The effects of different antioxidant agents on the microtensile bond strength of composite resin to bleached Enamel / Efecto de diferentes agentes antioxidantes en la resistencia a la microtracción de la resina compuesta al esmalte blanqueado

Abstract The objective of this in vitro study is to examine the effect of antioxidants on the bonding strength of composite resin to bleached enamel. One hundred twenty non decay teeth were used in this study. Specimens were cut from the enamel cement junction. Then the specimens were randomly assigned into two groups-office bleaching and home bleaching. Bleaching antioxidants were applied to the first 12 subgroups. The specimens in the remaining 12 groups were kept in artificial saliva for 14 days and antioxidants were applied. Composite resin restoration was applied to all specimens. A cutting device was employed to obtain six specimens (0.9mm) from each tooth, and the microtensile bond strength (μTBS) test was performed. Data were analyzed using one-way ANOVA, the paired t-test, and Duncan's post hoc test (p=0.05). In office bleaching specimens, immediate antioxidant application increased the μTBS values (p0.05). Mean μTBS values in the groups to which antioxidants were applied two weeks after home bleaching were higher than those in the groups in which antioxidants were applied immediately. The use of antioxidants after bleaching may increase the MTBS value. The clinician should take this into account especially in immediate restoration applications after bleaching.

Resumen El objetivo de este estudio in vitro fue examinar el efecto de los antioxidantes sobre la resistência adhesiva de la resina compuesta al esmalte blanqueado. En este estudio se utilizaron ciento veinte dientes sin caries. Se cortaron especímenes a nivel de la unión esmalte-cemento. A continuación, los especímenes se asignaron aleatoriamente a dos grupos: blanqueamiento en el consultorio y blanqueamiento en casa. Se aplicaron antioxidantes de blanqueamiento a los primeros 12 subgrupos. Los especímenes de los 12 grupos restantes se mantuvieron en saliva artificial durante 14 días y se aplicaron antioxidantes. Se aplicó una resina compuesta a todos los especímenes empleando un dispositivo de corte para obtener seis especímenes (0,9mm) de cada diente, y se realizó la prueba de resistencia a la adhesión por microtensión (μTBS). Los datos se analizaron mediante un ANOVA de una vía, la prueba t pareada y la prueba post hoc de Duncan (p=0,05). En las muestras de blanqueamiento de oficina, la aplicación inmediata de antioxidantes aumentó los valores de μTBS (p0,05). Los valores medios de μTBS en los grupos a los que se aplicaron antioxidantes dos semanas después del blanqueo en casa fueron mayores que los de los grupos en los que se aplicaron antioxidantes inmediatamente. El uso de antioxidantes después del blanqueamiento puede aumentar el valor de μTBS. El clínico debe tenerlo en cuenta, especialmente en las aplicaciones de restauración inmediatas tras el blanqueamiento.

The cytotoxic and oxidative effects of restorative materials in cultured human gingival fibroblasts.

The aim of this study was to evaluate the cytotoxic and oxidative effects of the most commonly used dental restorative materials on human gingival fibroblast cells (HGFCs). HGFCs were obtained from healthy individuals. The tested restorative materials were a microhybrid resin based composite, a compomer resin, a glass ionomer cement, and an amalgam alloy. One hundred eight cylindirical samples, 10 mm in diameter and 2 mm in height, were prepared according to ISO 10993-12:2002 specifications (n = 9 in the tested subgroups). Freshly prepared and aged samples in artificial saliva at 37 °C (7 and 21 d) were placed into well plates and incubated. Wells without dental materials were constituted as the control group. After 72 h incubation period, cytotoxicity was determined using the neutral red (NR) assay. Oxidative alterations were assessed using total antioxidant capacity (TAC) and total oxidant status (TOS) assay kits. Data were analyzed using the ANOVA and LSD post hoc tests. All tested materials led to significant decreases in the cell viability rates (33-73%) compared to the control group. Glass ionomer and resin composite were found to be more cytotoxic than amalgam alloy and compomer. The highest TAC level was observed in glass ionomer after seven-day aging and these changes prevented an increase in TOS levels. Increases in TAC levels after seven-day aging in all groups exhibited significant differences with freshly prepared samples (p < 0.05). In all material groups, TOS levels of freshly prepared samples differed statistically and significantly from samples aged for 7 and 21 d (p < 0.05). The data obtained suggested that all the tested materials exhibited cytotoxic and pro-oxidant features. Freshly prepared samples caused higher TOS levels. However, oxidant status induced by materials decreased over time.

Monomer release from nanohybrid composites after bleaching.

The evaluation of the effect of bleaching on monomer release from two composite resins was performed by bleaching two nanohybrid composite resins Filtek Z550 and Tetric N-Ceram using two bleaching products Whiteness HP Maxx and Vivastyle. In total, 20 samples were made from each composite resin from which four groups were fabricated (two for each bleaching product). The samples were stored in a 75% ethanol solution, and the solutions were renewed after 1, 7, and 28 days. The monomer release was analyzed using high performance liquid chromatography. The data were analyzed using repeated measures analysis of variance and least significant difference multiple comparison test (α = 0.05). Monomers were found to be released from both composite resins. The amounts of monomer released were found to decrease over time (P < 0.05); however, the resins were not affected by bleaching, and the released monomers were well below toxic doses.

