Nerve transposition and implant placement in the atrophic posterior mandibular alveolar ridge

Inferior alveolar nerve repositioning surgical techniques and outcomes - a systematic review

Inferior alveolar nerve (IAN) lateralization (IANL) or transposition (IANT) are both techniques allowing for dental implant placement in posterior atrophic mandibles. The aim of this study was to systematically review the implant survival rate and the complications associated with IAN reposition techniques with simultaneous implant placement in atrophic posterior mandibles. This systematic review was conducted following PRISMA guidelines (Preferred Reporting Items for Systematic review and Meta-Analysis). The review was designed to answer the following PICO question: Is IAN repositioning (I) a safe and efficient technique (O) to treat patient looking for fixed dental rehabilitation of an atrophic posterior mandible (P). Thirty-three articles were reviewed, including a total of 899 patients, and approximately 950 IAN repositioning procedures. Dental implant survival rate ranged between 86.95% and 100% with a mean dental survival rate of 90.16%. Among the 269 patients who underwent IANT, there were 93% immediate neurosensory disturbance, and 15% persistent neurosensory disturbance. Among the 350 patients who underwent IANL, there were 93% immediate neurosensory disturbance, and 6% persistent neurosensory disturbance. IANT and IANL are reliable techniques allowing safe dental implant placement in atrophic posterior mandible with high patient satisfaction. IANL seems to cause less persistent neurosensory disturbances compared to IANT. The level of evidence is poor due to the high number of bias present in the included studies. IAN neurosensory disturbance assessment should be better homogenized in order to increase comparability.

Complications Associated with Rehabilitation of a Unilateral Partially Edentulous Mandible with Inferior Alveolar Nerve Transposition and Implant Placement: A Clinical Report

Rehabilitation of an edentulous posterior mandible to restore function and arch stability can be accomplished with a removable partial denture or an implant supported fixed partial denture. If the alveolus is severely resorbed, implant placement becomes challenging due to inadequate bone and the position of the inferior alveolar nerve. This report details a situation where a mandibular fracture occurred soon after inferior alveolar nerve (IAN) transposition and simultaneous implant placement. The prosthodontic reconstruction was completed using a fixed-dental prosthesis.

Two-stage distalization of the mental foramen to manage posterior mandibular vertical bone deficiency-a prospective observational study

Inferior alveolar nerve (IAN) transpositioning is a modality utilized to manage posterior mandibular vertical deficiency. Several complications have been reported including improper implant positioning, mandibular body fracture, and neurosensory disturbance. The aim of this prospective observational study was to introduce a two-stage mental foramen distalization technique to minimize the complications associated with IAN transpositioning. Ten patients with severely atrophied mandibular ridges were included. Cone beam computed tomography was ordered to accurately locate the position of the IAN and its incisive terminal branch before designing the outline of two cortical osteotomies anterior and posterior to the mental foramen. The osteotomies were created using a piezoelectric device, followed by separation and identification of the nerve. The incisive branch was severed to freely transpose the IAN. A new foramen was created far distally and the cortical windows were repositioned and fixed with two screws. Healing was uneventful for all patients. Neurosensory recovery was assessed by MRC scale. All cases showed full recovery within 6 weeks, except for two patients who showed complete recovery after 16 weeks. Four months postoperative, all patients showed complete consolidation of the cortical windows without any signs of failure implants were placed at the pre-planned surgical sites. Histomorphometric analysis of core biopsies from seven surgical sites showed bone area percentages ranging from 46% to 63%. The two-stage mental foramen distalization technique is a predictable and safer technique for IAN transpositioning specifically in cases of vertical bone deficiency associated with limited inter-arch space.

Mandibular Body Fracture during Inferior Alveolar Nerve Transposition: Review of Literature

Inferior alveolar nerve transposition is a useful adjunctive surgery in implant dentistry when there is insufficient bone between the ridge crest and the inferior dental canal. However, if this surgery is done carelessly, complications such as mandibular fracture and permanent lower lip numbness can occur. This article reports the first case of bilateral mandibular body fracture occurring during inferior alveolar nerve transposition. The surgical management of a complicated bilateral displaced mandibular body fracture is explained herein. A literature review of mandibular fracture after inferior alveolar nerve transposition is also presented. Adhering to the principles of fracture, treatment is mandatory for the successful management of mandibular fracture after inferior alveolar nerve transposition.

