Fixed versus removable orthodontic appliances to correct anterior crossbite in the mixed dentition : a randomized controlled trial

Objective: To compare the effectiveness of fixed and removable orthodontic appliances in correcting anterior crossbite with functional shift in the mixed dentition. Subjects and methods: Consecutive recruitment of 64 patients who met the following inclusion criteria: early to late mixed dentition, anterior crossbite with functional shift, moderate space deficiency in the maxilla, i.e. up to 4mm, a non-extraction treatment plan, the ANB angle > 0 degree, and no previous orthodontic treatment. Sixty-two patients agreed to participate. The study was designed as a randomized controlled trial with two parallel arms. After written consent was obtained, the patients were randomized, in blocks of 10, for treatment either with a removable appliance with protruding springs or a fixed appliance with multi-brackets. The main outcome measures assessed were success rate, duration of treatment, and changes in overjet, overbite, and arch length. The results were also analysed on an intention-to-treat basis. Results: The crossbite was successfully corrected in all patients in the fixed appliance group and all except one in the removable appliance group. The average duration of treatment was significantly less, 1.4 months, for the fixed appliance group (P < 0.05). There were significant increases in arch length and overjet in both treatment groups, but significantly more in the fixed appliance group (P < 0.05 and P < 0.01). Conclusion: Anterior crossbite with functional shift in the mixed dentition can be successfully corrected by either fixed or removable appliance therapy in a short-term perspective