Hydroxyapatite as an in-office agent for tooth hypersensitivity: a clinical and scanning electron microscopic study

Pain caused by hypersensitivity is very common and a variety of agents have been tried and tested to put an end to this ailment, but with limited or short-term success. The search for an agent that would predictably and permanently occlude the tubules and blend with them has prompted the use of durapatite/hydroxyapatite (HAP), which is the principal inorganic constituent of the tooth.

A total of 486 hypersensitive teeth in 45 patients with hypersensitive symptoms confirmed by visual analog scale and verbal rating scale were divided into four groups. Two were treated with HAP in two forms (dry sol gel and liquid precipitate form), and the other two groups included a positive control group (distilled water) and a negative control group (no treatment). The responses were evaluated at 0 and 1 days, and 1, 2, 4, and 8 weeks, for all groups. Ten freshly extracted teeth were prepared and treated as mentioned previously and subjected to scanning electron microscopy to assess the tubule occlusion.

HAP-treated teeth showed statistically significant reduction in hypersensitive symptoms (P <0.001) compared to the other groups at the end of 1 day and 1, 2, and 4 weeks, but at the end of 8 weeks all four groups showed no statistical differences (P <0.5). The scanning electron microscopic study showed completely obliterated dentinal tubules in the HAP-treated specimens, whereas the other groups showed predominantly open or partially occluded tubules.

HAP shows definite potential as an effective and permanent desensitizer when used as an in-office procedure. However, further long-term studies and comparative clinical trials with other popular desensitizing methods need to be carried out to prove its superiority.