Excavation of carious enamel and dentine using bioactive glass air-abrasion

Objectives: The null hypothesis investigated in this study was that bioactive glass air-abrasion would not selectively remove carious enamel or dentine from occlusal lesions, compared to conventional alumina air-abrasion. Methods: A histologically validated visual caries scale was used to assess the presence and extent of occlusal carious lesions in extracted human molars. Twenty carious teeth potentially requiring operative intervention and 20 sound teeth were selected (N = 40). Ten samples from each group were air-abraded with alumina and 10 with bioactive glass, creating two carious and two sound sub-groups. Carious samples were air-abraded until deemed clinically caries free and sound samples were abraded for the same time as samples in the corresponding carious group. Scanning electron microscope examination of resin replicas before and after air-abrasion allowed tissue removal to be scored. The rate of sound dentine removal with alumina and bioactive glass air-abrasion was measured gravimetrically. Results: showed that bioactive glass abrasion removed substantial amounts of enamel from carious samples (9/10) but not from sound teeth (0/10). Alumina air-abrasion resulted in substantial enamel removal in both groups (carious (10/10), sound (9/10)). Fissures in all groups experienced slight surface modification resulting in microscopic roughening of the enamel surface. Alumina air-abrasion removed sound dentine 6 times quicker than bioactive glass air-abrasion. Conclusion: Bioactive-glass abrasion was shown to be capable of removing carious enamel from fissures while leaving sound enamel clinically undamaged. Alumina air-abrasion was more aggressive and less discriminate in removing enamel from both carious and sound fissures as well as sound dentine.