Dental implant placement with inferior alveolar nerve repositioning in severely resorbed mandibles: a retrospective multicenter study of implant success and survival rates, and lower lip sensory disturbances

Abstract

Background: The purpose of this study was to analyze medium-to-long-term implant success and survival rates, and lower lip sensory disturbance after placement of dental implants with simultaneous inferior alveolar nerve (IAN) repositioning.

Methods: Fifteen patients (3 men, 12 women) treated in two centers were included in this retrospective study. The ages of the participants ranged from 19 to 68. A total of 48 dental implants were placed in 23 posterior mandibular segments simultaneously with IAN transposition or lateralization. The residual bone above the IAN ranged from 0.5 to 7.0 mm. Crestal bone changes were measured using cone beam computed tomography (CBCT) images. Disturbance of the IAN was evaluated subjectively using a modified questionnaire.

Results: The healing process was uneventful in fourteen patients. In one patient, spontaneous fracture of the operated mandible occurred on tenth day after the surgery. The implant in the fracture line was removed at the time of open reduction and fixation. One more implant was lost after 5 years of loading. Therefore, the overall dental implant survival rate was 95.8%, whereas all implants in function were judged as successful after a follow-up period of 1 to 10 years. Transient neurosensory disturbances (ND) were observed in all patients who underwent IAN lateralization and IAN transposition. At follow-up times of 3 years, 5 years, and 10 years, weak hypoesthesia remained in two subjects treated with IAN transposition. None of the patients developed neuropathic pain after the procedure.

Conclusions: Within the limitations of this study, we conclude that reconstruction of severely resorbed mandibles with dental implants in conjunction with IAN repositioning is an effective and reliable technique. Although neurosensory disturbances are the most common complication after surgery, they tend to resolve over time. Advanced surgical skills are required to perform this technique.

Keywords: Dental implant success rate; Dental implant survival rate; Inferior alveolar nerve lateralization; Inferior alveolar nerve transposition; Neurosensory disturbance.

Conflict of interest statement

George Deryabin and Simonas Grybauskas declare that they have no competing interests.

Figures

Fig. 1

CBCT scan before surgery. a A panoramic view. b A coronal view

Fig. 2

CBCT scan 2 years after surgery. a A panoramic view. b A coronal view

Fig. 3

The intraoral view of the final restoration. Notice bilateral posterior crossbite. (Prosthodontist: Renat Aubov)

Fig. 4

A questionnaire to register neurosensory disturbances after the operation

Fig. 5

A full corticotomy performed with a piezoelectric saw creating a rectangular bony window lateral to the inferior alveolar canal

Fig. 6

The neurovascular bundle is mobilized from the canal and retracted laterally while the implants are installed

Fig. 7

Additional horizontal bone augmentation is performed by means of GBR

Fig. 8

Another case of nerve lateralization. The neurovascular bundle is mobilized from the canal and retracted laterally while the implant is installed

Fig. 9

Additional horizontal bone augmentation is performed by means of autogenous onlay block graft. The cortical bony window (after creating access to the IAN) is utilized as a source of autogenous bone

Fig. 10

CBCT scan before surgery. A panoramic and cross-sectional view

Fig. 11

A full corticotomy performed with a piezoelectric saw creating a rectangular bony window lateral to the inferior alveolar canal. The osteotomy window was extended anteriorly to expose the mental foramen and incisive branch

Fig. 12

The bony window is removed and the neurovascular bundle is mobilized from the canal. The incisive branch is severed, and the IAN freed from the canal and moved laterally

Fig. 13

The neurovascular bundle is mobilized from the canal and retracted laterally while the implants are installed. Two titanium miniscrews are placed halfway on the lateral side of the mandible at the osteotomy lines to maintain the displaced neurovascular bundle in a new position and indicate its new location

Fig. 14

CBCT scan after surgery. A panoramic and cross-sectional view

Fig. 15

Intraoral view at the time of second-stage surgery. Notice a lack of keratinized gingiva

Fig. 16

A split thickness flap is separated exposing the periosteum. Two titanium miniscrews indicate the new location of the displaced IAN

Fig. 17

Vestibuloplasty with free gingival graft is performed

Fig. 18

Intraoral view at the time of uni abatment placement

Fig. 19

a, b Final restoration. (Prosthodontist: Evgeniy Shor)

Fig. 20

CBCT scans 2 years after the delivery of the final prothesis

Fig. 21

a A panoramic view of CBCT scan after IAN lateralization with implant placement. b A panoramic view of CBCT scan after open reduction and fixation of the mandible. c A panoramic view 1 year after the delivery of the final prothesis