Abstract

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 postloading examination revealed minimal bone loss (<1 mm).

Introduction

Implants have become a valid treatment modality for the totally1,2 or partially3,4 edentulous patient. Resorption of the residual alveolar ridge has introduced the use of various bone-grafting techniques5,–17 in an attempt to restore the alveolus in a condition that allows placement of root form implants in situations where excessive bone resorption has occurred. Other authors have advocated the application of distraction osteogenesis for localized alveolar ridge augmentation.18,–22 The posterior mandible presents a challenge to clinicians because of the presence of the inferior alveolar nerve (IAN). transposing of the IAN (TIAN) has been suggested as an alternative treatment to allow placement of longer implants, better initial stabilization, and reduced treatment time.23 –34

Jensen and Nock23 were the first to describe placement of dental implants in the posterior mandible in conjunction with TIAN. They used a large round bur to create a channel in the lateral mandibular cortical plate distal to the mental foramen to permit TIAN. Several modifications have been described since then.24,26,–28,30 Neurosensory disturbance has been reported after performing TIAN.24,31,34 In the majority of the cases, it appears to be transient.24,34 There are limited data regarding success rate of implants when performing TIAN. Rosenquist28 reported an implant survival rate of 93.6%. Kan et al34 reported a 93.8% success rate when the follow-up period was 41.3 months.

Several authors have reported different techniques regarding preparation of a lateral access window (LAW) that allows access to the IAN. In all the cases, the presence of bone coronally to the canal of the IAN is indicated to provide stability to the fixtures during installation (Figure 1A and B).23,24,26,–28,30 The literature lacks data regarding the amount of bone that is needed above the canal of the IAN when performing TIAN. Jensen and Nock23 indicated that the superior part of the osteotomy for the LAW should be several millimeters below the crest of the residual mandibular alveolar ridge. Similarly, Rosenquist24 suggested that the cortex lateral to the canal should be removed en block. The coronal part of the block is located several millimeters below the crest of the alveolus. Friberg et al26 suggested that the osteotomy for the LAW should be performed several millimeters below the crest of the residual alveolar ridge. They also suggested that special care must be taken not to remove too much bone superior to the canal of the IAN. A close approach to the bone crest may interfere with countersinking and marginal implant bone support. Smiler27 reported that the superior part of the cortical bone should be left intact during osteotomy for LAW. Jensen et al30 were the first to introduce some guidelines regarding the presence of bone above the canal of the IAN. They suggested that 5 mm of bone should be present above the canal of the IAN to perform TIAN. Rosenquist et al28 reported that the presence of residual bone above the canal of the IAN was indicated when performing TIAN. Kan et al34 reported that TIAN was performed in situations where a minimum of 5 mm of bone was present above the canal of the IAN (average: 6.8 mm, range: 5–10 mm).

Figures 1–5. Figure 1. (A) Preoperative view, left side. (B) Preoperative view, right side. Figure 2. Computerized tomography scan revealing minimal bone height above the inferior alveolar nerve. Figure 3. After 2 vertical and 2 horizontal osteotomies, the cortical bone is removed from the lateral access window. Figure 4. The inferior alveolar nerve is retracted. Figure 5. Autogenous particulate bone graft is placed around the implants. Resorbable collagen membrane will cover the bone graft

Figures 1–5. Figure 1. (A) Preoperative view, left side. (B) Preoperative view, right side. Figure 2. Computerized tomography scan revealing minimal bone height above the inferior alveolar nerve. Figure 3. After 2 vertical and 2 horizontal osteotomies, the cortical bone is removed from the lateral access window. Figure 4. The inferior alveolar nerve is retracted. Figure 5. Autogenous particulate bone graft is placed around the implants. Resorbable collagen membrane will cover the bone graft

It seems that a specific amount of bone (≥5 mm) is needed above the canal of the IAN to perform TIAN. However, and to the author's best knowledge, no suggestion has been provided for cases where bone above the canal is minimal.

