Cleft Skeletal Asymmetry: Asymmetry Index, Classification and Application

Area of Science:

• Craniofacial surgery
• Orthodontics
• 3D imaging analysis

Background:

• Unilateral cleft lip and palate (UCLP) causes significant 3D facial skeletal asymmetry.
• Quantitative assessment of this asymmetry is crucial for effective treatment planning and outcome evaluation.

Purpose of the Study:

• To develop and validate an asymmetry index (AI) for quantitatively measuring 3D facial skeletal asymmetry in UCLP patients.
• To demonstrate the AI's utility in guiding surgical interventions and assessing treatment outcomes.

Main Methods:

• Cone-beam computed tomography (CBCT) scans of 25 UCLP patients and 50 controls (ages 15-20) were analyzed.
• 3D anthropometric analysis and landmarking were performed.
• An asymmetry index (AI) was calculated to quantify skeletal asymmetry.

Main Results:

• The AI values in the UCLP group were significantly higher than in the control group across most landmarks.
• Facial skeletal asymmetry in UCLP patients varied individually, affecting upper, middle, and lower facial regions.
• Asymmetry generally increased with landmark distance from the midsagittal plane.

Conclusions:

• The developed asymmetry index (AI) accurately captures 3D facial skeletal asymmetry in UCLP.
• The AI serves as a reliable tool for classifying asymmetry extent and guiding orthognathic surgery planning.
• The AI is effective for measuring treatment outcomes and improvements in facial symmetry.