Neurophysiological changes associated with implant placement

Objectives: The objective of the study was to evaluate the feasibility of a standardized Quantitative Sensory Testing (QST) protocol extra- and intraoral in patients to detect and quantify sensory disturbances of the inferior alveolar nerve due to the proximity of implantation procedures to the inferior alveolar nerve canal.

Material and methods: Patients who had obtained an implant placement were examined by implementing a comprehensive QST protocol for extra- and intraoral use. The study included 33 patients after implant placement in the lower jaw and one patient suffering from an inferior alveolar nerve injury. Patients were tested bilaterally (chin and mucosal lower lip).

Results: Comparing the implanted vs. the control side, QST parameters revealed no significant neurophysiological changes in all parameters. Evaluating the development of sensory disturbances in dependency of the proximity of the implant to the inferior alveolar nerve canal, mechanical QST parameters showed no significant correlation. The mean distance of the inserted implant to the inferior nerve canal was 2.65 ± 1.75 mm. In the case of one patient suffering from impairment of the nerve function due to implant placement, we found abnormal sensory responses to touch coexisting with numbness and temperature algesia.

Conclusions: Monitoring of trigeminal nerve fiber functions by QST intra- and extraoral is feasible to evaluate oral sensory pattern after implantation procedures. Sensory disturbances of the inferior alveolar nerve were shown to be avoided by keeping an average safety zone of 2.65 mm between implant and nerve.