Volume 16, Number 1, March 2004

Mandibular Lengthening by Distraction Osteogenesis: Role of Periosteum and Endosteum

Thongchai Nuntanaranont, Wilad Sattayasunskul, Surapong Vongvatcharanon

Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Prince of Songkla University, Songkhla, Thailand


Abstract
Objective: To study the role of the periosteum and endosteum in new bone formation by distraction osteogenesis.
Materials and Methods: Twenty four rabbits were divided into 3 groups of perieosteum destruction (group P), endosteum destruction (group E), and a control group (group C). After right mandibular body osteotomy followed by distractor placement, the buccal periosteum in the segment between the second and third screws was removed by scalpel in group P. In group E, the endosteum was scraped out from both bone ends between the second and third screws. In group C, both periosteum and endosteum were preserved during the surgical operation. After a latency period of 3 days, bone lengthening was started at a rate of 1 mm per day for 10 days, after which the newly formed bone was allowed to consolidate for 6 weeks with the device serving as an external fixator. Radiographs were taken at the following time intervals: 2 weeks, 4 weeks, and 6 weeks after completion of distraction and 6 months after consolidation. The animals were sacrificed 6 weeks after completion of distraction and 6 months after consolidation for the gross macroscopic, histological, and radiological examinations and stability measurement of the distracted segment.
Results: New bone was generated in all animal groups. The buccal cortex was incompletely formed in groups P and E but was completely formed and indistinguishable in the control group after 6 months. Histologically, the newly formed bone in the control group had a more mature appearance and better organised bone spicules than in groups P and E. In addition the remodelling process occurred more rapidly in the control group. However, quantitative analysis of the newly formed bone by densitometry revealed no statistically significant differences at each time interval among the 3 groups except for a decline in density in the control group after 6 months due to the bone remodelling process. The stability of the regenerated bone of the lengthened segment was best in the control group, with groups P and E showing marked changes in the length of the distracted distance.
Conclusion: Although groups P and E exhibited slower new bone maturation, the amount of newly formed bone was equal in all groups. It could be stated that the periosteum and endosteum are probably not indispensable or particularly important for adequate callus formation. This may be due to the rich blood supply of the craniofacial skeleton. However the instability of the segment caused by the slow maturation and remodelling of the newly formed bone in groups P and E should be noted, and a longer consolidation period is recommended to avoid instability of the regenerated segment in such cases.


Key words: Distraction osteogenesis, Mandible, Periosteum

Asian J Oral Maxillofac Surg. 2004;16:21-33.
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