Reproducibility of three-dimensional posterior cranial base angles using low-dose computed tomography

Area of Science:

• Craniofacial anatomy and development
• 3D imaging and cephalometry
• Orthognathic surgery and orthodontics

Background:

• The posterior cranial base angle is vital for craniofacial development.
• Reproducibility of 3D posterior cranial base angle measurements is critical for clinical applications.
• Existing 2D cephalometric angles have limitations when translated to 3D.

Purpose of the Study:

• To determine the most reproducible three-dimensional (3D) posterior cranial base angles.
• To compare the reproducibility of 12 different 3D posterior cranial base angles.
• To evaluate angles derived from 2D cephalometry and new anthropological concepts.

Main Methods:

• Retrospective analysis of low-dose computed tomography (CT) data from 20 adult patients.
• Two independent observers identified 3D landmarks twice using Maxilim software.
• Performed 3D cephalometric analyses to measure 12 posterior cranial base angles.

Main Results:

• Inter-observer correlation coefficients varied significantly among the tested angles.
• The 3D angle R4 demonstrated the highest reproducibility (correlation coefficient of 0.827).
• The 3D angle R2 showed the lowest reproducibility (correlation coefficient of -0.177).

Conclusions:

• The null hypothesis of equal reproducibility was rejected.
• The 3D angle R4, utilizing specific landmarks (basion, superior optic, crista galli inferior), is the most reproducible.
• The R4 angle is recommended as a reference for future 3D cephalometry in orthodontics and orthognathic surgery.