Methods: Ten subjects with natural dentition, 11 with bimaxillary fixed tooth-supported prostheses (TSP) and 10 with bimaxillary fixed implant-supported prostheses (ISP) (mean age 69 (range 61-83)) chewed a hazelnut while their vertical and lateral jaw movements were recorded. Data obtained during the first chewing cycle were analyzed.
Results: The trajectory of the mandibular movement was obviously smoother for the subjects with natural dentition, while more stuttering and probing behavior was apparent for those with prostheses (TSP and ISP). The total number of pixels in the figures created by plotting mandibular movement during the chewing cycle differed between the groups (P=0.055), being 94.8 x 103 for the natural group, 68.6 x 103 for the TSP group (P=0.049) and 63.2 x 103 for the ISP group (P=0.024), clearly illustrating the wider range of mandibular movement for those with natural teeth. The ratio of cycle axis/cycle width differed (P=0.033), being 0.27 for the natural group, 0.15 for the TSP group (P=0.009) and 0.19 for the ISP group (P=0.084).
Conclusions: Individuals with fixed tooth- or implant-supported fixed prostheses in both jaws demonstrate an altered performance during the first chewing cycle. We propose that these differences are due to impairment or absence of sensory signaling from PMRs in the TSP and ISP group.