Effects of alpha-tocopherol antioxidant on fracture strength and adhesion of endodontically treated teeth restored after dental bleaching.

This study evaluated the effect of different concentrations of alpha-tocopherol in gel form on fracture strength, hybrid layer formation, and microtensile bond strength of endodontically treated teeth bleached with 40% hydrogen peroxide (H2 O2 ). Sixty bovine incisors were randomized into one of six groups (n = 10 incisors per group) defined by the interventions carried out after endodontic treatment. In the control group, no additional intervention was carried out, while all teeth in the five intervention groups were bleached with 40% H2 O2 and subsequently treated with alpha-tocopherol at concentrations of 15% (15AT), 20% (20AT), or 25% (25AT), with 10% sodium ascorbate (10SA), or with nothing (40HP). Fracture strength was evaluated in a mechanical testing machine, hybrid layer formation was assessed using scanning electron microscopy, and bond strength was determined using microtensile bond-strength testing. Data were analyzed using Kruskal-Wallis and Dunn's tests. No statistically significant difference regarding fracture strength was observed among groups. Hybrid layer formation was greater in the 15AT group than in groups 40HP and 10SA. Teeth in groups 15AT, 20AT, and 25AT demonstrated higher bond strength than teeth in groups 40HP and 10SA. Alpha-tocopherol, preferably at 15%, effectively reverses the deleterious effects, of bleaching, on hybrid layer formation and bond strength to dentin.

Effect of antioxidants after post-space irrigation on the adhesive interface of glass fiber post cementation.

OBJECTIVE: This study evaluated the effects of antioxidants, 10% sodium ascorbate (SA) or 20% alpha-tocopherol (AT), after post-space irrigation with 2.5% sodium hypochlorite +17% EDTA (SH) or 1% peracetic acid (PA) on the adhesive interface after glass fiber post cementation. MATERIALS AND METHODS: Sixty bovine roots were endodontically treated. After preparation, the post-space was irrigated with SH or PA followed or not by the use of antioxidants (SA or AT) (n = 10). Push-out bond strength test, failure mode, and dentin penetrability analysis using confocal laser microscope were performed in the cervical, middle, and apical thirds. Data from bond strength and dentinal penetrability were evaluated by one-way ANOVA and Tukey post hoc test (p < 0.05). RESULTS: SH showed the lowest bond strength regardless of the third (p < 0.05). In apical third, mixed failure was the most incident in all groups. Only in the cervical third of the post-space, SH-AT provided the greatest tag extension of the cementation system into dentin (p < 0.05). However, in the middle and apical thirds, SH-AT, SH-SA, and PA-SA provided the largest tag extensions (p < 0.05), but similar to each other (p > 0.05). CONCLUSIONS: The use of antioxidants only favored bond strength when SH was used and dentin penetrability of the adhesive and conventional resin cementation, regardless of the solution used to irrigate the post-space. CLINICAL SIGNIFICANCE: The use of antioxidants (10% sodium ascorbate and 20% alpha-tocopherol) after post-space irrigation with sodium hypochlorite appears to increase the bond strength favoring the glass fiber post-cementation.

Surface and intra-pulpal temperature variation during tooth whitening photoactivated with LED/laser.

This study evaluated the variation of surface and intra-pulpal temperature, during bleaching protocol, using LED/laser. The 35% (HP35), 15% (HP15) and 6% (HP6) gels were used associated with LED/laser applied every 1 min for 30 min in a human canine. The evaluation of surface temperature variation (∆Ts) was performed using a pHmeter and the intra-pulpal temperature variation (∆Ti) was performed using a digital thermometer, at times of 1-, 5-, 10- 15- and 30-min. Statistical analysis was performed using the two-way repeated measures ANOVA test and Bonferroni post-hoc test was used at a significance level of 5%. HP35 and HP15 showed greater temperature variation than HP6 up to 10 min of surface evaluation, showing no differences between them. In the intra-pulpal evaluation, no group showed differences throughout the procedure.

Impact of cleansing protocols to remove endodontic sealer residues on the adhesive interface: Bonding with universal adhesive systems.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of cleansing protocols to remove sealer residues using different cleaning strategies and the effect of bond strength of two universal adhesives to dentin impregnated with epoxy resin-based sealer. MATERIALS AND METHODS: Fifty bovine dentin specimens were impregnated with epoxy resin-based sealer containing calcium hydroxide (Sealer Plus) and submitted to cleansing protocols (n = 10): negative control (NC), positive control (PC), 95% ethanol (ET), xylol (XI), and amyl acetate (AA). Specimens were evaluated by scanning electron microscope (SEM). Other 100 specimens were submitted to the same protocols (n = 20). Each protocol was divided into subgroups (n = 10) according to the universal adhesive system used: Scotchbond Universal (SU); Ambar Universal (AU). Bond strength was evaluated by micro-shear bond test (µSBT). Persistence of residues data were assessed with Kruskal-Wallis and Dunn's tests. µSBT data were analyzed with two-way ANOVA (α = 5%). RESULTS: ET presented higher persistence of residues compared to AA and XI (p < 0.05). AA and XI were similar from each other (p > 0.05). AU and SU presented similar µSBT values, regardless of the cleansing solution (p > 0.05). SU-NC presented the highest µSBT among all conditions (p < 0.05). CONCLUSION: The bond strength of universal adhesives was not affected by different amounts of sealer residues after different cleaning protocols. CLINICAL SIGNIFICANCE: Non-polar substances such as amyl acetate and xylol are effective for removing residues from epoxy resin-based endodontic sealers.

