The effect of dentifrice with nano-carbonate apatite for dentin hypersensitivity

Objectives: The aim of this study was to evaluate the effect of a dentifrice containing nano-carbonate apatite (n-CAp) on the occlusion of dentinal tubules using an oral simulation model for 12 days in vitro.

Methods: In order to minimize of inter-sample variations in each group, one dentin specimen was cut in five parts and again embedded with vinyl poly siloxane into a five-hole acrylic mold. The dentin specimens were etched with 6% citric acid for 1 minute to completely open the dentinal tubules. Eighty human dentin specimens were divided randomly into the following four groups; the negative control group (G1: 0% n-CAp), experimental group (G2: 20% n-CAp), positive control groups (G3: Sensodyne® containing SrCl2 and G4: DenShield® containing Novamin). They were applied to an oral simulation model, which was circulated during demineralization for 4 hours and remineralization for 20 hours per day. The specimens of each group were brushed 3 times per day, 10 strokes each with a V8 Cross Brushing Machine. All the specimens were evaluated by SEM. The area of the dentinal tubules was quantified using an Image analyzer. The results between the groups were analyzed by one-way ANOVA and Tukey's post hoc analysis using the SPSS 12.0 statistical package program (SPSS Inc. U.S.A).

Results: When the oral simulation model was applied for 3 days, the areas of the dentinal tubules had decreased greatly in all groups. However, 20% n-CAp group showed that tubule areas had decreased continually during cycling for 12 days. Also, this group (G2: 1.38±0.40) showed significantly higher occlusion effects than other groups (G1: 3.16±1.02, G3: 3.05±0.93, G4: 3.04±1.14, P<0.05).

Conclusion: When the oral simulation model was applied, which can indirectly reflect the in vivo situation, the dentifrice containing 20% n-CAp for 12 days was the most effective in occluding the dentinal tubules.