This article, the second in a two-part series, continues the discussion of inferior alveolar nerve lateralization/transposition for dental implant placement. The aim of this article is to review the scientific literature and clinical reports in order to analyse the neurosensory complications, risks and disadvantages of lateralization/transposition of the inferior alveolar nerve followed by implant placement in an edentulous atrophic posterior mandible.
A comprehensive review of the current literature was conducted according to the PRISMA guidelines by accessing the NCBI PubMed and PMC databases, as well as academic sites and books. The articles were searched from January 1997 to July 2014. Articles in English language, which included adult patients between 18 - 80 years of age who had minimal residual bone above the mandibular canal and had undergone inferior alveolar nerve (IAN) repositioning, with minimum 6 months of follow-up, were included.
A total of 21 studies were included in this review. Ten were related to IAN transposition, 7 to IAN lateralization and 4 to both transposition and lateralization. The IAN neurosensory disturbance function was present in most patients (99.47% [376/378]) for 1 to 6 months. In total, 0.53% (2/378) of procedures the disturbances were permanent.
Inferior alveolar nerve repositioning is related to initial transient change in sensation in the majority of cases. The most popular causes of nerve damage are spatula-caused traction in the mucoperiosteal flap, pressure due to severe inflammation or retention of fluid around the nerve and subsequent development of transient ischemia, and mandibular body fracture.
Rehabilitation of edentulous atrophic posterior mandibles by inferior alveolar nerve (IAN) lateralization (IANL) or transposition (IANT), followed by implant placement, demonstrates many advantages; however, it also carries with it some disadvantages, such as neurosensory disturbance (ND) [
Diagnostic methods of ND that have been used by different authors include: light touch (LT), two-point discrimination (2-PD), pain test (PT), pin-prick sensation test and brush stroke direction (BSD) method [
The literature also presents several cases of mandibular fracture as a result of IANL and IANT followed by implant placement in an edentulous atrophic posterior mandible [
The aim of this article is to review the scientific literature and clinical reports in order to analyse the neurosensory complications, risks and disadvantages of inferior alveolar nerve lateralization or transposition followed by implant placement in edentulous atrophic posterior mandible.
IAN damage during IANL is defined as damage to the neurovascular bundle after performing lateral reflection of the IAN. The damage or complication may occur due to exerting too much traction with a small contact area instrument upon the neurovascular bundle during its extraction from the canal or nerve traction during surgery, which may lead to ischemia of the neurosensory bundle [
IAN damage during IANT is defined as the damage to the neurosensory bundle after performing incisive nerve transaction. The damage is, first of all, due to the transaction itself, which disconnects the anterior region of the mandible from the neurovascular bundle, which means that no innervations will remain to the anterior teeth (if they are present). Other complications that may occur due to IANT include oedema, hematoma or chronic compression after surgery [
LT test is performed in order to investigate lower lip and chin sensation. Static light touch with a soft feather or a cotton-tipped applicator is performed on the chin and lip regions. The patient needs to tell the practitioner when he/she feels a light touch and to show the exact location. The results are compared with a control site [
BSD test, in which the same feather or cotton-tipped applicator is used as in LT. This time, however, a dynamic stroke movement is performed from left to right and then from right to left. The patient needs to identify the direction of the stroke [
2-PD test is performed using sharp callipers. With the patient’s eyes closed, the distance between two points of the callipers is increased until the patient can feel the callipers’ points as two separate points of contact [
PT/Pin-prick sensation test is done by using a sharp explorer. The result is positive when the patient can differentiate between pressure pain (done with a blunt tip that measures the same diameter as the explorer) and the pain caused by a sharp explorer [
The review is registered in international prospective register of systematic reviews ‘PROSPERO’ [
Registration number: CRD42015016357.
The review included studies, case reports, clinical trials conducted on humans. Studies were published in English between January 1997 and July 2014, and included a minimum of 6 months of follow-up. Letters and PhD theses were excluded, as well as abstracts, reviews and studies on animals.