The purpose of this clinical report is to describe treatment of a patient where minimal crestal bone was observed coronal to the canal of the IAN. Autogenous bone graft was placed around the implants and covered with a collagen membrane.

Clinical Report

A 56-year-old woman presented at the Center for Prosthodontics and Implant Dentistry, Loma Linda University, for treatment of her partial mandibular edentulism (Figure 1). Clinical examination revealed edentulism at the area of teeth #18 to #20, #30, and #31. Extensive resorption was observed. A computerized tomography scan taken from the mandible indicated that the IAN was 1 to 2 mm below the crest of the residual alveolar ridge. At the area around the mental foramen, the canal of the IAN was at the same level with the crest of the residual alveolar ridge (Figure 2). The patient had a history of dissatisfaction with removable partial denture. The decision to perform TIAN was made.

After performing crestal incision, full-thickness labial and lingual flaps were reflected. Osteotomy of the LAW was performed (Figure 3). Two vertical and 2 horizontal osteotomies were performed. The IAN was retracted (Figure 4).23,24,26,–28,30 With an acrylic resin, surgical stent threaded hydroxyapatite-coated root form implants (SteriOss, Nobel Biocare, Yorba Linda, Calif) were placed at the area of teeth #18 to #20, #30, and #31. The autogenous bone from the LAW was particulated and placed around the implants (Figure 5). Resorbable collagen membrane (BioGuide, Osteohealth Co, Shirley, NJ) was placed above the graft material (Figure 6). The flaps were sutured. A panoramic radiograph was taken after implant surgery (Figure 7).

Figures 6–8. Figure 6. After lateral osteotomy and the retraction of the inferior alveolar nerve, the 4–5 coronal implant threads are exposed. Autogenous bone graft will cover the exposed threads, and a collagen membrane will be placed above the graft and the implants. Figure 7. Panoramic radiograph, postoperative view. Figure 8. Final result left (A) and right side (B)

Figures 6–8. Figure 6. After lateral osteotomy and the retraction of the inferior alveolar nerve, the 4–5 coronal implant threads are exposed. Autogenous bone graft will cover the exposed threads, and a collagen membrane will be placed above the graft and the implants. Figure 7. Panoramic radiograph, postoperative view. Figure 8. Final result left (A) and right side (B)

Second-stage surgery was performed 6 months after implant surgery. Implants appeared clinically osseointegrated as tested with the Perio-Test Unit (Perio-Test, Siemens, Bensheim, Germany). Implants were restored with cement-retained metal-ceramic restorations (Figure 8). Three-year postloading radiographic examination (nonstandardized periapical radiographs) revealed minimal marginal bone loss (<1 mm). The patient reported transient hypesthesia that lasted for 3 months, but no further symptoms of neurosensory disturbance were observed.

Discussion

Implant dentistry is based on a team approach between surgeons and prosthodontists.1,2 The described clinical report offers some alternative suggestions when planning treatment for a patient with an excessively resorbed posterior mandible. Prosthodontists need to be familiar with different surgical treatment options in order to refer patients appropriately and coordinate treatment with the surgeons.

In the presented case, TIAN was performed in a situation with minimal bone height above the canal of the IAN. Some authors have demonstrated the potential of placing dental implants several millimeters above original bone level in conjunction with 1-stage bone grafting.13 –15 In these cases, vertical ridge augmentation and implant placement are performed simultaneously. However, to follow this technique, a minimum of 6 to 8 mm original bone height is needed above the canal of the IAN to provide primary implant stability. In situations with excessive resorption of the posterior mandible, as in the presented case, application of this technique is not feasible because of the lack of adequate bone volume to provide primary implant stability.

Mandibular block autografts have been used for vertical alveolar ridge augmentation before placing dental implants.5,8,11 Anticipated vertical augmentation is 5 mm 6 months after bone grafting.11 In a severely resorbed mandible, as in the presented case, 10-mm vertical ridge augmentation would be needed. Two-stage bone grafting offers inadequate results in severely resorbed cases.

