Immediate and Sustained Reduction of Dentine Hypersensitivity from Hydroxyapatite Toothpaste

Methods: This was a double-blind, 2-product, randomized, parallel study. Male/female adults in good general/dental health were enrolled if they had a Yeaple score<30 and Schiff score≥2 on exposed roots of two teeth. Subjects with other conditions that could contribute to oral sensitivity, or medical/dental conditions incompatible with study objectives were excluded. The test-toothpaste contained HAP, K-citrate, Zn-citrate-trihydrate, 1450ppm fluoride; positive control contained arginine, calcium carbonate, 1450ppm fluoride.

Toothpastes were applied by rubbing with finger onto the exposed dentine for 30sec. Sensitivity was assessed before and after toothpaste application (immediately; 8h later) using the Yeaple tactile and Schiff air-blast methods.  

The outcome variable per subject for each stimulus was defined as the average score of two teeth. Within/between group differences were assessed for statistical significance by paired t-tests and repeated measurement analysis.

Results: 102 subjects completed the study. Both toothpaste reduced sensitivity immediately and 8h after application (p<0.0001). Immediately after application, the mean change in Yeaple score was 11.2g (s.e.=1.3g) for the test and 5.9g (s.e.=1.4g) for the control toothpaste; the difference (test-control) was statistically significant (p<0.01). For the Schiff score the reduction was 0.6 (s.e.=0.08) for test and 0.7 (s.e.=0.08) for control toothpaste. Eight hours after application, the change in Yeaple score was 9.5g (s.e.=1.4g) and 7.6g (s.e.=1.1g) for test and control pastes respectively; Schiff scores were reduced by 0.8 (s.e.=0.08) in test and by 0.9 (s.e.=0.09) in control group. Between-group differences were not statistically significant after 8h.

Conclusions: Test and control toothpaste significantly reduced dentine sensitivity immediately and 8h after application. A greater reduction after tactile stimulus was found for the test paste than the positive control immediately after application.