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Mandibular lower border: donor site of choice for alveolar grafting
British Journal of Oral and Maxillofacial Surgery (2002) 40, 429–432 © 2002 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Science Ltd. All rights reserved. doi:10.1016/S0266-4356(02)00196-1, available online at http://www.idealibrary.com on
Mandibular lower border: donor site of choice for alveolar grafting C. J. Cotter, ∗ A. Maher, ∗ C. Gallagher, † D. Sleeman ‡ ∗ Lecturer;
†Registrar; ‡Professor and Head of Department, Oral and Maxillofacial Surgery, Department of Dental Surgery, University Dental Hospital, Cork, Ireland SUMMARY. In this paper we describe a technique for harvesting bone from the mandibular lower border, for the rehabilitation of partially dentate patients. We have used the technique in 15 patients, age range 21–52, with minimal short-term morbidity. © 2002 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Science Ltd. All rights reserved. be seen and the site of the graft can be chosen to correspond with the natural curve of the alveolus that is to be reconstructed. A reciprocating saw, with copious saline irrigation, is used to make longitudinal cuts into the bone on each side through the outer cortical plate including the lower border and a transverse cut is used to join these two cuts (Figs 1–3). An osteotome is then used to deliver the graft by tapping its upper edge, which separates quite easily from the underlying cancellous bone (Figs 4 and 5). Bone can be harvested from both sides, leaving an intact central portion if desired. A rim of lower border remains lingually, maintaining the height of the mandible. The recipient site is prepared by perforating the cortex with multiple small burr holes. The graft is transferred to the recipient site, trimmed to ensure congruity of fit, and secured with titanium microscrews. Gross deficiencies between graft and recipient site are filled with remaining graft bone and the wounds are closed. The fixtures are sited at a second operation 6 months after the primary procedure. Our technique differs from that previously described in that we use a marginal rather than a vestibular incision and we use a reciprocating saw and osteotome to harvest the graft instead of burrs.
INTRODUCTION The rehabilitation of edentulous and partially dentate patients has been revolutionised by the technique of osseointegration. During placement of an implant the aim is to have at least 1 mm of cortical bone around the fixture for adequate stability. In many cases the residual alveolar ridge is not thick enough to achieve this. In other cases adequate bone exists but not where it is required for optimal functional and aesthetic prosthetic reconstruction. On these occasions, bone grafting is indicated. Autogenous grafts have been taken from various sites including the iliac crest, fibula, calvarium, rib, maxillary tuberosity, mandibular ramus, mandibular coronoid process and mandibular symphysis.1 The use of a mandibular lower border graft has been briefly described.2 While it is possible to harvest large amounts of bone from extraoral sites, a permanent cutaneous scar is produced and second-site morbidity is less acceptable to patients.3 It is likely that in the future most of the demand for implant-based reconstruction will come from partially dentate patients who need a moderate amount of bone. We describe the technique of harvesting the mandibular lower border graft in detail and report on our experience of donor site morbidity.
Patients Fifteen patients aged between 21 and 52 presented with partial edentulism of the maxilla and insufficient bone in which to place implant fixtures. Between one and six teeth were missing. All had lower border grafts placed as described above. There was one failure, when the graft slipped during placement of the fixture. Twenty-four fixtures have been successfully placed to date, and three patients are awaiting placement. The patients were followed up by telephone questionnaire to find out the subjective outcome. Postoperative pain during the first 3 days was assessed by assigning a
PATIENTS AND METHODS Technique The operation is done under general anaesthesia but it may be possible to do it under local anaesthesia and sedation in suitable patients. The recipient site is exposed by a buccal flap in the standard fashion. An estimate is made of the amount of bone that will be needed. The mandibular symphysis is exposed to the lower border through a marginal incision with vertical relieving incisions. Bone can now 429
430
British Journal of Oral and Maxillofacial Surgery
Fig. 1 The bone cuts are made with a reciprocating saw. The graft is separated by tapping on the upper portion with an osteotome (upper hatched line).
Fig. 3 Intraoperative view of the bone cuts.
severity score between 1 and 10. Swelling was assessed by asking the patients when it resolved completely and whether it was noticed only by themselves or by others, and whether it prevented normal social activity. We then
Fig. 2 Lingual view of the bone cuts (continuous lines).
Fig. 4 Intraoperative view showing harvesting of the graft with an osteotome.
