show that, after cross-linking to collagen, the bound polyelectrolyte caches prenucleation cluster singlets into chain-like aggregates along the fibrillar surface to increase the pool of mineralization precursors available for intrafibrillar mineralization. Higher-quality mineralized scaffolds with better biomechanical properties are achieved compared with mineralization of unmodified scaffolds in polyelectrolyte-stabilized mineralization solution. Collagen-ligand interaction provides insights on the genesis of heterogeneously mineralized tissues and the potential causes of ectopic calcification in nonmineralized body tissues.

Instability of resin-dentin bonds is the Achilles’ heel of adhesive dentistry. To address this problem, a chelate-and-rinse extrafibrillar dentin demineralization strategy has been developed that keeps intrafibrillar minerals within collagen fibrils intact to prevent activation of endogenous proteases that are responsible for collagen degradation within hybrid layers. The objective of the present study was to evaluate the potential of using chitosan >40 kDa as an antimicrobial extrafibrillar dentin-chelating agent to enhance bond durability. Transmission electron microscopy provided evidence for retention of intrafibrillar minerals and smear plugs in dentin conditioned with 1 wt% chitosan. Analyzed by Kruskal-Wallis analysis of variance, Dunn’s statistic, and separate Mann-Whitney tests, tensile bond strengths to wet- and dry-bonded dentin indicated that chelating dentin with chitosan for 60 s prior to bonding did not result in a significant decline in resin-dentin bond strength when compared with that of phosphoric acid etching ( P > 0.05). Gelatinolytic activity within the hybrid layers was examined via in situ zymography after 24-h storage or after thermomechanical cycling and analyzed with 3-factor analysis of variance. After 24 h, enzymatic activity was detected only within completely demineralized phosphoric acid–etched dentin, with values derived from dry bonding significantly higher than those derived from wet bonding ( P < 0.05). Negligible fluorescence was detected within hybrid layers when dentin was conditioned with chitosan, even after thermomechanical cycling, as compared with the controls. Reduction in water permeability in chitosan-conditioned dentin, attributed to smear plug retention, also fostered long-term bond stability. Antibacterial testing performed with live/dead staining indicated that the acetic acid–solubilized chitosan possessed antibacterial activities against 3 single-species biofilms: Streptococcus mutans, Actinomyces naeslundii, and Enterococcus faecalis. Taken together, the new chitosan-based extrafibrillar demineralization strategy retains intrafibrillar minerals, reduces endogenous protease-initiated collagen degradation, prevents water permeation within hybrid layers, and kills bacteria on dentin surfaces, which are crucial factors for enhancing resin-dentin bond durability.

AIM To evaluate the effect of instrumentation using Reciproc Blue (RB; VDW, Munich, Germany) and XP-endo Shaper (XP-S; FKG Dentaire, La Chaux-deFonds, Switzerland) systems on the area of untouched canal wall (AUCW), accumulated hard-tissue debris (AHTD) and the efficacy of three irrigation protocols on percentage reductions (red%) of AHTD within C-shaped canals of mandibular molars. METHODOLOGY Seventy mandibular molars with C-shaped canals were scanned, matched and assigned to two shaping groups (n = 35): RB and XP-S. Following instrumentation, specimens were triple-matched with respect to the amount of remaining debris and assigned to three irrigation subgroups (n = 10): syringe-and-needle irrigation (SNI), XP-endo Finisher (XP-F; FKG Dentaire) and passive ultrasonic irrigation (PUI). The AUCW% and AHTD% after instrumentation and the red% of AHTD after irrigation were calculated from micro-computed tomography. Data were analysed using comparisons for two groups (RB vs. XP-S) or multiple subgroups followed by pairwise comparison procedures (SNI vs. XP-F vs. PUI) at α = 0.05. RESULTS For RB and XP-S, 33.04% and 30.45%, respectively, of the canal wall remained untouched (P > 0.05). For both groups, the apical third had larger AUCW% than the coronal third (P

