Advances in tissue engineering offer potential alternatives to current mandibular reconstructive techniques; however, before clinical translation of this technology, a relevant animal model must be used to validate possible interventions.
To establish the critical-sized segmental mandibular defect that does not heal spontaneously in the rat mandible.
Design and Setting
Prospective study of mandibular defect healing in 29 Sprague-Dawley rats in an animal laboratory.
The rats underwent creation of 1 of 4 segmental mandibular defects measuring 0, 1, 3, and 5 mm. All mandibular wounds were internally fixated with 1-mm microplates and screws and allowed to heal for 12 weeks, after which the animals were killed humanely.
Main Outcomes and Measures
Analysis with micro–computed tomography of bony union and formation graded on semiquantitative scales.
Seven animals were included in each experimental group. No 5-mm segmental defects successfully developed bony union, whereas all 0- and 1-mm defects had continuous bony growth across the original defect on micro–computed tomography. Three of the 3-mm defects had bony continuity, and 3 had no healing of the bony wound. Bone union scores were significantly lower for the 5-mm defects compared with the 0-, 1-, and 3-mm defects (P < .01).
Conclusions and Relevance
The rat segmental mandible model cannot heal a 5-mm segmental mandibular defect. Successful healing of 0-, 1-, and 3-mm defects confirms adequate stabilization of bony wounds with internal fixation with 1-mm microplates. The rat segmental mandibular critical-sized defect provides a clinically relevant testing ground for translatable mandibular tissue engineering efforts.