Mandibular lower border: donor site of choice for alveolar grafting
Fig. 5 The defect after the graft has been harvested.
asked about any sensory disturbance in the chin and lip or teeth and finally whether they noticed any change in the profile of the chin since the graft was taken. The patients were assessed by the referring dentist about any visible physical change in the area of the chin after the healing phase.
RESULTS Postoperative pain scores varied between 2 and 8 with the mode being 5, and two patients gave scores of more than 5. There did not seem to be a correlation between the size of the graft and pain score. There was little swelling after the first week and in most cases this did not prevent normal social activities. Patients who reported longer periods of swelling tended to have had larger grafts. Six patients complained of altered sensation at the point of the chin. This resolved within 6 months in all except one. There was no complaint of altered sensation indicating a mental nerve distribution. Two patients noticed increased sensitivity of the lower teeth, which in one case persisted for more than 6 months. Five of the patients said that they could either see or palpate a change at the donor site, but in all cases it was minor and did not pose any aesthetic problem for the patient. There did not seem to be a correlation between the size of the graft and this complaint. The referring dentists did not perceive any change in the aesthetics of the chin in any patient.
DISCUSSION The most commonly used intraoral donor site is the mandibular symphysis. It has the advantage of being
431
readily accessible and carries little morbidity.4 The roots of the mandibular incisors are at risk during the cutting of the bone and when the graft is being levered from the underlying bone. This can lead to obliteration of the pulp canal and necrosis of the pulp.5 The amount of cortical bone available is limited, which is the major disadvantage. The cortical plate of the mandible is thickest at the lower border and is maximal as one approaches the midline. Sufficient bone can be harvested at the lower border to both increases the width of the deficient alveolus and to increase its height by up to 4 mm. There is enough bone in the lower border available to allow the placement of six fixtures in the anterior maxilla. These are major advantages over the symphysis graft. The natural anteroposterior curve of the donor site in the lower border can be matched to that of the recipient site, to form a natural-looking reconstructed alveolus. The curve at the lower end of the graft corresponds well to the buccolingual morphology of a well-formed edentulous alveolus. This aids in the achievement of an aesthetic emergence profile. Technically the lower border graft is simpler than the traditional symphysis graft, as the natural flaring of the mandible allows easy lift-off of the graft from underlying bone. The site is well away from the vulnerable roots of the incisors and canines. Changes in the profile of the chin result from a change in the underlying bony morphology or changes in the overlying soft tissues. Our group of patients showed no discernible change of significance in chin morphology. There is always a risk of chin ptosis when the origin of the mentalis muscle is stripped from bone.6 Our group of patients showed no evidence of this but they were predominantly young and may be at less risk of this complication. The altered sensation perceived by our patients at the point of the chin is most likely the result of stripping of soft tissue from the underlying bone. One would expect this to resolve completely with time. We feel that complaints of sensitive teeth may be related to gingival recession associated with healing of the marginal incision rather than any disturbance to the pulpal blood supply. The operation site is well away from the apical neurovascular bundles. If local gingival conditions are unfavourable a horizontal vestibular incision may be used avoiding compromised gingiva but risking a higher rate of wound dehiscence.7 It is possible to measure the changes in soft tissue and tooth sensation objectively after graft harvesting.8 This would be a worthwhile exercise and would require a prospective study. We assessed sensory change by simple questioning; ultimately it is the patient’s perception of functional change that is most important. Fears have been expressed that removing part of the lower border in this fashion may predispose to fracture of the mandible. We have not experienced this complication,
432
British Journal of Oral and Maxillofacial Surgery
but it seems prudent to counsel patients against vigorous sports for 6 weeks. We have shown in this preliminary report that the mandibular lower border graft is a successful way of augmenting edentulous spaces. The procedure has a low morbidity and acceptability by patient is good. We now advocate this technique as the procedure of choice for augmentation of deficient anterior alveolar ridges where the edentulous space is between one and six teeth. REFERENCES 1. Tolman DE. Reconstructive procedures with endosseous implants in grafted bone: a review of the literature. Int J Oral Maxillofac Implants 1995; 10: 275–294. 2. Collins TA. Onlay bone grafting in combination with Branemark implants. Oral Maxillofac Clin North Am 1991; 3: 893–902. 3. Sindet-Pedersen S, Enemark H. Reconstruction of alveolar clefts with mandibular or iliac crest bone grafts: a comparative study. J Oral Maxillofac Surg 1990; 48: 554–558. 4. Misch CM, Misch CE, Resnik RR, Ismail YH. 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. 5. Hoppenreijs TJM, Nijdam ES, Freihofer HPM. The chin as a donor site in early secondary osteoplasty: a retrospective clinical and radiological evaluation. J Craniomaxillofac Surg 1992; 20: 119–124.
