ABSTRACT
INTRODUCTION: If adhesive restorations are carried out imme-diately, the Shear Bond Strength (SBS) to bleached enamel is reduced. The use of antioxidants can be highlighted since it seems to be a more effective alternative to reduce or remove the residual oxygen and immediate improvement in SBS. AIM: The purpose of this in-vitro study was an attempt to regain the lost bond strength, for which, the comparison of SBS of composite resin to bleached enamel was carried out using various antioxidants i.e., 5% grape seed extract, 5% pine bark extract, 5% pomegranate peel extract. MATERIALS AND METHODS: Labial enamel surfaces of 50 extracted human maxillary central incisors were randomly divided into 5 groups based on the antioxidant used as follows: Group I (n=10): Bleaching with 40% hydrogen peroxide gel for 10 minutes, without the use of an antioxidant; Group II (n=10): Bleaching followed by the use of 5% grape seed extract solution; Group III (n=10): Bleaching followed by the use of 5% pine bark extract solution Group IV (n=10): bleaching followed by the use of 5% pomegranate extract solution; and Group V (n=10): Control group in which no Bleaching was done. SBS of the specimens was tested using universal testing machine. The data were tabulated and statistically analyzed using computer software Statistical Package for Social Sciences (SPSS) version 16.0. One-way analysis of variance (ANOVA) followed by Mann Tukey Post hoc test. RESULTS: Mean SBS values were compared in all the groups and there was a statistically significant difference present among the groups (p<0.05). The SBS values were observed to be significantly higher in unbleached teeth (control group) followed by 5% pine bark extract, 5% grape seed extract, 5% pomegranate extract and the group in which teeth bleached with no antioxidant used. CONCLUSION: The use of antioxidant immediately after bleaching the enamel surface, completely neutralizes the deleterious effects of bleaching and increases the SBS significantly. Among the antioxidants, 5% pine bark extract application after bleaching showed better bond strength.
ABSTRACT
INTRODUCTION: The purpose of this study was to compare the incidence of dentinal micro cracks after instrumentation with various types of NiTi files in rotary and reciprocating motion. MATERIALS AND METHODS: One hundred human extracted mandibular central incisors were taken and divided into 10 groups (n=10 teeth per group). Group 1- No preparation, Group 2 - Hand instrumentation, Groups 3,4 - ProTaper files in rotary and reciprocating motion, Groups 5,6 - ProTaper Next files in rotary and reciprocating motion, Groups 7,8 - Oneshape files in rotary and reciprocating motion, Groups 9,10 - Reciproc files in rotary and reciprocating motion. Specimens were sectioned horizontally at 3,6 and 9 mm from the apex and dentinal micro cracks were observed under a stereomicroscope. RESULTS: There was a statistically significant difference between the groups (p<0.05). There were no significant differences in crack formation between the groups (Protaper Next - Rot, Protaper Next - Rec, Reciproc - Rec); (ProTaper - Rot, ProTaper - Rec, Oneshape - Rot), (Oneshape - Rot, Reciproc - Rot), (One shape Reciproc, Reciproc - Rec); (p >.05). CONCLUSION: Least cracks were seen in canals instrumented with Pro Taper Next files both in rotary and reciprocating motion. Full sequence rotary systems showed less cracks than single file systems and full sequence rotary systems showed less cracks in reciprocating motion than in rotary motion.
