Prediction of Implant Occlusal Forces in the Treatment Planning Phase

Objectives: This study aims at predicting the occlusal forces on implants from the occlusal forces on the remaining teeth before implant insertion, to enable performing stress analysis in the treatment planning phase.
Methods: The study protocol was approved by the Ethics Committee of Niigata University and written informed consent to participate in this study was obtained from patients who requested implant-supported prostheses to replace molars in the free-end edentulous mandible and had posterior occlusal support on the contralateral side. Before implant treatment, occlusal pressure and occlusal contact areas during maximum intercuspation of the remaining teeth were registered by pressure-sensitive sheets (Dental Prescale, Fuji Photo Film, Tokyo, Japan) and the sheet registrations were subsequently analyzed using an image scanner (Occluzer FPD-707, Fuji Film) that measured occlusal contact areas and occlusal force per contact. Force values on each mandibular tooth were then calculated. Measurements and calculations were repeated for teeth and implants after implant-supported crowns were retained. The relation between occlusal forces on different groups of teeth before treatment and occlusal force on implants after superstructure set was analyzed by linear regression analysis (n=7).
Results: A positive correlation was found between implant occlusal forces and total occlusal forces on the following groups of teeth before treatment: ipsilateral posterior teeth (correlation coefficient, r=0.58, regression coefficient, r²=0.34) and remaining teeth of the hemiarch (r=0.54, r²=0.29). Regarding the regression equation, intercept and slope were 44.76 and 0.26 for the former and 48.67 and 0.22 for the latter.
Conclusions: Our results suggest that occlusal force on implant-supported crowns that replace missing molars of a free-end edentulous mandible could be predicted before treatment from occlusal forces on ipsilateral posterior teeth or the remaining teeth of the hemiarch. Increasing the sample size is necessary to further improve the fit of the regression model.