6. Rubens BC, West RA. Ptosis of the chin and lip incompetence: consequences of lost mentalis muscle support. J Oral Maxillofac Surg 1989; 47: 359–366. 7. Misch CM. Comparison of intraoral donor sites for onlay grafting prior to implant placement. Int J Oral Maxillofac Implants 1997; 12: 767–776. 8. Nkenke E, Schultze-Mosgau S, Radespiel-Troger M, Kloss F, Neukam FW. Morbidity of harvesting of chin grafts: a prospective study. Clin Oral Implants Res 2001; 12: 495–502.
The Authors C. J. Cotter MB, FDSRCS Lecturer A. Maher BDS, MB Lecturer C. Gallagher MB, FDSRCS, FFDRCS Registrar D. Sleeman FDSRCS, FRCS, FFDRCS Professor and Head of Department, Oral and Maxillofacial Surgery, Department of Dental Surgery, University Dental Hospital, Cork, Ireland Correspondence and requests for offprints to: Dr C. J. Corter MB, FDSRCS, Lecturer, Oral and Maxillofacial Surgery, Department of Dental Surgery, University Dental Hospital, Cork, Ireland. Tel: +353 21 454 5100; Fax: +353 21 454 5539 Accepted 10 June 2002
Mandibular lower border: donor site of choice for alveolar grafting C. J. Cotter, ∗ A. Maher, ∗ C. Gallagher, † D. Sleeman ‡ ∗ Lecturer;
†Registrar; ‡Professor and Head of Department, Oral and Maxillofacial Surgery, Department of Dental Surgery, University Dental Hospital, Cork, Ireland SUMMARY. In this paper we describe a technique for harvesting bone from the mandibular lower border, for the rehabilitation of partially dentate patients. We have used the technique in 15 patients, age range 21–52, with minimal short-term morbidity. © 2002 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Science Ltd. All rights reserved. be seen and the site of the graft can be chosen to correspond with the natural curve of the alveolus that is to be reconstructed. A reciprocating saw, with copious saline irrigation, is used to make longitudinal cuts into the bone on each side through the outer cortical plate including the lower border and a transverse cut is used to join these two cuts (Figs 1–3). An osteotome is then used to deliver the graft by tapping its upper edge, which separates quite easily from the underlying cancellous bone (Figs 4 and 5). Bone can be harvested from both sides, leaving an intact central portion if desired. A rim of lower border remains lingually, maintaining the height of the mandible. The recipient site is prepared by perforating the cortex with multiple small burr holes. The graft is transferred to the recipient site, trimmed to ensure congruity of fit, and secured with titanium microscrews. Gross deficiencies between graft and recipient site are filled with remaining graft bone and the wounds are closed. The fixtures are sited at a second operation 6 months after the primary procedure. Our technique differs from that previously described in that we use a marginal rather than a vestibular incision and we use a reciprocating saw and osteotome to harvest the graft instead of burrs.
INTRODUCTION The rehabilitation of edentulous and partially dentate patients has been revolutionised by the technique of osseointegration. During placement of an implant the aim is to have at least 1 mm of cortical bone around the fixture for adequate stability. In many cases the residual alveolar ridge is not thick enough to achieve this. In other cases adequate bone exists but not where it is required for optimal functional and aesthetic prosthetic reconstruction. On these occasions, bone grafting is indicated. Autogenous grafts have been taken from various sites including the iliac crest, fibula, calvarium, rib, maxillary tuberosity, mandibular ramus, mandibular coronoid process and mandibular symphysis.1 The use of a mandibular lower border graft has been briefly described.2 While it is possible to harvest large amounts of bone from extraoral sites, a permanent cutaneous scar is produced and second-site morbidity is less acceptable to patients.3 It is likely that in the future most of the demand for implant-based reconstruction will come from partially dentate patients who need a moderate amount of bone. We describe the technique of harvesting the mandibular lower border graft in detail and report on our experience of donor site morbidity.
