Agreement analysis of three mandibular third molar retention classifications.

Introduction: Pell & Gregory and Winter classifications are basic in third molar categorization; Sánchez-Torres classification is used in Mexico, but it has not been previously evaluated.

Objective: To assess the degree of agreement in the radiographic evaluation of impacted mandibular third molar with the use of three classifications: Pell & Gregory, Winter and Sánchez-Torres.

Method: Observational, descriptive, inter-observer degree of agreement study that included 10 oral and maxillofacial surgeons and 10 training residents, who recorded the radiographic categorization of third mandibular molars (left and right) according to Pell and Gregory, Sánchez-Torres and Winter classifications. Inter-observer degree of agreement was assessed with Fleiss' kappa test.

Results: Pell and Gregory classification obtained the lowest degree of agreement (kappa = 0.05 and 0.185), followed by Sánchez-Torres classification (kappa = 0.125 and 0.326); Winter had the best agreement, with kappa = 0.28 and 0.636 for oral and maxillofacial surgeons and training residents, respectively.

Conclusion: The Winter classification showed an acceptable (moderate) degree of agreement to classify mandibular third molars by training residents.