In vivo measurements of some functional aspects with mandibular fixed prostheses supported by implants

Maximal occlusal force and oral tactile sensibility were recorded in 21 edentulous patients wearing maxillary complete dentures and mandibular fixed prostheses supported by Branemark implants. Bite force was measured with a miniature force transducer between antagonistic molars and premolars, and the passive tactile sensibility of the fixtures was recorded in the horizontal and vertical directions with spring balances. The active tactile sensibility was tested using steel foils (100 to 10 microns). The range of maximal occlusal force recorded was from 35 to 330N with highest values observed on the second premolars (mean 143N). Significantly lower forces were found on molars and first premolars (p < 0.01). The detection threshold of minimal pressure was about 330 g in the horizontal, and 388 g in the vertical direction. This difference was not statistically significant. The average number of incorrect assessments when testing steel foils was 16.6 errors, out of 100 recordings. Similar results when using these 3 test modalities had been found on overdentures supported by two mandibular implants and occluding with maxillary complete dentures. The results of this study suggest that mandibular implants supporting fixed prostheses are not likely to improve oral tactile sensibility and maximal occlusal force in the presence of maxillary complete dentures.