Abstract
The purpose of this study was to investigate occlusal contact relationships during lateral excursions in the primary dentition.
A custom computer system combining lower jaw movement and three-dimensional tooth shape to display tooth contacts during mandibular movements. Lower jaw movement along all 6 degrees of freedom was measured with an opto-electronic movement analysis system at a sampling frequency of 100 Hz. Tooth shape was measured using a three-dimensional digitizer at 0.2 mm intervals. These two sets of measurements were then converted to the same coordinate system in order to establish the three-dimensional relationship between upper and lower occlusal surfaces at any mandibular position. At every mandibular position, the distance between the upper and lower occlusal tables was calculated. Distances of less than 0.2 mm were defined as an area of occlusal contact.
Occlusal contact areas of 5 children (3 boys and 2 girls, with a mean age of 5 year-7 month) were analyzed during lateral excursion using this system. None of the subjects had dental caries. The normal primary occlusion of the children was under continuous oral management in our department.
The results of this preliminary study are as follows:
1. Computer graphics can be used to visually display changing occlusal contact area during lateral excursions in the primary dentition.
2. The occlusal contact area of every tooth can be quantified during lateral excursions in the primary dentition using this system.
3. Our preliminary results indicate that occlusal contact occurs at the primary deciduous second molars on both the working and non-working sides during lateral excursion.
4. Further studies are needed to determine the functional role of these occlusal contacts in the primary dentition.