Objectives To examine the relation between bruxism and gastroesophageal reflux disease (GERD) and the contribution of depression, anxiety and impaired sleep quality to that association. Methods A three-centre case-control study was conducted consisting of 887 consecutive clinically-diagnosed bruxism patients aged 18–75 years and 887 matched controls. Diagnosis of GERD was based on the Montreal definition: moderate/severe symptoms ≥ one day/week or mild symptoms ≥ two days/week. Logistic regression was used to evaluate the association between bruxism and GERD. Mediation analyses were used to test whether the association between bruxism and GERD was mediated by depression, anxiety or impaired sleep quality. Results Binary logistic regression identified that GERD was associated with bruxism (odds ratio, 6.87; 95% confidence interval (CI), 4.34–10.88). This association was stronger in females (odds ratio, 12.27; 95% CI, 5.81–25.91) than in males (odds ratio, 3.99; 95% CI, 2.17–7.32). Multinomial logistic regression identified that GERD was associated with all types of bruxism (sleep bruxism alone, odds ratio, 6.71, 95% CI, 4.22–10.68; awake bruxism alone, odds ratio, 13.06, 95% CI, 5.32–32.05; overlap of sleep bruxism and awake bruxism, odds ratio, 6.48, 95% CI, 3.05–13.77). Ordinal logistic regression identified that longer GERD duration (> 2 years vs ≤ 2 years) was associated with bruxism frequency (odds ratio, 1.50; 95% CI, 1.10–2.05). Mediation analyses found that the association between bruxism and GERD was partially-mediated through depression, anxiety and impaired sleep quality. Conclusions Clinically-diagnosed bruxism is associated with symptomatic GERD and is partially-mediated through depression, anxiety and impaired sleep quality. Clinical Significance Because bruxism is strongly associated with symptomatic GERD and patients with frequent bruxism symptoms tend to suffer from GERD for extensive time-periods, dentists should consider evaluation of GERD status as an elemental part of the medical examination of bruxism, especially severe bruxism.

Objectives The present study evaluated the long-term dentine bonding effectiveness of five universal adhesives in etch-and-rinse or self-etch mode after 12 months of water-ageing. Methods The adhesives evaluated included All-Bond Universal, Clearfil Universal Bond, Futurabond U Prime&Bond Elect and Scotchbond Universal. Microtensile bond strength and transmission electron microscopy of the resin-dentine interfaces created in human coronal dentine were examined after 24 h or 12 months. Results Microtensile bond strength were significantly affected by bonding strategy (etch-and-rinse vs self-etch) and ageing (24 h vs 12 months). All subgroups showed significantly decreased bond strength after ageing except for Prime&Bond Elect and Scotchbond Universal used in self-etch mode. All five adhesives employed in etch-and-rinse mode exhibited ultrastructural features characteristic of collagen degradation and resin hydrolysis. A previously-unobserved inside-out collagen degradation pattern was identified in hybrid layers created by 10-MDP containing adhesives (All-Bond Universal, Scotchbond Universal and Clearfil Universal Bond) in the etch-and-rinse mode, producing partially degraded collagen fibrils with intact periphery and a hollow core. In the self-etch mode, all adhesives except for Prime&Bond Elect exhibited degradation of the collagen fibrils along the thin hybrid layers. The three 10-MDP containing universal adhesives did not protect surface collagen fibrils from degradation when bonding was performed in the self-etch mode. Conclusions Despite the adjunctive conclusion that bonds created by universal adhesives in the self-etch bonding mode are more resistant to decline in bond strength when compared with those bonds created using the etch-and-rinse mode, bonds created by universal adhesives are generally incapable of defying ageing.

Recent studies have shown that ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) inactivates endogenous dentin proteases, thereby preventing collagen degradation and improving the durability of adhesive bonds to dentin. Bond durability is routinely assessed by monotonic microtensile testing, which does not consider the cyclic nature of mastication. Objective To characterize the effect of an EDC pretreatment on the fatigue crack growth behavior of resin–dentin bonds. Methods Bonded interface Compact Tension (CT) specimens were prepared using a three-step etch-and-rinse adhesive and hybrid resin–composite. Adhesive bonding of the treated groups included a 1 min application of an experimental EDC conditioner to the acid-etched dentin. The control groups did not receive EDC treatment. The fatigue crack growth resistance was examined after storage in artificial saliva for 0, 3 and 6 months. Results There was no significant difference in the immediate fatigue crack growth resistance of the EDC-treated and control groups at 0 months. However, after the 3 and 6 months storage periods the EDC-treated groups exhibited significantly greater (p ≤ 0.05) fatigue crack growth resistance than the control specimens. Significance Although the EDC treatment maintained the fatigue crack growth resistance of the dentin bonds through 6 months of storage, additional studies are needed to assess its effectiveness over longer periods and in relation to other cross-linking agents.

