| Summary: | 碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 96 === Distraction osteogenesis has been widely used in congenital anomalies to correct craniofacial deficiency. Clinically it is frequently conducted on growing patients for early establishment of normal physiological functions. However, the effects on temporomandibular joints undergoing mandibular distraction are still controversial, and the influence of growth was not taken into consideration in most of the research. In this study, we investigated the effects on bone remodeling of TMJs in growing mini-pigs in which unilateral mandibular distraction osteogenesis was performed.
Six (5~12 weeks, 6~15kg weight) Lee-Sung genus of mini-pigs were divided into 4 groups: 1) Experimental group A (n=1), received osteotomy and the distractor device (Leibinger intraoral distractor) was fixed on one side of the mandible. After one-week latency period, the mandible was distracted for 2 weeks with the velocity of 0.9 mm/day. The animals were sacrificed after a consolidation period of 4 weeks. 2) Experimental group B (n=2), the animals received the similar treatment as Experimental group A, except that they were sacrificed after a consolidation period of 8 weeks. 3) Control group (n=1), the distraction was little for the distractor was broken after 4 days of distraction. And 4) Normal group, 2 healthy mini-pigs without any operation were used. To examine the changes of bone remodeling of TMJs, polychrome labeling of bone was performed.
According to the bone labeling, the bone deposition and remodeling in the TMJs was very active during the entire experimental period. The thickness of cartilage of condyles decreased after 4 weeks of consolidation period, and it didn’t return to normal after 4 weeks later. The bone deposition of the glenoid fossa was more active in the experimental group then in the normal and control groups after 4 or 8 weeks of consolidation period. These findings revealed not only the condyle but also the glenoid fossa adapt to the distraction. Remarkable bone resorption around the fixation screws of distractors was also noted. Therefore, they cannot provide enough stability during the distraction.
In conclusion, distraction osteogenesis is an effective way to lengthen the mandible with subtle and transient changes in bone remodeling of TMJ. A longer-term observation will reveal whether these changes would last and affect the mandibular movement and function.
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