Osteodistraction of mandibles with a small bone defect at the planned osteotomy site: a histological pilot study in dogs.

AIM: To develop a treatment plan for cases in which a bone defect is located on the osteotomy line of mandibular osteodistraction (DO). SUBJECTS AND METHODS: Bilateral DO was performed in 17 Mongrel dogs. Prior to surgery, the 34 hemi-mandibles were randomly allocated to three groups: C (n = 10; a standard DO was performed), D - G (n = 12; a bone defect was created on the DO osteotomy line), and D + G (n = 12; the bone defect on the osteotomy line was grafted). After one week of latency, 8 days of distraction, and 4 weeks of consolidation the animals were sacrificed, and the newly formed bone were examined. RESULTS: In group C, two zones of immature trabecular bone originating from host bone margins were separated by a central fibrous zone. In group D + G uniform new bone formation of the entire distraction gap was observed. In group D - G the distraction gap was mainly filled with fibrous tissue. The values for the newly formed bone volume and trabecular thickness were not significantly different between groups D + G and C, but were higher than values in group D - G (p < 0.05). CONCLUSION: When a mandibular defect is located at the site of distraction osteotomy, DO can be performed simultaneous with bone grafting of the defect.