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The conventional radiotherapy protocol to treat head-and-neck cancer is usually followed by tooth-decay onset. Radiation impact on mineralized tooth structures is not well-understood. This systematic review aimed to collect the recorded effects of therapeutic radiation on tooth chemical, structural and mechanical properties, in relation with their means of investigation.Systematic search (January 01 2012 - September 30 2021) terms were "Radiotherapy", "Radiation effects", "Dental enamel", "Dentin", "Human" and "Radiotherapy" NOT "Laser".PubMed, DOSS and Embase databases were searched.Selected studies compared dental enamel, coronal and root dentin properties before and after in vitro or in vivo irradiation up to 80 Gy.The systematic search identified 353 different articles, with 28 satisfying inclusion criteria. Their reference lists provided two more. Twenty-two studies evaluated dental enamel evolution, nine assessed coronal dentin and eight concerned root dentin. Coronal and root dentin results indicate a major impact of the radiation on their organic matrix. Dental enamel's chemical properties are less modified. Enamel and root dentin's hardness are decreased by therapeutic radiation, but no consensus arises for coronal dentin.Our findings revealed some interesting information about enzymatic degradation mechanisms of dentin organic matrix and highlighted that dental hard-tissue characterization requires highly specific expertise in materials science. That scientific knowledge is necessary to design suitable protocols, adequately analyze the obtained data, and, thus, provide relevant conclusions.Better knowledge and understanding of the mechanisms involved in the degradation of enamel and dentin would enable development of new preventive and therapeutic methods for improved medical care of patients undergoing radiotherapy.

To evaluate in vitro the mechanical, biological, and polymerization behavior of a flowable bulk-fill composite with fibers as a dispersed phase.EverX Flow™ (GC Corporation) (EXF), one conventional bulk-fill composite (Filtek™ Bulk Fill Posterior Restorative, 3 M (FBF)), and one flowable bulk composite without fibers (SDR® flow+, Dentsply (SDR)) were tested. Samples were characterized in terms of flexural strength (ISO 4049), fracture toughness (ISO 20795-1), and Vickers hardness. Polymerization stress and volumetric shrinkage were evaluated. The in vitro biological assessment was achieved on cultured primary Human Gingival Fibroblast cells (HGF). The cell metabolic activity was evaluated using Alamar Blue assay at 1, 3, and 5 days of contact to the 3 tested composite extracts (ISO 10993) and cell morphology was evaluated by confocal microscopy. Data were submitted to One-Way analysis of variance (ANOVA) and independent t-test (α = 0.05).FBF showed statistically higher Vickers hardness and flexural modulus than EXF and SDR. However, EXF showed statistically higher KEXF had a significantly higher fracture toughness validating its potential use as a restorative material in stress bearing areas. EXF showed higher shrinkage stress values, and less cytotoxic effect. Fiber reinforced flowable composite is mainly indicated for deep and large cavities, signifying the importance for assessing its shrinkage stress and biological behavior.

While dental composite long-term aging has already been studied in the past, no data exist about the early aging while it might be detrimental regarding the composites' longevity. This study aims to better understand the effects of early water exposure on dental composites. Dental resin composites with different fillers ratio were subjected to water exposure during 24 h, 1 week, or 1 month. After photopolymerization, the samples were stored at different conditions, whether in wet or dry condition (W, D, respectively) and in wet conditions after a first 24 h storage in dry conditions (DW). Three-point bending tests were performed to measure the flexural modulus. The samples were then subjected to a sorption/desorption protocol. While the matrix alone did not undergo any mechanical degradation with exposure time, the composites matrices presented a decrease in elastic modulus. This decrease was the highest for the matrix with nonsilanized fillers. Interestingly, the DW condition was detrimental for all the samples. Regarding the sample with nonsilanized fillers in DW for 1 month presented an elastic modulus lower than the matrix alone. These results were assigned to the sorption capacity of the polymer matrix, suggesting that the diffusion mechanisms and the nature of water molecules are determinant in the composite degradation. This study showed that dental composite early degradation mechanisms after water exposure are involved in the polymer matrix postpolymerization process as soon as after 24 h. Such mechanisms are detrimental in terms of the dental composite efficiency and have to be understood.

Contains fulltext : 154871.pdf (Publisher’s version ) (Closed access) OBJECTIVE: Due to an increased focus on erosive tooth wear (ETW), the European Federation of Conservative Dentistry (EFCD) considered ETW as a relevant topic for generating this consensus report. MATERIALS AND METHODS: This report is based on a compilation of the scientific literature, an expert conference, and the approval by the General Assembly of EFCD. RESULTS: ETW is a chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria, and it is characterized by loss of the natural surface morphology and contour of the teeth. A suitable index for classification of ETW is the basic erosive wear examination (BEWE). Regarding the etiology, patient-related factors include the pre-disposition to erosion, reflux, vomiting, drinking and eating habits, as well as medications and dietary supplements. Nutritional factors relate to the composition of foods and beverages, e.g., with low pH and high buffer capacity (major risk factors), and calcium concentration (major protective factor). Occupational factors are exposition of workers to acidic liquids or vapors. Preventive management of ETW aims at reducing or stopping the progression of the lesions. Restorative management aims at reducing symptoms of pain and dentine hypersensitivity, or to restore esthetic and function, but it should only be used in conjunction with preventive strategies. CONCLUSIONS: Effective management of ETW includes screening for early signs of ETW and evaluating all etiological factors. CLINICAL RELEVANCE: ETW is a clinical condition, which calls for the increased attention of the dental community and is a challenge for the cooperation with other medical specialities.

International audience; People with eating disorders suffer from a mental disorder that negatively affects their physical and/or mental health. The three most frequent eating disorders are binge eating disorder, bulimia nervosa, and anorexia nervosa. Environmental and genetic factors are involved in the pathogenesis of eating disorders in vulnerable persons. Although treatment varies among different types of eating disorders, nutrition, medical care combined with psychotherapy and medications are standard of care. The aim of this review is to give an overview of the oral health impact of eating disorders with a special emphasis on the periodontium. Oral health professionals have a unique role to play in the early diagnosis of eating disorders because of the important impact that eating disorders have on the oral cavity. In vomiting-associated eating disorders, the risk of erosive tooth wear is mainly localized to the palatal surfaces of the incisors. Emerging evidence also indicates a high frequency of gingivitis and gingival recessions associated with compulsive toothbrushing. A holistic approach, including oral health and functional rehabilitation, should be promoted by physicians, psychiatrists, and dentists for people with eating disorders.

Different kinds of interactions between the restorative material and mineralized dental tissues result in secondary caries around dental composites. Of these, the mechanical interactions have to be carefully investigated. Due to the elastic mismatch between dental tissues and the composite restoration, complex stresses and strains develop at their interface. This complex mechanical environment disturbs the demineralization-remineralization equilibrium of dental hard tissues. The fluid flow both over and within enamel and dentin, associated with their complex ultrastructure and mechanical behavior, is a key factor. It is known that external mechanical loading can indirectly promote the dissolution of enamel and dentin through a pumping action of cariogenic fluids in and out of microgaps at the interface between mineralized tissues and composite. Mechanical loading can also directly influence the physicochemical behavior of dental hard tissues by inducing complex strain and stress fields on the crystal scale. It is important to consider both the direct and indirect paths by which mechanical loading can influence the apatite dissolution kinetics. Therefore, a system atic approach should be used to investigate the mechanism of secondary caries formation considering the tooth-composite interface as a unique complex in which each element has an influence on the other.