Self-assembled nanolayering structures have been reported in resin-dentin interfaces created by adhesives that contain 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP). These structures have been hypothesized to contribute to bond durability. The objective of the present study was to determine the extent of nanolayering in resin-dentin interfaces after application of commercialized 10-MDP-containing self-etch and universal adhesives to human dentin. Seven commercialized adhesives were examined: Adhese Universal (Ivoclar-Vivadent), All-Bond Universal (Bisco, Inc.), Clearfil SE Bond 2, Clearfil S3 Bond Plus, Clearfil Universal Bond (all from Kuraray Noritake Dental Inc.), G-Premio Bond (GC Corp.), and Scotchbond Universal (3M ESPE). Each adhesive was applied in the self-etch mode on midcoronal dentin according to the respective manufacturer’s instructions. Bonded specimens ( n = 6) were covered with flowable resin composite, processed for transmission electron microscopy, and examined at 30 random sites without staining. Thin-film glancing angle X-ray diffraction (XRD) was used to detect the characteristic peaks exhibited by nanolayering ( n = 4). The control consisted of 15%wt, 10%wt, and 5%wt 10-MDP (DM Healthcare Products, Inc.) dissolved in a mixed solvent (ethanol and water weight ratio 9:8, with photoinitiators). Experimental primers were applied to dentin for 20 s, covered with hydrophobic resin layer, and examined in the same manner. Profuse nanolayering with highly ordered periodicity (~3.7 nm wide) was observed adjacent to partially dissolved apatite crystallites in dentin treated with the 15% 10-MDP primer. Three peaks in the 2θ range of 2.40° (3.68 nm), 4.78° (1.85 nm), and 7.18° (1.23 nm) were identified from thin-film XRD. Reduction in the extent of nanolayering was observed in the 10% and 5% 10-MDP experimental primer-dentin interface along with lower intensity XRD peaks. Nanolayering and characteristic XRD peaks were rarely observed in specimens prepared from the commercialized adhesives. The sparsity of nanolayering in resin-dentin interfaces created by commercialized adhesives challenges its clinical effectiveness as a mechanism for improving bond longevity in dentin bonding.

Objectives Identification of the mechanism of chemical coupling of a phosphate ester monomer to zirconia via a computational modeling approach enables materials scientists to design new coupling agents that can resist hydrolytic degradation of bonds made by methacrylate resins to zirconia. We investigated the possibility of chemical bonding between 10-methacryloyloxydecyldihydrogenphosphate (MDP) and tetragonal zirconia, and the effect of pH reaction conditions on such prospective chemical bonds. Methods A tetragonal zirconia crystal model was created. An “Our-own N-layered integrated molecular orbital and molecular mechanics” (ONIOM) method was used to simulate two potential configurations of the MDP–ZrO2 system: double-coordinate and single-coordinate. Thermodynamic calculations were used to ascertain if the reaction could proceed spontaneously and to compare the stability of the two possible configurations. Short-term testing of shear bond strength (SBS) was done to evaluate bonding improvement of MDP to alumina-sandblasted zirconia surfaces in neutral, acidic or alkaline environments. Results Digital models of coordinate bonds between MDP and tetragonal zirconia were constructed. Thermodynamic calculations indicated that the Gibbs free energy for forming double-coordinate and single-coordinate configurations were −461.2 kJ/mol and −450.9 kJ/mol, respectively. Equilibrium constants for the double-coordinate and single-coordinate configurations were 6.4 × 1080 and 9.8 × 1078, respectively. Application of MDP in alkaline conditions showed the highest SBS, whereas acid conditions resulted in lower SBS. Significance MDP can establish a “true” chemical bond with zirconia spontaneously. The double-coordinate configuration was identified to be more energetically favorable than the single-coordinate configuration for the coupling of MDP to zirconia. Alkaline conditions may positively affect formation of MDP–ZrO2 coordination bonds.

