In vivo sensitivity of human root dentin to air blast and scratching

Background: The present study evaluated the prevalence of radicular sensitivity to scratching as well as the effects of a common oxalate desensitizing agent on sensitivity to air blast and scratching. Methods: Eighty-seven patients self-reporting dentin hypersensitivity, with at least two hypersensitive teeth, were included. Prior to any treatment, their sensitivity to air blast was recorded and rated as absent or present, and the force necessary to trigger pain when scratching was measured with a scratchometer in cN. For each patient one sensitive tooth was treated with an oxalate desensitizing agent and the other one with a placebo solution. The same measurements were carried out after treatment. Results: Following treatment with a placebo solution, 70% of the teeth remained sensitive to air blast while only 38% of the desensitizing agent-treated teeth remained sensitive to air blast (P <0.01). The mean force required to elicit pain prior to any treatment was 44 17 cN. This force statistically increased significantly after application of the placebo (53 +/- 17 cN) (P <0.05). After using the desensitizing agent, the force was even higher (95 +/- 24 cN) (P <0.01). Only 8% of the teeth treated with the desensitizing agent did not respond to treatment compared to 37% of the teeth treated with the placebo solution. Conclusions: The placebo solution had a significant effect on sensitivity to air blast and to scratching (P <0.05). The oxalate desensitizing agent was more effective than the placebo solution at decreasing the sensitivity both to air blast and to scratching (P <0.01). The sensitivity to air blast seems to be overestimated because, after using the desensitizing agent, 38% of the teeth remained sensitive to air blast but only 8% remained sensitive to scratching. Pulpal inflammation may be involved in those teeth that did not respond to treatment.