Surgical exposure and orthodontic alignment of palatally displaced canines: can we shorten treatment time?

Treatment duration by morphology and location of impacted maxillary canines: A cone-beam computed tomography investigation

INTRODUCTION

This study aimed to identify whether patients with impacted maxillary canines take longer to treat than orthodontic patients without an impacted canine. We also sought to identify factors that are predictive of increased treatment duration in patients with impacted maxillary canines and treated by surgical exposure.

METHODS

A retrospective investigation of 37 patients with an impacted maxillary canine, treated by surgical exposure and fixed appliance therapy, was undertaken. In addition, an age- and sex-matched control group of 39 patients (without impacted canines) was also collected. Patient age, sex, and total treatment duration were recorded. For patients with an impacted canine, patient records and pretreatment cone-beam computed tomography datasets were assessed. Point coordinates identifying relevant landmarks were recorded, and a geometric method was used to calculate variables describing canine location, orientation, and apical morphology.

RESULTS

Controlling for age and sex, linear regression identified a statistically significant increase in treatment duration of 46.7 and 41.5 weeks for palatal and labial/midalveolar impacted canines, respectively, vs controls (P <0.002). Age and sex of patients with impacted canines collectively affected treatment duration (P = 0.04), with females of increased age being treated faster than younger males. Rotation of the impacted canine crown had a highly significant effect on treatment duration, with every degree of rotation increasing treatment duration by 0.32 weeks (P <0.001). There was a significant degree of multicollinearity between the other radiographic variables. Collectively, radiographic variables describing canine displacement significantly prolonged treatment duration (P <0.001) and explained 29.8% of the variability in total treatment time. The apical morphology of impacted maxillary canines was significantly associated with increased treatment duration (P = 0.01) and explained 11.3% of the overall treatment variability (P = 0.01).

CONCLUSIONS

Increased total treatment duration of surgically exposed impacted maxillary canines is associated with increasing mesiopalatal canine crown rotation, worsening displacement, and hooked apical morphology.

The effectiveness of minimally-invasive corticotomy-assisted orthodontic treatment of palatally impacted canines compared to the traditional traction method in terms of treatment duration, velocity of traction movement and the associated dentoalveolar changes: A randomized controlled trial

Objective: To evaluate the effectiveness of a minimally-invasive corticotomy-assisted treatment of palatally impacted canines (PICs) compared with the traditional method by evaluating treatment time, the velocity of movement, and the associated dentoalveolar changes. Materials and methods: Forty-six patients with palatally or mid-alveolar upper impacted canines were recruited and distributed into two groups: the corticotomy-assisted traction group (CAT group, mean age: 20.39±2.27 years) and the traditional treatment group (TT group, mean age: 20.26±2.17 years). The closed surgical approach was used in both study groups. The velocity of traction movement, traction duration and overall treatment duration were evaluated clinically. In addition, the bone support ratios and the amount of root resorption were assessed on cone-beam computed tomography (CBCT) images. Results: At the end of treatment, significant differences were found between the two groups regarding the velocity of traction movement, traction time, and overall treatment time (P<0.05). The mean velocity of traction movement in the CAT group was greater than the TT group ( x velocity=1.15±0.35 mm/month; 0.70±0.33 mm/month, P=0.027, respectively). The duration of the active traction and the overall orthodontic treatment in the CAT group were significantly shorter than the TT group by 36% and 29%, respectively. The mean bone support ratios of the aligned canines did not differ significantly between the two groups (88% vs. 89% in the CAT and TT groups, respectively). No significant differences were found between the two groups regarding the mean amount of root resorption on the adjacent laterals ( x resorption = 1.30±1.18 mm; 1.22±1.02 mm, P=0.612, in CAT and TT groups, respectively). Conclusions: The traction movement velocity of the palatally impacted canines can be increased using minimally-invasive corticotomy-assisted orthodontic treatment. The side effects of the acceleration procedure were minimal and almost similar to those of the traditional technique.