Histomorphometric evaluation of short-term changes in masseter muscle after lengthening the rabbit mandible by distraction osteogenesis.
OBJECTIVE
Structural changes in muscles may affect the process during and after distraction osteogenesis (DO) of the mandible. However, the response of the masticatory muscles is still not well defined after gradual lengthening of the mandible. In this experimental study, short-term structural changes in masseter muscles of the rabbits are evaluated after mandibular DO.


METHODS
Left mandibles of 10 New Zealand rabbits were lengthened by DO for 7 days in the rate of 1 mm/day. Mandibles of all animals were removed at the end of the consolidation period. Muscle biopsy samples of distracted and contralateral sides were histopathologically investigated, and histomorphometric results were statistically analyzed.


RESULTS
Atrophy, hypertrophy, regeneration, and concomitant mild interstitial edema and fibrosis were found more evident in experimental side biopsy samples 30 days after distraction. Histomorphometric analysis revealed a statistically significant decrease in the mean regions of masseter muscle fibers of the distracted sides compared with the control sides (P <.05).


CONCLUSIONS
This experimental study showed that the structure of masseter muscle is influenced during and shortly after mandibular distraction osteogenesis. Atrophic changes of the ipsilateral masseter muscles may be regarded as regenerative response that occurs during and shortly after distraction period.
Department of Oral and Maxillofacial Surgery, Dental Faculty, Ankara University, Ankara, Turkey. tuzhakan@hotmail.com
Hakan H
HH
Tüz
Reha S
RS
Kisnisci
Omer
O
Günhan
D000818:Animals; D001284:Atrophy; D001706:Biopsy; D002467:Cell Nucleus / Q000473:pathology; D003238:Connective Tissue / Q000473:pathology; D004487:Edema / Q000473:pathology; D005355:Fibrosis; D006984:Hypertrophy; D007091:Image Processing, Computer-Assisted; D008334:Mandible / Q000601:surgery*; D008406:Masseter Muscle / Q000473:pathology*; D016555:Matched-Pair Analysis; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D019857:Osteogenesis, Distraction / Q000295:instrumentation / Q000379:methods; D011817:Rabbits; D012038:Regeneration / Q000502:physiology; D013997:Time Factors