Our aim was to investigate the structural changes of dentinal tubules in specimens obtained from both hypersensitive and naturally desensitized areas in wedge-shaped defects on the same exposed cervical dentin surface of a hypersensitive tooth. A new biopsy technique that makes use of a hollow, cylindrical diamond bur was designed so that specimens from exposed root dentin of vital teeth could be obtained. Twenty-two dentin biopsy pairs were divided into two groups; one was prepared for scanning electron microscopy (SEM) and the other for microradiography (MR). Small hypersensitive areas were identified by a scratch test on exposed human dentin in vivo. SEM observation of the dentin biopsies showed that the orifices of many dentinal tubules in hypersensitive areas were open and that membranous structures appeared on the walls of dentinal tubules. In naturally desensitized areas on the same dentin surface, most of the dentinal tubules were obturated with rhombohedral crystals of all sizes; membranous structures were not observed in these tubules. These results showed that hypersensitivity occurred on the exposed dentin when most of the tubular orifices were open.
Transmission electron microscopy (TEM) and x-ray microanalysis (XMA) were used for the study of the ultrastructure of the lumens of dentinal tubules in superficial layers of dentin specimens obtained by use of a new biopsy technique from both hypersensitive and naturally desensitized areas of exposed root surfaces, in vivo. The TEM images showed clearly that the lumens of most of the tubules were occluded with mineral crystals in naturally desensitized areas, but such lumens were empty and surrounded with peritubular and intertubular dentin in hypersensitive areas. Moreover, electron-dense structures that lined peritubular dentin were observed in the empty lumens of dentinal tubules.
Sixty adult patients were examined for dentin hypersensitivity prior to periodontal surgery. Stimuli used included mechanical, cold water and compressed air blasts. A subjective assessment of the degree of hypersensitivity for each stimulus was recorded. This presurgical examination revealed 249 hypersensitive areas among 60 subjects. Following surgery there was over a 100% increase in the pain (hypersensitivity) score. Desensitization with a 10% strontium chloride hexahydrate dentifrice was begun 1 week after surgical treatment. After 7 weeks of dentifrice use the pain score was reduced 75.5% in the test group. This was a reduction to a point below the preoperative level. The placebo group showed a reduction of 34.2% which was still above the preoperative level. These results agree with other clinical studies that have demonstrated a desensitizing effect of strontium chloride.
Sialolithiasis in children is rare. Four cases of sialolithiasis in the submandibular gland occurring in children < or = 10 years old are reported. True and distal oblique occlusal radiographs were found to be useful for detection of the sialolith. A review of the literature on sialolithiasis in children is presented.
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