Treating Growing Patients With Mandibular Prognathism and Maxillary Constriction

Radiographic Analysis of Skeletal and Dentoalveolar Changes Following the Treatment of Mandibular Prognathism and Maxillary Constriction in Growing Patients Using Two Different Treatment Protocols: A Randomized Controlled Trial

This randomized controlled trial intends to test the efficacy of two treatment protocols in the correction of Class III malocclusion with maxillary constriction. We have to options, either to modify the growth using inter-maxillary traction based on an upper fixed appliance that is used in the same time for rapid maxillary expansion or to inhibit mandibular growth by a removable mandibular retractor (RMR) supplied with an expansion screw.

Inclusion Criteria:

1. growing male and female patients aged between 12 and 15 years
2. Angle's class III malocclusion
3. skeletal class III relationship judged clinically and confirmed radiographically (-4 < ANB < + 1)
4. An anterior crossbite involving two or more teeth or an edge-to-edge incisor relationship with or without an anterior shift of the lower jaw upon closure
5. normal inclination of the lower incisors or slightly proclined (i.e., the IMPA between 85° and 100°
6. maxillary constriction requiring expansion judged clinically and confirmed radiographically
7. permanent dentition
8. no previous orthodontic treatment

Exclusion Criteria:

1. skeletal class III malocclusion caused predominantly by maxillary deficiency (SNA<78° with a normal SNB angle)
2. severe skeletal class III presenting mainly due to mandibular protrusion (ANB < - 4° with no functional shift on closure)
3. contraindications for the use of the mini-screws, such as osteoporosis (addressed with cortisone and its derivatives) or those undergoing radiation treatment
4. a convergence between the mandibular canine root and the first premolar root ,which was assessed radiographically
5. facial asymmetry, characterized by a mandibular midline deviation exceeding 2 mm from the facial midline
6. MM angle >35° or SN-MP angle > 40°
7. The existence of cleft lip or craniofacial syndromes and/or palate abnormalities and
8. The existence of supernumerary teeth or missing ones except for the third molars.