PURPOSE: Odontogenic infections are a common problem in emergency departments and impose a burden on hospital budgets and provider time. Compounding this is the lack of evidence guiding the patient's initial evaluation. The purpose of this study was to derive evidence-based guidelines for the use of computed tomographic (CT) imaging in the management of odontogenic infections. MATERIALS AND METHODS: A prospective cohort study was designed. Patients with an odontogenic infection presenting to the emergency department from November 1, 2016 to November 30, 2017 were eligible for inclusion. The outcome variable was need for CT imaging, which was based on the location of the abscess. The potential predictor variables were demographics, history items, examination findings, and laboratory values. The association between the outcome and predictor variables was determined using classification and regression tree analysis and standard logistic regression analysis. RESULTS: There were 129 patients who met the inclusion criteria and consented to participation. The patients were 53.5% men and the mean age was 42.5 years. The most common fascial spaces involved were vestibular (58.2%), submandibular (18.6%), pterygomandibular (6.2%), buccal (5.4%), and lateral pharyngeal (5.4%). The classification and regression tree analysis identified mandibular inferior border blunting at the body as the best predictor for necessitating a CT scan and identified a mouth opening smaller than 25 mm as the second best predictor. These 2 predictors had an accuracy of 96.9% for needing a CT scan. The logistic regression analysis identified these 2 variables and odynophagia, floor of mouth induration, and white blood cell count as relevant predictors for needing CT imaging. CONCLUSION: The 2 physical examination findings of mandibular inferior border blunting at the body and restricted mouth opening were found to be strongly associated with the need for CT imaging. Further studies should be directed at validating these criteria in larger multicenter studies.