The information source was the MEDLINE (NCBI PubMed and PMC) database and other scientific electronic databases.
According to the PRISMA guidelines, an electronic search was conducted using the MEDLINE (NCBI PubMed and PMC) database to locate articles concerning IAN lateralization or IAN transposition and implant placement in an edentulous atrophic posterior mandible. The search terms used were: “INFERIOR ALVEOLAR NERVE LATERALIZATION”, ”INFERIOR ALVEOLAR NERVE REPOSITIONING”, ”INFERIOR ALVEOLAR NERVE TRANSPOSITION”, ”IMPLANTS IN ATROPHIC POSTERIOR MANDIBLE + REPOSITIONING”, ”INFERIOR ALVEOLAR NERVE TRANSPOSITION + MENTAL”, ”IMPLANTS IN ATROPHIC POSTERIOR MANDIBLE + LATERALIZATION”, ”IMPLANTS IN ATROPHIC POSTERIOR MANDIBLE + TRANSPOSITION”, ”MANDIBULAR ATROPHY + REPOSITIONING”, and ”INFERIOR ALVEOLAR NERVE + MINIMAL BONE HEIGHT”. Due to the low number of relevant articles and to ensure the sensitivity of the systemic review process, articles were searched from January 1997 to July 2014. Bibliographies of the selected articles were also manually searched. Titles derived from this broad search were independently screened by two authors based on the inclusion criteria. Disagreements were resolved by discussion. Full reports were obtained for all the studies that were deemed eligible for inclusion in this paper.
PRISMA flow diagram.
Inclusion criteria for the selection were:
Articles regarding to IANL and IANT procedures;
All article types in English;
Clinical reports with minimum 6 months follow-up;
Studies on adult (between ages 18 and 80) human beings, with no immunologic diseases, uncontrolled; diabetes mellitus, osteoporosis, or other contraindicating systemic conditions.
Exclusion criteria for the selection were:
Clinical reports with no minimum 6 months of follow-up;
Not enough information regarding the selected topic;
Studies on animals;
Studies of patients with immunologic diseases, uncontrolled diabetes mellitus, osteoporosis or other contraindicating systemic conditions;
Studies of adolescents (under 18 years of age) and elderly people (over 80).
Article review and data extraction was performed according to a PRISMA flow diagram (
The search displayed 876 results from the NCBI PMC and PubMed databases and 3 results from other sources (dental-tribune.com, acta.tums.ac.ir, hindawi.com/journals). A total of 879 search results were screened. Preliminary exclusion was made by duplication and relevancy (n = 841). A total of 38 titles and abstracts were selected according to relevancy after the removal of duplications. Exclusion was made by information amount regarding the selected topic (n = 11). Twenty-seven articles were examined. Another exclusion was made based upon follow-up time (n = 6). Finally, 21 articles were included in the systematic review. Data was included for 638 patients.
Studies of adult human beings between ages 18 and 80 years of age with minimal residual bone above the mandibular canal, in which IANL and IANT + implant placement had been performed, were selected.
Data was independently extracted from reports in the form of variables according to the aim and themes of the present review as listed below.
