Three-dimensional reproducibility of natural head position

Area of Science:

• Craniofacial imaging and analysis
• Biomedical engineering
• Orthodontics and dentofacial orthopedics

Background:

• Natural head position (NHP) is a reliable reference in the sagittal plane for craniofacial analysis.
• Increasing use of 3D imaging necessitates evaluation of NHP reproducibility in coronal and axial planes.
• Assessing NHP's stability over time is crucial for accurate 3D craniofacial measurements.

Purpose of the Study:

• To evaluate the reproducibility of natural head position (NHP) over time.
• To assess NHP's reliability in sagittal, coronal, and axial planes using 3D imaging.
• To establish a hierarchy of NHP reproducibility across different spatial planes.

Main Methods:

• 3D photographs of 28 adult volunteers were captured at 5 time points over 1 week.
• Reference points on the face were marked, and their orientation was recorded using a 3D camera system.
• Superimposition of photographs and analysis of marker parallelism were performed using specialized software.

Main Results:

• No statistically significant differences in NHP were found across the 5 time points in any plane.
• A significant difference in mean angular deviations was observed between the planes.
• Reproducibility hierarchy: coronal > axial > sagittal planes.

Conclusions:

• Natural head position is reproducible in sagittal, coronal, and axial planes within the study's parameters.
• The coronal plane exhibits the least variation, indicating superior reproducibility.
• Findings support the use of NHP in 3D craniofacial analysis across multiple planes.