Distraction osteogenesis is a technique described in the literature for alveolar ridge augmentation.18,–22 Although this technique has been studied primarily for the resorbed premaxillary area,22 several reports18–20 have demonstrated its potential use for vertical ridge augmentation in the posterior mandible. With this technique, a bony segment needs to be released by performing vertical and horizontal osteotomies. A distraction device is placed along the horizontal osteotomy. The surgeon must have at least 8 mm of bone above the canal of the IAN to make horizontal and vertical osteotomies and have a large-enough segment to fixate to and transport with a given device.47 Situations with minimal bone height (<7mm) above the canal of the IAN are not suitable for the distraction osteogenesis technique.47

In the presented case, the autogenous bone from the LAW was particulated and placed in particulate form around the implants. Rosenquist24 recommended positioning of the cortical bone en block. Particulate graft was used to avoid mechanical trauma to the IAN from fixation process of the block. In addition, incorporation of graft material and bone loss around implants placed in conjunction with particulate bone graft appears to be favorable.6,9,10,13 –15

A concern has been reported regarding the morbidity of TIAN.31 Davis et al25 surveyed 22 practitioners performing TIAN; 9 of 190 patients experienced a disconcerting level of burning dysesthesia. Friberg et al26 reported a 7-month evaluation of 10 patients and found hypesthesia and paresthesia in 30% of the jaws. Rosenquist28 noted that 6 of 100 patients had either diminished or no neurosensation at 18 months postoperatively. Jensen et al30 reported 10% of the patients had signs of neurosensory disturbance. Haers and Sailer29 reported light paresthesia in 76.5% of their patients at 12 months. Kan et al34 reported a 52.4% incidence of neurosensory disturbance 41.3 months after surgery. Risks regarding neurosensory disturbance should be considered and explained to the patient during treatment planning.

Conclusion

In a clinical situation with minimal bone height above the canal of the IAN, implant placement and TIAN may be considered in conjunction with autogenous particulate bone grafting. A prospective clinical study and long-term follow-up are needed in order to validate the use of this technique in cases with excessive alveolar ridge resorption.

