MICROLEAKAGE AND MICROSHEAR BOND STRENGTH OF DIFFERENT TYPES OF DENTAL COMPOSITE RESTORATIVE MATERIALS

Document Type : Original Article

Authors

1 Assistant Professor of Dental Biomaterials, Faculty of Dental Medicine Al Azhar University, Cairo (Boys).

2 Lecture of Dental Biomaterials, Faculty of Dental Medicine Al Azhar University, Cairo (Boys).

Abstract

The present study was conducted to evaluate the microleakage and microshear bond strength of different types of dental composite. For microleakage test, 45 caries-free human permanent maxillary molars with no crack, decay, or structural deformities were collected. A standard Class V cavity was prepared on the buccal surface of each tooth. The cavity of each tooth was acid etched and the adhesive material was applied to the etched surface, gently dried and cured. The prepared teeth were divided randomly into three groups, (15 for each group) according to the types of composite. Group A: Tetric EvoCeram nanohybrid composite (Ivoclar vivadent Inc. USA and Canada), Group B: Tetric EvoCeram Bulk fill composite (Ivoclar vivadent Inc. USA and Canada) and Group C: Sonic Fill Bulk fill composite (Kerr Restoratives, USA). The specimens in each group were restored with the corresponding composite and cured according to manufacturer’s instructions.  The  specimens  were  submitted  to  thermo-cycling,  covered  with  nail  varnish, followed by immersion in dye solution. Each tooth was sectioned longitudinally using hard tissue microtome. The microleakage was measured using digital microscope at ×10 magnification. The dye penetration in the specimens was evaluated for both the occlusal and gingival surfaces based on a scoring system. Kruskal-Wallis test was used to determine the difference between microleakage scores in the three study groups at a 0.05 level of significance. For microshear bond strength test 30 caries-free human permanent mandibular molars with no crack, decay, or structural deformities were collected. The occlusal surface of the teeth were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. A dentine slice with thickness 2 mm was sectioned perpendicular to the long axis of each tooth. The surfaces of dentin slides were acid etched and the adhesive material was applied to the etched surface, gently dried and cured. The specimens were divided into three main groups (10 for each group) according to the type of composite resins used as in microleakage test. Composite resins was placed, cured and the specimens were submitted to thermocycling before testing. The recorded values of bond strengths in (MPa) were collected, tabulated and statistically analyzed. One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups. The results showed that Tetric EvoCeram nanohybrid composite had the highest scores of microleakage followed by Tetric EvoCeram Bulk fill and Sonic Fill Bulk fill which showed the lowest scores. The results also showed that Sonic Fill Bulk fill composite had the highest microshear bond strength value followed by Tetric EvoCeram Bulk fill and Tetric EvoCeram nanohybrid composite which showed the lowest value.