Maxillary Canine Impaction and Adjacent Incisor Root Resorption

Maxillary canine impaction and root resorption of adjacent lateral incisors is a well-known and relatively common phenomenon in orthodontic practice. The risk of canine impaction and associated root resorption is relatively high in patients needing orthodontic treatment. Early diagnosisremains a critical problem, and there are no straightforward clinical clues concerning the treatment planning, prediction, or prevention as regards canine impaction and the associated root resorption of the adjacentlateral incisor. The introduction of CBCT in dentomaxillofacial radiology has created new diagnostic challenges, including some potential opportunities for evaluating the impacted canines. With this new technology, it was obligatory to investigate and determine if this new information provides another and better way of diagnostic approach, treatment planning, improved treatment outcome and early prediction. Consequently, the present thesis attempted to link the radiological observations to diagnostic, therapeutic and further preventive measures. The main objectives were to develop an improved diagnostic methodology that would enable optimal diagnosis, treatment, and early prediction. The diagnostic accuracy for the detection of simulated canine-induced external root resorption lesions in maxillary lateral incisors was compared between conventional panoramic radiographic imaging and CBCT systems in vitro. The results show that the performance of CBCT imaging was significantly better than that of panoramic radiography. After the CBCT had been proven to perform better than conventional 2D panoramic images, the question to be answered remained whether there is a difference between CBCT machines. Therefore, the subjective image quality of the different CBCT systems in vitro was determined. The results suggest that the CBCT radiographic method is moresensitive and that high image quality is important when trying to detect root resorption. There were no significant differences between the CBCT systems in the detection of root resorption. The findings of a previous in vitro study were confirmed in vivo: the results show that CBCT was a reliable diagnostic method for the localization of impacted canines and the detection of root resorption of adjacent lateral incisors. The treatment of impacted canines usually requires a multidisciplinary approachand is associated with prolonged treatment times, increased costs, complexity, and a risk of failure and complications. The diagnostic consequences of using 2D or 3D radiography may have a significant impact on therapeutic interventions. Therefore, this aspect was investigated by comparing the orthodontic treatment planning between conventional and CBCT-based planning. Similarly, the influence on pre-surgical treatment planningwas also studied. The findings of those studies show no statistically significant difference in treatment planning or in pre-surgical treatmentplanning between the use of conventional and CBCT sets. The only significant difference was related to the precise localization of impacted canine but had no effect in the treatment plans. However, a high confidencelevel was observed in CBCT treatment based planning. The influence of CBCT on the treatment methods used and treatment outcomes achieved for orthodontically treated patients was then investigated. No difference was found either in the number of treatment methods or treatment outcome. Inthe last part of this thesis, a method for early prediction and prevention of canine impaction and root resorption was explored. Early prediction based on radiographic factors might clinically stimulate the application of preventive measures. Therefore, a prediction model for root resorption on panoramic radiographs was constructed. The early prediction of root resorption might reduce complications before, during and/or after treatment because additional clinical measure can be taken. The prediction of root resorption was carried out on the basis of available panoramicradiographs because they are routinely present in orthodontic records. Furthermore, the diagnosis of root resorption based on panoramic radiographs is difficult, and the final prediction model for root resorption could be a helpful tool in justifying the need for additional CBCT examination. The purpose was to reduce the need for additional radiation exposure, certainly in cases where the probability of the presence of root resorption is low. Finally, the prediction model for canine impaction was established on the basis of CBCT with a high level of accuracy, which mayhelp orthodontists in identifying the probability of impaction, which, in turn, is helpful in defining the optimal intervention method.

Keywords:Root resorption

Disciplines:Dentistry

Project type:PhD project