Objective Resin-based composites are widely used in dental restorations; however, their volumetric shrinkage during polymerization leads to several issues that reduce the restoration survival rates. For overcoming this problem, a deep study of shrinkage phenomena is necessary. Methods In this study, micro-tomography (μ-CT) is combined with digital volume correlation (DVC) to investigate the effect of several factors on the polymerization strain of dental composites in model cavities: the presence/absence of an adhesive, the use of transparent/blackened cavities, and irradiation times between 1 and 40 s. Results The results indicate that the presence of an adhesive at the interface between the cavity and composite does not reduce the total strain but instead limits it to a preferential direction. In addition, regardless of the conditions, the main strain is generated along the axis parallel to the polymerization irradiation (the vertical axis). Finally, the total strain appears to occur in the first 5 s of irradiation, with no further evolution observed for longer irradiation times. Significance This work provides new insight into resin-based composite shrinkage and demonstrates the benefit of coupling DVC and μ-CT to better understand the degradation mechanisms of these materials.

Purpose To investigate the relationship between the microstructure of CAD/CAM blocks and the quality of adhesion as function of the surface treatment and resin cement type. Materials and methods Two nano-ceramic composite resin CAD/CAM blocks, Lava Ultimate (LU) and Cerasmart (CS), and two Leucite-reinforced glass ceramic CAD/CAM IPS blocks, Empress® CAD (EM) and InitialTM LRF (IR), received either Hydrofluoric acid (HF) or sandblasting (SB) surface treatments. The blocks were then luted using two dual-cure resin cements, LinkForce (LF) and Multilink Automix (ML) with their corresponding silanes, resulting in 16 study groups. The luted blocks were then thermal-cycling (TC) for 5000 cycles and subjected to a microtensile bond strength (μTBS) test. Scanning electron microscopy (SEM) micrographs of the treated surfaces were analyzed using ImageJ software and XRD analyses were performed for the two ceramic blocks. The data obtained were submitted to Games-Howell post-hoc nonparametric test to compare combinations of groups or treatments and a linear mixed-effects model for the factors surface treatment, block type, and resin cement, together with their first-degree interactions (α = 0.05). Results The lowest mean μTBS values were obtained with LU-HF, whereas the highest mean μTBS values were obtained with CS regardless of resin cement type and surface treatment method. IR-HF mean μTBS were significantly higher than IR-SB, EM-SB, and EM-HF. Analysis using ImageJ software demonstrated significant differences in the density and pore size after HF surface treatment. Conclusions The specific microstructure of each block material within the same family group impacted the micromechanical retention and the bonded interface strength.

Objectives This study aimed to evaluate the interface between a calcium silicate cement (CSC), Biodentine and dental adhesives in terms of sealing ability. Materials and methods Microleakage test: 160 standardized class II cavities were prepared on 80 extracted human molars. The cavities were filled with Biodentine and then divided into 2 experimental groups according to the time of restoration: composite resin obturation 15 minutes after Biodentine handling (D0); restoration after 7 days (D7). Each group was then divided into 8 subgroups (n = 5) according to the adhesive system used: etch-and-rinse adhesive (Prime & Bond); self-etch adhesive 2 steps (Optibond XTR and Clearfil SE Bond); self-etch adhesive 1 step (Xeno III, G-aenial Bond, and Clearfil Tri-S Bond); and universal used as etch-and-rinse or self-etch (ScotchBond Universal ER or SE). After thermocycling, the teeth were immersed in a silver nitrate solution, stained, longitudinally sectioned, and the Biodentine/adhesive percolation was quantified. Scanning electron microscopic observations: Biodentine/adhesive interfaces were observed. Results A tendency towards less microleakage was observed when Biodentine was etched (2.47%) and when restorations were done without delay (D0: 4.31%, D7: 6.78%), but this was not significant. The adhesives containing 10-methacryloyloxydecyl dihydrogen phosphate monomer showed the most stable results at both times studied. All Biodentine/adhesive interfaces were homogeneous and regular. Conclusions The good sealing of the CSC/adhesive interface is not a function of the system adhesive family used or the cement maturation before restoration. Biodentine can be used as a dentine substitute.

Behavioral, nutritional, and local risk factors for oral health are frequent in people with anorexia nervosa. However no self-report questionnaire is available for screening in clinical practice or for research purposes. The objective of this study was to design a questionnaire to identify risk factors and symptoms of oral diseases and to test its reliability as a self-report form among people with anorexia nervosa. A 26-item questionnaire was designed based on a sound literature review performed by a group of dentists, psychiatrists, and epidemiologists specialized in the field of eating disorders. Sixty-nine anorexia nervosa inpatients (mean age 18.72 ± 5.1) were included from four specialized units. The questionnaire was first self-reported by the patients, then the same questionnaire was administrated by a dentist during a structured face-to-face interview as the gold standard. The concordance between the two forms was evaluated globally and item per item using Cohen’s kappa statistical tests. The overall concordance between the self-report questionnaire and the face-to-face structured interview was 55%. Of the 26 items, 19 showed significant concordance. Items relating to water intake, extracted teeth, gingival status, and oral hygiene had the best concordance (all kappa coefficients &gt, 0.4). A questionnaire that identifies risk factors and symptoms of oral diseases in anorexia nervosa was developed and tested. The 26-item form of the questionnaire (long version) is moderately reliable as a self-reported form. A short version of the questionnaire, including the 10 most reliable items, is recommended for oral risk assessment in patients with anorexia nervosa. The clinical value of the self-administered questionnaire remains to be evaluated.

International audience; Objectives - A national questionnaire study was performed to document knowledge and opinions of French dental students (FDSs) about minimal intervention (MI) in dentistry especially caries risk assessment (CRA) and dental sealants (DSs). Materials and methods - A questionnaire was administered to the fifth-year dental FDSs (n = 1370) from the 16 French dental schools. Descriptive and statistical analyses were performed. Results - The response rate was 84.5%. A large majority of respondents (87.8%) linked MI with minimally invasive dentistry and 77.4% considered MI as a concept based on prevention. About 80% stated they use CRA in clinical practice, mostly without any specific form. If 80.4% of the respondents would base their treatment plans on CRA, only 55.1% would regularly plan preventive regimens according to individual risk level. However, while 96.6% declared they perform preventive DSs, only 44.3% considered therapeutic sealants as a routine treatment. Although 75.1% of FDSs stated that they had sufficient learning and training related to CRA, 55.9% thought that they need further education about preventive and therapeutic DSs. Conclusion - Although FDSs seem to be aware of the importance of CRA and preventive strategies, this study shows the need to harmonize the teaching in cariology according to the latest European recommendations. Clinical relevance - A national questionnaire study showed variability towards knowledge and opinions of FDSs related to MI in cariology. This may impact care provisions in their future professional life showing the urgent need to harmonize the teaching of MI in cariology in France.

