ヒト下顎切歯狭窄根管の構造に関する組織学的研究

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In recent years, attempts have been made to extend tooth life through improvement of oral health, progress of preventive dentistry, and the 8020 (Eighty-Twenty) Campaign. In aging people, reduction in size and volume of the dental pulp chamber occurs owing to continuous secondary dentin deposition and reparative dentin formation. As a result of the sequence of this deposition, there is a tendency toward eventual pulp and canal obstruction. This study describes the anatomical morphology and canal histology in mandibular incisors with obstructed pulp chamber and canal in radiographs. Seventeen extracted human mandibular incisors with obstructed pulp chamber and canal in dental rediographs were selected from 130 extracted human teeth for preclinical endodontic training of students, and used for this experiment. The age, sex and race of the patients were unknown. remaining dental calculus or debris was not removed. The teeth were radiographed from clinical and proximal views using dental X-ray film (Ektaspeed Plus, Eastman Kodak, USA)/ After macroscopic observation of the teeth, soft X-rays were taken with SRO-M50 (Sofron). The teeth were left in air for spontaneous drying and then immersed in 100% alcohol. The teeth were embedded in light-cure glycol methaacrylate plastic (Technovit^[○!R] 7200VLC, Kulzer, Germany) and cured in a Block Dry Unit (MG-4600, Exact, Germany) at low temperature. Horizontal sections were cut at 0.75 mm intervals from the incisal edge to the root apex. Longitudinal central specimens of the root canal were cut labio-lingually. These specimens were polished thinly and examined by transmitted and reflected light of an optical microscope. 1. Morphological appearance was seen macroscopically. (1) Attrition was clearly visible: 88.2% (15 teeth). (2) Abrasion was clearly visible: 64.7% (11 teeth). (3) Calculus forms were strongly adherent to the apical root portions in almost all teeth. 2. In radiographs, the pulp horns and chambers in two teeth had not been obliterated and were left behind. Canal obstruction (obliteration) by radiographic observations was observed particularly within the pulp of the cervical two-thirds of the roots. 3. Histological observations revealed that the dentin deposition occurred on all the four walls of the roots. Periodontal tissue destruction, attrition and abrasion may be considered as important etiologic factors of increasing incidence of elaboration of reparative dentin and mineralization in the dental pulp.
2006-12-31

ヒト下顎切歯狭窄根管の構造に関する組織学的研究

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