Avaliação in vitro da microdureza de compósitos ortodônticos submetidos ao desafio erosivo.

Abstract

Dental erosion is the irreversible loss of tooth surface without bacterial involvement. The etiological factors involved in dental erosion are considered extrinsic (acid exposure by diet) and intrinsic (acid reflux, anorexia and bulimia nervosa). Currently, the acids present in foods and drinks are considered the major etiological factors for the development of erosive lesions in enamel, which can also hasten the dental materials. This study evaluated the in vitro effect of erosive challenge and immersion in cola drink on Vickers microhardness (VHN) of orthodontic composites. Forty specimens of each of the three composite (Transbond XT, Quick Cure and Ortho Cem) were prepared (4 x 2 mm) and distributed into 4 groups (n=10): erosive challenge, artificial saliva immersion (control 1), continuous cola immersion and artificial saliva immersion (control 2). Erosive challenge was performed 4 times per day (5 min) in cola drink for 2 h in artificial saliva for 7 days. Samples of cola immersion group were soaked in cola drink for 5 weeks, the solution was renewed every two days. Control samples were immersed in artificial saliva for 7 days (control 1) and 5 weeks (control 2). VHN measurements were performed before and after erosive challenge and immersion. Data were evaluated by paired Student’s T-test, ANOVA one-way and Tukey tests (α = 0.05). After 7 days of erosive challenge, there was no statistical difference between VHN values before and after erosive challenge and artificial saliva immersion. However, after 5 weeks of cola drink and artificial saliva immersion, significant reduction in VHN values was observed for all composites when compared to baseline values, and specimens immersed in cola drink showed lower VHN compared to those immersed in saliva, regardless of composite composition. After 7 days of erosive challenge, there was no alteration in superficial VHN of orthodontic composites. However, after 5 weeks of immersion in cola drink, significant reduction of VHN values was observed for all composites.