Thanks to their high porosity and surface area, mesoporous bioactive glasses (MBGs) have gained significant interest in the field of medical applications, in particular, with regards to enhanced bioactive properties which facilitate bone regeneration. The aim of this article is to review the state of the art regarding the biocompatibility evaluation of MBGs and provide a discussion of the various approaches taken. The research was performed using PubMed database and covered articles published in the last five years. From a total of 91 articles, 63 were selected after analyzing them according to our inclusion and exclusion criteria. In vitro methodologies and techniques used for biocompatibility assessment were investigated. Among the biocompatibility assessment techniques, scanning electron microscopy (SEM) has been widely used to study cell morphology and adhesion. Viability and proliferation were assessed using different assays including cell counting and/or cell metabolic activity measurement. Finally, cell differentiation tests relied on the alkaline phosphatase assay; however, these were often complemented by specific bimolecular tests according to the exact application of the mesoporous bioactive glass. The standardization and validation of all tests performed for MBG cytocompatibility is a key aspect and crucial point and should be considered in order to avoid inconsistencies, bias between studies, and unnecessary consumption of time. Therefore, introducing standard tests would serve an important role in the future assessment and development of MBG materials.

Objectives To assess in vitro the effect of experimental mesoporous BAG, on human dental pulp cells (hDPCs) behavior in terms of cytocompatiblity and bioactivity via mineralization potential. Methods Fine (FP) and large particles (LP) of a fixed BAG composition named 0NaMBG have been elaborated by a sol-gel process. In vitro assessment was achieved on cultured primary hDPCs using indirect contact. The effect of the concentration of 800 μg/mL on cell metabolic activity and cytotoxicity were examined by performing Alamar blue and crystal violet assays. Alizarin Red staining was used to detect and quantify the formation of mineralized nodules and ALP activity was colourimetrically quantified. The expression of Odontogenic markers: DMP-1 and osteopontin (OPN) expression and cell morphology was evaluated by confocal microscopy. Results According to the Alamar blue and crystal violet assay, 0NaMBG samples were non-cytotoxic. Cells treated with 0NaMBG particles expressed higher metabolic activity than control cells, especially for LP. Both FP and LP significantly increased both extra and intra cellular ALP activity. hDPCs exhibited good cell spreading and adhesion in the presence of FP and LP extracts by confocal imaging. Further, Alizarin red S assay demonstrated more mineralization nodules and significant enhancement of the extracellular calcium deposition when cells were interfaced with both FP and LP compared to the control cells. Moreover, LP extracts enhanced the production and secretion of odontogenic markers: dentin matrix protein 1 (DMP-1) and osteopontin. Significance LP have a higher surface area and pore volume, which could explain their greater bioactivity in contact with pulp cells. The clinical relevance of these findings implicate that 0NaMBG could be used as fillers in dental therapeutic materials suitable for dentin and/or pulp tissues preservation.

Objective The superior textural properties of sol–gel derived bioactive glasses compared to conventional melt quench glasses accounts for their accelerated bioactivity in vitro. Several studies have explored ways to improve the surface properties of sol–gel glasses in order to maximise their efficiency for bone and tooth regeneration. In this study, we investigated the effect of order of network modifying precursor addition on the textural properties of sol–gel derived bioactive glasses. Methods The effect of precursor addition order on the glass characteristics was assessed by switching the order of network modifying precursor (calcium acetate monohydrate and sodium acetate anhydrous) addition for a fixed composition of bioactive glass (75SiO2:5CaO:10Na2O:10P2O5). Results The results of this study showed that the order of precursor addition does influence the porosity of these glasses. For the glasses of a fixed composition and preparation conditions we achieved a doubling of surface area, a 1.5 times increase in pore volume and a 1.2 times decrease in pore size just by the mixing the network modifying precursors and adding them together in the sol–gel preparation. Significance This simple and straightforward route adaptation to the preparation of bioactive glasses would allow us to enhance the textural properties of existing and novel composition of bioactive glasses and thus accelerate their bioactivity.

Objective Many new dental composites containing mesoporous silica fillers have been developed to improve rheological properties and enhance the resin–filler interface. To investigate the correlation between the cytocompatibility of several dental composites and their composition; two aspects have been considered: presence of bisphenol A (BPA)-glycidyl methacrylate (Bis-GMA) or triethyleneglycol-dimethacrylate (TEGDMA) among the resin monomers and presence of porous particles among the filler blends. Methods Five commercial composites with different resin matrices and mineral fillers were compared to four experimental composites designed without any BPA-based monomers or TEGDMA. Porous fillers, with or without silanation, were added in some of the experimental composites. Two reference resin matrices were also selected. Cytocompatibility with cultured primary human gingival fibroblasts was assessed by confocal laser scanning microscopy with time-lapse imaging. Fourier transform infrared spectroscopy was used to control monomer conversion rate. Results Conversion rates of the experimental composites ranged from 57% to 71%, a comparable ratio for dental composites. Experimental samples were better tolerated than tested commercial samples not containing TEGDMA and significantly better than those containing TEGDMA. Experimental composites with porous fillers exhibited good cytocompatibility, especially when surfaces were silanated. Significance Cytotoxicity was associated with resin amount and especially resin nature. Composites containing porous fillers might behave as if the resin trapped into pores has no effect on toxicity. The cytotoxicity of composites with and without BPA derivatives was mainly attributed to the release of residual TEGDMA rather than the BPA derivatives.

Impaired oral health is a well-known complication in individuals with eating disorders, although this is difficult to identify by mental health professionals. The aim of this study was to evaluate the relationship between routine blood parameters and two oral health outcomes (dental erosion, reduced periodontium) in women with eating disorders. A face-to-face interview and a clinical oral examination were carried out in a cohort of 70 women from an addiction and psychiatry hospital unit. Biochemical and hematological parameters were collected in medical records at admission. Biological factors associated with a generalized reduced periodontium (≥ 30% of sites with clinical attachment loss ≥ 3 mm) and dental erosion [a basic erosive wear examination (BEWE) score ≥ 3] were determined by logistic regression models. Forty-five women with either anorexia nervosa (n = 27) or bulimia nervosa (n = 18) were included in the study. None of the women had active periodontitis or other inflammatory comorbidity. Women with ≥ 30% of sites with clinical attachment loss ≥ 3 mm and those with a BEWE score ≥ 3 were older than women that did not exhibit a generalized reduced periodontium or dental erosion (37.1 ± 10.4 versus 28.8 ± 7.4, p

Statement of problem Different parameters can influence the adaptation of computer-assisted design and computer-assisted manufacturing (CAD-CAM) inlay/onlay restorations. However, systematic reviews to identify and discuss these parameters are lacking. Purpose The purpose of this systematic review was to summarize the scientific literature investigating all parameters that can influence both the marginal and internal adaptation of CAD-CAM inlay/onlay restorations. Material and methods An electronic search was conducted by 2 independent reviewers for studies published in English between January 1, 2007 and September 20, 2017 on the PubMed/MEDLINE, Scopus, and Web of Science databases and in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Factors investigated in the selected articles included the type of CAD-CAM system, virtual space parameters, version of the software, type of block, luting procedure, type of restoration, sample size and aging procedure, evaluation method, and number of measurement points per specimen. Results A total of 162 articles were identified, of which 23 articles met the inclusion criteria. Nine studies investigated adaptation with different restorative materials, 2 evaluated adaptation according to the type of preparation design, 9 compared adaptation before/after thermomechanical loading, and 2 before/after cementation, 1 study investigated marginal adaptation based on whether the optical scan was made intraorally or extraorally, 1 compared adaptation with 5 and 3 axis CAM systems, and 1 assessed adaptation with 4 different intraoral scanners. The risk of bias was high for 7, medium for 15, and low for 1 of the studies reviewed. The high level of heterogeneity across the studies excluded meta-analysis. Conclusions Most of the studies reported clinically acceptable values for marginal adaptation. The performance of a CAD-CAM system is influenced by the type of restorative material. A nonretentive cavity preparation exhibited better adaptation than a retentive preparation. Most studies showed that thermomechanical loading affected the quality of marginal adaptation. Cementation increased marginal discrepancies. No statistically significant difference was found for marginal fit of onlays between intraoral and extraoral optical scans using a stone die. The number of milling axes, the type of digital camera, and the region measured were statistically significant in relation to marginal/internal adaptation. Values of adaptation recorded failed to reproduce the preestablished spacer parameters in the software. Clarification is needed concerning adaptation according to the type of preparation design, the type of material, the choice of intrinsic parameters for the CAD process, the type and shape of milling instruments, and the behavior of the material during milling. Adaptation of CAD-CAM inlay/onlays should be evaluated under clinical conditions.