References

References
1
Adell
,
R.
,
U.
Lekholm
,
B.
Rockler
, and
P-I.
Branemark
.
A 15-year study of osseointegrated implants in the treatment of the edentulous jaw.
Int J Oral Surg
1981
.
10
:
387
416
.
2
Adell
,
R.
,
B.
Eriksson
,
U.
Lekholm
,
P-I.
Branemark
, and
T.
Jemt
.
Long-term follow-up study of osseointegrated implants in the treatment of totally edentulous jaws.
Int J Oral Maxillofac Implants
1990
.
5
:
347
359
.
3
Jemt
,
T.
,
U.
Lekholm
, and
R.
Adell
.
Osseointegration in the treatment of partially edentulous patients: a preliminary study of 876 consecutively installed fixtures.
Int J Oral Maxillofac Implants
1989
.
4
:
211
217
.
4
Jemt
,
T.
and
P.
Petterson
.
A 3-year follow-up study on single implant treatment.
J Dent
1993
.
21
:
203
208
.
5
Misch
,
C. M.
,
C. E.
Misch
,
R. R.
Resnik
, and
Y. H.
Ismail
.
Reconstruction of maxillary alveolar defects with mandibular symphysis grafts for dental implants: a preliminary procedural report.
Int J Oral Maxillofac Implants
1992
.
7
:
360
366
.
6
Buser
,
D.
,
K.
Dula
,
H. P.
Hirt
, and
R. K.
Schenk
.
Lateral ridge augmentation using autografts and barrier membranes: a clinical study with 40 partially edentulous patients.
J Oral Maxillofac Surg
1996
.
54
:
420
432
.
7
Triplett
,
R. G.
and
S.
Schow
.
Autologous bone grafts and endosseous implants: complementary techniques.
J Oral Maxillofac Surg
1996
.
54
:
486
494
.
8
Misch
,
C. M.
Comparison of intraoral donor sites for onlay grafting prior to implant placement.
Int J Oral Maxillofac Implants
1997
.
12
:
767
776
.
9
Nevins
,
M.
,
J. T.
Mellonig
,
D. S.
Clem
,
G. M.
Reiser
, and
D. A.
Buser
.
Implants in regenerated bone: long-term survival.
Int J Periodontics Restorative Dent
1998
.
18
:
35
45
.
10
Simion
,
M.
,
S. A.
Jovanovic
,
P.
Trisi
,
A.
Scarano
, and
A.
Piattelli
.
Vertical ridge augmentation around dental implants using a membrane technique and autogenous bone or allografts in humans.
Int J Periodontics Restorative Dent
1998
.
18
:
9
23
.
11
Proussaefs
,
P.
,
J. L.
Lozada
,
A.
Kleinman
, and
M.
Rohrer
.
The use of ramus autogenous block grafts for vertical alveolar ridge augmentation and implant placement: a pilot study.
Int J Oral Maxillofac Implants
2002
.
17
:
238
248
.
12
Proussaefs
,
P.
,
J. L.
Lozada
, and
M. D.
Rohrer
.
A clinical and histologic evaluation of block onlay graft in conjunction with autogenous particulate and inorganic bovine mineral (Bio-Oss). A case report.
Int J Periodontics Restorative Dent
2002
.
22
:
567
673
.
13
Simion
,
M.
,
P.
Trisi
, and
A.
Piatelli
.
Vertical ridge augmentation using a membrane technique associated with osseointegrated implants.
Int J Periodontics Restorative Dent
1994
.
14
:
497
511
.
14
Simion
,
M.
,
S. A.
Jovanovic
,
P.
Trisi
,
A.
Scarano
, and
A.
Piatelli
.
Vertical ridge augmentation around dental implants using a membrane technique and autogenous bone or allografts in humans.
Int J Periodontics Restorative Dent
1998
.
18
:
9
23
.
15
Tinti
,
C.
and
S. P.
Benfenati
.
Vertical ridge augmentation: surgical protocol and retrospective evaluation of 48 consecutively inserted implants.
Int J Periodontics Restorative Dent
1998
.
18
:
435
443
.
16
Proussaefs
,
P.
,
L. J.
Lozada
,
A.
Kleinman
, and
M.
Rohrer
.
The use of Titanium mesh in conjunction with autogenous bone graft and inorganic bovine mineral (Bio-Oss) for localized alveolar ridge augmentation. A human study.
Int J Periodontics Restorative Dent
2003
.
23
:
185
195
.
17
Lozada
,
J. L.
and
P.
Proussaefs
.
Clinical, radiographic, and histologic evaluation of maxillary bone reconstruction by using a titanium mesh and iliac graft: a case report.
J Oral Implantol
2002
.
28
:
9
14
.
18
Hidding
,
J.
,
F.
Lazar
, and
J. E.
Zoller
.
The vertical distraction of the alveolar bone.
J Craniomaxillofac Surg
1998
.
26
:
72
76
.
19
Gaggl
,
A.
,
G.
Schultes
, and
H.
Karcher
.
Distraction implants: a new possibility for the augmentative treatment of the edentulous atrophic mandible. Case report.