Risk of bias (e.g., lack of information or selective reports on variables of interest) was assessed at the study level. The risks were indicated as lack of precise information of interest in each individual study that can blind the reader from particular information about the examined samples. The Cochrane Collaboration tool for assessing risk of bias [
The search displayed 876 results from the NCBI PMC and PubMed databases and 3 results from other sources (dental-tribune.com, acta.tums.ac.ir, hindawi.com/journals). A total of 879 search results were screened. Preliminary exclusion was made by duplication and relevancy (n = 841). A total of 38 titles and abstracts were selected according to relevancy after duplication removal. Exclusion was made according to information amount regarding the selected topic (n = 11). Twenty-seven full text articles assessed for eligibility. During the eligibility stage, articles that did not meet the inclusion and exclusion criteria were filtered as follows: no minimum 6 months of follow-up (n = 6). In the end, 21 articles were included in the systematic review. Data was included for 638 patients (
A total of 21 studies were included in this review. Ten were related to IANT, 7 to IANL and 4 to both IANT and IANL (
Description of studies included in the review
Study | Year of publication | Procedure performed | Number of patients |
---|---|---|---|
Morrison et al. [1] | 2002 | Transposition | 12 |
Chrcanovic et al. [2] | 2009 | Transposition | 15 |
Kan et al. [3] | 1997 | Lateralization | 10 |
Transposition | 5 | ||
Khajehahmadi et al. [4] | 2013 | Lateralization | 10 |
Transposition | 11 | ||
Ferrigno et al. [6] | 2005 | Transposition | 15 |
Karlis et al. [7] | 2003 | Transposition | 1 |
Kan et al. [8] | 1997 | Transposition | 1 |
Peleg et al. [10] | 2002 | Lateralization | 10 |
Del Castillo Pardo et al. [14] | 2008 | Lateralization | 1 |
Proussaefs [15] | 2005 | Transposition | 1 |
Hashemi [16] | 2005 | Lateralization | 11 |
Vasconcelos et al. [17] | 2008 | Transposition | 1 |
Hashemi [18] | 2010 | Lateralization | 87 |
Lorean et al. [19] | 2013 | Transposition and reposition | 57 |
Gasparini et al. [20] | 2014 | Transposition | 35 |
Quantius [21] | 2010 | Lateralization | 70 |
Barbu et al. [23] | 2014 | Lateralization | 7 |
Dal Ponte et al. [24] | 2011 | Transposition | 1 |
Vetromilla et al. [25] | 2014 | Lateralization | 125 |
Transposition | 150 | ||
Suzuki et al. [26] | 2012 | Lateralization | 1 |
Proussaefs [27] | 2005 | Transposition | 1 |
Data supplied was checked for the following risks of bias within the selected studies: low number of patients (10 or fewer); ND examined by less than 2 methods; random selection of patients; exact post-operative outcomes not indicated for each patient. Any discrepancies or unusual patterns were checked with the study investigator. After analysing of the risk of bias (
Assesment of the risks of bias
Study | Low number of |
ND examined |
Random |
Exact post-operative outcomes |
---|---|---|---|---|
Morrison et al. [1] | - | - | - | - |
Chrcanovic et al. [2] | - | + | + | + |
Kan et al. [3] | + | - | + | - |
Khajehahmadi et al. [4] | - | - | + | + |
Ferrigno et al. [6] | - | - | - | - |
Karlis et al. [7] | + | + | - | - |
Kan et al. [8] | + | Not mentioned | - | - |
Peleg et al. [10] | - | + | - | - |
Del Castillo Pardo et al. [14] | + | + | - | - |
Proussaefs [15] | + | + | - | - |
Hashemi [16] | - | Not mentioned | + | - |
Vasconcelos et al. [17] | + | Not mentioned | + | - |
Hashemi [18] | - | + | - | - |
Lorean et al. [19] | - | - | - | + |
Gasparini et al. [20] | - | - | - | - |
Barbu et al. [23] | + | + | - | + |
Dal Ponte et al. [24] | + | + | + | - |
Suzuki et al. [26] | + | Not mentioned | + | - |
Proussaefs [27] | + | + | + | - |
ND = neurosensory disturbances.