This study evaluates dental and periodontal health in anorexia nervosa and bulimia nervosa patients.Seventy females with eating disorders (36 anorexia nervosa) attending a public hospital Psychiatry and Addiction unit were compared with age-matched controls (n = 70). Full-mouth examination and oral hygiene behaviours were recorded for all participants.More frequent dental attendance and toothbrushing were observed in patients with eating disorders than in controls (p 0.01), while lower plaque index and bleeding on probing were observed in controls than in patients (p ≤ 0.03). Percentages of sites with gingival recession2 mm were higher in patients with eating disorders than in controls (2.3 ± 4.1 versus 0.0 ± 0.1, p 0.01). The BEWE score2 was significantly more frequent in bulimia nervosa patients than in anorexia nervosa patients (76.5% versus 41.7%, p 0.01). Regarding periodontal parameters, mean plaque index, bleeding on probing and clinical attachment loss were increased in anorexia nervosa patients compared to bulimia nervosa patients.The present data suggest different oral health approaches in eating disorder patients according to diagnosis type.Periodontal and dental health should be considered rigorously in patients with eating disorders. Personalized oral hygiene recommendations and treatments can be delivered according to the type of eating disorder.

The aim of this study was to assess the influence of CaO/Na2O ratio on the structural and textural properties of mesoporous bioactive glasses generated from an acetic acid catalysed acetate based sol-gel system. The glass network formers (SiO2 and P2O5) were fixed and the network modifiers were varied [75SiO2:XCaO:(15-X)Na2O:10P2O5 where X = 5, 10, 15, in mole percent] such that increasing alkaline earth oxide is compensated by decreasing alkali oxide. The glass properties were assessed using techniques such as XRF, XRD, FTIR, BET/BJH, SEM, TEM and ICP. The rapid gelling of the sol resulted in the deposition of the calcium and sodium acetate precursors on the particle surface which required thermal treatment to facilitate their entry into the glass network. The results of our study demonstrated that the porosity was clearly driven by CaO in the composition possibly due to its inferior fluxing effect in comparison to Na2O. The sample with highest CaO content reached a high surface area and pore volume (535 m2 g−1 and 0.33 cm3 g−1) even in a non-surfactant based preparation suggesting that acetic acid catalysed acetate system favours improved textural properties. In vitro SBF tests confirmed the potential of the sample with highest CaO for earlier apatite formation.

Objectives The purpose of this work is a proof of concept to introduce a new quantitative 3D-analysis of dental erosion obtained by focused ion beam (FIB) tomography associated with silver nitrate penetration into porosities in etched enamel. Methods One sample selected was sound enamel after removal of the aprismatic surface. The other was studied after applying an additional attack with orthophosphoric acid. Both surfaces were infiltrated with silver nitrate via immersion. After dehydration, samples were observed in a dual column FIB/SEM station. Serial FIB sectioning was conducted with a current of 3 nA at 30 keV and an increment step of 20 nm for the healthy enamel and of 40 nm for the etched one. 3D analysis was performed with Fiji software and BoneJ plugin and several parameters were obtained to characterize the tissue: non-mineralized phase content (NMP), connected porosity fraction (CPF) and degree of anisotropy (DA) of the NMP. Results Healthy enamel showed an NMP content of 0.5 vol.%, with a bimodal distribution of non-mineralized regions, inside the prisms and between the prisms. No silver penetration was noticed in the healthy enamel, demonstrating the absence of open porosity. In contrast, silver nitrate penetration after acidic exposure was observed, up to a depth of 12 μm, which allowed the calculation of an interconnected porosity volume fraction (CPF) of 3.1 vol.%, mostly between the prisms. Values for DA of 0.56 for sound enamel and 0.81 for acid-etched surface were determined, highlighting a higher degree of anisotropy in the latter. Significance Quantitative analysis of FIB tomography using NMP, CPF and DA should contribute to a better understanding and follow up of dental erosion, correlation between erosion and attrition or abrasion process, and the ability to develop enamel remineralization procedures.

International audience; Background and objectives: Strategies to achieve dentin remineralization is at present an important target of restorative dentistry. Remineralization of dentin by a bioactive material is complete only when the tissue regains its functionality. This is achieved when there is adequate apatite formation which most importantly translates into improved mechanical properties of dentin as a result of intrafibrillar mineralization. Bioactive glass (BAG) is a well-known implant material for bone regeneration and is proven to have excellent ability of apatite formation. Hence, recent studies have proposed BAGs as one of the most desired materials for remineralization of dentin. Therefore the aim of this systematic review was to scope the evidence of bioactive glass to remineralize dentin.Methods: The following research question was formulated: "Is there strong evidence for bioactive glass to remineralize dentin?" Three databases (Web of science, PubMed and Science direct) were scanned independently following PRISMA guidelines. Inclusion and exclusion criteria were set to identify relevant articles based on title and abstract screening. Finally, potentially relevant articles were downloaded and the full text was scrutinized to select the articles included in this review.Results: The first phase of search returned 303 articles. A total of 19 papers with full text were scrutinized for inclusion, of which 3 papers were chosen for the final synthesis. All three studies confirm that BAG treatment leads to enhanced apatite formation in dentin. Only 1 of the 3 studies has reported the mechanical properties of dentin after BAG treatment and it revealed that the Young's modulus and flexural bend strength of BAG treated dentin were much lower than natural dentin even though they had similar apatite content.Conclusions: This review highlights the importance of assessing the mechanical properties of dentin alongside to the newly formed apatite content in order to prove BAGs efficiency to remineralize this tissue. Though studies have confirmed that BAGs stimulate excellent apatite formation in dentin, it should be concluded that there isn't sufficient evidence for bioactive glass to effectively remineralize this tissue as the mechanical properties of the BAG treated dentin haven't been well explored.

International audience; Objectives No recent study has addressed the effect of diving conditions (pressure increase) on adhesive restorations. We evaluated the impact of a simulated hyperbaric environment on microleakage of the dentine-composite resin interface. The ultimate aim was to propose recommendations for restorative dentistry for patients who are divers to limit barodontalgia (dental pain caused by pressure variations of the environment) and may lead to dangerous sequelae.Methods We bonded 20 dentine disks by using an adhesive system (Scothbond Universal) to ten intact composite cylinders and ten composite cylinders with porosity (Ceram X mono). For each group, the samples were divided into two subgroups, one submitted to a simulated hyperbaric environment and the other to an ambient environment. All samples were immersed in a silver nitrate solution to evaluate microleakage at the interface after analysis with a camera.Results Dye percolation for groups in the hyperbaric environment was greater than groups in ambient environment. For each subgroup, dye percolation was greater for samples with than without porosity.Conclusions High percolation percentages demonstrate that our simulated hyperbaric condition led to loss of sealing at the dentine-composite resin interface, especially with porous composites.Clinical significance Respect of the protocol and the quality of condensation for adhesive restorations are important in all clinical situations, especially for patients who are divers. A more interventionist approach must be adopted with these patients.

