The influence of a selected desensitizer on marginal microleakage of a class V composite restoration subjected to thermocycles: an in vitro study.

INTRODUCTION: Dentin hypersensitivity is a painful clinical condition. The frequency of its occurrence varies from 8 to 57%, depending on tested group and different methods of investigations. Recommended desensitizing agents have different mechanism of action and effectiveness. We are still looking for solutions that will improve their effectiveness and simultaneously allow for wider use of e.g. as a base material, counteracting postoperative hypersensitivity, reducing marginal microleakage. The aim of the study was to assess the effect of a selected desensitizing agent occluding dentin tubules with calcium hydroxyapatite on marginal microleakage formation of a class V composite restorations subjected to thermocycles. MATERIALS AND METHODS: In study it was used 40 molars and premolars, which were alternately assigned into two groups. In both groups standardized cavities were prepared. In the study group (study group - SG) before application of bonding agent Teethmate Desensitizer (f. Kuraray, Noritake Dental Inc., Okayama, Japan) was used. In the control group (control group - CG) OptiBond All-in-one (f. Kerr, Bioggio, Switzerland) bonding agent was used and cavities were filled using composite material Gradia Direct (f. GC Europe N.V., Leuven, Belgium). After storage in saline, teeth were subjected to 600 thermocycles, passive dye penetration test was done, teeth were cut in the area of filling, according to its long axis. Under light microscope magnification value of microleakage was measured and marginal microleakage rate (M) was counted. The results of the tests were statistically analyzed using the package STATISTICA 12.0 (StatSoft, USA). RESULTS: The average value of M for the SG group was 0.46 (min 0.05, max 0.76, SD 0.226) and for CG was 0.22 (min 0, max 0.74, SD 0.235). The differences between M values were statistically significant (p = 0.0094). CONCLUSION: A reduction in the number of retention sites for the bonding system, facilitates the formation of microleakage in the experimental conditions and reduces the degree of adhesion of the composite material to the hard tissues of the tooth.

Pre-application of dentin bonding agent prevents discoloration caused by mineral trioxide aggregate.

BACKGROUND: To evaluate tooth discoloration by newly developed calcium silicate-based materials, and to examine the pre-application of dentin bonding agent (DBA) for preventing discoloration caused by mineral trioxide aggregate (MTA). METHODS: The roots of 50 premolars were randomly divided into five groups (n = 10) and cavities were prepared from resected root surfaces. MTA was placed in the cavities of teeth belonging to the ProRoot MTA (MTA) and RetroMTA (RMTA) groups. For teeth belonging to the ProRoot + DBA (MTA-B) and RetroMTA + DBA (RMTA-B) groups, DBA was first applied to the cavities prior to the addition of MTA. Teeth in the control group were restored with composite resin only (i.e., without MTA). After 12 weeks, MTA was removed from the MTA and RMTA groups and bleaching agents were applied for 3 additional weeks. Color assessments were recorded at baseline, and 1, 4, and 12 weeks, as well as after bleaching. A one-way ANOVA was performed to assess the differences between the two types of MTAs and color changes following DBA pre-application in each MTA group. A p-value of < 0.05 was considered indicative of statistical significance. RESULTS: Following 12 weeks of MTA treatment, there was a significant difference between the discoloration in the MTA and RMTA groups (p < 0.05). However, no significant difference was observed between the RMTA and RMTA-B groups (p > 0.05). Following bleaching, the color changes (ΔE values) of the MTA group were not significantly different from those of the MTA-B group (p > 0.05). The difference of ΔE between the RMTA group after internal bleaching and the RMTA-B group was also not significant (p > 0.05). CONCLUSIONS: RetroMTA caused significantly less discoloration than ProRoot MTA. Pre-application of DBA reduced discoloration caused by ProRoot MTA. MTA discoloration was improved equally well between DBA pre-application and post-bleaching.

Impact of Dentinal Tubule Orientation on Dentin Bond Strength.

