Changes in mandibular shape after early treatment in subjects with open bite: a geometric morphometric analysis

Area of Science:

• Orthodontics
• Craniofacial development
• Biometrics

Background:

• Anterior open bite (OB) in growing individuals presents complex challenges in craniofacial development.
• Effective treatment strategies are crucial for optimizing mandibular growth and correcting OB.
• Geometric morphometrics offers advanced tools for analyzing subtle shape changes.

Purpose of the Study:

• To compare mandibular modifications in growing anterior open bite subjects treated with Rapid Maxillary Expansion and bite block (RME/BB) versus Quad Helix with crib (QH/C).
• To evaluate treatment effects against a Control Group (CG) using Geometric Morphometric Method (GMM) and conventional cephalometrics.

Main Methods:

• 34 subjects with dentoskeletal OB were divided into RME/BB and QH/C groups; both compared to a matched CG.
• Lateral cephalograms taken before treatment (T1) and long-term follow-up (T2) were analyzed.
• GMM, Procrustes analysis, and principal component analysis were applied to assess shape changes.

Main Results:

• RME/BB treatment resulted in a significant decrease in the Condylar axis to mandibular plane angle compared to CG and QH/C.
• GMM revealed increased mandibular ramus height in the RME/BB group.
• A tendency towards counterclockwise mandibular rotation was observed with RME/BB compared to other groups.

Conclusions:

• RME/BB treatment induces significant changes in mandibular ramus shape and promotes a counterclockwise rotation tendency.
• These findings highlight the distinct effects of RME/BB on mandibular morphology in growing OB patients.