Mesoporous silica has been considered as fillers to elaborate nanocomposites polymer-silica. The organic part of conventional dental resin mixed with mesoporous silica, has been photopolymerized using visible irradiation and camphorquinone as an initiator. The porosity filling has been followed using differential scanning calorimetry, X-ray diffraction, nitrogen adsorption/desorption isotherms, scanning electronic microscopy (SEM), transmission electron microscopy (TEM), helium density measurements. The silica porous volume is completely filled with the dental resin and composites can be obtained when silica weight fraction is below 25%. Thermo-mechanical analyses have been performed showing a thermal dilatation coefficient around 80 · 10 −6 °C −1 .

The purpose of this study was to investigate thein vitrobiocompatibility of two dental composites (namely A and B) with similar chemical composition used for direct restoration using three-dimensional confocal laser scanning microscopy (CLSM) time-lapse imaging. Time-lapse imaging was performed on cultured human HGF-1 fibroblast-like cells after staining using Live/Dead®. Image analysis showed a higher mortality rate in the presence of composite A than composite B. The viability rate decreased in a time-dependent manner during the 5 h of exposure. Morphological alterations were associated with toxic effects; cells were enlarged and more rounded in the presence of composite A as shown by F-actin and cell nuclei staining. Resazurin assay was used to confirm the active potential of composites in cell metabolism; results showed severe cytotoxic effects in the presence of both no light-curing composites after 24 h of direct contact. However, extracts of polymerized composites induced a moderate decrease in cell metabolism after the same incubation period. Composite B was significantly better tolerated than composite A at all investigated end points and all time points. The finding confirmed that the used CLSM method was sufficiently sensitive to differentiate the biocompatibility behavior of two composites based on similar methacrylate monomers.

International audience; Statement of problemRecent polymer-based computer-assisted design and computer-assisted manufacturing (CAD-CAM) materials have been commercialized for inlay restorations, a polymer-infiltrated ceramic-network (PICN) and composite resin nanoceramics. Little independent evidence regarding their mechanical properties exists. Internal adaptation is an important factor for the clinical success and longevity of a restoration, and data concerning this parameter for inlays made with these blocks are scarce.PurposeThe purpose of this in vitro study was to evaluate and compare the mechanical properties (flexural strength, flexural modulus, Vickers hardness, fracture toughness) and the internal adaptation of these recent polymer-based blocks with a lithium disilicate glass-ceramic block.Material and methodsThe materials tested in this study were a PICN material (Vita Enamic), 2 composite resin nanoceramics (Lava Ultimate; 3M ESPE and Cerasmart; GCDental Products), and a lithium disilicate glass-ceramic (IPS e.max CAD). Mechanical properties were evaluated according to ISO norm DIS 6872:2013. Bar-shaped specimens (18×3×3 mm) were prepared and submitted to a 3-point bend test using a universal testing machine at a cross-head speed of 0.5 mm/min. In addition, identical cavities were prepared in 60 human mandibular extracted molars (n=15) and optically scanned to receive mesioocclusodistal inlays milled with the 4 materials tested in a CEREC Inlab milling machine. The replica technique and a stereomicroscope (×20) were used to measure the internal fit of the inlays at 9 preselected locations. All data were statistically analyzed using 1-way ANOVA and the post hoc Tukey multiple comparison or Games-Howell test (α=.05).ResultsThe mean flexural strength of the tested blocks ranged from 148.7 ±9.5 MPa (Vita Enamic) to 216.5 ±28.3 MPa (Cerasmart). The mean flexural modulus ranged from 23.3 ±6.4 GPa (Vita Enamic) to 52.8 ±10.5 GPa (IPS e.max CAD). The mean Vickers hardness ranged from 0.66 ±0.02 GPa (Cerasmart) to 5.98 ±0.69 GPa (IPS e.max CAD). The mean fracture toughness ranged from 1.2 ±0.17 MPa.m1/2 (Cerasmart) to 1.8 ±0.29 MPa.m1/2 (IPS e.max CAD). The values for internal discrepancy ranged from 119 ±55 μm to 234 ±51 μm. The mean internal discrepancy was significantly higher for Lava Ultimate (P

Due to an increased focus on erosive tooth wear (ETW), the European Federation of Conservative Dentistry (EFCD) considered ETW as a relevant topic for generating this consensus report.This report is based on a compilation of the scientific literature, an expert conference, and the approval by the General Assembly of EFCD.ETW is a chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria, and it is characterized by loss of the natural surface morphology and contour of the teeth. A suitable index for classification of ETW is the basic erosive wear examination (BEWE). Regarding the etiology, patient-related factors include the predisposition to erosion, reflux, vomiting, drinking and eating habits, as well as medications and dietary supplements. Nutritional factors relate to the composition of foods and beverages, e.g., with low pH and high buffer capacity (major risk factors), and calcium concentration (major protective factor). Occupational factors are exposition of workers to acidic liquids or vapors. Preventive management of ETWaims at reducing or stopping the progression of the lesions. Restorative management aims at reducing symptoms of pain and dentine hypersensitivity, or to restore esthetic and function, but it should only be used in conjunction with preventive strategies.Effective management of ETW includes screening for early signs of ETW and evaluating all etiological factors.ETW is a clinical condition, which calls for the increased attention of the dental community and is a challenge for the cooperation with other medical specialities.

International audience; The capacity of mesoporous silica to be used as filler in nanocomposite polymer–silica has been studied. One constituent of dental resin, triethyleneglycol dimethacrylate (TEGDMA), has been considered and its polymerization has been performed using a light curing process and camphorquinone as initiator. The filling of the silica mesoporosity has been followed using X-ray diffraction, nitrogen adsorption/desorption isotherms, differential scanning and thermo-mechanical analyses, helium density measurements and SEM analysis. These characterizations show that more than 90% of the porous volume is filled with the polymer, when the silica weight% stays below 50%.

Anchorage devices are increasingly used in orthodontics, and their clinical performance is directly dependent on the tissue response to these devices. This study aims to identify assessment parameters for evaluating tissue reactions around orthodontically loaded implants and to propose parameters to be included in a standardized method. Several electronic databases (PubMed, ScienceDirect, the Cochrane database) were explored for papers from January 1999 to December 2009. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement was used as a guideline for the methodology of systematic reviews. Twenty-five publications were selected from 123 potentially relevant abstracts. The selected studies mainly aimed to answer a clinical question and particularly the ability of immediate loading in orthodontics. Very few studies aimed to understand the healing mechanism around the devices leading to a lack of information on this topic. The most frequent combination of assessment methods was clinical evaluation, histology/histomorphometry and intravital bone labeling. Although the dog model is mainly used, pigs represent an interesting animal model, especially when studying devices in growing bone. Despite the extensive use of miniscrews in growing individuals, only few studies have included young subjects in their protocol. Moreover, in such studies, an oral hygiene program is absolutely necessary to avoid complications. Finite element analysis could improve the knowledge of the relationship between design and bone reaction; unfortunately, this elaborated method is complex and impossible to perform routinely. For standardization, the authors recommend to include specific criteria in study protocols when assessing tissue response to orthodontically loaded devices.

