Effectiveness of Aligners Versus Rapid Maxillary Expansion

Aim of the study is to assess the effectiveness of Invisalign® First clear aligners compared to tooth-borne Hyrax-type maxillary expander on palatal morphology in growing subjects using 3D technology. This two-arm parallel-group randomized prospective clinical trial will include patients with: indications for maxillary expansion treatment, age between 6 and 10 years old, mixed dentition, good standard of oral hygiene, good compliance during treatment as assessed by the practitioner. Patients will be assigned to one of two expansion methods (arm A: Invisalign® First clear aligners, arm B: tooth-borne Hyrax-type maxillary expander) according to a computer-generated randomization list shortly before the start of expansion Primary outcome measure will be the change in palatal morphology (palatal volume and surface area variations). Secondary outcomes will be: arch dimensions (upper inter-canine width, upper inter-molar width, anterior segment length, posterior segment length), complications, patients' satisfaction and periodontal health. Due to the nature of the intervention blinding will not be possible. Potential statistical differences between the two intervention groups will be evaluated.