Five Misunderstandings About Case-Study Research

Abstract

Previous studies have shown that molar teeth pulsate at rest and displace linguo-apically during clenching at the intercuspal position. These results suggested that teeth do not contact adjacent teeth and the distance between all adjacent teeth decreases during clenching. This study was conducted to investigate the interproximal contact relationship during clenching by a CCD microscope. Two subjects (Males: Aged 28 years) with normal dentition and occlusion were selected for in vivo observation. The observed contact points had optimum tightness which was defined by the insertion of a 50 microns thick stainless steel strip with some resistance, but not by that of a 110 microns strip. A space existed between the teeth at rest and the CCD microscope positioned on the buccal side could detect light from the lingual side. For dynamic observation, a lingual plate with a light source was fitted to each subject. When the subjects clenched, the light band was divided. Furthermore, a digital tension gauge was used to measure the interproximal force for pulling thin Titanium strips. The interproximal force significantly increased during clenching. In vitro, to estimate the relation between the width of the light band and the interproximal distance, two extracted teeth were used. Light bands were analyzed by computer. The distance between adjacent teeth at rest was 3-21 microns, and interproximal spaces disappeared during clenching. These results suggested that teeth do not contact adjacent teeth at rest but they do during clenching.