This study aimed to determine the impact of dentinal tubule orientation on dentin bond strength to provide a reference for clinical cavity preparation in resin-bonded restoration. Patients aged 13-16 years were selected, including 18 males and 21 females. Forty-eight human maxillary first premolars from orthodontic extractions were chosen to prepare the test models with the dentinal tubule orientations perpendicular and parallel to the bonding substrate. The test models in the vertical and parallel groups were divided into three groups: total-etching with 20% phosphoric acid, total-etching with 35% phosphoric acid and self-etching, with the dentinal tubule surfaces bonded with composite resin blocks in each group. After the standard test models of dentinal tubule-composite resin blocks were placed in distilled water and stored at 37°C for 24 h, shearing tests were performed using a universal material testing machine at a crosshead speed of 0.5 mm/min. The bond strength values in the vertical group were 19.33±1.59 MPa for the 20% phosphoric acid group, 21.39±2.34 MPa for the 35% phosphoric acid group, and 16.88±1.54 MPa for the self-etching group. The bond strength values in the parallel group were 24.53±1.99 MPa for the 20% phosphoric acid group, 25.16±2.88 MPa for the 35% phosphoric acid group, and 20.83±1.99 for the self-etching group. After using same total-etching adhesive, the shear bond strength of the parallel group was higher than that of the vertical group, and the difference was statistically significant (P<0.05). Regardless of vertical group or parallel group, the difference in the bond strength value between the total-etching groups and the self-etching group was statistically significant (P<0.05). It was concluded that the dentin bonding substrate which was parallel to the direction of the dentin tubule achieved an improved bond strength; the total-etching adhesives achieved higher bond strengths in dentin bond than the self-etching adhesives.

Natural saliva as an adjuvant in a secondary caries model based on Streptococcus mutans.

OBJECTIVE: Two factors for secondary caries formation were evaluated using an artificial biofilm model, saliva as additive in culture medium and bonding procedures of composite materials for artificial gap creation. DESIGN: Standardized cavities were prepared in bovine tooth samples (n = 44), treated with two different bonding pretreatments, restored and after artificial ageing incubated with Streptococcus mutans in a Mueller-Hinton-Broth-Sugar medium with or without human saliva for seven days. Secondary caries formation was analyzed using confocal laser scanning microscopy and transversal microradiography. RESULTS: Lesions were significantly pronounced in groups using saliva, but were not influenced by the bonding pretreatments. CONCLUSIONS: The results indicate that the addition of saliva, but not the type of bonding procedure influences the outcome in the present biofilm-based secondary caries model.

Prevention of coronal discoloration induced by regenerative endodontic treatment in an ex vivo model.

OBJECTIVES: The aim of this study was to assess the effect of sealing the pulp chamber walls with a dentin-bonding agent (DBA) on prevention of discoloration induced by regenerative endodontic procedures (REPs) in an ex vivo model. MATERIALS AND METHODS: Ninety-six bovine incisors were prepared and randomly divided into two groups. In one group, the pulp chamber walls were sealed with DBA before placement of triple antibiotic paste (TAP) containing minocycline inside the root canals, but in the other group, DBA was not applied. After 4 weeks, the root canals were filled with human blood and each group was then randomly divided into four subgroups (n = 12) according to the endodontic cements placed over the blood clot (ProRoot MTA, OrthoMTA, RetroMTA, or Biodentine). The color changes (∆E) were measured at different steps. The data were analyzed using t test and two-way ANOVA. RESULTS: The specimens in which dentinal walls of pulp chamber were sealed with DBA showed significantly less coronal discoloration at each step of regenerative treatment (p < 0.001). However, application of DBA did not completely prevent the clinically perceptible coronal color change. Sealing the blood clot with different endodontic cements did not result in significant difference in coronal discoloration (p > 0.05). CONCLUSIONS: Sealing the pulp chamber walls before insertion of TAP decreased coronal discoloration following REP using different endodontic cements but did not prevent it. CLINICAL RELEVANCE: Discoloration of teeth undergoing REPs is an unfavorable outcome. Considering the significant contribution of TAP containing minocycline to the coronal tooth discoloration even after sealing the pulp chamber walls, the revision of current guidelines in relation to the use of TAP with minocycline might need to be revised.

