What Is Important for Confirming Negative Margins When Resecting Mandibular Ameloblastomas?

Abstract

The purpose of this study was to assess the utility of intraoperative radiographs and frozen sections in achieving negative margins and preventing recurrence of mandibular ameloblastomas. This was a retrospective cohort study of patients who underwent resection (≥1cm) of mandibular ameloblastomas from 2005 through 2015. Patients were included if they had at least 1-year follow-up and complete records. Demographic variables included age, gender, and type of resection (segmental vs marginal). Predictor variables were type of margin assessment: 1) frozen section, 2) intraoperative exvivo specimen radiograph, 3) both, or 4) none. The outcome variables were final margin status and recurrence rate. Accuracy of intraoperative radiographic margins was determined by comparison with histologic margin distance. Descriptive statistics were conducted with the Fisher exact test. The study sample consisted of 35 patients (47.5 ± 20.4yr old; 16 men) who underwent 25 segmental and 10 marginal resections. Ten had frozen sections only, 3 had exvivo specimen radiographs only, 10 had no intraoperative measurements, and 12 had both. There were no positive frozen sections. One patient had a positive posterior bony margin at final pathology despite negative frozen section histology. There was no difference in recurrence rate at latest follow-up among cohorts. The anterior radiographic margin was 11.8 ± 5.9mm compared with 11.5 ± 7.5mm by histology (P= .124). Theposterior radiographic margin was 12.3 ± 5.3mm compared with 9.8 ± 6.5mm histologically (P=.546). Margin distances that were at least 5mm when measured with specimen radiographs had histologic margin distances of at least 5mm in 25 of 30 resection margins (83.3%). Resection of ameloblastoma with planned margins of at least 1cm is sufficient to prevent recurrence of ameloblastoma. Achieving a radiographic margin of at least 5mm provided a histologic margin of at least 5mm 83.3% of the time.