Abstract:

Objective　To investigate the condensability of mandibular length.Methods　In six goats were used in the study. Corticotomy at right mandibular angleswas performed via extral-oral accession. Special deviceswere applied to shorten the mandi- ble by 0·5 mm per three days respectively.Results　①Mandibular angles of the six goatswere shorten by 0·8 cm to 1·3 cm re- spectively in 48 days to 78 days;②In spite of the lower ascending ramus moving forward and angles being blunt, the occulusion scarcely varied because of contralateral bite-lock;③X-ray demonstrated that, at first, bone density in contracted areas declined , and then increased gradually to almost normal density;④Under microscope there were three tissues layers from central to lateral within the bone gap: fiber layer, cartilage layer and bone layer, and fiber layer gradually transform into cartilage layer with the fixed time. At the end of fixation they all transform into bone tissue.Conclusion　Contraction osteogenesis is actually a process of compression, absorption and rebuilding. It is feasible that using contraction osteogenesis to shorten the mandible via cortcotomy.

Key words: mandible, condensability, animal-study