An in vitro investigation of the effect and retention of bioactive glass air-abrasive on sound and carious dentine

Objectives To examine the removal rate of sound and carious dentine using bioactive glass air-abrasion and investigate abrasive particle retention of alumina and bioactive glass on abraded dentine. Methods Crushed bioactive glass was investigated as an alternative air-abrasive to alumina at air pressures of 138, 413 and 689 kPa in the presence or absence of water. The correlation coefficient between the amount of dentine removed using bioactive glass air-abrasion and the Knoop Hardness Number of dentine was calculated. The comparative retention of bioactive glass (BG) and alumina (AL) abrasive on human dentine blocks were calculated as atomic ratios acquired by spectral analysis between air-abrasive tracers (Si for bioactive glass, and Al for alumina) and Ca. A total of 60 dentine blocks were abraded using Al or BG in 12 groups of 5 using three different pressures in using wet and dry air-abrasion. Results The amount of dentine removed using bioactive glass air-abrasion had a Somers’ D coefficient of 0.65 for the Knoop hardness. Wet air-abrasion caused a significant (p 0.05) decrease in the amount of abrasive retained on the surface for Al air-abrasion at 138 and 413 kPa and BG air-abrasion at 413 and 689 kPa. Conclusion There was a negative correlation between propellant pressure and abrasive retained. Bioglass removed healthy dentine at a higher rate than carious dentine – the difference however, being less than with equivalent alumina air-abrasion, thus making it a potentially more selective instrument for clinical caries excavation.