To evaluate the effectiveness of TRUShape® 3D Conforming Files, compared with Twisted Files, in reducing bacteria load from root canal walls, in the presence or absence of irrigant agitation.Extracted human premolars with single oval-shaped canals were infected with Enterococcus faecalis. Teeth in Group I (N=10; NaOCl and QMix® 2in1 as respective initial and final irrigants) were subdivided into 4 subgroups: (A) TRUShape® instrumentation without irrigant activation; (B) TRUShape® instrumentation with sonic irrigant agitation; (C) Twisted Files without irrigant agitation; (D) Twisted Files with sonic irrigant agitation. To remove confounding factor (antimicrobial irrigants), teeth in Group II (N=10) were irrigated with sterile saline, using the same subgroup designations. Specimens before and after chemomechanical débridement were cultured for quantification of colony-forming units (CFUs). Data from each group were analyzed separately using two-factor ANOVA and Holm-Sidak multiple comparison (α=0.05). Canal wall bacteria were qualitatively examined using scanning electron microscopy (SEM) and light microscopy of Taylor-modified Brown and Brenn-stained demineralised sections.CFUs from subgroups in Group I were not significantly different (P=0.935). For Group II, both file type (P0.001) and irrigant agitation (P0.001) significantly affected log-reduction in CFU concentrations. The interaction of these two factors was not significant (P=0.601). Although SEM showed reduced canal wall bacteria, bacteria were present within dentinal tubules after rotary instrumentation, as revealed by light microscopy of longitudinal root sections.TRUShape® files removed significantly more canal wall bacteria than Twisted Files when used without an antibacterial irrigant; the latter is required to decontaminate dentinal tubules.Root canal disinfection should not be focused only on a mechanistic approach. Rather, the rational choice of a rotary instrumentation system should be combined with the use of well-tested antimicrobial irrigants and delivery/agitation techniques to establish a clinically realistic chemomechanical débridement protocol.

Objective This work measured the amount of bound versus unbound water in completely-demineralized dentin. Methods Dentin beams prepared from extracted human teeth were completely demineralized, rinsed and dried to constant mass. They were rehydrated in 41% relative humidity (RH), while gravimetrically measuring their mass increase until the first plateau was reached at 0.064 (vacuum) or 0.116 g H2O/g dry mass (Drierite). The specimens were then exposed to 60% RH until attaining the second plateau at 0.220 (vacuum) or 0.191 g H2O/g dry mass (Drierite), and subsequently exposed to 99% RH until attaining the third plateau at 0.493 (vacuum) or 0.401 g H2O/g dry mass (Drierite). Results Exposure of the first layer of bound water to 0% RH for 5 min produced a -0.3% loss of bound water; in the second layer of bound water it caused a -3.3% loss of bound water; in the third layer it caused a -6% loss of bound water. Immersion in 100% ethanol or acetone for 5 min produced a 2.8 and 1.9% loss of bound water from the first layer, respectively; it caused a -4 and -7% loss of bound water in the second layer, respectively; and a -17 and -23% loss of bound water in the third layer. Bound water represented 21-25% of total dentin water. Chemical dehydration of water-saturated dentin with ethanol/acetone for 1 min only removed between 25 and 35% of unbound water, respectively. Significance Attempts to remove bound water by evaporation were not very successful. Chemical dehydration with 100% acetone was more successful than 100% ethanol especially the third layer of bound water. Since unbound water represents between 75 and 79% of total matrix water, the more such water can be removed, the more resin can be infiltrated. © 2014 Academy of Dental Materials.

N-Acetylcysteine (NAC), a cysteine prodrug and glutathione (GSH) precursor, has been used for several decades in clinical therapeutic practices as a mucolytic agent and for the treatment of disorders associated with GSH deficiency. Other therapeutic activities of NAC include inhibition of inflammation/NF-κB signaling and expression of proinflammatory cytokines. N-Acetylcysteine is also a nonantibiotic compound possessing antimicrobial property and exerts anticarcinogenic and antimutagenic effects against certain types of cancer. Recently, studies describing potentially important biological and pharmacological activities of NAC have stimulated interests in using NAC-based therapeutics for oral health care. The present review focused on the biological activities of NAC and its potential oral applications. The potential side effects of NAC and formulations for drug delivery were also discussed, with the intent of advancing NAC-associated treatment modalities in oral medicine.

