Dentin hypersensitivity is conventionally defined as an episode of short sharp pain arising from exposed dentin after the application of thermal, tactile, chemical, osmotic, or evaporative stimuli, which cannot be caused by any other dental pathology and/or defect. The discomfort caused by dentinal hypersensitivity (DH) is one of the main challenges that dentists face in day to day clinical practice.

Dentin hypersensitivity presents an incidence of about 35% of the population worldwide and occurs mainly between 20 and 50 years of age.

Various treatment modalities exist in the form of desensitizing agents, restorations and laser.

Of the existing materials, no literature evidence of long term complete eradication of dentin hypersensitivity exists.

Recently, a bioactive material namely nano-hydroxyapatite is widely used in dentistry for tooth remineralization and in medicine as a bone substitute.Apart from being bio-compatible, nano-sized particles have similar morphology, structure and crystallinity compared with dental apatite.

Nanohydroxyapatite when applied on the surface of the dentin, it occludes the tubular openings  and  remineralizes the surface. This creates a dual action and the final end product being similar to the inorganic composition of the tooth. On the other hand over a period of time, the stability of the formed layer remains questionable due to wearing off the layer by external factors. Hence, in order to stabilize and to create an effective barrier, adjuvants has been recommended to be used along with desensitizing agent for management of dentin hypersensitivity.

One such is the use of laser.

Laser is been reported to play a noticeable role in treating hypersensitive dentin and providing consistent and repeated results by altering the surface by melting and resolidifying the surface and seals the exposed dentinal tubules by coagulation of proteins. However, direct irradiation of exposed dentin with laser would result in the propagation of the laser beam directly to the underlying pulpal tissue resulting in generation of heat causing undesirable effects on the tissues due to low absorption coefficients of diode lasers in dentin.

Hence to bring in the synergic effect and to overcome each individual drawback, combination of both 10% nanohydroxyapatite desensitizer and 940nm diode laser irradiation have been attempted. Though the literature evidence exists with this combination, the application protocol is standardized to only once. So this questions about the actual depth of penetration of the desensitizer into the dentinal tubules and its stability over a period of time. Hence this clinical study was undertaken to explore the effects of desensitizing agent by applying it for a continued period of time followed by application of laser for prolonged desensitizing effect.