Influência da contaminação cavitária na adaptação marginal das restaurações de resina composta / Influence of cavity contamination on marginal adaptation of composite resin restorations

Objetivo: avaliar a influencia da contaminação cavitária na adaptação marginal das restauraçõesde resina composta e a associação da lisozima ao sistema adesivo. Materiais e Métodos:Foram selecionados 40 terceiros molares permanentes e confeccionados preparos cavitários classeV com pontas diamantadas cilíndricas 1090 (4 mm de largura, 6 mm de comprimento e 1,5 mmde profundidade). Todos os dentes foram esterilizados e divididos aleatoriamente em 4 grupos(n=10): G1: sistema adesivo (SA) e restauração com resina composta (RC); G2: cavidadescontaminadas com 10 μl de Streptococcus mutans (0,5 de Mc Farland), SA e RC; G3:sistema adesivo associado com lisozima (ADL) e RC e G4: cavidades contaminadas com 10 μlde Streptococcus Mutans (0,5 de Mc Farland), ADL e RC. A lisozima foi adicionada ao SA com ummicrobrush embebido no SA e na lisozima em pó. Os dentes foram impermeabilizados e imersosem azul de metileno por 4 horas a 37ºC. Os dentes foram seccionados e fotografados. Resultados:A avaliação da microinfiltração foi feita por dois avaliadores utilizando o Programa Tpsdig. Paraavaliar a calibração entre os examinadores, foi utilizado o teste de Correlação de Pearson. As médiasdas porcentagens de fendas e bolhas foram submetidas ao teste de Kruskal Wallis com 5% designificância. Conclusão: a contaminação cavitária com Streptococcus mutans acarretou na formaçãode fendas entre a resina composta e as margens cavitárias. A lisozima associada ao sistemaadesivo não influenciou na formação de fendas e bolhas nas restaurações de resina composta.

Objective: evaluate the influence of cavity contamination on marginal adaptation of compositerestorations and the association of lysozyme to the adhesive system. Materials and Methods:Were selected 40 permanent third molars and made cavity preparations class V with cylindricaldiamond burs 1090 (4 mm wide, 6 mm long and 2 mm deep). All teeth were sterilized and randomlydivided into 4 groups (n = 10): G1: adhesive system (SA) and restoration with compositeresin (CR); G2: cavity contaminated with 10 μl of Streptococcus mutans (0.5 McFarland), SA andRC; G3: adhesive system associated with lysozyme (ADL) and RC and G4: cavity contaminated with10 μl of Streptococcus mutans (0.5 Mc Farland), ADL and RC. Lysozyme was added to the SA witha microbrush embedded in the SA and powdered lysozyme. The teeth were sealed and immersedin a methylene blue for 4 hours at 37 ° C. The teeth were sectioned and photographed. Results:The evaluation of microleakage was made by two reviewers using the Tpsdig Program. To assessthe calibration of examiners, we used the Pearson correlation test. The mean percentages of cracksand bubbles were submitted to Kruskal Wallis test at 5% significance level. Conclusion: the cavityStreptococcus mutans contamination resulted in the formation of cracks between the compositeresin and the cavity margins. Lysozyme associated with the adhesive system did not influence theformation of cracks and bubbles in the composite restorations.

Hypersensitivity to Dental Composites and Resin-Bonding Agents.

Adverse reactions to dental materials are not an uncommon occurrence, although hypersensitivity has gained much renewed interest in light of public concerns over the safety of dental materials. Hypersensitivity can affect both patients and dental professionals and may manifest as either allergic contact dermatitis or stomatitis. Methacrylic monomers, such as MMA, EGDMA, TEGDMA and Bis-GMA, have been documented as causative allergens, however, little has been documented on the risk of such monomers in composites and bonding agents. The purpose of this article is to examine the current evidence and aspects of hypersensitivity to resin composites and bonding systems that are relevant within a dental setting. Clinical relevance: In the dental profession, dental materials have historically been documented as a cause of hypersensitivity. However, there remains little recent evidence on such reactions. The aims of this article are to highlight both the risk of hypersensitivity to dental composites and resin-bonding agents and the importance of reporting adverse reactions appropriately.

