Effect of ambient pH and different chewing cycle of contact wear on dental composite material

Abstract

Background: The purpose of this study was to effect of ambient pH and different two chewing cycles of wear on restorative nanohybrid- and microhybrid-filled composite material in intraoral tribology. Methods: All specimens were stored in the artificial saliva for 7 days before the chewing tests. Then, composite specimens were subjected to chewing simulation using a computer-controlled chewing simulator (F = 50N [vertical movement 2 mm and horizontal movement 0.7 mm] 120.000 and 240.000 chewing cycles, 1.2 Hz frequency, and 37°C ambient temperature), immersed artificial saliva (about pH = 5.7), and citric acid solution (about pH = 3.2). Steatite balls were used as antagonists for every experiment chewing test cycle (d = 6 mm). Specimen's microhardness values determined with Vickers hardness method before chewing tests. Mean volume loss values were determined using noncontact three-dimensional (3D) laser scanning device. Furthermore, two-dimensional and 3D analysis of the mean volume loss wear surface of the composite material was performed both immersed artificial saliva and citric acid. Mean values and standard deviations were calculated and statistical analysis was performed using one-way analysis of variance. In addition, scanning electron microscopy analysis was performed to examine surface wear tracks. Results: The surface morphology of both composite materials was severely damaged in immersed citric acid solution. This can be explained by the more damage to the organic matrix structure of the composite material in citric acid solution than immersed artificial saliva. Conclusion: The results obtained in this study will help to understand the effect of the pH value of the third abrasive surface on the composite material in the three-body wear mechanism.