Theory Of Dentin Sensitivity

INTRODUCTION :

Sensitive teeth as is a very commonly encountered chief complaint in dental clinics. However, there is no definitive standard of care in addressing the clinical presentation of dentin sensitivity till date. Epidemiological research suggests that 8 – 35% of the population experience dentin sensitivity. Self-reported dentin sensitivity is higher among individuals in their third and fourth decades of life ranging from 45 – 57.2%.[1, 2]Sensitivity is characterized by short, sharp pains that are commonly due to exposed dentin. Sensitivity arises when thermal, evaporative, mechanical, or osmotic stimuli are applied to exposed dentin. Sensitivity can also be caused by internal factors such as change in pH.[3]
There are many theories

Changes in the hydraulic conductance of dentin have been used as a method of screening for the efficacy of desensitizing agents. Although this model works well for agents that desensitize by occluding tubules, it is not suitable for those that modify nerve activity. Filling the dentinal tubules with a protein solution more closely simulates dentinal fluid. A dilution of plasma with phosphate-buffered saline (PBS) provides the opportunity to evaluate the effects of desensitizing agents or methods that might precipitate plasma proteins in dentinal fluid[7,

The consequences of bacterial and toxin ingress may require years to manifest damage, until the retreating pulp succumbs to the insult that results in clinically detectable symptoms. 5a 7 Provisional restorations oRen demonstrate microleakage that allows the ingress of bacteria, and prepared teeth are often contaminated with saliva during various stages in the fabrication of fixed partial dentures (FPDs). Restorations are often luted with zinc phosphate (ZPC) or glass ionomer (GI) cements. The acidic nature of these Cements [15]can remove part of the smear layer. Pashley [16] and Zaimoglu and KevserlO demonstrated that cement can be forced into the patent tubules before the luting agent sets. The cement can displace an equal amount of dentinal fluid, which may cause excessive hydrostatic pressure and resultant irritation of pulpal tissues.7 Tooth sensitivity after cementation has been a problem with GI cements.lO However, when GI is selected as a base, no sensitivity is elicited.lls I2 Sensitivity was frequent when GIC was used as a luting agent, especially if the remaining dentinal thickness (RDT) was less than 1 rnrn.ll This sensitivity could have been a result of the prolonged low pH of cement9 during setting and/or hydrostatic pressure that enabled cement to enter dentinal tubules.7T lo This can result in