Brännström M
Department of Oral Pathology, Karolinska Institutet, Huddinge, Sweden.
Proc Finn Dent Soc. 1992;88 Suppl 1:7-13.
Hypersensitive dentin appears to be mainly the result of an activation of the dentinal pain fibres, the A-fibres, at the pulpal wall. The stimuli which activate these nerves are primarily those which remove fluid from the dentinal tubules and mobilize capillary forces, causing a rapid outward flow. Application of a cold stimulus causes the fluid to contract, resulting in a similar rapid outward flow in the pulpal region of the tubules. Hypersensitivity to cold is also marked when there is a fluid-filled gap containing bacteria in the tooth. Experiments have shown that a freshly exposed dentin surface with patent tubules is more sensitive than a surface contaminated by a smear layer. Inflammation in the adjacent pulpal region can also increase sensitivity. The development of hypersensitive cervical and occlusal surfaces is due to mechanical and acidic effects from the oral environment, toothbrush abrasion, erosive components in the diet, plaque and bacterial invasion of dentin. Sometimes dentin is exposed by restorative therapy and occasionally eccentric occlusal loads can contribute to hypersensitivity. The sensitivity may persist unless the open tubular apertures are sealed.
过敏牙本质似乎主要是牙髓壁上牙本质疼痛纤维（A 纤维）激活的结果。激活这些神经的刺激主要是那些从牙本质小管中去除液体并调动毛细作用力，导致快速向外流动的刺激。施加冷刺激会使液体收缩，导致在小管的牙髓区域出现类似的快速向外流动。当牙齿中存在含有细菌的充满液体的间隙时，对冷的过敏也很明显。实验表明，具有开放小管的新暴露牙本质表面比被玷污层污染的表面更敏感。相邻牙髓区域的炎症也会增加敏感性。过敏的颈部和咬合面的形成是由于口腔环境的机械和酸性作用、牙刷磨损、饮食中的侵蚀成分、牙菌斑和细菌侵入牙本质。有时牙本质会因修复治疗而暴露，偶尔偏斜的咬合负荷也会导致过敏。除非开放的小管孔被密封，否则敏感性可能会持续存在。