Objectives A multicentric randomized, 3-year prospective study was conducted to determine for how long Biodentine, a new biocompatible dentine substitute, can remain as a posterior restoration. Materials and methods First, Biodentine was compared to the composite Z100®, to evaluate whether and for how long it could be used as a posterior restoration according to selected United States Public Health Service (USPHS)’ criteria (mean ± SD). Second, when abrasion occurred, Biodentine was evaluated as a dentine substitute combined with Z100®. Results A total of 397 cases were included. This interim analysis was conducted on 212 cases that were seen for the 1-year recall. On the day of restoration placement, both materials obtained good scores for material handling, anatomic form (0.12 ± 0.33), marginal adaptation (0.01 ± 0.10) and interproximal contact (0.11 ± 0.39). During the follow-up, both materials scored well in surface roughness (≤1) without secondary decay and post-operative pain. Biodentine kept acceptable surface properties regarding anatomic form score (≤1), marginal adaptation score (≤2) and interproximal contact score (≤1) for up to 6 months after placement. Resistance to marginal discoloration was superior with Biodentine compared to Z100®. When Biodentine was retained as a dentine substitute after pulp vitality control, it was covered systematically with the composite Z100®. This procedure yielded restorations that were clinically sound and symptom free. Conclusions Biodentine is able to restore posterior teeth for up to 6 months. When subsequently covered with Z100®, it is a convenient, efficient and well tolerated dentine substitute. Clinical relevance Biodentine as a dentine substitute can be used under a composite for posterior restorations.

The aim of this study was to characterize to photopolymerization curves of two dental composite resins (Z100® from 3M ESPE Corp., and Tetric® Ceram® from Ivoclar Vivadent Corp.) according to the time exposure, the curing mode and the type of light source (halogen versus light emitting diode light curing units). The behavior and durability of composite resin do not depend only on their global shrinkage but also on their kinetic of polymerization which was studied with a mercury dilatometer. Four characteristics could be highlighted: the initial dilatation peak, the angle formed by the initial drop of shrinkage with the vertical axis, the angle formed by the secondary drop of shrinkage with the vertical axis and the intersection point between the two drops of shrinkage. The temperature rise was studied using a thermocouple to determine the position of the temperature peak in regard to the dilatation peak of the shrinkage curve. This is of interest for the clinical use of dental resin and light sources as well as curing procedures.

Objectives The purpose of this study was to evaluate the adhesion to dental ceramic by Vickers indenter methodology. This technique allows the creation of adhesive fractures and determines the influence of the surface treatment on adhesive capacities. Methods A single bond adhesive system (One Step ® Bisco) was applied to ceramic Vitapan 3D Master CE 0124 samples. Ceramic samples were polished with 500 or 4000-grit paper, sandblasted or not (Sa/NSa), treated with fluorhydric acid or not (A/NA) and silane or not (Si/NSi). The experimental groups (Gr) were: (Gr 1) 4000; (Gr 2) 4000 + Si; (Gr 3) 4000 + Sa + A; (Gr 4) 4000 + Sa + A + Si; (Gr 5) 500 + Sa + A + Si. Each sample was indented with the diamond Vickers indenter Leitz Durimet 2 (Wetzlar, Germany) using a load of 20 N for 30 s. The surfaces of the debonded areas were observed in an optical microscope providing a digital image of the debonded surface. The adhesion bond strength was calculated according to the formula of Engel and Roshon [Engel PA, Roshon DD. Indentation-debonding of an adhered surface layer. J Adhesion 1979;10(33): 237–53]. The statistical analysis was conducted using Student's t test ( p Results The values obtained for each group were: (Gr 1) 32 MPa; (Gr 2) 52 MPa; (Gr 3) 112 MPa; (Gr 4) 131 MPa; (Gr 5) 265 MPa. There is a significant improvement in bond strength with the silane application on the 4000 polished surface (Gr 2). However, there is no significant difference when silane is applied or not on a sanded and etched ceramic (Gr 4). Bond strengths were higher with 500 grit polished, sanded, etched with silane application on the surface (Gr 5). Significance The Vickers indenter methodology is able to discriminate between the influences of different surface treatments on the adhesion of an adhesive layer on a feldspathic ceramic.

International audience

Crystal structure of human tooth enamel was investigated using high-resolution neutron powder diffraction. Excellent agreement between observed and refined patterns is obtained, using the hexagonal hydroxyapatite model for the tooth enamel, where a large hydroxyl deficiency ?70% is found in the 4e site. Rietveld refinements method combined with the difference Fourier maps have revealed, however, that the hydroxyl ions are not only disordered along the c-axis but also within the basal plane. Additional H ions located at the 6h site and forming anions were found.

Objectives: The aim of this study was to evaluate the mechanical and physical properties of a newly developed fiber reinforced dental composite. Materials and Methods: Fiber reinforced composite EverX Posterior (EXP, GC EUROPE), and other commercially available bulk fill composites, including Filtek Bulk Fill (FB, 3M ESPE), SonicFill (SF, Kerr Corp.), SureFil (SDR, Dentsply), Venus Bulk Fill (VB, HerausKultzer), Tetric evoceram bulk fill (TECB, Ivoclar Vivadent), and Xtra Base (XB, Voco) were characterized. Composite samples light-cured with a LED device were evaluated in terms of flexural strength, flexural modulus (ISO 4049, n = 6), fracture toughness (n = 6), and Vickers hardness (0, 2, and 4 mm in depth at 24 hr, n = 5). The EXP samples and the fracture surface were observed under a scanning electron microscopy. Data were statistically analyzed using one-way ANOVA and unpaired t-test. Results: EXP, FB, and VB had significantly higher fracture toughness value compared to all the other bulk composite types. SF, EXP, and XB were not statistically different, and had significantly higher flexural strength values compared to other tested composite materials. EXP had the highest flexural modulus, VB had the lowest values. Vickers hardness values revealed SF, EXP, TECB, and XB were not statistically different, and had significantly higher values compared to other tested composite materials. SEM observations show well dispersed fibers working as a reinforcing phase. Conclusions: The addition of fibers to methacrylate-based matrix results in composites with either comparable or superior mechanical properties compared to the other bulk fill materials tested. (Restor Dent Endod 2015;40(4):262-270)

It is generally accepted that in vitro cell material interaction is a useful criterion in the evaluation of dental material biocompatibility. The objective of this study was to use 3D CLSM time lapse confocal imaging to assess the in vitro biocompatibility of dental composites. This method provides an accurate and sensitive indication of viable cell rate in contact with dental composite extracts. The ELS extra low shrinkage, a dental composite used for direct restoration, has been taken as example. In vitro assessment was performed on cultured primary human gingival fibroblast cells using Live/Dead staining. Images were obtained with the FV10i confocal biological inverted system and analyzed with the FV10-ASW 3.1 Software. Image analysis showed a very slight cytotoxicity in the presence of the tested composite after 5 hours of time lapse. A slight decrease of cell viability was shown in contact with the tested composite extracts compared to control cells. The findings highlighted the use of 3D CLSM time lapse imaging as a sensitive method to qualitatively and quantitatively evaluate the biocompatibility behavior of dental composites.