Management of Limited Vertical Bone Height in the Posterior Mandible: Short Dental Implants Versus Nerve Lateralization With Standard Length Implants

Inferior alveolar nerve lateralization (IANL) and short dental implants (SDI) are 2 viable implant-based treatment approaches in the presence of atrophied posterior mandible. Despite the risks of dysfunction, infection, and pathologic fractures in IANL, it becomes possible to place standard implants. The purpose of this study was to compare SDI and IANL approaches from clinical and radiographic aspects. Fifteen subjects having unilateral atrophic mandibles were allocated to SDI and IANL treatment groups. Following surgical procedures, early postoperative complications, implant survival, and periimplant clinical and radiographic parameters including probing pocket depth, attachment level, keratinized tissue amount, vertical tissue recession, and marginal bone loss were recorded at baseline and 1-year after prosthetic rehabilitation. In both groups, no implant was lost. Except usual postoperative complications, 2 patients had transient paraesthesia after IANL. According to time-dependent evaluation, both groups showed significant increase in probing pocket depth and attachment level at 1-year follow-up compared with baseline (P < 0.05). Except a slight but significant increase in mesial surface of SDI group (P < 0.05), no remarkable time-dependent change was identified in vertical tissue recession. Keratinized tissue amount did not exhibit any inter- or intragroup difference during whole study period. Marginal bone loss did not show any difference between IANL and SDI groups at follow-up. SDI placement or standard length implant placement with IANL can be considered promising alternatives in the treatment of atrophic mandibular posterior regions. However, SDI may be preferred in terms of lower complication risk.

The influence of initial alveolar ridge defect morphology on the outcome of implants in augmented atrophic posterior mandible: an exploratory retrospective study

OBJECTIVES

Clinicians commonly consider atrophic site topography as an important determinant in deciding the augmentation technique to utilize, as well as forecasting the likelihood of success. The purpose of this retrospective study was to examine the influence of initial atrophic posterior mandible morphology on the outcome of implants placed following augmentation.

MATERIALS AND METHODS

A total of 52 patients contributed 71 edentulous sites, and 185 implants were placed with mean follow-up of 37.97 months. The initial defect morphology was classified according to ABC classification (Journal of Oral Implantology, 37, 2013a and 361). Ridge augmentation was performed by "cortical autogenous tenting" (CAT) followed by either simultaneous or delayed implant placement after 4-6 months of healing. The European Academy of Osseointegration success criteria were used to evaluate implant outcomes.

RESULTS

The overall survival and success rates of dental implants were 98.91% and 80%, respectively. Cumulative success and survival rates in CAT group were 95% and 100% after 2 years of follow-up. The highest marginal bone loss (MBL) was observed (1.26 mm ± 0.99) around implants placed in augmented edentulous sites with initially narrow and flat alveolar crest (defect class CII). Conversely, least MBL (0.48 mm ± 0.78) was detected around implants placed into edentulous sites with two sloped boney walls (defect class AII). Differences between MBL observed around implants placed into initial defect class C, initial defect type and class A (I, II), as well as class BII, were statistically significant (P < 0.05). Among all implants, 148 were considered as successful, 26 exhibited satisfactory survival, nine with compromised survival, and two implants failed.

CONCLUSION

The present data confirmed the effect of initial ridge morphology on the outcome of implants placed into augmented bone. Specifically, class A and class B atrophic ridge defects, with one and two vertical boney walls, respectively, may be considered as more favorable recipient sites than class C defects with flat morphology. This conclusion is based on least MBL around implants placed into initial defect class A and class B augmented sites, and higher MBL in implants placed into class C recipient sites. A randomized controlled trial is warranted to examine these exploratory observations.

Lateralization Technique and Inferior Alveolar Nerve Transposition

Bone resorption of the posterior mandible can result in diminished bone edge and, therefore, the installation of implants in these regions becomes a challenge, especially in the presence of the mandibular canal and its contents, the inferior alveolar nerve. Several treatment alternatives are suggested: the use of short implants, guided bone regeneration, appositional bone grafting, distraction osteogenesis, inclined implants tangential to the mandibular canal, and the lateralization of the inferior alveolar nerve. The aim was to elucidate the success rate of implants in the lateralization technique and in inferior alveolar nerve transposition and to determine the most effective sensory test. We conclude that the success rate is linked to the possibility of installing implants with long bicortical anchor which favors primary stability and biomechanics.

