title: Estimating third molar extraction difficulty: a comparison of subjective and objective factors.
abstract: OBJECTIVE
  The purpose of this study was to compare and contrast subjective and objective assessments of variables associated with third molar (M3) extraction difficulty.
  
  
  METHODS
  To address the research purpose we implemented a prospective cohort study and enrolled a sample of surgeons removing M3s in an ambulatory care setting. Predictor variables were categorized as demographic, anatomic, or operative. The outcome variables were subjective and objective rankings of the importance of the variables in terms of estimating M3 extraction difficulty. Subjective rankings were made by surveying the surgeons and asking them to rank each variable's importance on a scale ranging from 0 (not important) to 100 (extremely important). Objective rankings of each variable's importance were made using the absolute values of coefficients derived from a multivariate linear regression model with extraction time as the outcome. Appropriate uni-, bi-, and multivariate statistics were computed.
  
  
  RESULTS
  The sample consisted of 14 surgeons who removed 450 M3s from 150 subjects from June 2002 to August 2003. Based on the multivariate linear regression model, variables associated with M3 extraction time were gender, arch location, Winter's classification, tooth morphology, number of teeth extracted, procedure type, and surgical experience. For these variables, there was a strong, statistically significant correlation (r = 0.86; P <.01) between the standardized coefficient absolute values and the surgeons' estimates of importance.
  
  
  CONCLUSIONS
  There was a large, positive correlation between variables that surgeons consider most important in determining M3 extraction difficulty and those exhibiting the most influence over extraction times in a multivariate model.
authors.affiliation: Harvard School of Dental Medicine, Massachusetts General Hosital, Boston, MA 02114, USA.
authors.forename: Srinivas M
authors.initials: SM
authors.lastname: Susarla
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Dodson
mesh_terms: D000328:Adult; D002983:Clinical Competence; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008964:Molar, Third / Q000033:anatomy & histology / Q000601:surgery*; D011379:Prognosis; D012737:Sex Factors; D013515:Surgery, Oral / Q000592:standards*; D013997:Time Factors; D014081:Tooth Extraction