Tubular Occluding Effects of Various Bioactive Glass Loading in Toothpaste

Objectives: To determine the most ideal and effective bioactive glass loading in toothpaste formulations to treat dentine hypersensitivity.
Methods: This laboratory study contained two parts. The first part involved the analysis of dentine permeability using hydraulic conductance model. 30 dentine discs were divided equally into 6 groups treated with either 0%, 2.5%, 5.0%, 7.5%, 10.0% or 15.0% bioactive glass loading. Dentine permeability of each specimen was measured as percentage flow reduction at four different time points; before toothpaste application, after toothpaste application, after saliva immersion and after acid challenge. Data were analysed by one paired t-test to determine if there were any significant differences with the control group (0% loading) and between the test groups. The second part of the study involved the observation of the surface tubular occlusive effect of the dentine discs using scanning electron microscope (SEM).
Results: Increasing the bioactive glass loading resulted in greater fluid flow reduction. The percentage reduction showed a steep rise from 0% to 5% loading but slowed steadily from 5% to 15%, with the highest reduction at 15%. The bioactive glass loading that were found to reduce dentine permeability significantly were those loading which was ≥ 5%. However, when the comparison was made between the test groups, there was no significant difference between 5%, 7.5%, 10% and 15%. This result was substantiated by the SEM analysis. Before toothpaste application, the dentine surface showed minimal to zero tubule occlusion. Tubule occlusion increased immediately after toothpaste application and was further increased after saliva immersion. The occlusion decreased after acid challenge.
Conclusions: Increasing the loading beyond 5% was able to reduce fluid flow significantly but the effect was too small to be considered significant. Therefore, despite 15% loading being the most effective, 5% loading was deemed as the most ideal concentration in toothpaste formulation to treat dentine hypersensitivity.