Incidence of Inferior Alveolar Nerve Injury with Mandibular Dental Implants

Method: A retrospective analysis of 266 consecutive patients who had undergone dental implant placement in the mandible. Patients were treated by one surgeon using a standard protocol at The Manchester Dental Implant Clinic. Data collected from the clinical notes included; patient demographics, implant system, planning, placement protocol, implant position, length and diameter and results of standardized neurosensory tests post-operatively. Data were analyzed using frequency and descriptive tests in SPSS version 17.0.

Results:585 dental implants were placed in 266 consecutive patients July 1997-October 2011. Male:Female ratio=108:158. Mean age=56years[range=17-81]. Nine patients[M:F=4:5] had IANI following implant placement. This equates to an incidence of 3.5% per patient and 2.7% per implant placed. Seven patients[M:F=4:3] had permanent neuropathy and two (both female) recovered normal sensation within 60 day follow-up. All patients with neuropathy experienced paresthesia. No patients suffered with neuropathic pain. Of the patients with IANI, the Straumann implant system was used in 8 and Frialit-2 system in 1 patient. Implant length ranged from 6-14mm, diameter 3.3-4.8mm. Three patients had undergone bone augmentation prior to implant placement. Cone-beam CT scanning was used in 1/9 patients. The remainder were planned using plain radiography. The small sample size of patients with IANI did not allow for further statistical evaluation.

Conclusion: IANI is a significant and avoidable complication of mandibular dental implant placement. The results of this study suggest a low rate of IANI following implant placement in this patient cohort in comparison with other studies which have reported rates up to 40%. This may be due to good pre-operative planning, standardized technique and experience of the surgeon. Further research and evidence-based protocols are required in prevention and management of IANI following mandibular dental implant placement.