Made available in DSpace on 2018-12-11T17:20:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-07-15 National Natural Science Foundation of China Secondary caries and hybrid layer degradation are two major challenges encountered in long-term resin-dentin bond stability. As a link between resin and dentin, adhesives that possess both antimicrobial and anti-proteolytic activities are in demand for eliminating bacteria-induced secondary caries and preventing hybrid layers from degradation. In the present study, a new quaternary ammonium methacryloxy silane (QAMS) prepared from sol-gel chemistry was incorporated into experimental adhesives to examine their antimicrobial effect and anti-proteolytic potential. This functional methacrylate resin monomer contains polymerizable methacryloxy functionalities as well as a positively-charged quaternary ammonium functionality with a long, lipophilic -C18H37 alkyl chain for puncturing the cell wall/membrane of surface-colonizing organisms. Antibacterial testing performed using agar diffusion test, live/dead bacterial staining and colony-forming unit counts all indicated that the QAMS-containing adhesives killed Streptococcus mutans and Actinomyces naeslundii in a dose-dependent manner via a predominant contact-killing mechanism. Gelatinolytic activity within the hybrid layers created by these adhesives was examined using in-situ zymography. Hybrid layers created with 0% QAMS-containing adhesive exhibited intense green fluorescence emitted by the hydrolyzed fluorescein-conjugated gelatin, with 4-fold increase in enzymatic activity compared with an experimental adhesive containing 5% QAMS. Taken together, incorporation of 5% QAMS in the experimental adhesive provides simultaneous antimicrobial and anti-proteolytic activities that are crucial for the maintenance of long-term resin-dentin bond integrity. Statement of Significance: Durability of resin-dentin interfacial bond remains a clinically-significant challenge. Secondary caries caused by bacteria and the degradation of hybrid layers via endogenous dentin proteases are two important contributors to the poor resin-dentin bond durability. The present study developed a new 5% QAMS-containing adhesive that provides simultaneous antimicrobial and dentin protease inhibition functions to extend the longevity of resin-dentin bonds. State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics West China Hospital of Stomatology Sichuan University The Dental College of Georgia Augusta University Department of Restorative Dentistry Institute of Science and Technology São Paulo State University UNESP São Jose dos Campos Department of Biomedical and Neuromotor Sciences DIBINEM University of Bologna – Alma Mater Studiorum State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases School of Stomatology The Fourth Military Medical University Department of Restorative Dentistry Institute of Science and Technology São Paulo State University UNESP São Jose dos Campos

Fatigue of resin–dentin adhesive bonds is critical to the longevity of resin composite restorations. Objectives The objectives were to characterize the fatigue and fatigue crack growth resistance of resin–dentin bonds achieved using two different commercial adhesives and to identify apparent “weak-links”. Methods Bonded interface specimens were prepared using Adper Single Bond Plus (SB) or Adper Scotchbond Multi-Purpose (SBMP) adhesives and 3M Z100 resin composite according to the manufacturers’ instructions. The stress-life fatigue behavior was evaluated using the twin bonded interface approach and the fatigue crack growth resistance was examined using bonded interface Compact Tension (CT) specimens. Fatigue properties of the interfaces were compared to those of the resin–adhesive, resin composite and coronal dentin. Results The fatigue strength of the SBMP interface was significantly greater than that achieved by SB (p ≤ 0.01). Both bonded interfaces exhibited significantly lower fatigue strength than that of the Z100 and dentin. Regarding the fatigue crack growth resistance, the stress intensity threshold (ΔKth) of the SB interface was significantly greater (p ≤ 0.01) than that of the SBMP, whereas the ΔKth of the interfaces was more than twice that of the parent adhesives. Significance Collagen fibril reinforcement of the resin adhesive is essential to the fatigue crack growth resistance of resin–dentin bonds. Resin tags that are not well hybridized into the surrounding intertubular dentin and/or poor collagen integrity are detrimental to the bonded interface durability.

Objectives To examine whether solvents and changing the molecular structure of 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP) affect its chemical affinity to Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP). Methods The present work investigated the chemical affinity between Y-TZP and 10-MDP dissolved in different solvents (acetone/ethanol/water or mixture) using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and thermodynamic calculations. Shear bond strength (SBS) tests were used to evaluate the influence of different solvents on 10-MDP bonding. In addition, several phosphate ester monomer variants were created by changing the 10-MDP molecular structure. Changes included extending/shortening the spacer chain-length, and installing hydroxyl or carboxyl groups as side chains at different positions along the spacer chain. The thermodynamic parameters of the complexes formed between the 10-MDP variants and tetragonal zirconia were evaluated. Results The acquired data indicated that solvent is necessary for the formation of Zr–O–P bonds between 10-MDP and Y-TZP. Solvents affected the chemical affinity of 10-MDP to Y-TZP; acetone facilitated the best bonding, followed by ethanol. Changing the molecular structure of 10-MDP affected its chemical affinity to Y-TZP. The variants 15-MPDP, 12-MDDP, 6-hydroxyl-10-MDP and 6-carboxy-10-MDP all exhibited higher thermodynamic stability than 10-MDP when coordinated with tetragonal zirconia. In contrast, 2-MEP, 5-MPP, 10-hydroxyl-MDP, 10-carboxy-MDP, 5,6-dihydroxyl-10-MDP and 5,6-dicarboxy-10-MDP exhibited lower thermodynamic stability. Significance 10-MDP coordinates with zirconia through dissociating in solvents. Changing the molecular structure of 10-MDP theoretically affects its chemical affinity to Y-TZP.