Br J Oral Maxillofac Surg
1999
.
37
:
481
485
.
20
Urbani
,
G.
,
G.
Lombardo
,
E.
Santi
, and
U.
Consolo
.
Distraction osteogenesis to achieve mandibular vertical regeneration: a case report.
Int J Periodontics Restorative Dent
1999
.
19
:
321
332
.
21
Chiapasco
,
M.
,
E.
Romeo
, and
G.
Vogel
.
Vertical distraction osteogenesis of edentulous ridges for improvement of oral implant positioning: a clinical report of preliminary results.
Int J Oral Maxillofac Implants
2001
.
16
:
43
51
.
22
Jensen
,
O. T.
,
R.
Cockrell
,
L.
Kuhlke
, and
C.
Reed
.
Anterior maxillary alveolar distraction osteogenesis: a prospective 5-year clinical study.
Int J Oral Maxillofac Implants
2002
.
17
:
52
68
.
23
Jensen
,
O.
and
D.
Nock
.
Inferior alveolar nerve repositioning in conjunction with placement of osseointagreted implants. A case report.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
1987
.
63
:
263
268
.
24
Rosenquist
,
B.
Fixture placement posterior to the mental foramen with transposing of the inferior alveolar nerve.
Int J Oral Maxillofac Implants
1991
.
7
:
45
50
.
25
Davis
,
H.
,
B.
Rydevik
,
G.
Lundborg
,
N.
Danielsen
,
J. E.
Hausamen
, and
F.
Neukam
.
Mobilization of the inferior alveolar nerve to allow placement of osseointagratable fixtures.
In: Worthington P, Branemark P-I, eds. Advanced Osseointegraion Surgery: Applications in the Maxillofacial Region. Chicago, Ill: Quintessence; 1992:129–144
.
26
Friberg
,
B.
,
C. J.
Ivanoff
, and
U.
Lekholm
.
Inferior alveolar nerve transposing in combination with Branemark implant treatment.
Int J Periodontics Restorative Dent
1992
.
12
:
440
449
.
27
Smiler
,
D. G.
Repositioning the inferior alveolar nerve for placement of endosseous implants: technique note.
Int J Oral Maxillofac Implants
1993
.
8
:
145
150
.
28
Rosenquist
,
B.
Implant placement in combination with nerve transposing: experience with the first 100 cases.
Int J Oral Maxillofac Implants
1994
.
9
:
522
531
.
29
Haers
,
P. E.
and
H. F.
Sailer
.
Neurosensory function after lateralization of the inferior alveolar nerve and simultaneous insertion of implants.
Oral Maxillofac Surg Clin North Am
1994
.
7
:
707
716
.
30
Jensen
,
J.
,
O.
Reiche-Fischel
, and
S.
Sindet-Petersen
.
Nerve transposing and implant placement in the atrophic posterior mandibular alveolar ridge.
J Oral Maxilofac Surg
1994
.
52
:
662
668
.
31
Krough
,
P. H.
,
P.
Worthington
,
W. H.
Davis
, and
E. E.
Keller
.
Does the risk of complication make transposing the inferior alveolar nerve in conjunction with implant placement a “last resort” surgical procedure.
Int J Oral Maxillofac Implants
1994
.
9
:
249
254
.
32
Hirsch
,
J-M.
and
P-I.
Branemark
.
Fixture stability and nerve function after transposition and lateralization of the inferior alveolar nerve and fixture installation.
Br J Oral Maxillofac Surg
1995
.
33
:
276
281
.
33
Kan
,
J. Y. K.
,
J. L.
Lozada
,
P. J.
Boyne
,
C. J.
Goodacre
, and
K.
Rungcharassaeng
.
Mandibular fracture after endosseous implant placement in conjunction with inferior alveolar nerve transposing: a patient treatment report.
Int J Oral Maxillofac Implants
1997
.
12
:
655
659
.
34
Kan
,
J. Y. K.
,
J. L.
Lozada
,
C. J.
Goodacre
,
W. H.
Davis
, and
O.
Hanisch
.
Endosseous implant placement in conjunction with inferior alveolar nerve transposing: an evaluation of neurosensory disturbance.
Int J Oral Maxillofac Implants
1997
.
12
:
463
471
.

Author notes

Periklis Proussaefs, DDS, MS, is an assistant professor in the Graduate Program in Implant Dentistry, School of Dentistry, Loma Linda University, Loma Linda, Calif, and is in private practice with an emphasis on implant and prosthetic dentistry in Encino, Calif. Address correspondence to Dr Proussaefs at Graduate Program in Implant Dentistry, School of Dentistry, Loma Linda University, School of Dentistry, Loma Linda, CA 92350 (pProussaef@hotmail.com).