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Tooth loss has been shown to induce neuroplastic changes in the sensorimotor cortical area of the brain that represents jaw muscles. Dental implants placed into extraction sites reversed these changes. Since muscles are highly plastic, we hypothesize that the cortical changes after dental extraction also are reflected in jaw-opening muscles and that these changes are prevented/reversed following dental implant placement.

Fifteen rats were randomly allocated in four groups; extraction 1 (Ext-1, n=4), extraction 2 (Ext-2, n=4), implant group (n=4) and control group (n=3). The anterior digastric (AD) muscle was obtained from the extraction groups after 1 and 2 months, respectively, and from the implant group after 3 weeks. The samples were analyzed with immunohistochemical and morphological techniques. Our results showed; 1) intermediate and low oxidative fast MyHCII fibers predominated AD muscle, 2) oxidative capacity of fibers was higher in the central region, 3) extraction caused a shift towards fibers with lower oxidative capacity in the central region, 4) placement of dental implants increased the oxidative capacity of fibers in both central and peripheral region.

We conclude that in the AD muscle, loss of teeth cause a tendency to shift against fibers with faster contraction properties and lower oxidative capacity, while treatment with implants tends to reverse it. Interestingly, these alterations followed the change pattern of the cortical motor area for the AD muscle i.e. larger proportion of fibers with higher oxidative capacity and fine motor control were associated with increased motor representation sites (MRS) for the AD muscle.