Effects of different orthodontic primers on enamel demineralization around orthodontic brackets.

AIM: The purpose of this work is to evaluate the effectiveness of one self-etching and two filled orthodontic primers on enamel demineralization around orthodontic brackets. METHODS: Brackets were bonded to 84 bovine teeth and the vestibular enamel surfaces covered with acid-resistant nail varnish exposing 1 mm of space on each side of the bracket base. The teeth were allocated to four groups, using either Transbond XT conventional primer on etched enamel (group 1), Transbond Plus Self-Etching Primer on untreated enamel (group 2), Pro Seal filled resin primer on etched enamel (group 3), or Opal Seal filled resin primer on etched enamel (group 4). Each tooth was subjected to 15,000 strokes of brushing followed by exposure to an acid challenge. Calcium-ion release from each sample was calculated using atomic absorption spectrophotometry. Data were analyzed using one-way ANOVA and a post hoc Tukey test. Differences were considered statistically significant at p ≤ 0.05. RESULTS: Statistically significant differences were observed between the four groups (p < 0.001). No significant difference was found between the controls (group 1) and the Opal Seal group. Higher calcium release was observed in the Pro Seal group and the self-etching primer group compared to the controls. The highest calcium release was recorded in the self-etching primer group. CONCLUSION: Filled sealants may not have a protective effect against enamel demineralization. Transbond Plus Self-Etching Primer should be used cautiously, considering the risk of demineralization involved in its application.

Efeito de sistemas resinosos e acesso ao conduto na resistência de união de pinos de fibra de vidro cimentados à dentina radicular / Effect of resin system and acess to the root canal on the bond strength of fiber glass post cemented to the root dentin

O sistema de cimentação e sua fotoativação, a profundidade do condutor radicular e a morfologia da dentina podem influenciar a resistência de união de pinos cimentados ao conduto radicular. Este estudo in vitro, em caráter hipotético, avaliou o efeito de sistemas resinosos e dos níveis de acesso ao conduto na resistência de união de pinos de fibra de vidro cimentados ao conduto radicular. Foram utilizados 135 dentes bovinos, distribuídos de acordo com um delineamento em blocos completos aleatorizados. As coroas foram seccionadas na junção cemento-esmalte e as raízes receberam tratamento endodôntico, preparo e cimentação de pinos de fibra de vidro Reforpost nº3 (Angelus), usando os seguintes sistemas: RelyX ARC/Adper Scotchbond Multi-Purpose plus (3M ESPE); C&B/All-Bond 2 (Bisco) e RelyX U200 (3M ESPE). As raízes foram então divididas, de acordo com o nível de acesso ao conduto: coronal, médio e apical, formando 9 grupos em estudo (n=15). Depois da cimentação, foram obtidos dois espécimes em cada terço radicular, com 1,0 mm de espessura. Foi realizado o ensaio de resistência ao cisalhamento por extrusão, usando célula de carga de 20N e velocidade de 0,5mm/min, e registrada a força máxima (MPa) para o deslocamento do pino. Os espécimes foram examinados em estereoscópio para identificação do modo de fratura. Imagens foram obtidas por microscopia eletrônica de varredura para a avaliação da linha de cimentação. O efeito dos fatores em estudo e de sua interação sobre a resistência de união nos terços coronal, médio e apical do conduto foi verificado por ANOVA e teste de Tukey (p≤0,05). Quando o acesso ao conduto foi feito no terço coronário, o sistema d cimentação (p=0,790), o terço radicular avaliado (p=0,224), e a interação (p=0,443) não mostraram efeito significativo...

Postoperative sensitivity of self etch versus total etch adhesive.

