Purpose: Previous studies have shown that molar teeth pulsate at rest and displace linguoapically during clenching at maximal intercuspation. The aim of this study was to investigate interproximal contact during clenching by means of a charge coupled device (CCD) microscope. Materials and Methods: Two male subjects aged 28 years with normal dentition and occlusions were selected for in vivo research. Optimum contact tightness was observed at contact points that were defined by some resistance to the insertion of a 50-µm-thick stainless steel strip, with no resistance to the insertion of a 110- µm strip. Spaces between the teeth were detected using a CCD microscope on the buccal side by light bands emitted from the lingual side. During static observation, the chosen distance between the microscope and light guide was maintained using a special device. For dynamic observation, a palatal and lingual plate with a light source was fitted to each subject. Subjects were directed to clench with habitual occlusal force. To compare with in vivo observations, the relation between the width of the light band and the interproximal distance was estimated in vitro using 2 extracted teeth. Light bands were analyzed using software. Results: In the 2 subjects studied, there was a 3- to 21-µm distance between adjacent teeth at rest, which disappeared during clenching. Conclusion: The results of the study sample examined indicate that teeth do not make contact with adjacent teeth at rest, but do so during clenching.