Measuring mandibular asymmetry in Class I normal subjects using 3D novel coordinate system

Area of Science:

• Dentistry
• Orthodontics
• Medical Imaging

Background:

• Orthodontic treatment is crucial for cosmetic dentistry and achieving facial balance.
• Accurate diagnosis of asymmetry, from facial morphology to dental occlusion, is essential.
• Mandibular asymmetry significantly impacts dental occlusion, making its measurement vital.

Purpose of the Study:

• To measure mandibular asymmetry in Class I molar relationship patients.
• To compare right and left sides of the mandible using a novel 3D imaging technique.
• To evaluate the effectiveness of 3D software in quantifying mandibular asymmetry.

Main Methods:

• Retrospective collection of 35 cone beam computed tomography (CBCT) scans, with 7 excluded.
• Establishment of a new coordinate system using mid-sagittal, Frankfort horizontal, and frontal planes.
• Selection of five mandibular landmarks and division of the mandible into four parts for 3D angular analysis.

Main Results:

• Significant bilateral differences were found in the angles between ramus length and the mid-sagittal plane (MSP) and frontal plane (FP).
• A significant lateroanterior shift of the left mandibular ramus compared to the right was observed.
• The 3D analysis revealed statistically significant asymmetries in mandibular structure.

Conclusions:

• The 3D method using multiple angles and planes effectively replicates and quantifies mandibular structures.
• This approach provides a valid tool for assessing mandibular asymmetry in orthodontic diagnosis.
• Understanding these asymmetries is key to achieving harmonious facial balance through orthodontic treatment.