小児歯槽部骨折が顎骨の成長発育に与える影響

スンクスを用いた基礎的研究

抄録

To investigate the influence of alveolar fractures sustained during growth on the development of the mandibular bone, 29 male house musk shrews (Suncus murinus) aged 4-weeks were studied. An originally designed forceps was used to fracture the alveolar bone at the right side of the mandible of each shrew in the experimental group. Untreated shrews served as control. Immediately and 6, 10, and 15 weeks after the fracture, the healing process of the fracture was examined radiologically and histologically. The bone mineral density was measured by peripheral quantitative computed tomography (pQCT) and morphometric analysis was performed 15 weeks after the fracture, and the right and left sides of the mandible were compared.
The results were as follows:
1) Small fractured segments of the alveolar bone were partially resorbed by osteoclasts 6 weeks after fracture, and new bone tissue was concurrently observed in the surrounding region. Fifteen weeks after fracture, the amount of new bone had increased, and the new bone appeared to be well-mineralized lamellar bone. The fractured segments were connected with the surrounding new bone, and the alveolar fracture had apparently healed clinically.
2) Fifteen weeks after fracture, however, the histological findings of the fractured mandibles differed from those of the control group, and the bone mineral density of the fracture site was lower than that of the opposite site of the mandible.
3) On morphometric analysis, some variables of the mandibular ramus differed significantly between the right and left sides of the mandible 15 weeks after unilateral alveolar fracture.
4) No obvious difference was observed radiologically, histologically, or morphometrically between the right and left sides of the mandible in the control group.
These results suggest that a long time may be required for alveolar fractures to recover histologically, even in the case of minor fractures. When sustained during growth, such fractures may influence the development of the mandible.