Reliability of an instrument on cognitive-practical capacities for the treatment of minimal dental caries intervention in the Dentistry Career / Confiabilidad de instrumento sobre capacidades cognitivo-prácticas para el tratamiento de mínima intervención de caries dental en la Carrera de Estomatología

Objective: The objective of this research was to determine the reliability of the instrument on cognitive-practical capacities necessary for the treatment of minimal intervention of dental caries in the Stomatology Career. Methods: Pilot study that describes the extent to which a previously designed instrument is understandable and functional. The sample consisted of 52 professors from the stomatology career. The information was collected in two stages, a test in which the instrument was applied and after 15 days a retest was performed. The variables consisted of 21 items resulting from the design and prior validation. The mean of variability was calculated for each item at the time of the test and retest, the internal consistency through Cronbach's alpha, a comparison of the mean of the instrument's items according to Student's t test, and the correlation coefficient was calculated. intraclass. Results: The test and retest showed value of the total means of 2.43 and 2.47 respectively, expressing that the objectives of the instrument are partially achieved. The scores showed good coherence (Cronbach's alpha 0.817 and 0.801 in test and retest). The hypothesis test being t ≤0.05 in both moments it is accepted that all the items were related. Conclusions: Reliability was demonstrated with regard to internal consistency and temporal stability in each of its items.

Objetivo: El objetivo de esta investigación fue determinar la confiabilidad de instrumento sobre capacidades cognitivo-prácticas necesarias para el tratamiento de mínima intervención de la caries dental en la Carrera de Estomatología. Métodos: Estudio piloto que describe en qué medida un instrumento previamente diseñado es comprensible y funcional. La muestra estuvo integrada por 52 profesores de la carrera de estomatología. La información fue recogida en dos etapas, una prueba en la que se aplicó el instrumento y trascurridos 15 días se realizó una segunda prueba. Las variables consistieron en 21 ítems resultantes del diseño y la validación previa. Se calculó la media de variabilidad para cada ítem en el momento de la prueba y la segunda prueba, la consistencia interna a través del alfa de Cronbach, una comparación de la media de los ítems del instrumento según t de Student y se calculó el coeficiente de correlación intraclase. Resultados: La prueba y segunda prueba mostraron valor de las medias totales de 2,43 y 2,47 respectivamente, expresando que los objetivos del instrumento se logran parcialmente. Las puntuaciones mostraron buena coherencia (alfa de Cronbach 0,817 y 0,801 en prueba y segunda prueba). La prueba de hipótesis al ser t ≤0,05 en ambos momentos se acepta que todos los ítems se relacionaron. Conclusiones: Se demostró la confiabilidad en lo que se refiere a la consistencia interna y estabilidad temporal en cada uno de sus ítems.

Does refurbishing composites lead to short-term effects or long-lasting improvement?

PURPOSE: To evaluate the clinical performance of refurbished resin composite restorations compared to untreated (negative control) restorations over a period of 10 years. METHODS: 26 subjects (having a total of 52 composite restorations) were recruited. All restorations in the refurbished group showed clinical features rated bravo according to modified USPHS criteria. Untreated restorations were those that had been deemed acceptable (alpha or bravo rated); these were used as controls. Two examiners performed assessments at baseline and during the 5th and 10th years after the intervention. Wilcoxon tests were performed for within-group comparisons, Friedman tests were used for multiple within-group comparisons, and Mann Whitney tests were used for between-groups comparisons. Kaplan-Meier survival curves were calculated, and the Mantel-Cox test was used to compare curves. P < 0.05 was considered statistically significant. RESULTS: In both groups, 10-year scores were significantly different from baseline scores in all clinical parameters except secondary caries. There were no statistically significant differences in the survival analysis of groups (log-rank test, P = 0.376). Refurbishing treatment improved the anatomy, roughness, luster, and marginal adaptation of restorations with a short-term effect, with most properties rated acceptable after 10 years of clinical service. The clinical characteristics were similar for all groups at the 10th year.

Is there difference of Streptococcus mutans count and adherence on amalgam and resin occlusal restorations? A blind clinical study

To compare the number of colony forming units CFU and agar adherence of S. mutans on amalgam AM and resin composite RC occlusal restorations. Sixty-five healthy patients older than 18 years with high caries risk who had at least one occlusal AM and RC restorations n=130 were selected. METHODS: The restorations were evaluated according to the alpha Ryge criteria Cohen-Kappa 0.8. For each patient, a biofilm sample was taken using an impression tray technique with previously loaded with solid trypticase yeast extract cysteine sucrose with bacitracin agar placed over the AM restorations and RC restorations in the same patients. The tray was placed inside an oven at 37 °C for 48 h, and the S. mutans count was then performed. Data were analyzed with the test Wilcoxon with a 95% confidence level. RESULTS: RC restorations had statistically significant higher number of CFU of S. mutans than AM restorations p<0.05. CONCLUSIONS: In adult patients with high caries risk, RC occlusal surfaces showed greater agar adherence of S. mutans count than AM restorations...