The Effect of Loading of Bioactive Glass in Desensitizing Polishing Pastes on Tubular Occlusion

Objective: To determine 1) the most effective loading of the bioactive glass in a prophylactic polishing paste containing Bioactive glass particles that provides a more effective tubular occlusion and 2) the ideal application time required to achieve this objective using an in-office rotary cup with a fixed pressure and speed. Materials and Methods: 60 dentine discs were divided equally into 15 groups treated with 0%, 5.0%, 15.0% and 25.0% bioactive glass loading respectively and Nupro ® at different applications (30, 60 and 120 seconds). Dentine permeability (Percentage flow rate) of each specimen was measured using a modified Pashley hydraulic conductance model at four different time points: (1) before toothpaste application, (2) after toothpaste application, (3) after saliva immersion and (4) after an acid challenge. Data were analysed by ANOVA to determine whether there were any significant differences with the control group (Nupro ® ) compared to the test groups at three different time intervals (30, 60 and 120 seconds). 20 dentine discs were analysed to observe the surface tubular occlusive effect following application of the various loadings at different times using scanning electron microscope (SEM). Results: There was an increased percentage fluid flow rate (FR) reduction with increasing bioactive glass loading (0.0%, 5.0%, 15.0%, 25.0%) compared to the control material Nupro ® . The 25% bioactive glass loading was the most effective in reducing fluid flow at the various time points although there were no significant differences between the 15% and 25% glass loading. The 25.0% bioactive glass loading at 120 seconds also demonstrated effective tubular occlusion compared to the control prophylaxis paste. A comparison between the control and the various glass loadings at the various time points using SEM demonstrated increasing tubule occlusion with increasing time of application. Tubular occlusion also increased following artificial saliva immersion but decreased following an acidic challenge. Conclusions: Increasing the bioactive glass loading resulted in a greater fluid flow rate reduction with an increase of time of applications. Overall, the most effective application was with the 25% loaded bioactive glass at 120 seconds although the application of the 15% loaded bioactive glass prophylaxis paste for 30 seconds demonstrated effective tubular occlusion and fluid flow reduction.