Maxillary canine impaction in orthodontic patients with and without agenesis: a cross-sectional radiographic study

To assess potential associations between maxillary canine impaction (MCI) and agenesis status as well as between MCI and gender.

The records of 182 orthodontic patients with agenesis (excluding the third molars) and 630 orthodontic patients without agenesis were examined. Diagnosis of MCI was based on pretreatment panoramic radiographs. Maxillary canines that had not erupted as a result of physical barrier or deflection in the eruption path at the dental age of at least 12 years were considered impacted. Logistic regression analysis was used to test for the associations of interest.

MCI was detected in 5.6% (n = 35) of the nonagenesis group (28 female and 7 male participants) and in 18.1% (n = 33) of the agenesis group (20 female and 13 male participants). Bilateral impaction was detected in 12 patients (34.3%) of the nonagenesis group and in 11 patients (33.3%) of the agenesis group. There was evidence that maxillary lateral incisor agenesis (odds ratio = 5.1, 95% confidence interval [CI] 2.5-10.5, P < .001) and second premolar agenesis (odds ratio = 2.6, 95% CI 1.0-6.6, P = .042) were significant MCI predictors after adjusting for gender. The odds of MCI were 69% higher in female versus male subjects after adjusting for agenesis status (95% CI 0.97-2.92, P = .063).

This study indicates that there is evidence that agenesis status is a strong predictor of MCI, whereas gender is a weak predictor of MCI. Caution should be exercised in interpreting the results because of the observational nature of the present study.