OBJECTIVE: To compare postoperative sensitivity following composite restoration placed in supra gingival class-V cavities using self etch adhesive and total etch adhesive. STUDY DESIGN: A randomized clinical trial. PLACE AND DURATION OF STUDY: Operative Dentistry Department of Armed Forces Institute of Dentistry, Rawalpindi, from July to December 2009. METHODOLOGY: A total of 70 patients having class-V supra gingival carious lesions were divided into two groups. Classes-V cavities not exceeding 3 mm were prepared. One treatment group was treated with self etch adhesive (adhe SE one Ivoclar) and the control group was treated with total-etch adhesive (Eco-Etch Ivoclar) after acid etching with 37% phosphoric acid. Light cured composite (Te-Econom Ivoclar) restoration was placed for both groups and evaluated for postoperative sensitivity immediately after restoration, after 24 hours and after one week. Data was recorded on visual analogue scale. RESULTS: Comparison of sensitivity between the two treatment groups on application cold stimulus after 24 hours of restoration showed significant difference; however, no statistically significant difference was observed at baseline, immediately after restoration and at 1 week follow-up with cold stimulus or compressed air application. CONCLUSION: Less postoperative sensitivity was observed at postoperative 24 hours assessment in restoration placed using SE adhesives compared to TE adhesives. Thus, the use of SE adhesives may be helpful in reducing postoperative sensitivity during 24 hours after restoration placement.

Effect of sodium ascorbate on dentin bonding after two bleaching techniques.

The purpose of this study was to analyze the influence of 10% sodium ascorbate (SA) on the hybrid layer, resin tag length, and bond strength to dentin after bleaching. Six groups were tested: G C, control; G SA, sodium ascorbate (SA) + restoration; G CP, bleaching with carbamide peroxide (CP) + restoration; G CP+SA, bleaching with CP + SA+ restoration; G HP, bleaching with 35% hydrogen peroxide (HP) + restoration; and G HP+SA, HP + SA + restoration. After dental bleaching, the dentin was exposed and the antioxidant solution was applied to groups G SA, G CP+SA, and G HP+SA, before bonding procedures. The teeth were sectioned in the mesiodistal direction. One section was decalcified, and the specimens were embedded in paraffin and sectioned in the longitudinal direction with a thickness of 6 µm. Fifteen slices of each specimen were selected according to a systematic sample of slices with an interval proportional to the total number of slices obtained for each tooth. The specimens were stained using the Brown & Brenn method, and an optic microscope was used to analyze the hybrid layer thickness and resin tag length. The remaining tooth segment was sectioned into stick-shaped specimens and used for microtensile bond strength testing (0.5 mm/min). Statistical analysis was performed using two-way analysis of variance and Fisher test. The results for hybrid layer + tag formation (in micrometers) were G C, 13.27 Aa; G SA, 11.85 Ba; G CP, 6.84 Bb; G CP+SA, 9.02 Ab; G HP, 7.28 Bb; and G HP+SA, 9.22 Ab; bond strength results (in MPa) were G C, 49.5 Aa; G SA, 51.7 Aa; G CP, 37.16 Bb; G CP+SA, 47.69 Aa; G HP, 32.39 Ab; and G HP+SA, 39.67 Ab. Tooth bleaching with CP or HP impairs the formation of the hybrid layer and resin tags and reduces the microtensile bond strength. Statistically, the use of SA significantly increases the hybrid layer thickness and resin tag length. The microtensile bond strength values for carbamide peroxide increased, but the microtensile bond strength for hydrogen peroxide was not affected.

Postoperative hypersensitivity and its relationship to preparation variables in Class I resin-based composite restorations: findings from the practitioners engaged in applied research and learning (PEARL) Network. Part 1.

BACKGROUND: This study investigated postoperative hypersensitivity at 1, 4, and 13 weeks following resin-based composite (RBC) restorations of occlusal caries and its relationship with prepreparation (baseline) sensitivity and preparation-related variables, including dentin caries activity, cavity dimension and volume, and lesion radiographic visibility. METHODS: Investigators in a practice-based research network enrolled patients with occlusal caries deemed to require operative treatment. The 45 dental practitioners then placed restorations using their preferred techniques. Complete baseline data on 665 restorations from 602 patients included patient-reported sensitivity (pre-preparation); dentists' ranking of dentin caries on opening the enamel; measurements of preparation depth, width, and length; and patient demographics. At 1, 4, and 13 weeks post-treatment, patients anonymously reported any sensitivity to hot and cold stimuli, sweets, clenching, and chewing, as well as quality-of-life indicators related to the restorations. RESULTS: At baseline, 30% of teeth had reported sensitivities of ≥3 on an anchored scale from 0 to 10 points and were designated as appreciable hypersensitivity (AH). Appreciable hypersensitivity at baseline was related to lesion radiographic visibility and patient age but not to dentin caries activity ranking, type of posterior tooth, gender, or race/ethnicity. Patients reported on 491 restorations at 4 weeks post-treatment--18% had AH. Of those who had AH, 39% (34 of 87) had no baseline AH. With restoration, 63% of teeth with baseline AH no longer had AH. Changes in AH were not associated with preparation depth, length, width, or volume. CONCLUSION: Patient-reported occlusal caries tooth sensitivity was high at baseline and eliminated by RBC restoration in 63% of cases; however, new sensitivity after restoration was reported in 10% of lesions that had none at pretreatment. Sensitivity was not related to preparation dimensions, volume, tooth type, or patient demographics (other than age) in these early lesions.