Nerve Retraction During Inferior Alveolar Nerve Repositioning Procedure: A New Simple Method and Review of the Literature

Nerve repositioning surgery is one of the treatments chosen for the patients with edentulous posterior atrophic mandible. Like any other treatments, this therapy has its advantages and disadvantages, indications and contraindications. The most important complication of this procedure is neurosensory disturbance. This problem may occur at different stages of the treatment. One common time when nerve damage happens is when the nerve is located outside the canal and drilling and insertion of the implant are performed. Accordingly, this report describes a simple and feasible method to retract and protect nerves outside the canal during the treatment of nerve transposition. This will reduce the risk of nerve damage.

Cortical Bone Augmentation Versus Nerve Lateralization for Treatment of Atrophic Posterior Mandible: A Retrospective Study and Review of Literature

PURPOSE

We sought to assess implant success/survival/failure rate following cortical autogenous tenting technique (CATT) versus inferior alveolar nerve transposition (IANT) in the posterior mandible.

MATERIALS AND METHODS

Patients who underwent these two procedures between 2007 and 2011 were analyzed. CATT was performed using lateral ramus block graft and implants were inserted simultaneously or after 4 to 6 months. In IANT, implants were placed simultaneously after nerve transposition with or without mental foramen involvement. Data regarding marginal bone level (MBL), pus discharge (PD), neurosensory dysfunction (NSD), implant mobility, and failure were collected. Success rate was measured based on Pisa Consensus. Independent sample t-test with a significance level of 0.05 was used to compare implant dimensions and MBL changes between the two techniques.

RESULTS

A total of 118 patients with a mean age of 54.85 years were included. The mean follow-up after CATT and IANT was 37.97 and 18.51 months, respectively. The overall survival and success rates of dental implants in the CATT group were 98.73% and 71.52%, respectively. The corresponding values for IANT subjects were 98.74% and 94.56%, respectively. Implant length and diameter in IANT group were significantly longer and wider than implants used after CATT (p value < .001). MBL changes in both techniques were less than 1 mm (p value = .79). Two cases of NSD, seven PD, and two implant failures were found in the CATT group. For IANT patients, seven permanent NSD, two PD, two implant failures, and one mandibular fracture were documented.

CONCLUSION

Both techniques had implant survival rates similar to implants placed in unaltered bone. A higher implant success rate, albeit with higher incidence of long-lasting nerve damage, was observed in the IANT group.

Nanostructured guidance for peripheral nerve injuries: a review with a perspective in the oral and maxillofacial area

Injury to peripheral nerves can occur as a result of various surgical procedures, including oral and maxillofacial surgery. In the case of nerve transaction, the gold standard treatment is the end-to-end reconnection of the two nerve stumps. When it cannot be performed, the actual strategies consist of the positioning of a nerve graft between the two stumps. Guided nerve regeneration using nano-structured scaffolds is a promising strategy to promote axon regeneration. Biodegradable electrospun conduits composed of aligned nanofibers is a new class of devices used to improve neurite extension and axon outgrowth. Self assembled peptide nanofibrous scaffolds (SAPNSs) demonstrated promising results in animal models for central nervous system injuries, and, more recently, for peripheral nerve injury. Aims of this work are (1) to review electrospun and self-assembled nanofibrous scaffolds use in vitro and in vivo for peripheral nerve regeneration; and (2) its application in peripheral nerve injuries treatment. The review focused on nanofibrous scaffolds with a diameter of less than approximately 250 nm. The conjugation in a nano scale of a natural bioactive factor with a resorbable synthetic or natural material may represent the best compromise providing both biological and mechanical cues for guided nerve regeneration. Injured peripheral nerves, such as trigeminal and facial, may benefit from these treatments.

Mandibular all-on-four therapy using angled implants: a three-year clinical study of 857 implants in 219 jaws

Immediate function with Brånemark implants is well established for the mandible. This article describes a series of 857 implants placed consecutively in which very few implants failed or lost bone despite the dynamic healing conditions of simultaneous dental extractions and bone leveling. Though these findings are relatively early, 3 years or fewer, it appears that the immediate function All-on-Four procedure can be done with a high degree of confidence for the mandible--putting into question the need for additional implants.

