Retrospective evaluation of the factors affecting the categorical classification of permanent first molar teeth with compulsory extraction

Permanent first molars are the called keys to occlusion, and their unplanned loss causes occlusal disorders. In our study, it was aimed to retrospectively evaluate the radiographic factors affecting the categorical classification degree of the extraction space by examining the panoramic radiographs recorded in the database of children aged 7-14 years who had their permanent first molar teeth extracted between 2008 and 2019 in our faculty. One hundred fifty two teeth of patients who met the inclusion criteria were examined radiographically. The developmental stage of the second molar, the germ presence of the third molar, and the angulation of the second molar were determined on the panoramic radiograph taken before the extraction. The distance between the second premolar and the second molar tooth was measured on the panoramic radiograph taken after extraction, and the measured value was categorized according to the classification of Teo et al. Category 1 represented complete space closure. The relationship between the space closure and the germ presence of the third molar, the developmental stage of the permanent second molar, and the angulation of the tooth were examined. In addition, maxilla and mandible were compared in terms of space closure success. The level of p <0.05 was considered significant. In our study, it was found that the closure of the extraction space in the maxilla was more successful than the mandible (p<0.001). When the relationship between the closure of the extraction space and the stage of tooth development was examined, the result was found to be significant (p<0.01). It was determined that category 1 closure can be seen in almost every stage in the maxilla, and the "D" and "E" stages in the mandible constituted most of the cases with complete space closure. When the relationship between angulation and space closure of the second molar adjacent to the extracted first molar tooth was examined, although no significant relationship was found (p>0.05), the angle was seen between 25°- 40° in 66.6% of the teeth with category 1. When the relationship between the presence of the third molar and space closure was examined, statistically difference was not obtained (p>0.05); however, it was found that 85% of the teeth with category 1 closure had the germ of the third molar tooth. In the study, it was concluded that there is a need for prospective studies with long term follow up, in which an equal number of data were provided on the factors evaluated with the inclusion of clinical examination.