Made available in DSpace on 2018-12-11T17:12:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-07-01 National Natural Science Foundation of China Objective A recently-launched universal adhesive, G-Premio Bond, provides clinicians with the alternative to use the self-etch technique for bonding to dentine without waiting for the adhesive to interact with the bonding substrate (no-waiting self-etch; Japanese brochure), or after leaving the adhesive undisturbed for 10 s (10-s self-etch; international brochure). The present study was performed to examine in vitro performance of this new universal adhesive bonded to human coronal dentine using the two alternative self-etch modes. Methods One hundred and ten specimens were bonded using two self-etch application modes and examined with or without thermomechanical cycling (10,000 thermal cycles and 240,000 mechanical cycles) to simulate one year of intraoral functioning. The bonded specimens were sectioned for microtensile bond testing, ultrastructural and nanoleakage examination using transmission electron microscopy. Changes in the composition of mineralised dentine after adhesive application were examined using Fourier transform infrared spectroscopy. Results Both reduced application time and thermomechanical cycling resulted in significantly lower bond strengths, thinner hybrid layers, and significantly more extensive nanoleakage after thermomechanical cycling. Using the conventional 10-s application time improved bonding performance when compared with the no-waiting self-etch technique. Nevertheless, nanoleakage was generally extensive under all testing parameters employed for examining the adhesive. Conclusion Although sufficient bond strength to dentine may be achieved using the present universal adhesive in the no-waiting self-etch mode that does not require clinicians to wait prior to polymerisation of the adhesive, this self-etch concept requires further technological refinement before it can be recommended as a clinical technique. Clinical significance Although the surge for cutting application time to increase user friendliness remains the most frequently sought conduit for advancement of dentine bonding technology, the use of the present universal adhesive in the no-waiting self-etch mode may not represent the best use of the adhesive. Department of Prosthodontics Guanghua School and Hospital of Stomatology & Guangdong Provincial Key Laboratory of Stomatology Sun Yat-sen University Department of Restorative Dentistry Institute of Science and Technology São Paulo State University UNESP São Jose dos Campos Key Laboratory of Oral Medicine Guangzhou Institute of Oral Disease Stomatology Hospital of Guangzhou Medical University Department of Biomedical and Neuromotor Sciences DIBINEM University of Bologna – Alma Mater Studiorum College of Graduate Studies Augusta University State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases School of Stomatology The Fourth Military Medical University Department of Restorative Dentistry Institute of Science and Technology São Paulo State University UNESP São Jose dos Campos National Natural Science Foundation of China: 2015A030401035 National Natural Science Foundation of China: 81400555 National Natural Science Foundation of China: 81500883