Mandibular all-on-four therapy using angled implants: a three-year clinical study of 857 implants in 219 jaws

Immediate function with Brånemark implants is well established for the mandible. This article describes a series of 857 implants placed consecutively in which very few implants failed or lost bone despite the dynamic healing conditions of simultaneous dental extractions and bone leveling. Though these findings are relatively early, 3 years or fewer, it appears that the immediate function All-on-Four procedure can be done with a high degree of confidence for the mandible-putting into question the need for additional implants.

Inferior alveolar nerve lateral transposition

PURPOSE

We determined the outcomes of 18 inferior alveolar nerve lateral transposition procedures in 15 consecutive patients. The advantages and disadvantages of this technique are discussed.

RESULTS

The surgical protocol for inferior alveolar nerve transposition, followed by implant placement, presented excellent results, with complete recovery of the sensitivity within 6 months after the surgical procedure.

DISCUSSION

Inferior alveolar nerve transposition is an option for prosthetic rehabilitation in cases of moderate or even severe bone reabsorption for patients that do not tolerate removable dentures.

CONCLUSIONS

It is concluded that inferior alveolar nerve transposition can be safely and predictably performed with low risk to the mental nerve sensibility. Each patient should be advised of the chance of permanent nerve deficit throughout the distribution of the mental nerve. Alternative restorative solutions should also be considered.

Endosseous alveolar distractor (LEAD™) in the management of residual alveolar ridge resorption

BACKGROUND

Lack of sufficient alveolar bone height or width is one of the most frequent problems in the dental rehabilitation of the edentulous patient.

METHODS

A prospective study to evaluate the efficacy of an endosseous alveolar distractor (LEADTM) in managing residual alveolar ridge resorption was carried out. The complications related to the surgical procedure and the quantitative changes in the regenerate over a 6 month period following distraction were studied in 13 cases with alveolar ridge atrophy.

RESULT

Desired ridge augmentation was achieved in 11 cases. In 2 cases the distraction failed. Some unusual complications were encountered.

CONCLUSION

The LEAD™ alveolar distractor produces consistent augmentation of the alveolar bone but is confronted with stability issues.

Inferior Alveolar Nerve Transposing in a Situation with Minimal Bone Height: A Clinical Report

Previous studies have indicated that at least 5 mm of bone is needed above the canal when performing transposing of the inferior alveolar nerve (TIAN). In this clinical report, TIAN was performed in a situation where minimal (< 2 mm) bone height was present above the canal of the IAN. Preoperative examination with computerized tomography scan revealed 2 mm of bone above the canal at the area of teeth #18 to #20, #30, and #31. The TIAN was performed by opening a lateral access window along the lateral side of the mandible. Five threaded hydroxyapatite-coated root form implants were placed at the area of teeth #18 to #20, #30, and #31. Autogenous bone from the lateral access window that was removed en block was particulated and placed around the implants. A resorbable collagen membrane was placed around the graft material. Implants were restored with cement-retained implant-supported metal-ceramic crowns. Three-year post-loading examination revealed minimal bone loss (< 1 mm).

Alveolar Ridge Augmentation: A Comparative Longitudinal Study Between Calvaria and Iliac Crest Bone Grafts

Insertion of endosseous implants is often difficult because of lack of supporting bone. In the case of severe atrophy of the jaws, a large volume of autogenous bone can be harvested from the iliac crest and calvaria. Both grafts undergo partial resorption with time, but the rate of bone loss has not been fully elucidated. The aim of this study was to evaluate the alveolar bone height gain (ABHG) obtained with iliac crest and calvaria bone grafts. Twenty-five patients had mandibular bone grafts, 32 had maxillary bone grafts, and 11 had both mandibular and maxillary bone grafts. Measures were made on preoperative, postoperative, and follow-up radiographs. A general linear model was used to evaluate the rate of ABHG plotted against months elapsed from the time of the operation to the time of follow-up. General linear model output showed a statistically significant effect for only the type of donor bone graft (P = .004), with a better ABHG for calvaria. The iliac crest bone grafts lost most of the ABHG in the first 6 months, whereas calvaria bone grafts lost ABHG over a greater interval of time. The type of bone graft is the strongest predictor of ABHG, and calvaria bone graft had a higher stability than did iliac bone graft. However, the gap in ABHG between the 2 grafts tended to decrease over time.

