Dentinal hypersensitivity (DH) is a global oral health issue and a significant challenge for most dental professionals. Symptoms of dentinal hypersensitivity are generally reported by the patient and are difficult to describe and challenging to accurately diagnose because other dental diseases have to be ruled out first, such as dental caries, cracked-tooth syndrome, and defective restorations, among others. The condition has been defined by an international workshop on DH as follows: “DH is characterized by short, sharp pain arising from exposed dentine in response to stimuli, typically thermal, evaporative, tactile, osmotic or chemical and which cannot be ascribed to any other dental defect or pathology”.1,2 (Figure 1).
Figure 1. Pictorial display of origin of pain associated with sensitive teeth.
Dentinal hypersensitivity incidence ranges from 4-74%.1 The variations in the reports may be because of difference in populations and different methods of investigations. The methods employed are usually patient questionnaires or clinical examinations. A slightly higher incidence of DH is reported in females than in males. While DH can affect the patient of any age, most affected patients are in the age group of 20–50 years, with a peak between 30 and 40 years of age.3-9 The most common teeth affected by DH are the canines and premolars and the buccal aspect of cervical area is the commonly affected site.4 Among periodontal patients, the frequency is much higher (60-90%).5-7
Dentin is covered by enamel on the crown surface and by a thin layer of cementum on the root surface of the tooth and is sensitive to stimuli. DH develops in two phases: lesion localization and lesion initiation. Lesion localization occurs by loss of protective covering, enamel and cementum over the dentin, thereby exposing the dentinal tubules. Exposure is attributed to attrition, abrasion, erosion and abfraction. However, dentinal exposure mostly occurs due to gingival recession which can be due to toothbrush abrasion, pocket reduction surgery, tooth preparation for crown, excessive flossing or secondary to periodontal diseases.18 In the second phase, the exposed dentin will only be sensitized if the tubular plugs and the smear layer are removed exposing them to the external environment. Both mechanical and chemical factors are effective in removing the smear layer from the dentinal tubules. A couple culprits involved in removing the smear layer are acidic foods and acidic drinks.