Evaluation of the relationship between mandibular third molar tooth impaction and mandibular morphology in panoramic radiographs: A retrospective study

The aim of this thesis is to evaluate the relationship between third molar embeddedness and mandibular morphology in patients with impacted mandibular third molars in digital panoramic radiographs with dimensional, angular and proportional measurements in patients with impacted mandibular third molars who applied to Ankara Yıldırım Beyazıt University Faculty of Dentistry. The material of our study consisted of 330 patients, 60.5% (n=199) female and 39.5% (n=131) male, between the ages of 18-31 years, who applied to Ankara Yıldırım Beyazıt University Faculty of Dentistry. In our study, 9 dimensional, 4 angular and 1 proportional parameters were evaluated. The data obtained in the study were analyzed using SPSS 22 package program. Mann-Whitney U test was used for comparisons between paired groups that were not normally distributed, and Kruskall Wallis H test was used for comparisons between three or more groups. The relationship between categorical data was analyzed by Chi-Square analysis. Correlation test analysis was used for relationships between variables. Intraobserver reliability was examined with ICC (Intraclass Correlation). Descriptive statistical method (Mean, Median, Standard Deviation, Minimum-Maximum) was used to evaluate the study data. In our study, when the impacted mandibular third molars were grouped according to the Winter classification, 69.2% were found in the mesioangular position, 23.9% in the vertical position and 8.9% in the horizontal position. In the Pell and Gregory classification according to occlusal surface, the most common depth of burial was found to be Class A (53.33%), followed by Class B (39.39%) and Class C (7.28%). Classification of depth according to ramus showed that the most common burial depth was Class 2 (65.95%). In the experimental group with impacted mandibular third molars, condyle length, coronoid length, mandibular corpus width, sigmoid notch depth, retromolar space distance, antegonial notch depth were significantly lower than the control group with erupted mandibular third molars. In the angular measurements made in our study, Co/Cr angle was significantly higher in the experimental group than in the control group. Alpha angle was significantly higher in the control group than in the experimental group. The ratio of the retromolar space distance to the width of the third molar was significantly higher in the control group than in the experimental group. In conclusion, it was found that mandibular third molar impactedness is associated with various parameters in mandibular morphology. By using measurements on panoramic radiographs taken from patients, various parameters can be used to predict the impacted tooth. Key words: Impacted tooth, Mandible, Panoramic radiography