Journal of Oral Rehabilitation 1999 26; 932 – 935 Occlusal force distribution on the dental arch during various levels of clenching H. KUMAGAI*, T. SUZUKI † , T. HAMADA*, P. SONDANG*, M. FUJITANI ‡ & H. NIKAWA* *Department of Prosthetic Dentistry, School of Dentistry, Hiroshima University, Hiroshima, † Department of Geriatric Dentistry, Faculty of Dentistry, Tokyo Medical and Dental University, Tokyo, Japan, and ‡ Department of Operative Dentistry, School of Dentistry, Hiroshima University, Hiroshima at the molar region followed by the premolar and SUMMARY The purpose of this study was to explore the occlusal force distribution on the dental arch in anterior teeth region. The proportion of occlusal the intercuspal position and to evaluate the rela- force (occlusal force at each region/total occlusal tionship between the clenching strength and the force) on molar regions increased as clenching occlusal force distribution. These variables were strength increased. On the contrary, the proportion recorded using the Dental Prescale System in 16 of occlusal force on the premolar and anterior teeth regions decreased as clenching strength increased. healthy young adults. The number of tooth con- tacts, occlusal force and occlusal contact area in- These findings suggest that control of occlusal force is important in diagnosis of the nature of occlusal creased linearly as clenching strength increased. contacts. The distribution of the occlusal force was greatest Introduction Understanding the nature of contacts is important for the better diagnosis and treatment of stomatognathic diseases (Ehrlich & Taicher, 1981). Occlusal equi- librium in the intercuspal position especially, is of great importance. Regarding the number and the area of occlusal contact in the intercuspal position, some in- vestigations have examined this variable (Korioth, 1990). However, few researchers reported an analysis on the distribution pattern of occlusal contacts in the intercuspal position (Korioth & Hannam, 1994; Sato, 1997). In clinical research on occlusion, various techniques are used to assess the nature of occlusal contacts in the intercuspal position (Battistuzzi, Eschen & Peer, 1982). However, few techniques can make quantitative analy- sis of occlusal contact area and occlusal force. The Dental Prescale System* is able to make quanti- tative analysis of occlusal contact area and occlusal force at every contact point. Dental Prescale is flexible and permits natural occlusion and prevents mandibular displacement during clenching (Suzuki et al., 1997). The purpose of this study was to evaluate the oc- clusal force distribution on the dental arch during vari- ous levels of clenching measured by the Dental Prescale System. Materials and methods Thirteen males and three females with an average age of 23·2 years were selected as subjects. All of the sub- jects had complete dentition without third molars, and none of them had signs or symptoms of cran- iomandibular disorders. The subjects understood the nature of the research project and consented to participate. The subjects were asked to clench in the intercuspal position at 20, 40, 60, 80 and 100%, respectively, of the maximum voluntary contraction (MVC) of the masseter muscles for 2 s. The subjects were able to * Fuji Photo Film, Tokyo, Japan. © 1999 Blackwell Science Ltd 932