Sensory responses from loading of implants: a pilot study

Osseointegrated implants lack a periodontal ligament. Nevertheless, masticatory function in subjects with implant-supported restorations appears similar to function in those with natural dentition. It is not clear how the neurophysiologic mechanisms that modulate jaw movement are associated with osseointegrated implants. This study examined the output from the inferior alveolar nerve during implant loading.

In 3 dogs, 3 premolars were extracted in the mandible and 2 endosseous titanium implants were placed, allowed to osseointegrate for 3 months, and loaded with vibration force at the threshold response for tooth vibration, at 2x threshold, and at 3x threshold. Neurophysiologic recordings were made from the inferior alveolar nerve during loading of both implants and the adjacent molar and canine. The response magnitude in action potentials in the 50- ms poststimulus period and latency of inferior alveolar afferents in milliseconds were compared following implant loading.

Detectable inferior alveolar nerve responses were recorded following loading from both the implants and the teeth at 2x and 3x threshold. However, the response magnitude of teeth (canine, 2.38 +/- 0.18 at 2x, 2.78 +/- 0.2 at 3x; molar, 2.2 +/- 0.16 at 2x, 2.5 +/- 0.21 at 3x) was twice that of the implants (anterior, 1.3 +/- 0.12 at 2x, 1.68 +/- 0.13 at 3x; posterior, 0.8 +/- 0.1 at 2x, 1.53 +/- 0.15 at 3x). The differences in response magnitude between the teeth and implants were significant (P < .05). The latency of response was similar.

Management of the occlusion for implant-supported restorations has been empirically developed. An underlying assumption has been that implant-guided jaw function lacks significant proprioception to modulate mastication and related jaw movements. This animal study provides preliminary evidence that force application to implants does elicit a proprioceptive response.

Loading of implants does elicit a sensory response that can be observed in the inferior alveolar nerve. The implications are that during occlusal function, information from regions associated with the implant can provide knowledge that could potentially modulate jaw activity in a manner similar to natural teeth.