Background: The reasons why root sensitivity occurs in some periodontally diseased teeth are still unknown. It is possible that root sensitivity may be related to changes of intradental myelinated nerve fibers, which are responsible for dentine sensitivity.
Objective: The aim of this study was to define the pattern of myelinated nerve fiber changes in the pulps of teeth with and without root sensitivity in the presence of chronic periodontitis.
Materials and methods: A total of 33 cross-sectioned human dental pulp specimens were collected from noncarious, intact, permanent teeth sensitive to electric and thermal (cold) stimulus (10 hypersensitive teeth with chronic periodontitis (HTPP group), 15 nonsensitive teeth with chronic periodontitis (NTPP group), and 8 nonsensitive teeth with healthy periodontium (control group)). The morphometric parameters were estimated using light microscopy and image-analyzing computer program Image-Pro Plus.
Results: The means of myelinated nerve fiber density, fiber and axon diameter, area, perimeter, length, width, g ratio, index of circularity, and myelin sheath thickness in NTPP group significantly differed from HTPP group and the control group teeth (p<0.001). The great reduction in the density of myelinated nerve fibers in NTPP group was accompanied by unequal decrease in the number of very large-diameter myelinated nerve fibers. The mean values of morphometric parameters of all myelinated nerve fibers in HTPP group were almost the same as those in the control teeth, and no significant difference was observed.
Conclusion: The findings of the present study suggest that the reason for enhanced root sensitivity has likely nothing to do with changes of the innervation of myelinated nerves in the dental pulp. While, decreased sensitivity of periodontally diseased teeth may be related to the degeneration of myelinated nerve fibers in the pulp.