An investigation of post-operative morbidity following chin graft surgery

AIM

The aim of this prospective study was to evaluate the morbidity at the donor site following harvest of chin bone for intra-oral augmentation.

METHOD

The morbidity experienced by 27 consecutive patients who had undergone chin bone harvesting to augment intra-oral sites prior to implant placement at the Department of Oral and Maxillofacial Surgery, University Dental Hospital of Manchester was evaluated at one week, one, three and 12 months post-operatively.

RESULTS

Nine (33%) patients suffered post-operative morbidity. One patient experienced paraesthesia of the chin and lower lip and a further patient, paraesthesia of the gingivae immediately post-operatively. Both patients had full recovery when reviewed at three months. Two patients experienced pain at the graft site for up to three months post-operatively. Five (18.5%) patients experienced woodiness/numbness of the lower anterior teeth at the first post-operative visit and at 12 months, two patients continued to have no sensitivity in the lower anterior incisor teeth. None of the patients reported altered contour or change in profile of the chin area. Twenty-three (85.2%) patients had successful grafts with placement of implants thereafter.

CONCLUSION

It is important for GDPs and specialists to make patients aware of the possible morbidities following harvest of bone from the chin.

Implant Stability, Tissue Conditions, and Patient Self-Evaluation after Treatment with Osseointegrated Implants in the Posterior Mandible

BACKGROUND

Implant treatment in the posterior mandible is considered challenging because of bone resorption and the presence of the inferior alveolar nerve, which may result in the use of short implants.

PURPOSE

To evaluate implant stability, tissue conditions, and patient opinion after treatment with implant-supported bridges in the posterior mandible.

MATERIALS AND METHODS

Thirty-four patients treated with implant-supported bridges in the posterior mandible according to a two-stage protocol were clinically and radiographically examined and interviewed after a mean functional time of 3.9 years. One hundred five Brånemark implants (Nobel Biocare AB, Gothenburg, Sweden) were placed in premolar and molar regions to support 40 bridges. Twenty-eight implants were placed anterior to the mental foramen, and 77 implants were placed posterior to the mental foramen. Bridges were supported either by two or by three implants. After 2 to 6 years, the bridges were removed to analyze the resonance frequency of the implants with the use of a special instrument (Osstell instrument, Integration Diagnostics AB, Gothenburg, Sweden), and an implant stability quotient (ISQ) was recorded for each implant.

RESULTS

One implant was lost. An ISQ range of 59 to 90 (mean, 70.05) expressed stability of fully integrated implants in the posterior mandible. Significantly higher (p < .024) ISQ values were found in implants in three-implant bridges when compared with implants in two-implant bridges. There were no differences in ISQ values between molars/premolars, implant types, implant widths, implant lengths, anchoring depth, or uni- or bilateral mandibular bridges. Good mucosal health in the periimplant soft tissue and minor bone resorption around the implants were observed. Patients were generally very satisfied with the treatment outcome.

CONCLUSIONS

High implant stability can be reached in the posterior mandible. The implants were more stable in three-implant bridges than in two-implant bridges. The patients were highly satisfied with the treatment, and few complications were seen.

Alveolar distraction before insertion of dental implants in the posterior mandible

We investigated the efficacy of alveolar distraction for reducing crown height:implant length ratio in the posterior mandible. Ten alveolar distractions were done in seven patients. The pre-distraction ratio of required crown height to bone height available for implantation was in all cases > or =1. Two implants were placed in each distracted area (total 20 implants). Before distraction, the mean (SD) predicted crown height was 12.8 (2.1) mm; mean bone height available for implantation was 7.8 (1.5) mm. After distraction and insertion of implants, mean crown height was 8.1 (1.9) mm, and mean implant length was 11.3 (1.9) mm. Before distraction, the mean required crown height:available bone height ratio was 1.7 (0.3); after distraction and insertion of implants, the mean crown:implant ratio was 0.7 (0.2) (P<0.0005). Alveolar distraction is effective for increasing the height of the alveolar ridge in the posterior mandibular region, and should be considered when the height of the predicted crown that is required is greater than or equal to the maximum height of bone available for implantation.

