D21. Failure Rates Based on Alveolar Cleft Size: An Analysis of the Critical Size Defect for rhBMP-2/DBM and Iliac Crest in Alveolar Bone Grafting

Abstract

PURPOSE: Iliac crest bone graft (ICBG) is the standard of alveolar bone grafting (ABG). However, recombinant human bone morphogenetic protein(rhBMP-2) with demineralized bone matrix (DBM) has been proposed as an alternative. We aim to identify the critical size defect of failure rates for ICBG and rhBMP-2/DBM. METHODS: A retrospective review evaluated patients undergoing ABG from 2016-2022. Patients with genetic syndromes, bilateral clefts, and missing postoperative cone beam computed tomography (CBCT) were excluded. The 3-dimensional volumetric defect sizes were calculated using preoperative CBCT scans. The primary outcome was bony bridge formation based on postoperative imaging. Logistic regression was used to model graft failure rates and identify the maximal point, which defined the critical point. RESULTS: Among 148 patients screened, 62 were included who underwent ABG (ICBG: n=28; rhBMP-2/DBM: n=34). There was no significant difference in bridge formation between graft types. The critical point in failure rate was calculated to be 829.3mm3 and 857.8mm3 for rhBMP-2/DBM and ICBG, respectively. Upon Fisher-exact analysis, there were increased bridge failures in clefts greater than the critical point for both ICBG (p<0.001) and rhBMP-2/DBM (p=0.005). The critical point did not vary between graft types (p=0.772) CONCLUSION: Our findings identified a higher probability of graft failure beyond the predicted critical size defect for each respective bone graft. Clinicians can better counsel families of patients with larger defects with a higher probability of treatment failure using either ICBG or rhBMP-2/DBM.