Asymmetry of normal mandibular condylar shape

Area of Science:

• Dental anthropology
• Biomedical engineering
• Quantitative morphology

Background:

• Conventional radiographic measurements of the facial skeleton lack detailed shape analysis.
• Fourier series offer a robust mathematical method for quantitative shape assessment and variation analysis.
• Mandibular condyle morphology is crucial for understanding temporomandibular joint function and facial development.

Purpose of the Study:

• To quantitatively analyze the shape of mandibular condyles using Fourier analysis.
• To investigate condylar shape symmetry on both intrasubject (left vs. right) and intersubject (male vs. female) bases.
• To compare the efficacy of Fourier analysis with conventional measurement techniques for skeletal morphology.

Main Methods:

• Digitization of mandibular condyle outlines from orthopantomographs of 40 healthy adults (20 men, 20 women).
• Application of Fourier series analysis to quantify condyle shape.
• Comparison of Fourier coefficients and reconstructed outlines to assess symmetry and variability.

Main Results:

• Significant intrasubject asymmetry in mandibular condyle shape was detected, indicating left and right condyles differ in form within individuals.
• A large interindividual variability in condyle shape was observed.
• No significant difference in mean condyle shape was found between male and female groups, suggesting symmetry between sexes.

Conclusions:

• Mandibular condyle shape is inherently asymmetric within individuals, a finding not captured by traditional linear/angular measurements.
• Fourier analysis provides a powerful tool for detailed shape quantification, revealing subtle morphological differences.
• While individual condyles vary significantly in shape, the average shape is consistent between sexes.