SEM Evaluation of Tubular Occluding Properties of Selected Desensitizing Toothpastes

Objectives: The aim of the present in vitro study using a dentine disc model (Mordan et al., 1997, Gillam et al., 1997) was to investigate the ability of both prototype and commercial desensitizing toothpastes to cover the dentine surface and occlude the dentinal tubules. Methods: Mid-coronal dentine discs with a thickness of 1 mm were sectioned from caries-free human molars. The dentine discs were polished and etched with 6% citric acid for 2 minutes. Each disc was halved, one for treatment with the selected toothpastes and one as a control. Both halves were quartered as paired samples. Each disk was brushed for 2 minute using a Braun Oral B Triumph Professional Care toothbrush with a number of selected toothpastes: UltraDEX Recalcifying & Whitening toothpaste (UltraDEX), a QMUL bioactive glass prototype (QMUL), Sensodyne^® Repair & Protect [SRP], Sensodyne^® Rapid Relief [SRR], Colgate Sensitive ProRelief^® [CSP], Pepsodent Ultra Complete Sensitive (Pepsodent) and Biorepair^® Plus toothpastes. The ability of both prototype and commercial toothpastes to occlude the dentine tubules before and after brushing was compared using Scanning Electron Microscopy (SEM) on both the etched and fractured dentine surface. Results: Dentine tubule occlusion with a reduction in the number and the size of open dentine tubules was evident for all the treated dentine discs. The particles that covered the dentine surface and/or occluded the open dentine tubules had different morphologies and distribution. The observations from the SEM images demonstrated that the UltraDEX, QMUL and SRR toothpastes provided a greater degree of surface coverage and tubular occlusion than the CSP, Pepsodent, SRP and Biorepair^® Plus toothpastes that provided limited coverage with a number of open tubules still visible. Conclusion:  The results of the present in vitro study would suggest that both prototype and commercial desensitizing toothpastes may be effective tubular occluding toothpastes.