Quantification and visualization of the tooth extraction effects on face with spatially dense geometric morphometrics

Area of Science:

• Orthodontics
• Facial Morphology
• Geometric Morphometrics

Background:

• Orthodontic treatment aims to improve dental occlusion and facial aesthetics.
• Understanding facial changes associated with different orthodontic approaches is crucial for treatment planning.
• Premolar extractions are common in orthodontics, but their full facial impact requires detailed evaluation.

Purpose of the Study:

• To evaluate facial changes in female Chinese patients undergoing orthodontic treatment.
• To compare the effects of different anchorage controls (mini-implants vs. no mini-implants) in extraction cases.
• To assess the influence of four first premolar extraction on facial morphology using geometric morphometrics.

Main Methods:

• Employed geometric morphometrics and multivariate statistics on 46 adult female patients.
• Classified patients into three groups: extraction with maximum anchorage (mini-implants), extraction without mini-implants, and non-extraction.
• Utilized partial least squares regression to analyze pre- and post-treatment facial changes.

Main Results:

• Significant upper and lower lip retrusion observed in extraction groups post-treatment.
• Maximum anchorage group showed minor, non-statistically significant depression in temple and cheek areas.
• Zygomatic region showed slight increase in mid-face in maximum anchorage group, but not statistically significant.
• Non-extraction group exhibited no statistically significant facial changes.

Conclusions:

• Anchorage choice and premolar extraction significantly affect lip shape and perioral regions.
• Extraction treatment did not significantly impact cheek and temple appearance compared to non-extraction.
• Spatially dense geometric morphometrics effectively quantifies and visualizes full facial changes, enhancing orthodontic outcome evaluation.