The aim of this work was to characterize the initial wear kinetics of two different types of glass ionomer cement used in dentistry (the conventional glass ionomer cement and the resin-modified glass ionomer cement) under sliding friction after 28-day storing in distilled water or Ringer’s solution. Sliding friction was applied through a pin-on-disk tribometer, in sphere-on-plane contact conditions, under 5 N normal load and 120 rotations per minute. The test lasted 7500 cycles and replicas were performed at 2500, 5000 and 7500 cycles. A profilometer was used to evaluate the wear volume. Data were analysed using Student’st-test at a significant level of 5%. There is no statistical significant difference between the results obtained for a given material with the maturation media (P>0.05). However, for a given maturation medium, there are significant statistical differences between the data obtained for the two materials at each measurement (P<0.0001). The wear rates of both materials decrease continuously during the running-in period between 0 and 2500 cycles. After 2500 cycles, the wear rate becomes constant and equal for both materials. The resin matrix contained in the resin-modified glass ionomer cement weakens the tribological behaviour of this material.

The authors also wish to express their appreciation to Beatrice Burdin, PhD, at the Microstructures Technology Center of University Claude Bernard Lyon1 for assistance with the SEM study. The AFM study was supported by the Characterization of Interactions Platform of the Nanobio Program, Grenoble University. We gratefully acknowledge the assistance on the English checking from Dr Huw Jones BSc PhD MRSC, Senior Lecturer in Chemistry for Environmental Science and Public Health, Middlesex University (UK).; International audience; AimTo compare the in vitro biocompatibility of Biodentine and White ProRoot((R)) mineral trioxide aggregate (MTA((R))) with MG63 osteoblast-like cells and to characterize the cement surface. MethodologyA direct contact model for MG63 osteoblast-like cells with cements was used for 1, 3 and 5days. Four end-points were investigated: (i) cement surface characterization by atomic force microscopy (AFM), (ii) cell viability by MTT assay, (iii) protein amount quantification by Bradford assay and (iv) cell morphology by SEM. Statistical analyses were performed by analysis of variance (anova) with a repetition test method. ResultsThe roughness of the cements was comparable as revealed by AFM analysis. The MTT test for Biodentine was similar to that of MTA((R)). Biodentine and MTA((R)) induced a similar but slight decrease in metabolic activity. The amount of total protein was significantly enhanced at day three (P

The mercury content of dental amalgams is a controversial subject with regard to the biological properties of these materials. The object of this study is to optimize the thermal treatments performed on an experimental powder in order to obtain a low mercury ratio (41% by weight) while preserving the desirable clinical qualities of the material. Using atomized powder, two types of thermal treatments are performed: A1, to obtain a partially annealed structure and A2, to obtain a complete homogenization. The kinetics of the amalgamation reaction is mainly evaluated by X-ray diffraction to identify the newly formed phases as a function of setting time. Mechanical properties are evaluated according to the ISO norms at 37 °C. Metallographical examination of the amalgams shows a «Ag-Hg» phase which acts as a matrix incorporating the «Cu-Sn» and «Ag-Sn» compounds. The setting kinetics of the A1 amalgams is linear and slightly more rapid than that of the A2 amalgam. The mechanical properties of the amalgams are significantly improved regarding the higher mercury content commercial amalgams. A specific thermal treatment permits us to slow down the diffusion of mercury between the different intermetallic compounds into the powder. The final amalgam composition, thus, most approaches the stoechiometric ratio calculated from a quaternary diagram.

The aim of this study was to place into perspective some factors that played an important role in the healing of periapical lesions after surgical end-odontic procedures. Root-ends were sectioned at different angulations on models and analyzed by photoelastimetry. Results showed that a section of the root-end through a plane perpendicular to the long axis of the tooth offers a better distribution of the stresses exerted on the apical region than the use of an inclined plane. The biological implications of these results have led the authors to propose a plan of resection that is perpendicular to the long axis of the tooth instead of the inclined plane commonly used.

Biliary atresia is a congenital disease treated by liver transplantation. Adults may have oral consequences of the medical therapy. Green teeth are oral manifestations of the induced hyperbilirubinemia. Gingival enlargement is associated with the immunosuppressive drug. This case report describes the successful treatment of an 18-year-old patient displaying severe green teeth and gingival enlargement.The gingival enlargement was treated by reducing the pathogenic oral microflora through scaling and root planing of the teeth, gingival excision surgeries, and conversion from cyclosporin to tacrolimus.Gingival enlargement and inflammation had completely disappeared after nonsurgical treatment for the maxilla and after surgical treatment for the mandible. The green coloration of the teeth was masked using composite restorations.This case report indicates that a patient's quality of life can be improved by a team approach combining pharmacologic and dental therapies.

Objectives Impedance spectroscopy is a non-destructive, quantitative method, commonly used nowadays for industrial research on cement and concrete. The aim of this study is to investigate the interest of impedance spectroscopy in the characterization of setting process of dental cements. Methods Two types of dental cements are used in this experiment: a new Calcium Silicate cement Biodentine™ (Septodont, Saint Maur-des Fosses, France) and a glass ionomer cement resin modified or not (Fuji II® LC Improved Capsules and Fuji IX® GP Fast set Capsules, GC Corp., Tokyo, Japan). The conductivity of the dental cements was determined by impedance spectroscopy measurements carried out on dental cement samples immersed in a 0.1 M potassium chloride solution (KCl) in a “like-permeation” cell connected to a potentiostat and a Frequency Response Analyzer. The temperature of the solution is 37 °C. From the moment of mixing of powder and liquid, the experiments lasted 2 weeks. Results The results obtained for each material are relevant of the setting process. For GIC, impedance values are stabilized after 5 days while at least 14 days are necessary for the calcium silicate based cement. Significance In accordance with the literature regarding studies of cements and concrete, impedance spectroscopy can characterize ion mobility, porosity and hardening process of dental hydrogel materials.

International audience; The aim of this study was to investigate the influence of the molecular mobility and the chemical structure of dimethacrylates most commonly used in dental composites on shrinkage stress from experimental matrices. METHODS: Three established neat monomers BisGMA (B), UEDMA (U) and TEGDMA (T), two experimental comonomers BisGMA-based (B-T(70/30) and B-T(50/50)) and two comonomers UEDMA-based (U-T(88/11) and U-T(66/33)) in weight%, were elaborated. Camphorquinone (CQ) and N,N-cyanoethylmethylaniline (CEMA), as photoinitiator and reducing agent, were added. Then the matrices were mixed by centrifugal force at room temperature. The viscosity (eta), the glass transition temperature of the monomers and comonomers systems (T(g(monomer)) and the maximum shrinkage stress (MSS) of each material (five replications) were statistically analysed by one-way ANOVA/Tuckey's test and Pearson's correlation procedure (p = 0.05). RESULTS: All formulations exhibited a newtonian rheological behavior. The viscosity of the comonomers systems can be divided in two groups: the pair B-T(70/30)/U-T(88/11) with the viscosity 3.5+/-3.10(-3)Pa.s and the pair B-T(50/50)/U-T(66/33) with the viscosity 0.28+/-3.10(-3)Pa.s. This pairs constituted samples allowing to compare the shrinkage stress of the BisGMA and UEDMA-based matrices with each other. The T(g(monomer)) of each group showed equivalent statistically values: -37.1 +/- 0.02 degrees C (U-T(88/11)) with -39.3 +/- 0.02 degrees C (B-T(70/30)) for the 3.5 Pa.s pair, and -53.1 +/- 0.03 degrees C (U-T(66/33)) with -58.5 +/- 0.01 degrees C (B-T(50/50)) for the 0.28 Pa.s one. There was a correlation between eta and T(g(monomer)) (r < 0.45 and p < 0.01). In decreasing order, the shrinkage stress was 14.11 +/- 0.3 MPa (T), 10.64 +/- 0.6 MPa (U-T(66/33)), 8.16 +/- 0.25 MPa (B-T(50/50)) without a significant difference compared to 8.04 +/- 0.5 MPa (U-T(88/11)), 6.83 +/- 0.52 MPa (U), 4.44 +/- 0.25 MPa (B-T(70/30)) and 0.33 +/- 0.3 MPa (B). There was a negative correlation between eta (r < -0.42 and p < 0.01), T(g(monomer)) (r < -0.41 and p < 0.01) and MSS. Whatever the viscosity, the UEDMA-based matrices developed higher shrinkage stresses than the BisGMA homologues. SIGNIFICANCE: The shrinkage stress development increase with the molecular mobility of the reacting medium. For the same molecular mobility, the large differences in stress values of the matrices studied are correlated to the structure and particularly the functionality of the monomers used.