Objectives 10-methacryloyloxydecyldihydrogenphosphate (MDP) containing primers improve bonding of yttria-stabilised tetragonal zirconia (Y-TZP) to methacrylate resins. The present study investigated the role played by water in the deterioration of MDP-mediated zirconia-resin bonds. Methods Grit-blasted Y-TZP plates were conditioned with two MDP primers and bonded with resin for shear bond strength (SBS) testing. Additional bonded plates were aged hydrothermally and compared with unaged Y-TZP after 24 h of water-storage or 6 months of water/acid/alkali-storage. The monoclinic phase ( m –ZrO 2 ) in different groups was determined by X-ray diffraction. Hydrolytic stability of the coordinate bond between MDP and zirconia in neutral/acid/alkaline environment was analysed using thermodynamic calculations. Microleakage and release of the element phosphorus from MDP-mediated Y-TZP/resin-bonded interfaces were evaluated via methylene blue dye infiltration and inductively coupled plasma-mass spectrometry (ICP-MS). Results Hydrothermal ageing did not significantly alter SBS. Ageing in acidic or neutral medium led to significant decline in SBS. The m –ZrO 2 phase increased after hydrothermal ageing but no m –ZrO 2 was detected in the water/acid/alkali-aged specimens. A higher equilibrium constant was identified in the MDP– t –ZrO 2 complex when compared with the MDP– m –ZrO 2 complex. MDP-conditioning failed to prevent infiltration of the methylene blue dye. Phosphorus was detected by ICP-MS from the solutions used for soaking the resin-bonded specimens. Conclusions Hydrolysis of the coordinate bond between MDP and ZrO 2 , rather than t → m phase transformation, weakens the bond integrity between MDP-conditioned Y-TZP and methacrylate resin. Clinical significance Hydrolysis of the coordinate bond between MDP and zirconia is responsible for deterioration of the integrity of the bond between MDP-conditioned Y-TZP and methacrylate resin.

Introduction The purpose of this study was to evaluate the in vitro antibacterial effect of AH Plus (Dentsply, DeTrey, Konstanz, Germany) incorporated with quaternary ammonium epoxy silicate (QAES) against Enterococcus faecalis . Methods QAES particles were synthesized by the cocondensation of tetraethoxysilane with 2 trialkoxysilanes (3-[trimethoxysilyl]propyldimethyloctadecyl ammonium chloride and 3-glycidyloxypropyltrimethoxysilane) through a 1-pot sol-gel route. Dried QAES particles were then characterized by attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy. AH Plus sealers incorporated with 0–8 wt% QAES were tested after 4 weeks of water aging to assess the in vitro antibacterial activity against E. faecalis by the direct contact test (DCT) and 3-dimensional image analysis of live/dead-stained E. faecalis biofilms using confocal laser scanning microscopy. Results The Fourier transform infrared spectroscopy spectrum of QAES particles revealed the coexistence of the characteristic absorbance band of the siloxane backbone (Si-O-Si) from 1,000–1,100 cm −1 , epoxide band peaking at ∼916 cm −1 , and C-N stretching vibration peaking at 1,373 cm −1 . The scanning electron microscopic image showed the spherical morphology of QAES particles with ∼120 nm in diameter and a rough surface. DCT results revealed that AH Plus alone (0 wt% QAES) after 4 weeks of water aging had no inhibitory effect on E. faecalis growth ( P = .569). AH Plus incorporated with QAES (2–8 wt%) showed antibacterial activity against E. faecalis as shown in DCT and biofilm viability results ( P Conclusions The incorporation of QAES into epoxy resin–based AH Plus may be a promising approach for controlling endodontic infection at the time of canal filling and preventing subsequent reinfection.

The present study compared the efficacies of the self-etching Teeth Primer (TP: 4-META), and the etchants Red Activator (RA; 65% phosphoric acid) and Green Activator (GA; 10% citric acid with 3% ferric chloride), for bonding to enamel and dentine of human primary and permanent teeth, when used with 4-META/MMA-TBB resin (Bondfill SB).Forty-eight non-carious primary canines and third molars were used. Eight groups were prepared: Group 1 (primary enamel with RA), Group 2 (permanent enamel with RA), Group 3 (primary enamel with TP), Group 4 (permanent enamel with TP), Group 5 (primary dentine with GA), Group 6 (permanent dentine with GA), Group 7 (primary dentine with TP) and Group 8 (permanent dentine with TP). Micro-tensile bond strengths (MTBS) were measured and analyzed statistically using ANOVAs and Tukey HSD tests at α=0.05. Efficacy of etching/priming and the morphology of bonded interfaces were observed with SEM.Etching/priming efficacy of TP on enamel was low. The MTBS of Group 2 was significantly higher than the other groups (Groups 1, 3 and 4). For dentine, significant differences in MTBS were observed, in the order of Groups 687=5 (p0.05). The MTBSs of permanent dentine were significantly higher than primary dentine. For primary teeth, there was no significant difference in the MTBSs between enamel and dentine, irrespective of primer or etchant (p0.05).TP primer/Bondfill SB may be used as an alternative to other adhesive/resin composite systems for bonding to enamel and dentine of primary teeth.

