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Accuracy of a predetermined transverse horizontal mandibular axis point
William W Nagy1, Thomas J Smithy, Carl G Wirth
1Graduate Prosthodontics, School of Dentistry, Marquette University, Milwaukee, WI 53233, USA. william.nagy@marquette.edu
The Journal of Prosthetic Dentistry
|May 16, 2002
Summary
An anatomical method for locating the transverse horizontal mandibular axis point is a reliable alternative to kinematic methods. This study found predetermined axis points to be consistently close to kinematic axis locations in subjects.
Area of Science:
- Dentistry
- Biomechanics
- Anatomy
Background:
- Locating the transverse horizontal mandibular axis is crucial for accurate dental articulator transfer.
- Kinematic methods offer precision, but anatomical methods can be simpler if a consistently accurate point is identified.
Purpose of the Study:
- To compare the accuracy of an anatomically predetermined hinge axis point with the kinematic hinge axis in vivo.
- To determine if an anatomical landmark can reliably approximate the kinematic axis for clinical use.
Main Methods:
- Forty subjects underwent assessment of their transverse horizontal mandibular axis.
- Anatomical hinge axis points were identified 10 mm anterior to the earpiece.
- Kinematic axis points were determined using the SAM Axiograph III and PC Axiotron, with accuracy confirmed to within 0.25 mm.
Main Results:
- The mean distance between predetermined and kinematic axis points was 1.1 mm (right) and 1.2 mm (left).
- Over 96% of predetermined points were within 2 mm of the kinematic axis.
- No significant differences were found between right and left sides or between genders.
Conclusions:
- The anatomically predetermined hinge axis point is a clinically acceptable and reliable landmark.
- This anatomical method simplifies the transfer of the mandibular arc of rotation to dental articulators.