title: Risk of periodontal defects after third molar surgery: An exercise in evidence-based clinical decision-making.
abstract: OBJECTIVE
  The object of this study was to apply evidence-based principles to answer the question, What is the risk of having periodontal defects on the distal aspect of the mandibular second molar (M2) following third molar (M3) removal?
  
  
  METHODS
  To identify relevant articles for review, we completed a computerized literature search of Medline. The inclusion criteria for articles included prospective cohort studies or randomized clinical trials with follow-up periods of 6 months or more, and preoperative and postoperative measurements of periodontal probing depths (PDs) or attachment levels (ALs).
  
  
  RESULTS
  Eight articles met the inclusion criteria. Overall, the reported mean changes in ALs or PDs on the distal of M2 6 months after M3 removal were clinically insignificant, ie, less than 2 mm. Six months after M3 removal, 52% to 100% of subjects had no change or improvement in ALs or PDs. Given periodontal disease present preoperatively, the number needed to treat (NNT) ranged from 3 to 10. Given healthy periodontal status preoperatively, 48% had worsening of their periodontal measures after M3 removal and the number needed to harm (NNH) was 2.
  
  
  CONCLUSIONS
  Commonly, the second molar periodontal probing depth or attachment levels either remain unchanged or improve after third molar removal. For subjects with healthy second molar periodontium preoperatively, the indication for third molar removal needs to be evaluated carefully as these subjects have an increased risk for worsening of probing depths or attachment levels after third molar removal.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, Massachusetts 02114, USA. dtrichardson@partners.org
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Richardson
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Dodson
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology*; D003657:Decision Making; D019317:Evidence-Based Medicine; D006801:Humans; D008964:Molar, Third / Q000601:surgery*; D017622:Periodontal Attachment Loss / Q000209:etiology*; D012307:Risk Factors; D014081:Tooth Extraction / Q000009:adverse effects*; D014095:Tooth, Impacted / Q000601:surgery