Results of individual studies are shown in
Results of individual studies
Study |
Number of |
Number of |
Implant survival rate | Results |
---|---|---|---|---|
Morrison |
20 IANT | 30 | 100% | All patients had initial change in sensation for about one month. 80% of the sites had returned to normal. 4 patients (4 sites in total) had persistent change in sensation. Each also said that the abnormality did not disturb to daily activities. According to objective tests, all sites were normal. 1 patient had painful unilateral dysesthesia for 3 months, in the end, had normal sensation. |
Chrcanovic |
18 IANT | 25 | 88% | All patients had initial paresthesia with complete recovery of the sensitivity within 6 months. |
Kan et al. [3] |
5 IANT |
64 | 93.8% |
For IANL - ND by LT was 16.7%, by BSD 16.7% and by 2-PD test it was 25%. Total ND was 33.3%. |
Khajehahmadi |
14 IANT |
65 | 100% |
For IANT - vitality test showed negative results at 1 week, 1, 3, 6, 12 months follow-up. All had normal values at 1 week before operation. |
Ferrigno et al. [6] | 19 IANT | 46 | 95.7% |
ND (registered by LT, PT and 2-PD tests) detected was 15.8% (3/19) by LT test, 15.8% (3/19) by PT, and 21% (4/19) by 2-PD test. Total ND was 21.1% (4/19). 9 patients had sensory recovery immediately after local anaesthesia. 10 patients had ND: in 6 cases, a total return of sensation |
Karlis et al. [7] | 1 IANT | 2 | 0% | 4 weeks post-op patient had pain and moderate oedema on the operated site, and paresthesia on right lower lip and chin. Panoramic X-ray showed radiolucency around posterior implant with no displaced linear fracture through inferior mandibular border. First, closed reduction with maxillo-mandibular fixation was done. After 1 week, open reduction + debridement and internal rigid fixation including removal of both implants was done. Iliac bone graft was placed in the operated site. Normal healing observed after 6 weeks. 6 months later, paresthesia was persisted. |
Kan et al. [8] | 1 IANT | 3 | 33.33% | 3 weeks post-op patient complained of pain in the operated site, clinical examination revealed mandibular body fracture at the two anterior implants area. 2 anterior implants were removed, open reduction + internal fixation with titanium mesh tray was done. Fracture healed without further complications. |
Peleg et al. [10] | 10 IANL | 23 | 100% | 4 patients had sensory recovery immediately after local anaesthesia. 6 patients had hypoesthesia immediately post-op. 5 patients had a total return of sensation during 3 - 4 weeks. 1 patient had a complete recovery after 6 weeks. None of the patients experienced permanent ND. |
Del Castillo |
1 IANL | 3 | 100% | Immediately post-op, the patient reported slight paresthesia of left half of the lower lip for few weeks. 6 months after implant placement, lip sensitivity was fully normal, and the patient had no paresthesia or neuralgias. |
Proussaefs [15] | 1 IANT | 5 | 100% | The patient had only a transient hyperesthesia for 3 months. |
Hashemi [16] | 11 IANL | - | - | Few complications were detected and IAN function presented in all patients. The average time for temporary anaesthesia was 7.3 days and after 3.3 months, in average, there was a complete recovery of the IAN. |
Vasconcelos |
1 IANT | 2 | 100% | Complete recovery of the sensitivity 7 months post-op. |
Hashemi [18] | 110 IANL | - | - |
The patients had ND in the first week follow-up: anaesthesia in 81 sites, hypoesthesia in 9 sites, burning in 9 sites, pain in 8 sites, pinching in 2 sites and tickling in 1 site. At 1 month follow-up, ND disappeared in 81 sites (74%). ND was in 12 sites: tickling in 8 sites, burning in 5 and pain in 4. At the end of first month, 9 sites of hypoesthesia returned to normal. At the end of second month, 95 sites returned to normal and ND remained in 15 sites: hypoesthesia in 8 and tickling in 7. After 3 months, ND was reported in 6 sites: hypoesthesia in 3 and tickling in 3. At the end of 6 months the ND was in 3 sites with tickling. 82 patients (94%) were satisfied with the results. |
Lorean et al. [19] |
68 IANL |
232 | 99.57% | 4 patients reported prolonged transient ND immediately post-op (5% of operations). The duration of post surgical ND was for 1 - 6 months, while in other cases for 0 - 4 weeks only. No permanent neural damage. No post-op sensibility of the anterior lower teeth. |
Gasparini |
