6 cm or 10 cm? What Is the Critical Defect Size in Mandibular Reconstruction Using Non- vascularized Bone Grafts

Background : A significant debate exists about the defect size boundary when using nonvascularized bone grafts (NVBG) in segmental mandibular defects. Although the 6 cm rule was well accepted for decades, there is no strong evidence supporting it. Moreover, various authors recommended NVBG for defects larger than 6 cm without setting any boundary. Therefore, the current retrospective study aimed to assess the defect size boundary (if any). Methods : The records of 236 patients with segmental mandibular defects were reviewed to analyze the relationship between success and defect length (size) and site and the source of NVBG. Results : Grafting was successful in 213 patients (113 failed). Success was not related to the patient’s age, gender, smoking status, or the graft source. Success was associated with benign tumor defects. The difference in trauma defects was insignificant, whereas osteomyelitis resulted in grafting failure. In the lateral defects, grafting was successful, whereas the differences in the anterior and lateroanterior defects were insignificant. The univariate logistic regression analyses revealed that success predictors were defects < 6 cm, defects < 10 cm, benign tumor defects, and lateral defects. However, failure was predicted for defects > 10 cm. The multivariate logistic regression analysis revealed that success was predicted when combining the factors: defects < 10 cm, lateral defects, and benign tumor defects. Conclusion : NVBG may be successful for defects < 10 cm, particularly for lateral defects due to benign tumors. Clinical trial registration No.: Not applicable.