Early prevention of maxillary canine impaction: a randomized clinical trial

Abstract

Summary Objectives To investigate the effect of three interceptive measures (slow maxillary expansion (SME) with removable plates (1), extraction of both upper deciduous canines (DC) (2) and no intervention (3)) on maxillary canine (MC) position in patients with early mixed dentition (EMD) and lack of upper arch space. These three groups were additionally compared to a control group (4) with adequate upper arch space. Null hypothesis None of the studied strategies outperforms the others regarding improvement of MC position. Trial design Four-arm parallel group prospective randomized controlled trial. Participants Patients in EMD with at least one impacted MC, non-resorbed DC, and no crossbite. Interventions Patients with a lack of space were randomly distributed to protocols (1), (2), and (3). Primary objective To assess the change in MC position after 18 months follow up. Secondary objectives To assess canine eruption and need for orthodontic intervention within 18–60 month follow up. Outcome assessment Five variables defined canine position: sector, canine-to-midline angle, canine-to-first-premolar angle, canine-cusp-to-midline distance, and canine-cusp-to-occlusal-plane distance on two panoramic radiographs at 0 (T1) and 18 months (T2). Mean differences between groups were compared with linear mixed models, corrected for age and sex. Randomization The patient allocation sequence was generated by an electronic randomization list. Blinding The operator taking the measurements was blinded to the groups. Results Seventy-six patients were included (142 canines, mean age 9.2 years, 60.5 per cent male, mean follow up 1.9 years), 19, 17, 14, and 26 patients in groups 1–4, respectively. In absence of dental crossbite in patients with lack of space and impacted MC, SME improved the canine sector (P = 0.040), compared to no intervention (P = 0.028). Canine-to-midline angle and canine-to-occlusal-plane distance significantly decreased in all groups at T2. Extraction improved the canine-to-first-premolar angle at T2 more than other strategies in EMD (P = 0.015–0.000). Conclusions Early SME improves the canine sector and reduces the need for major orthodontic intervention in the long term. Taking a first panoramic radiograph in EMD allows timely intervention in case of MC impaction. Trial Registration Number NCT05629312 (Clinical Trials.org). Trial status: follow up ongoing.