Delayed-Onset Infections After Lower Third Molar Extraction: A Case-Control Study

PurposeTo identify possible risk factors for delayed-onset infections and to develop a model for explaining the effects of these risk factors on the occurrence of delayed-onset infections in an outpatient clinic.Materials and MethodsA retrospective case-control study comprising a total of 178 lower third molar extractions performed between 2001 and 2004 in the Oral Surgery and Orofacial Implantology Department of the School of Dentistry of the University of Barcelona, Spain.ResultsBivariate analysis showed tooth sectioning, soft tissue and bone retention, and the position of the lower third molar (according to the classifications of Pell and Gregory, and of Winter) to be significantly associated with the development of delayed-onset infections. A logistic regression model included the following independent variables: position of the lower third molar according to Winter, and Pell and Gregory Classes I, II, and III, and degree of soft tissue retention.ConclusionsLower third molars with total soft tissue retention, a lack of distal space and with a vertical or mesioangular tilt are more likely to develop delayed-onset infections. Tooth sectioning, bone retention, and depth of inclusion could also be risk factors for such infections. Heavy smokers seem to be more prone to this complication.