An analysis of tooth position on initial tooth contact.

Area of Science:

• Biomechanical Engineering
• Dental Physiology
• Kinesiology

Background:

• Understanding normal mandibular kinematics is crucial for diagnosing and treating temporomandibular joint disorders.
• Previous studies have utilized various methods to analyze jaw movements, but detailed kinematic analysis of tooth tapping remains an area for further investigation.

Purpose of the Study:

• To quantitatively analyze the velocity and form of mandibular movements during tooth tapping in healthy subjects.
• To investigate the characteristics of tooth contact and associated sounds during the closing and opening phases of mandibular motion.

Main Methods:

• Utilized a closed-circuit television movement detector to record mandibular movements.
• Analyzed movement phases in transverse, sagittal, and coronal planes using u.v. charts and X-Y recordings.
• Correlated microphone signals with tooth contact events during tapping.

Main Results:

• Closing movements were observed to be more direct and faster than opening movements.
• Initial tooth contact occurred in a defined area, followed by cusp sliding to a centric position.
• Mandibular closing paths exhibited smooth curves with simple axis rotation, often exceeding clinically accepted distances.
• Microphone signals indicated tooth contact during unexpected phases, suggesting displacement outside the fully intercuspated position.

Conclusions:

• The study provides detailed kinematic data on mandibular function during tooth tapping.
• Findings suggest that normal jaw closing pathways may be more extensive than currently accepted.
• The detection of unexpected tooth contact signals highlights potential indicators of occlusal displacement.