Effect of pretreatment with calcium-containing desensitizer on the dentine bonding of mild self-etch adhesives.

Desensitizing agents are frequently applied to sensitive teeth and may affect subsequent resin bonding. The current study aimed to evaluate the bonding performance of two self-etch adhesives containing functional monomers to dentine pretreated with three new calcium-containing desensitizers. No desensitizer was applied in the control group. Groups 1, 2, and 3 were treated with an arginine-calcium carbonate-containing polishing paste, a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing paste, and an experimental hydroxyapatite paste, respectively. G-Bond and Clearfil S(3) Bond were used for bonding after desensitizer treatments. The microtensile bond strength (µTBS) was tested (n = 20 beams per group) and failure mode distribution was analyzed. Scanning electron microscopy was used to observe the occlusion of dentinal tubules. The mean (±SD) µTBS values, expressed in MPa, of groups 1, 2, and 3 and the control group were, respectively, 30.81 (7.79), 44.41 (8.02), 31.49 (6.13), and 41.40 (8.67) for G-Bond and 39.63 (9.59), 32.55 (7.86), 37.50 (8.60), 27.90 (6.52) for S3 Bond. Most failures were recorded as adhesive failure (69.375%), instead of cohesive failure or mixed failure. The dentinal tubules were seldom plugged in group 2, but were mostly occluded in groups 1 and 3. Two-way anova indicated that desensitizer application in association with a compatible adhesive system should be used when endeavoring to control hypersensitivity without adverse interference in bonding.

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations.

OBJECTIVES: The incidence of non-carious cervical lesions (NCCLs) has been increasing. The clinical performance of resin composites in NCCLS was previously unsatisfactory due to their non-retentive forms and margins lying on dentin. In order to address this problem, a lot of effort has been put into developing new dentin adhesives and restorative techniques. This article discusses these challenges and the criteria used for evaluating clinical performance as they relate to clinical studies, especially long-term clinical trials. Polymerization contraction, thermal changes and occlusal forces generate debonding stresses at adhesive interfaces. METHODS: In laboratory studies, we have investigated how these stresses can be relieved by various restorative techniques and how bond strength and durability can be enhanced. Lesion forms, restorative techniques, adhesives (adhesive strategies, bond strengths, bond durability, and the relationship between enamel and dentin bond strengths) were found to have a complex relationship with microleakage. With regard to some restorative techniques, only several short-term clinical studies were available. RESULTS: Although in laboratory tests marginal sealing improved with a low-viscosity resin liner, an enamel bevel or prior enamel etching with phosphoric acid, clinical studies failed to detect significant effects associated with these techniques. Long-term clinical trials demonstrated that adhesive bonds continuously degraded in various ways, regardless of the adhesion strategy used. SIGNIFICANCE: Early loss of restoration may no longer be the main clinical problem when reliable adhesives are properly used. Marginal discoloration increased over time and may become a more prominent reason for repair or replacement. Reliable and standardized criteria for the clinical evaluation of marginal discoloration should be established as soon as possible and they should be based on evidence and a policy of minimal intervention.

