Orthodontic Assessment of Mandibular Third Molar Impaction Patterns Across Skeletal Malocclusion Classes: A Retrospective Panoramic-Cephalometric Study

Background: Mandibular third molars are often evaluated during orthodontic diagnosis because their eruption or impaction can be influenced by the retromolar space and mandibular morphology. Objectives: This study aimed to assess mandibular third molar impaction patterns across skeletal malocclusion classes among Iraqi orthodontic patients using pretreatment panoramic and cephalometric records. Methods: This retrospective panoramic-cephalometric study included 270 orthodontic patients and 540 mandibular third molar sites. The skeletal class was determined using the ANB angle and categorized as Class I, II, or III. Mandibular third molar status was recorded as impacted, erupted, missing, or extracted. Impacted teeth were classified according to Winter’s and Pell and Gregory classifications. Associations were assessed using chi-square tests or the Fisher-Freeman-Halton exact test with Monte Carlo estimation, as appropriate. Age differences were evaluated using Welch’s t test and the Mann-Whitney U test. Results: Mandibular third molar impaction was present in 146 patients. Impaction status was significantly associated with skeletal class, with the highest frequency in Class II (63.2%) and the lowest in Class III (41.4%). Impaction pattern was also significantly associated with skeletal class. Mesioangular impaction was the most common Winter's pattern (67.0%), but Winter’s classification was not significantly associated with skeletal class. The Pell and Gregory level and the Pell and Gregory class were not significantly associated with skeletal classes. Conclusions: Mandibular third molar impaction was associated with skeletal malocclusion class, particularly Class II. Panoramic and cephalometric assessment may support orthodontic pretreatment evaluation.