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Dentin and dentinal tubules

Dentin provides elasticity and strength of the tooth, which allows him to withstand forces by chewing and injury. Dentin also raises important defense measures aimed at preserving the integrity of the pulp tissue.

In a normal, healthy conditions, when covered with enamel and dentin cement, liquid dentinal tubules can expand or shrink to affect cells in the pulp in response to thermal stimuli applied to the surface of the tooth. Therefore, dentin intact tooth can convert external stimuli in an appropriate message to the cells and nerves in the pulp - and-a function that is clinically useful to check their vital functions. Touch sensor function is triggered by elastic deformation due to overload detection, as a result of reflex and the removal of transient acute pain.

When enamel and cement, damaged for any reason, open the dentinal tubules, serve as ways of pulp for the entry of potentially harmful elements in the oral environment, including bacterial macromolecules, which may provoke inflammation (4).

The deeper the injury is more tubules participate (Fig. 2.2). On the periphery there are some 20,000 tubules per square millimeter, each having a diameter of 0,5 |im. In the pulp of a tooth ends tubular holes occupies a large surface area, because tubes, converge in the centre and get wider (2.5-3 |im) (20). Thus, on the inner surface of dentin there are more than 50 000 tubules per square millimeter. In dentin root, especially towards the top, tubes, become more widely spaced. In addition, in the tooth pulp part of dentin root, they are thinner and have a smaller diameter (approx. 1.5 in or |m). There are many branches between pipelines that provide relationship.

Motion of particles and macromolecules through dentinal tubules can occur not only from the external environment, cellulose, but in the opposite direction. Thus, following the injury, which led to the violation of the tight junctions, which usually holds odontoblasts together (71), the liquid pulp enter tubules and bring plasma proteins with antimicrobial properties (41).

The potential for items penetrates the dentinal tubules, as a rule, limited significantly different tissue structures, including collagen fibers and cellular processes. In odontoblasts usually held cytoplasmic processes in the bone. Differences exist, however, how far. Although some believe that these processes are drawn to enamel and cement interchanges others argue that only the innermost part (0.5-1 mm) dentin is filled in (15). A large number of tubes, also contain nerve endings. In addition, the cells belonging to the immunosurveillance systems for the pulp and paper extend dendrites in tubules of the predentin layer (52). Consequently, the space available in the tube to the transport of solid particles and macromolecules, as a rule, considerably less than tubular space per se (61) (Fig. 2.3). This is especially true in their tooth pulp ends. ..

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