American study demonstrates the positive effect of hydroxyapatite on dentin hypersensitivity

Dentin hypersensitivity is quite common, especially in patients who have had periodontitis. This disease is especially likely to cause receding gums and thus expose the necks of teeth. Exposed necks of teeth (dentin) are causing dentin hypersensitivity. Consequently, any external stimuli can be transmitted directly to the dental pulp via the dentinal tubules. Epidemiological data on sensitive teeth indicate a prevalance of up to 98%. There are now a number of oral care products which are designed to be effective in treating dentin hypersensitivity. Clinical studies and laboratory investigations show effective pain relief, in particular when hydroxyapatite toothpastes are used.


How effective is a hydroxyapatite toothpaste versus other commercially available oral care products in reducing dentin hypersensitivity?

Materials and methods

This double-blind, randomised, parallel clinical study (in situ) was carried out at the School of Dentistry in San Antonio, Texas (USA). A total of 80 test subjects took part in the study. Four dentine samples were worn in the oral cavity from each test subject. The test subjects were randomised into 4 groups, with each group using its respective test toothpaste twice a day over a period of 14 days. The toothpastes used were two different hydroxyapatite toothpastes (10% HAP and 15% HAP), a sodium monofluorophosphate toothpaste and a toothpaste containing amorphous calcium phosphate. The dentine samples were examined after 7 and 14 days using scanning electron microscopy.


Both hydroxyapatite toothpastes presented occlusion of the dentinal tubules. A layer of hydroxyapatite could also be seen on the dentine samples. Amorphous calcium phosphate was also able to occlude dentinal tubules, though to a lesser extent than hydroxyapatite. Sodium monofluorophosphate showed the lowest degree of tubule occlusion, which may be due to the abrasives rather than the fluoride.

Figure 1 and 2: Tooth surface with exposed dentinal tubules before (left) and after (right) treatment with hydroxyapatite.
Figure 1 and 2: Tooth surface with exposed dentinal tubules before (left) and after (right) treatment with hydroxyapatite.


The use of hydroxyapatite results in the deep, extensive occlusion of the dentinal tubules and can therefore prevent tooth sensitivity.

The published study can be read here.

Source:  Amaechi, B. T. et al. Evaluation of nanohydroxyapatite-containing toothpaste for occluding dentin tubules. Am J Dent 28: 33-39 (2015).