Aim: Through the use of CBCT images, many unidentified features of impacted canines can be easily resolved. The potential collision of impacted maxillary canines and adjacent teeth could lead to root resorption (RR). The aim of this study is to examine the prevalence, location and severity of RR on adjacent teeth caused by impacted maxillary canines and the association between the adjacent teeth and the features of maxillary impacted canines on CBCT. Methods: This study examined 89 subjects with 108 maxillary impacted canines, having had no previous orthodontic treatment (mean age: 18.3 ± 4.1 years). The following impacted-canine-related parameters were analyzed on the CBCT images: location; RR levels on adjacent teeth; occlusal line and midline distances of impacted canines; and the angulations of impacted canines to the midline, lateral incisor and occlusal line. Logistic regression was used to evaluate the association between RR and the measured parameters on CBCT. Results: In this study, we found that the majority of our patients with impacted maxillary canines were female (62.5%). Of the total 108 maxillary impacted canines, 60.2% resorbed the adjacent teeth of the affected quadrants. Lateral incisors were the most affected (34.3%). The mean age of subjects with RR was 16.7 ± 3.5 years. The frequency of RR was statistically significantly higher in female subjects (40.4%). Slight RR was the most frequent (30.5%) and the highest incidence noted at the apical third of the root (29.6%). Regarding the impacted maxillary canine angulation to the midline and adjacent tooth, higher values of angulation caused severe forms of RR (p < 0.05). Conclusion: The sensitivity of CBCT allows for the accurate diagnosis of the location and the degree of RR, alongside the angulation and distance of impacted canines to adjacent teeth. The association between the linear and angular features of the impacted maxillary canines and RR was confirmed.

Eradication of microorganisms present in the root canal system during endodontic therapy is one of the critical factors affecting the final outcome of endodontic treatment. However, even adequate technique of the root canal treatment and use of irrigants according to the established protocol does not lead to the complete elimination of microorganisms during endodontic treatment. The presence of Enterococcus (E.) faecalis inside the root canal system may be an important factor contributing to the failure of the treatment. Introducing agitation techniques in irrigation, such as passive ultrasonic irrigation (PUI) and the use of the activating instrument XP-endo Finisher (XPF), contribute to a better debridement and disinfection of the root canal. This study was conducted on 42 root canals experimentally inoculated with E. faecalis and exposed to three irrigation protocols. These have included a standard irrigation protocol using a syringe and needle, passive ultrasonic irrigation, and activation of the irrigant using an XPF instrument. The reduction in microorganisms was evaluated using the quantitative polymerase chain reaction in real-time (RT-PCR) as well as via the method of determining the number of colony forming units on nutrient medium (CFUs). The results of this study showed that the use of supplementary irrigation protocols, PUI, and XPF led to a significant decrease in the number of microorganisms inside the root canal of experimental teeth. These findings indicate a significant positive impact of these procedures on the disinfection of the root canal system.