The aim of this study was to record the effect of composite type and photoactivation mode on the stresses resulting from polymerization of five established composite resins: packable (Solitaire, Solitaire 2), micro-hybrid (Aelitefil, Z100) and hybrid (Clearfil AP-X).A mechanical testing machine was used to record the polymerization contraction stress (MPa) of cylindrical composite specimens (d=5mm; h=2mm; C-factor=1.25) at 0.1s intervals over a period of 400s. The samples were photopolymerized using a halogen light curing device under two types of light exposure: group 1, Standard (800mW.cm(-2)x60s); group 2, Exponential (logarithmic increase from 150 to 800mW.cm(-2) over 15s+800mW.cm(-2)x45s). The stress rate (SR: slope(MPa0-60s)) and the maximum shrinkage stress (MSS: MPa(400s)) of each material (five replications) were statistically analysed by one-way ANOVA/Scheffe's test and Pearson's correlation procedure (alpha=0.05). Finally, Student's t-test (two matched series) enabled the assessment of the effect of the irradiation method on the results.For group 1, in decreasing order, the MSS was 1.51+/-0.07MPa (Solitaire) statistically equivalent to 1.45+/-0.06MPa (Aelitefil), 1.29+/-0.08MPa (Solitaire 2), and 1.04+/-0.03MPa (Z100) statistically equivalent to 0.92+/-0.05MPa (Clearfil AP-X). Z100 showed the highest SR (0.045+/-6x10(-3)) and Solitaire, the lowest (0.017+/-2x10(-3)). There was no correlation between SR and MSS (r-0.33, p0.05). For group 2, the MSS and SR values were distributed in a similar way to those from group 1. There was a negative correlation between SR and MSS (r-0.43 and p0.01). The exponential ramp successfully reduced the MSS (-3.9%) and SR (-11%) values.There is no relationship between composite resin type, stress rate and shrinkage stress levels. The slower stress rate development, resulting from ramped light intensity, helped slightly to reduce the maximum polymerization stress.

International audience; Objectives. The aim of our in vitro study was to quantitatively evaluate dentin microleakage by means of the impedance technique.Methods. Forty-five 2 mm thick dentin disks were embedded in a hollow polyurethane resin cylinder. The system used was a 'like' permeation cell. Standard cylindrical cavities (1.5 mm deep, 3.5 mm diameter) were prepared on the occlusal side of the disk. The current passing through the dentin was measured to calculate impedance and to establish resistance of the sample. The doses were then randomly divided into nine groups (n = 5). Each group was bounded with a different adhesive system and fitted with microhybrid composite resin (Filtek P60). The initial measurement with the empty cavity and the record measurement (t = 0) were performed to evaluate initial resistance after filling. Samples were then thermocycted.Results. At t = 0, the highest value was obtained with EP (550%), the lowest with PLP (115%). The values of other adhesives ranged in a group (350-450%) without statistical difference. After thermocycling, all groups exhibited no significant difference (350-230%) except PLP (50%). The tower joint degradation rate (5%) was obtained with OS with a significant difference for all systems, the higher with PLP (35%). The results for other adhesives ranged from 20 to 27% without significant difference.Significance. Dentin microleakage may be quantified with the impedance technique and this has shown that, except for PLP, the differences between the two families of adhesives are slight. This methodology is able to prove the influence of thermocycling in terms of joint degradation. (C) 2003 Academy of Dental Materials.

To evaluate quantitatively the effect of six contemporary self-etching systems on dentin permeability by means of the electrochemical impedance technique and to correlate these results with their acidity.36 1.1 mm thick dentin disks were embedded in a hollow polyurethane resin cylinder. The system used was a "like" permeation cell: two electrodes immersed in a 10(-1) KCl solution were attached to a potentiostat. It was connected to a microcomputer controlled frequency response analyzer, and a 10 mV sinusoidal voltage signal over a frequency range of 1 Hz to 65 kHz was applied between the electrodes. The current passing through the dentin was measured to enable a calculation of impedance expressed in a complex number. To establish an evaluation of permeability variation, the resistance was noted for all specimens before and after the application of self-etching adhesive. A pH meter used with a combined glass-electrode measured the pH of all the systems.The higher decrease of the resistance of dentin samples was obtained with Experimental (EXP), which presented no significant difference with Touch and Bond (TB), Etch and Prime 3.0 (EP), and Etch Free Tenure (EF). These acidic monomers improved the dentin permeability respectively to 6.7, 5.1, 5.0 and 5.0%. The lowest values were obtained with Clearfil SE Bond (SEB) (2.0%), which showed significant difference with all the other systems. Prompt L-Pop (PLP) with 4.3% showed significant difference with EXP and SEB and no significant difference with the three other systems. The pH and permeability variation were not systematically correlated.Significant differences, in terms of quantitative evaluation of demineralization for self-etching systems on dentin, are of interest to clinical practitioners. Dentin bonding efficiency for this sort of adhesive system is not specifically related to this parameter, but low aggressiveness could be an area of concern on enamel.

To evaluate the influence of four light curing units on the stress induced by polymerization of two dentin bonding systems and a composite resin.Standardized kidney-shaped Class V cavities were prepared on the buccal and lingual surfaces at approximately 1 mm below the cemento-enamel junction (2 mm deep, 6-7 mm wide and 2 mm high). Two dentin bonding systems (DBS), Single Bond (SB), Optibond Solo Plus (OS+), and four light curing units (LCU): Astralis 7 (mode HIP 40 seconds), Elipar Highlight (soft start polymerization 40 seconds), GC e Light (8 mm tip) (fast cure of 12 seconds), and Optilux 501 (turbo tip) (fast cure of 10 seconds) were tested. The preparations were restored using the same microfilled composite (Filtek A110, shade A3). The teeth were thermocycled, immersed in a dye solution and sectioned. The enamel failures and the occlusal and cervical dentin microleakages were measured.No enamel and occlusal dentin microleakage was found. Concerning cervical dentin microleakage, with Single Bond, no significant difference was noted for all the light curing units (P0.05). With OptiBond Solo Plus, the filled adhesive, only two, the LCU Elipar and GC e Light, presented no statistical difference when all of the others exhibited statistical differences among themselves. The light intensity, the exposure duration, and the light source of the LCU are important parameters. When comparing the influence of the dentin adhesive, OS+ presented results significantly greater than SB, depending upon which lights were used. The Optilux 501 showed no significant difference. To act as a shock absorber, the adhesive needs to have time to compensate for the polymerization shrinkage.