Effect of accelerated aging and double application on the dentin bond strength of universal adhesive system.

BACKGROUND: Despite the many advantages of simplified adhesive systems, there are concerns about the durability of the adhesive layer over time. The aim was to investigate the effects of various aging methods and double application of an adhesive layer on the bond strength of the universal adhesive system using etch-and-rinse (ER) and self-etch (SE) strategies. MATERIALS AND METHODS: In this in vitro study, the occlusal enamel of 120 extracted, intact human third molars was removed to expose the dentin. Then, the samples were randomly divided into four groups of thirty according to All-Bond Universal (ABU) adhesive application strategy (ER and SE) and the number of adhesive layers (1 or 2). Then, each group was subdivided into three subgroups of ten according to aging method (control, thermal cycling, and 10% sodium hypochlorite [NaOCl]). The shear bond strength was measured at the strain rate of 0.5 mm/min. Data were analyzed using three-way ANOVA and Tukey's post hoc tests (P < 0.05). RESULTS: The effect of adhesive application strategy (P < 0.001) and aging method (P < 0.001) on the bond strength was statistically significant, but the effect of the double application was not statistically significant (P > 0.05). In addition, the interactive effect of adhesive application strategy-aging method was significant (P = 0.005). CONCLUSION: Using ABU with ER strategy leads to higher dentin bond strength compared to the SE method in the control and thermal cycling groups. However, no significant differences were observed between ER and SE strategies after aging with the NaOCl. Furthermore, the double application might not have any effect on the bond strength and durability.

Effect of an extra layer of hydrophobic resin on the microleakage of Cl V composite resin restorations with a universal adhesive system.

AIM: The aim of the present study was to evaluate the effect of the application of a hydrophobic resin on the microleakage of Cl V composite resin restorations using a universal adhesive system applied in the self-etch (SE) and etch-and-rinse (ER) modes. METHOD: Cl V cavities were prepared on the buccal surfaces of 64 human premolar teeth and divided into four groups (n = 16): ER, ER with hydrophobic resin (ERH), SE, and SE with hydrophobic resin (SEH). Microleakage at occlusal and gingival margins was evaluated using 0.5% methylene blue dye penetration technique under stereomicroscope at 40 × magnification. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests (P < 0.05). RESULTS: At the enamel margins, the ER group had significantly less microleakage than the SE and SEH groups (P < 0.001), but had no significant difference compared with the ERH group (P > 0.05). There was also no statistically-significant difference between the SE and SEH groups (P > 0.05). At the dentinal margins, the SE group had significantly less microleakage compared with the ER (P < 0.001) and ERH groups (P = 0.005). Furthermore, microleakage of the SEH group was significantly less than the SE group (P < 0.001). CONCLUSION: Applying an extra layer of hydrophobic resin significantly decreased microleakage in the SE mode at the dentinal margin, but had no significant effect in the ER mode.

Effect of two prophylaxis methods on marginal gap of Cl Vresin-modified glass-ionomer restorations.

Background. This study evaluated the effect of two prophylaxis techniques on the marginal gap of CI V resin-modified glass-ionomer restorations. Methods. Standard Cl V cavities were prepared on the buccal surfaces of 48 sound bovine mandibular incisors in this in vitro study. After restoration of the cavities with GC Fuji II LC resin-modified glass-ionomer, the samples were randomly assigned to 3 groups of 16. In group 1, the prophylactic procedures were carried out with rubber cup and pumice powder and in group 2 with air-powder polishing device (APD). In group 3 (control), the samples did not undergo any prophylactic procedures. Then the marginal gaps were measured. Two-way ANOVA was used to compare marginal gaps at the occlusal and gingival margins between the groups. Post hoc Tukey test was used for two-by-two comparisons. Statistical significance was set at P < 0.05. Results. There were significant differences in the means of marginal gaps in terms of prophylactic techniques (P < 0.001), with significantly larger marginal gaps in the APD group compared to the pumice and rubber cup group, which in turn exhibited significantly larger marginal gaps compared to the control group (P < 0.0005). In addition, the means of marginal gaps were significant in terms of the margin type (P < 0.001), with significantly larger gaps at gingival margins compared to the occlusal margins (P < 0.0005). Conclusion. The prophylactic techniques used in this study had a negative effect on the marginal gaps of Cl V resin-modified glass-ionomer restorations.

Evaluation of the Relationship between Serum Lipid Profile andOral Lichen Planus.

Background and aims. Oral lichen planus (OLP) is an immunologic disorder. A large number of studies have reported that lipid rafts have a key role in receptor signaling of lymphocytes. Here, we explore the potential of lipid rafts as targets for the development of a new class of agents to down-modulate immune responses and treat autoimmune diseases. Materials and methods. The present cross-sectional study evaluated 88 patients referring to the Department of Oral Medicine in 3 groups (Group 1: erosive OLP; Group 2: non-erosive OLP; Group 3: healthy). A total of 3 mL of blood sample was taken from each subject and the serum levels of cholesterol, triglycerides, HDL and LDL were determined. The mean outcomes of each group were compared with each other and analyzed two by two. Results. The results of statistical analyses showed no significant differences in mean HDL and LDL serum levels between the three groups. The results of post hoc LSD test showed that mean serum levels of subjects with erosive and non-erosive lichen planus were higher than those in healthy subjects. In relation to triglyceride serum levels, the mean serum levels of triglycerides were higher in erosive and non-erosive OLP patients compared to healthy subjects. Conclusion. Triglyceride and cholesterol can be considered to have a critical role in the incidence of lichen planus and in its manifestations as predisposing factors.