Development Of Bioactive Glass For Orthodontic Adhesive Removal And Remineralization

Objectives: To prepare a bioactive glass powder propelled via an air-abrasion handpiece to safely remove orthodontic bonding resin after orthodontic treatment while promoting re-mineralization of white spot lesions (WSLs).
Methods: Experimental bioactive glasses were prepared using the melt quench route with a similar composition to Bioglass 45S5, but with high sodium and phosphorus contents and a constant ratio of fluoride. The glass transition temperature (Tg) of each glass was measured using Differential Scanning Calorimetry (DSC) and the hardness of each glass was calculated . Bioactivity of each glass was tested before and after immersion in Tris buffer solution, using FTIR, and XRD.
Results: Based on the DSC data, increasing Na₂O content in the glass resulted in a decrease in Tg from 524 to 465 for Na₂O concentration of 20% and 30% respectively. There was a linear relationship between hardness and Tg. Hence, hardness decreased with increasing Na₂O content. Based on representative enamel hardness of ~3.5 GP , a glass with hardness comparable to that of enamel (3.64 GP) has been achieved. The results of XRD and FTIR revealed that these glasses are amorphous and can form apatite earlier than 45S5.
Conclusions: A novel bioactive glass with appropriate hardness and Tg with promise for removal of orthodontic cement has been developed. Further testing in terms of safety and efficiency of removal will be undertaken on healthy extracted premolars and with artificially-induced WSLs.