title: What Is Important for Confirming Negative Margins When Resecting Mandibular Ameloblastomas?
abstract: OBJECTIVE
  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.
  
  
  METHODS
  This was a retrospective cohort study of patients who underwent resection (≥1 cm) 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 ex vivo 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.
  
  
  RESULTS
  The study sample consisted of 35 patients (47.5 ± 20.4 yr old; 16 men) who underwent 25 segmental and 10 marginal resections. Ten had frozen sections only, 3 had ex vivo 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 ± 5.9 mm compared with 11.5 ± 7.5 mm by histology (P = .124). The posterior radiographic margin was 12.3 ± 5.3 mm compared with 9.8 ± 6.5 mm histologically (P = .546). Margin distances that were at least 5 mm when measured with specimen radiographs had histologic margin distances of at least 5 mm in 25 of 30 resection margins (83.3%).
  
  
  CONCLUSIONS
  Resection of ameloblastoma with planned margins of at least 1 cm is sufficient to prevent recurrence of ameloblastoma. Achieving a radiographic margin of at least 5 mm provided a histologic margin of at least 5 mm 83.3% of the time.
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA. Electronic address: zpeacock@partners.org.
authors.forename: Zachary S
authors.initials: ZS
authors.lastname: Peacock
authors.affiliation: DMD Candidate, Harvard School of Dental Medicine, Boston, MA.
authors.forename: Yisi D
authors.initials: YD
authors.lastname: Ji
authors.affiliation: Associate Professor of Pathology, Department of Pathology, Massachusetts General Hospital, Boston, MA.
authors.forename: William C
authors.initials: WC
authors.lastname: Faquin
mesh_terms: D000328:Adult; D000564:Ameloblastoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D001706:Biopsy; D005260:Female; D005629:Frozen Sections; D006801:Humans; D008297:Male; D008339:Mandibular Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D000072662:Margins of Excision; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control; D018365:Neoplasm, Residual / Q000473:pathology; D012189:Retrospective Studies; D016896:Treatment Outcome