Objectives: The aim of this study was to evaluate the validity of the existing classification and difficulty index of impacted mandibular third molars in clinical situations and propose a more practical classification system.
Materials and methods: This study included 204 impacted mandibular third molars in 154 patients; panoramic x-ray images were obtained before tooth extraction. Factors including age, sex, and pattern of impaction were investigated. All impacted third molars were classified and scored for spatial relationship (1-5 points), depth (1-4 points), and ramus relationship (1-3 points). All variables were measured twice by the same observer at a minimum interval of one month. Finally, the difficulty index was defined based on the total points scored as slightly difficult (3-4 points), moderately difficult (5-7 points), very difficult (8-10 points), and extremely difficult (11-12 points).
Results: The strength of agreement of the total points scored and difficulty index were 0.855 and 0.746, respectively. Most cases were classified as moderately difficult (73.0%). Although only 13 out of 204 cases (6.4%) were classified as extremely difficult, patients classified as extremely difficult were the oldest (P<0.05).
Conclusion: For difficulty classification, the authors propose one more difficult category beyond the existing three-step difficulty index: the clinician should consider the patient's age in the difficulty index evaluation.
Keywords: Classification; Impacted tooth; Third molar; Tooth extraction.
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