Evaluation of the impacted maxillary canines position, determination of the possible indicators of the impaction difficulty and the risk factors for adjacent teeth root resorption

Background/Aim. An impacted tooth is a tooth that could not erupt and take its place in the dental row. Impacted maxillary canines are a very frequent problem in the orthodontic practices. They are the second most impacted teeth, right after the third molars. The aim of this cross-sectional study was to evaluate the two-dimensional and three-dimensional position of the impacted maxillary canines as well as to make a descriptive study analysis of possible indicators of the impaction difficulty and risk factors for adjacent tooth root resorption. Methods. 94 subjects with 116 diagnosed maxillary canines impaction (CI) were included in the investigation. The two-dimensional position of the impacted canines (IC) was evaluated on the panoramic projection of the cone beam computed tomography (CBCT) images. Canine position (CP) to the X, Y and Z-axis was measured and scored using the novel classification system that incorporates three-dimensional information of CBCT imaging, the KPG index. Based on the KPG index value, impaction was defined as easy, moderate, difficult, and extremely difficult. Descriptive variables (gender, side of impaction, etc.) and numeric variables [age, canine distance to the occlusal plane (OccP), etc.] were tested with multiple logistic regression as potential predictors of the impaction difficulty and possible risk factors. Results. The mean age of the subjects was 19.8?5.2 years. The impactions were twice as more prevalent in females, compared to males. Most impactions were unilateral (71.4%) in palatal position. Adjacent root resorption was present in 27.3% cases of impaction, and the central incisor was mostly affected. More than half of impactions were of moderate level. In univariable analysis, canine distance to sagittal medial line (SML), canine angulation (CA) to SML and OccP and CA to first premolar were significant in impaction difficulty prediction. Multivariable analysis showed that CA to the first premolar could be a risk factor for adjacent root resorption. Conclusion. Most of the impacted maxillary canines were in palatal position, with KPG index value of moderate difficulty. Beside the position to the OccP and SML, CA to the first premolar should be estimated, as a part of diagnostic procedures, to evaluate the risk of adjacent root resorption, to prevent resorption and to decide on the treatment plan.