Mandibular Fracture as a Complication of Inferior Alveolar Nerve Transposition and Placement of Endosseous Implants: A Case Report

Placement of endosseous implants and inferior alveolar nerve transposition is a treatment option for patients with an edentulous posterior mandible with inadequate bone height superior to the inferior alveolar canal. Complications associated with these procedures include infection, prolonged neurosensory disturbances, and/or pathologic fracture. This report presents the surgical management of a patient with a mandible fracture after inferior alveolar nerve transposition with concurrent placement of two endosseous implants.

Effects of hydroxyapatite-coated and commercially pure titanium oral implant surfaces on compound nerve action potentials

The aim of this study was to investigate the effects of hydroxyapatite-coated and commercially pure titanium oral implants on nerve conduction. Isolated rat sciatic nerves were placed between two suction electrodes in a bath containing a tyrode solution. The implants were brought into intimate contact with the nerves and evoked compound action potentials (cAPs) were recorded before and after contact with the implants. The commercially pure titanium implants did not cause any change in cAPs. A gradual reduction in cAPs was observed for hydroxyapatite-coated implants. However, this reduction was < 50% after an application time of 120 min. Recovery of the cAPs in this group was recorded after approximately 60 min. We conclude that, although intimate contact with hydroxyapatite-coated implants leads to a reduction in cAPs in nerves in vitro, neither this surface nor a commercially pure titanium surface leads to irreversible neurotoxic effects.

Morbidity of harvesting of chin grafts: a prospective study

In a prospective study, 20 patients who underwent harvesting of chin grafts as outpatients, were followed up for 12 months (3 further patients with incomplete follow-up data were excluded from the study). Preoperatively and 7 days, 1, 3, 6 and 12 months postoperatively, follow-up data were assessed. Evaluation of the superficial sensory function of the inferior alveolar nerve was determined by the Pointed-Blunt Test and the Two-Point-Discrimination Test. Sensory disturbances were objectively assessed by testing thermal sensitivity with the "Pain and Thermal Sensitivity" Test (PATH Test). In addition, evaluation of the pulp sensitivity of teeth 35-45 was carried out by cold vitality testing. One week postoperatively, 8 patients were affected by superficial sensory impairment. 8 nerve territories showed hypoaesthetic reactions and 5 showed hyperaesthetic reactions. After 12 months, two patients still suffered from hypoaesthesia of one side of the chin. There was a statistically significant sensitivity impairment of the chin for all patients comparing the preoperative data of the Two-Point-Discrimination Test (left/right median: 8.17/8.17 mm, interquartile range (IQR) 1.00/2.00 mm) with the first postoperative measurement (left/right median 9.00/8.33 mm, IQR 1.67/2.66 mm). Comparing the latter to the last postoperative measurement there was significant tendency for regeneration of a nerve function (left/right median 8.00/7.84 mm, IQR 0.66/2.00 mm). In the PATH Test all hypoaesthetic areas could be identified by a reduction of thermal sensitivity. After the first postoperative examination 21.6% (n=38/176) of the examined teeth had lost their pulp sensitivity. After 12 postoperative months 11.4% (n=20/176) still did not react sensitively. Many of these were canines (n=8/20). Comparing the preoperative to the first postoperative examination, there was a significant reduction of pulp sensitivity. However, statistically significant recovery until the last postoperative follow-up could not be detected. The assessed data show that patients have to be informed extensively about disturbances of the inferior alveolar nerve function lasting longer than 12 months. Moreover, the loss of pulp sensitivity is a very frequent event which has always to be taken into account. Considering the high rate of complications with harvesting of chin grafts, more prospective trials should be done to find out whether there are other donor sites for autogenous bone which put less strain on patients.

Preimplant surgery of the bony tissues

STATEMENT OF PROBLEM

The rationale of preimplant surgery is the creation of an environment that is favorable to the function and long-term survival of endosseous dental implants. Indications for this type of surgery depend on anatomic conditions, implant type, and design of the superstructure. One essential requirement for successful implantation is the presence of sufficient bone in which the implants are placed. Besides the quantity of bone, the quality of bone and the intermaxillary relation play an important role.

PURPOSE

This article presents an overview of several techniques for specific implant conditions.