New obturation biomaterials have been introduced over the past decade to improve the seal of the root canal system. However, it is not clear whether they have really produced a three-dimensional impervious seal that is important for reducing diseases associated with root canal treatment. A review of the literature was performed to identify models that have been employed for evaluating the seal of the root canal system. In vitro and in vivo models are not totally adept at quantifying the seal of root canals obturated with classic materials. Thus, one has to resort to clinical outcomes to examine whether there are real benefits associated with the use of recently introduced materials for obturating root canals. However, there is no simple answer because endodontic treatment outcomes are influenced by a host of other predictors that are more likely to take precedence over the influence of obturation materials. From the perspective of clinical performance, classic root filling materials have stood the test of time. Because many of the recently introduced materials are so new, there is not enough evidence yet to support their ability to improve clinical performance. This emphasizes the need to translate anecdotal information into clinically relevant research data on new biomaterials.

Organically modified silicates represent an excellent example of organic-inorganic hybrids in materials science. The routes to achieve incorporation of organic functionalities include grafting and co-condensation (one-pot synthesis). Compared with the grafting method, the advantage of one-pot synthesis manifests as the tunability of both mechanical and biological properties. Herein, we report a silsesquioxane-silica hybrid (SqSH) with dual functional groups (alkylammonium and methacrylate chains) synthesized by the hydrolytic co-condensation of one tetraethoxysilane and two alkoxysilanes. Successful co-condensation is validated by attenuated total reflection-Fourier transform infrared (ATR-FTIR), 29Si nuclear magnetic resonance ( 29Si NMR), and thermogravimetric analysis (TGA). 3-(Trimethoxysilyl) propyldimethyloctadecyl ammonium chloride (SiQAC), one of the three precursors, simultaneously serves as a structure-directing agent in the modified Stöber reaction, resulting in SqSH particles with structural hierarchy of both ordered lamellar structure and spherical morphology, as revealed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The SqSH particles bear tunable mechanical properties and, when incorporated into bis-GMA/TEGDMA resin, antimicrobial activities against Streptococcus mutans, Actinomyces naeslundii, and Candida albicans.

Objectives Root canal treatment forms an essential part of general dental practice. Sodium hypochlorite (NaOCl) is the most commonly used irrigant in endodontics due to its ability to dissolve organic soft tissues in the root canal system and its action as a potent antimicrobial agent. Although NaOCl accidents created by extrusion of the irrigant through root apices are relatively rare and are seldom life-threatening, they do create substantial morbidity when they occur. Methods To date, NaOCl accidents have only been published as isolated case reports. Although previous studies have attempted to summarise the symptoms involved in these case reports, there was no endeavour to analyse the distribution of soft tissue distribution in those reports. In this review, the anatomy of a classical NaOCl accident that involves facial swelling and ecchymosis is discussed. Results By summarising the facial manifestations presented in previous case reports, a novel hypothesis that involves intravenous infusion of extruded NaOCl into the facial vein via non-collapsible venous sinusoids within the cancellous bone is presented. Conclusions Understanding the mechanism involved in precipitating a classic NaOCl accident will enable the profession to make the best decision regarding the choice of irrigant delivery techniques in root canal debridement, and for manufacturers to design and improve their irrigation systems to achieve maximum safety and efficient cleanliness of the root canal system.

The present work examined the effects of dipentaerythritol penta-acrylate phosphate (PENTA) as an alternative phosphate ester monomer for bonding of methacrylate-based resins to yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and further investigated the potential bonding mechanism involved. Shear bond strength testing was performed to evaluate the efficacy of experimental PENTA-containing primers (5, 10, 15, 20 or 30 wt% PENTA in acetone) in improving resin-Y-TZP bond strength. Bonding without the use of a PENTA-containing served as the negative control, and a Methacryloyloxidecyl dihydrogenphosphate(MDP)-containing primer was used as the positive control. Inductively coupled plasma-mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) were used to investigate the potential existence of chemical affinity between PENTA and Y-TZP. Shear bond strengths were significant higher in the 15 and 20 wt% PENTA groups. The ICP-MS, XPS and FTIR data indicated that the P content on the Y-TZP surface increased as the concentration of PENTA increased in the experimental primers, via the formation of Zr–O–P bond. Taken together, the results attest that PENTA improves resin bonding of Y-TZP through chemical reaction with Y-TZP. Increasing the concentration of PENTA augments its binding affinity but not its bonding efficacy with zirconia.