Does Upper Incisors Procline following Rapid Maxillary Expansion Facemask Therapy?

Abstract

Background: The present study is intended to evaluate the changes in upper incisor angulation, skeletal and dental parameters, soft-tissue and airway dimensions following rapid palatal expansion and maxillary protraction. Materials and Methods: Twenty class III subjects (mean age 11.3 years) were given bonded rapid maxillary expansion (RME) and facemask (FM) for 6 months. Pre- and posttreatment cephalogram were compared and dental, skeletal, soft-tissue, and airway changes were quantified. Results: The mean increase in SNA was 1.85° (P < 0.001) while SNB decreased by 1.85° (P < 0.001). Upper and lower face height increased (UFH 1.1 mm, P < 0.05; LFH 2.92 mm, P < 0.001). Upper lip moved forward (E line U/lip 1.27 mm, P < 0.001; S line U/lip 1.3 mm, P < 0.01). 1-SN decreased by 4.35° and 1-NA decreased by 4.50° with P < 0.01. Overjet improved by 3.07 mm (P < 0.001). Conclusion: RME and FM therapy resulted in maxillary forward movement; mandible rotated downward and backward; UFH and LFH increased. The upper lip exhibited forward movement, resulting in a less concave profile. Upper incisor retroclined and there was increase in overjet and no changes in airway dimensions. The upper incisors following RME and FM does not always procline; it is decided by the interaction of four factors – mesial dental movement, rotation of maxillary/occlusal plane, amount of expansion with RME (expansion effect), and reverse twin block if incorporated with FM.

Keywords

• class iii malocclusion
• facemask
• incisor retroclination
• rapid maxillary expansion