Implants maintain osseointegration with the inside of the bone over long periods of time, and mechanical factors are important for retaining function. Particularly, when natural teeth and implants are present together, differences in tissue displaceability when they are subjected to occlusal force may cause dynamic imbalance from strong to weak clenching.

Therefore, there is a school of thought that prosthetic implants should be given a lower occlusion than natural teeth. On the other hand, from the perspective of jaw function, it is also argued that prosthetic implants should be given the same occlusion as intact natural teeth neighboring the implant. In a study using two-dimensional finite element analysis, Maezawa et al. suggested that, even if the occlusal surface of the prosthetic implant is made lower than the occlusal plane, high clenching intensity can result in an excessive occlusal load on the prosthetic implant. In addition, Koyama et al. found no significant differences in occlusal contact point between prosthetic implants and natural teeth, even if clenching intensity varies. From these studies, it appears that the occlusal contact of implant prostheses is the same level on natural teeth, regardless of clenching strength, and that occlusal load on implant prosthesis increases more than contralateral natural teeth as clenching strength increases. Methods of quantitative evaluation used to clarify mechanical factors of implant prostheses include pressure-sensitive films for occlusal force diagnostic use and silicone testing materials, but few studies have examined the occlusal contact from weak to strong clenching strength under the same conditions.

In this department to date, Okuyama et al. used a pressure-sensitive film to examine the occlusal contact and to calculate the mean occlusal gap and occlusal load of implants that had progressed satisfactorily, as well as natural teeth. Imamura et al. used a new silicone test material and a pressure-sensitive film to develop a method for investigating changes in occlusal contact from weak to strong clenching intensity in subjects with natural dentition.

Occlusal contact is a reflection of the degree of functional recovery and measurement of factors such as number of occlusal contact points, contact area, and distribution. Occlusal center is advisable before and after treatment. Therefore, the purpose of this study was to investigate the occlusal contact of single implant superstructures at the mandibular first molar immediately after seating by using two different materials with an electromyogram. Ultimately, we aimed to obtain clinical suggestions for the occlusion that should be given to prosthetic implants through a longitudinal follow-up study.