Effects of bleaching agents and adhesive systems in dental pulp: a literature review

The dental pulp may be exposed to several irritants that are potentially noxious to the health and functions of this tissue. Each type of irritant or injury has different effects on the pulp, which are generally characterized by acute inflammation, chronic inflammation or necrosis. Common examples of irritants are dental caries, cavity preparation procedures, traumatic injuries, and chemical substances like bleaching agents and adhesive systems. The present study aimed to review the current knowledge about the effect of bleaching agents and adhesive systems in the human dental pulp. The review covered literature from 2004 to 2009, and only relevant manuscripts were included. Hand search of the references completed the review. Based on literature review, it may be concluded that all dental procedures associated with bleaching agents or adhesive systems involve risks to cause pulp damage. However, these risks can be minimized if the causal factors were known and avoided.

Carboxylesterase expression in human dental pulp cells: role in regulation of BisGMA-induced prostanoid production and cytotoxicity.

Biocompatibility of dentin bonding agents (DBA) and composite resin may affect the treatment outcome (e.g., healthy pulp, pulpal inflammation, pulp necrosis) after operative restoration. Bisphenol-glycidyl methacrylate (BisGMA) is one of the major monomers present in DBA and resin. Prior studies focused on salivary esterase for metabolism and degradation of resin monomers clinically. This study found that human dental pulp cells expressed mainly carboxylesterase-2 (CES2) and smaller amounts of CES1A1 and CES3 isoforms. Exposure to BisGMA stimulated CES isoforms expression of pulp cells, and this event was inhibited by catalase. Exogenous addition of porcine esterase prevented BisGMA- and DBA-induced cytotoxicity. Interestingly, inhibition of CES by bis(p-nitrophenyl) phosphate (BNPP) and CES2 by loperamide enhanced the cytotoxicity of BisGMA and DBA. Addition of porcine esterase or N-acetyl-l-cysteine prevented BisGMA-induced prostaglandin E(2) (PGE(2)) and PGF(2α) production. In contrast, addition of BNPP and loperamide, but not mevastatin, enhanced BisGMA-induced PGE(2) and PGF(2α) production in dental pulp cells. These results suggest that BisGMA may induce the cytotoxicity and prostanoid production of pulp cells, leading to pulpal inflammation or necrosis via reactive oxygen species production. Expression of CES, especially CES2, in dental pulp cells can be an adaptive response to protect dental pulp against BisGMA-induced cytotoxicity and prostanoid release. Resin monomers are the main toxic components in DBA, and the ester group is crucial for monomer toxicity.

Evaluation of cytotoxic effects of six self-etching adhesives with direct and indirect contact tests.

This study evaluated the cytotoxicity of self-etching primers/adhesives by direct contact and dentin barrier tests. The three two-step self-etching systems Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Prime&Bond NT/NRC (PB) and one-step self-etching systems Reactmer Bond (RB), Clearfil Tri-S Bond (CTS), and Adper Prompt L-Pop (AP) were examined. In direct contact tests, L929 cells were cultured in the presence of diluted solutions (50, 20, 10, and 1%) of primer/conditioner of adhesive systems. For dentin barrier tests, each system was applied onto 0.5 or 1.5 mm thick human dentin assembled in a simple pulp chamber device and incubated for 24 h at 37°C to make the diffusive components contact the L929 cells placed at the bottom of the chamber. The cytotoxic effects were assessed by MTT assay. Cell culture without application of any primers/adhesives served as the control for both tests. One-way ANOVA and Tukey HSD tests were used for statistical analyses. The direct contact tests demonstrated that CSE and CPB were less toxic than the other materials at all dilutions. In the dentin barrier tests, toxic effects of materials were reduced with an increase in thickness of intervening dentin. CSE and CPB showed less cytotoxicity than the other adhesives (p<0.05) when applied to 0.5 mm-thick dentin, and CSE was the least toxic in the 1.5 mm-dentin group (p<0.05). Dentin thickness positively affected biocompatibility of the tested bonding systems. Two-step self-etching systems with HEMA-based primers were more biocompatible than other self-etching adhesives.