49 IANT | - | - | Complications were in 6 cases: 1 case (2.8%) of transient anaesthesia and 5 cases (14.3%) of transient hypoesthesia (spontaneously resolving after 6 months). Among the hypoesthesia cases, 4 were of discriminative type and 1 of thermal type (cold). After 6 months there was a remission of symptoms. |
Barbu et al. [23] | 11 IANL | 32 | 100% | All patients had transient ND for 2 months. No permanent ND was detected. |
Dal Ponte |
1 IANT | 2 | 100% | During 7 postoperative days the patient had paresthesia of lower lip with some tingling feeling. Laser applications were performed in the region to help sensitivity recovery. |
Suzuki et al. [26] | 1 IANL | 2 | 100% | Patient had partial loss of sensitivity of right lower lip 7 days post-op, which was completely improved at 1 month follow-up. The results after loading were satisfactory. |
Proussaefs [27] | 1 IANT | 2 | 100% | Transient hyperesthesia for 3 months was reported. 3 years post-loading revealed no clinical signs of pathosis (i.e., mobility, probing depth < 3 mm, pain, BOP) |
ND = neurosensory disturbances; LT = light touch; 2-PD = two point discrimination; PT = pain test; IANL = inferior alveolar nerve lateralization; IANT = inferior alveolar nerve transposition.
It was difficult to compare or organise ND and treatment results because different authors provided different information regarding the IANL and IANT results and outcomes. For example, Del Castillo Pardo et al. [
We found, based upon the current selected literature, that the most popular procedure is IANL. We calculated that 62.2 % (235/378) of all the operations performed utilised IANL, and 37.8% (143/378) utilised IANT. Implant survival rates of 100% have been determined in 10 studies from the selected literature. Lorean et al. [
IANT is not currently considered a safe method; for that reason, it has received little consideration as a surgical technique for pre-prosthetic preparation of atrophic alveolar ridges in edentulous patients. Nevertheless, some authors have continued to analyse the validity of this surgical technique, especially in evaluating the residual functionality of the IAN following IANT. The reported risk of damage to the IAN ranges between 33% and 87%; however, in Gasparini et al. clinical study [
Reconstructive methods and implant-prosthetic strategies for the edentulous mandible in Cawood and Howell [
IANT is likely to be the most traumatic manoeuvre for the nerve. 10 - 17% traction is enough for the fibres to temporarily lose their conduction ability. A spatula-caused traction in the mucoperiosteal flap can lead to nerve twisting, even in areas far from the inured nerve. Therefore, more severe stretch damage may result in partial lesions of the axons and their myelin sheaths. This may lead to loss of sensibility as a result of stretching of the nerve [
Functional recovery depends on the nervous fibres’ regeneration ability and speed, which may vary between 1 to 3 mm a day [
Other complications/risks after this procedure include mandibular fracture at the operation site (the area of the bony window). The mandible is weakened by the removal of the buccal corticalis, and the simultaneous crestal implantation makes the mandible more susceptible to masticatory forces. Therefore, there is significant loss of structural integrity when a portion of the buccal cortex is removed during the lateralization procedure and combination with the placement of multiple implants can contribute to a potential fracture [
Other complications include implant loss, haemorrhage (result from transaction of the neurovascular bundle) and osteomyelitis [
The main limitations of this review were that 10 authors [
Inferior alveolar nerve repositioning is related with initial change in sensation in majority of cases for 1 to 6 months. The most popular causes of inferior alveolar nerve damage are; spatula-caused traction in mucoperiosteal flap, pressure due to severe inflammation or retention of fluid around the nerve trunk and subsequent development of transient ischemia, and mandibular body fracture. 99.47% (376/378) of procedures presented in this review, showed neurosensory disturbances and complications which were transient, while only 0.53% (2/378) of procedures demonstrate permanent neurosensory disturbances.
The authors report no conflicts of interest related to this study.