Dental age assessment for different climatic regions.

OBJECTIVE: The aim of this study was to evaluate the impact of several aspects of climate, such as temperature and altitude, on dental maturation. MATERIALS AND METHODS: The total sample consisted of 944 panoramic radiographs (473 Turkish children from Central Anatolia [228 girls and 245 boys] and 471 Turkish children from Eastern Anatolia [222 girls and 249 boys]). The children aged between 7.0 and 14.9 years. The radiographs were randomly selected from 2 cities in Turkey, Kayseri and Erzurum. Independent t tests and paired t tests were performed to compare sex, location, and age to determine the relationships between tooth developments. RESULTS: The Central Anatolian children were approximately 0.2 to 3.0 years more advanced in dental maturity than the Eastern Anatolian subjects. CONCLUSIONS: The development standards proposed by Demirjian are affected by climatic factors. However, further research and detailed information to gather data are needed.

Effect of water storage on the translucency of silorane-based and dimethacrylate-based composite resins with fibres.

OBJECTIVES: The purposes of this study were (1) to determine the translucency of silorane and dimethacrylate-based composite resins and (2) to evaluate the effect of water storage and reinforcement with fibre on the translucency of composite resins. METHODS: Two light-cured composite resins (A2 shade), Filtek Silorane (silorane-based composite) and Valux Plus (dimethacrylate-based composite), were used in this study. The first group was used as the control with no reinforcements, the second was reinforced with polyethylene (Ribbond THM) and the third was reinforced with a glass fibre (Everstick Net) for each composite resin. Colour measurements were measured against white and black backgrounds with a Shadepilot (Degu Dent Gmbh, Hanau, Germany) spectrophotometer and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded at baseline and at 24 h, 168 h and 504 h. Translucency of materials was calculated using the translucency parameter (TP) formula. Data were analyzed using repeated measures ANOVA and LSD post hoc tests (α=0.05). RESULTS: The highest baseline TP value was in the Valux Plus/non-fibre reinforced group (14.06±1) and the lowest in the Filtek Silorane/Ribond THM group (8.98±1.11). Repeated measures ANOVA revealed significant effects from the factors storage time, composite resin, composite resin×storage time and fibre×time (p=0.047; p=0.001; p=0.013; p=0.022, respectively). CONCLUSION: Within the limitations of the study, we concluded that inclusion of polyethylene and glass fibres did not alter the translucency of the different-based composite resins. The longest storage time resulted in the greatest change in translucency values of Filtek Silorane composite resins. CLINICAL SIGNIFICANCE: Considering the translucencies of composites with different formulations in the selection of composite resins for aesthetic restorations is important in terms of obtaining optimal aesthetic outcomes.

Three-year clinical performance of two indirect compositeinlays compared to direct composite restorations

Objective: Despite the incremental build-up of resin composite restorations, their polymerization shrinkage during curing presents a serious problem. Indirect composite resin systems represent an alternative in overcoming some of the deficiencies of direct composite restorations. The hypothesis of the present study states that the clinical performance of restorations may be affected by different generation and application techniques. Study Design: Sixty restorations (20 DI system (Coltène/Whaledent AG, Altstätten, Switzerland) composite inlays,20 Tescera ATL system (BISCO Inc. Schaumburg, Illinois, USA) composite inlays, and 20 direct composites)were applied to premolar teeth in 49 patients. Restorations were clinically evaluated by two examiners. Data were analyzed using the Kruskal-Wallis, Mann-Whitney U, Wilcoxon Signed Ranks, and X2 tests. Results: The Tescera ATL system performed significantly better than both direct composite restorations (p<0.001)and DI system (p<0.05).Conclusion: Within the limitations of this 3-year clinical study, indirect resin restorations showed better scores than direct restorations. In addition, the Tescera ATL system was found to be more successful than the DI system and direct composite restorations (AU)

Three-year clinical performance of two indirect composite inlays compared to direct composite restorations.

OBJECTIVE: Despite the incremental build-up of resin composite restorations, their polymerization shrinkage during curing presents a serious problem. Indirect composite resin systems represent an alternative in overcoming some of the deficiencies of direct composite restorations. The hypothesis of the present study states that the clinical performance of restorations may be affected by different generation and application techniques. STUDY DESIGN: Sixty restorations (20 DI system (Coltène/Whaledent AG, Altstätten, Switzerland) composite inlays, 20 Tescera ATL system (BISCO Inc. Schaumburg, Illinois, USA) composite inlays, and 20 direct composites) were applied to premolar teeth in 49 patients. Restorations were clinically evaluated by two examiners. Data were analyzed using the Kruskal-Wallis, Mann-Whitney U, Wilcoxon Signed Ranks, and X2 tests. RESULTS: The Tescera ATL system performed significantly better than both direct composite restorations (p<0.001) and DI system (p<0.05). CONCLUSION: Within the limitations of this 3-year clinical study, indirect resin restorations showed better scores than direct restorations. In addition, the Tescera ATL system was found to be more successful than the DI system and direct composite restorations.