Análise de falhas adesivas à zircônia sob diferentes tratamentos de superfície após ensaio de microtração / Zirconia failure analysis under different surface treatment after microtensile experiment

Considerando a importância do procedimento de cimentação adesiva para as restaurações indiretas, o propósito desse estudo foi analisar o tipo de falha ocorrida sob diferentes tratamentos de superfície e após ensaio de microtração entre dois substratos (zircônia Y-TZP e resina composta). Assim, 16 blocos (12mm X 12mm X 4mm) de uma zircônia completamente sinterizada foram polidos e divididos em 04 grupos de acordo com o tratamento de superfície a ser realizado sobre a zircônia: jateamento (G1), jateamento + “primer universal” (G2), “primer universal” (G3), e NaOH + “primer universal” (G4), previamente ao procedimento de cimentação. Os blocos de zircô-nia foram cimentados aos blocos de resina composta (12mm X 12mm X 4mm) previamente confeccionados e fotopolimerizados para em seguida serem cortados sob abundante refrigeração a fim de produzir secções de 0,8mm X 0,8mm X 8mm. Os “palitos” obtidos foram ensaiados em máquina universal de ensaios para detectar o tipo de falha ocorrida, que foi classificada em adesiva, coesiva ou mista. Os resultados evidenciaram uma maior percentagem de falhas mistas para os grupos G2 e G4 (65,2% e 67,3%, respectivamente), enquanto que o G3 apresentou maior percentagem de falhas adesivas (75,6%). Concluiu-se que o tratamento de superfície com jateamento com óxido de alumínio sobre a superfície da zircônia (G1) não é recomendado para a zircônia do tipo Y-TZP

Considering the importance of the adhesive cementation procedure for indirect restoration, the aim of this study was to analyze the failure kind met under different surface treatment and after microtensile test between two substrates (zirconia Y-TZP and resin composite). In this way, 16 blocks (12mm X 12mm X 4mm) of a zirconia completely sintering were polished and divided into 04 groups according to the surface treatment to be executed over the zirconia: sandblast (G1); sandblast + universal primer (G2); universal primer (G3); NaOH + universal primer (G4), previously to the cementation procedure. The zirconia blocks were cemented into the resin composite blocks (12mm X 12mm X 4mm) previously done and photopolimerized, to be in the sequence cut under copious refrigeration to produce sections of approximately 0.8mm x 0.8mm X 0.8mm. These obtained sticks were tested in a universal machine to detect the kind of failure, which was classified in adhesive, cohesive or mix. The results showed a higher percentage of mix failure to the group G2 and G4 (65.2% e 67.3%, respectively), while the group G3 showed a higher percentage of adhesive failure (75.6%). It was concluded that the sandblast treatment surface with aluminum oxide over the zirconia surface wasn’t recommended to the Y-TZP zirconia

Short-term in situ/ex vivo study of the anticariogenic potential of a resin-modified glass-ionomer cement associated with adhesive systems.

OBJECTIVE: As resin-modified glass-ionomer cement (RMGIC) is an adhesive material, its association to dentin bonding agents (DBAs) was previously proposed. This study investigated the adjunctive behavior of an RMGIC with etch-and-rinse bonding systems under in situ/ex vivo cariogenic challenge. METHOD AND MATERIALS: Bovine enamel blocks (3 3 3 3 2 mm) were randomly assigned to group VP, Vitremer + its own primer (3M ESPE); group VSB, Vitremer + Single Bond (3M ESPE); and group VPB, Vitremer + Prime and Bond 2.1 (Dentsply). Two blocks of each group were randomly placed in an acrylic palatal appliance, so each appliance included six blocks. Volunteers (n = 10) wore these appliances according to given instructions to promote a sucrose challenge eight times/day for 15 days. After this period, the blocks were removed from the devices and cleaned, and demineralization was assessed through longitudinal microhardness analysis (Knoop indenter, 25 g/5 s). Data were submitted to three-way ANOVA and Tukey test (P < .05). RESULTS: No treatment was able to completely avoid demineralization. All materials showed a statistically significant difference in mineral loss when the microhardness on the outer enamel was compared with deeper regions (P < .05). CONCLUSION: Association of the tested RMGICs with etch-and-rinse DBAs did not seem to be more beneficial against caries than the conventional treatment with RMGIC.