Patients Fifteen patients aged between 21 and 52 presented with partial edentulism of the maxilla and insufficient bone in which to place implant fixtures. Between one and six teeth were missing. All had lower border grafts placed as described above. There was one failure, when the graft slipped during placement of the fixture. Twenty-four fixtures have been successfully placed to date, and three patients are awaiting placement. The patients were followed up by telephone questionnaire to find out the subjective outcome. Postoperative pain during the first 3 days was assessed by assigning a
PATIENTS AND METHODS Technique The operation is done under general anaesthesia but it may be possible to do it under local anaesthesia and sedation in suitable patients. The recipient site is exposed by a buccal flap in the standard fashion. An estimate is made of the amount of bone that will be needed. The mandibular symphysis is exposed to the lower border through a marginal incision with vertical relieving incisions. Bone can now 429
430
British Journal of Oral and Maxillofacial Surgery
Fig. 1 The bone cuts are made with a reciprocating saw. The graft is separated by tapping on the upper portion with an osteotome (upper hatched line).
Fig. 3 Intraoperative view of the bone cuts.
severity score between 1 and 10. Swelling was assessed by asking the patients when it resolved completely and whether it was noticed only by themselves or by others, and whether it prevented normal social activity. We then
Fig. 2 Lingual view of the bone cuts (continuous lines).
Fig. 4 Intraoperative view showing harvesting of the graft with an osteotome.
Mandibular lower border: donor site of choice for alveolar grafting
Fig. 5 The defect after the graft has been harvested.
asked about any sensory disturbance in the chin and lip or teeth and finally whether they noticed any change in the profile of the chin since the graft was taken. The patients were assessed by the referring dentist about any visible physical change in the area of the chin after the healing phase.
RESULTS Postoperative pain scores varied between 2 and 8 with the mode being 5, and two patients gave scores of more than 5. There did not seem to be a correlation between the size of the graft and pain score. There was little swelling after the first week and in most cases this did not prevent normal social activities. Patients who reported longer periods of swelling tended to have had larger grafts. Six patients complained of altered sensation at the point of the chin. This resolved within 6 months in all except one. There was no complaint of altered sensation indicating a mental nerve distribution. Two patients noticed increased sensitivity of the lower teeth, which in one case persisted for more than 6 months. Five of the patients said that they could either see or palpate a change at the donor site, but in all cases it was minor and did not pose any aesthetic problem for the patient. There did not seem to be a correlation between the size of the graft and this complaint. The referring dentists did not perceive any change in the aesthetics of the chin in any patient.
DISCUSSION The most commonly used intraoral donor site is the mandibular symphysis. It has the advantage of being
431
readily accessible and carries little morbidity.4 The roots of the mandibular incisors are at risk during the cutting of the bone and when the graft is being levered from the underlying bone. This can lead to obliteration of the pulp canal and necrosis of the pulp.5 The amount of cortical bone available is limited, which is the major disadvantage. The cortical plate of the mandible is thickest at the lower border and is maximal as one approaches the midline. Sufficient bone can be harvested at the lower border to both increases the width of the deficient alveolus and to increase its height by up to 4 mm. There is enough bone in the lower border available to allow the placement of six fixtures in the anterior maxilla. These are major advantages over the symphysis graft. The natural anteroposterior curve of the donor site in the lower border can be matched to that of the recipient site, to form a natural-looking reconstructed alveolus. The curve at the lower end of the graft corresponds well to the buccolingual morphology of a well-formed edentulous alveolus. This aids in the achievement of an aesthetic emergence profile. Technically the lower border graft is simpler than the traditional symphysis graft, as the natural flaring of the mandible allows easy lift-off of the graft from underlying bone. The site is well away from the vulnerable roots of the incisors and canines. Changes in the profile of the chin result from a change in the underlying bony morphology or changes in the overlying soft tissues. Our group of patients showed no discernible change of significance in chin morphology. There is always a risk of chin ptosis when the origin of the mentalis muscle is stripped from bone.6 Our group of patients showed no evidence of this but they were predominantly young and may be at less risk of this complication. The altered sensation perceived by our patients at the point of the chin is most likely the result of stripping of soft tissue from the underlying bone. One would expect this to resolve completely with time. We feel that complaints of sensitive teeth may be related to gingival recession associated with healing of the marginal incision rather than any disturbance to the pulpal blood supply. The operation site is well away from the apical neurovascular bundles. If local gingival conditions are unfavourable a horizontal vestibular incision may be used avoiding compromised gingiva but risking a higher rate of wound dehiscence.7 It is possible to measure the changes in soft tissue and tooth sensation objectively after graft harvesting.8 This would be a worthwhile exercise and would require a prospective study. We assessed sensory change by simple questioning; ultimately it is the patient’s perception of functional change that is most important. Fears have been expressed that removing part of the lower border in this fashion may predispose to fracture of the mandible. We have not experienced this complication,
432
British Journal of Oral and Maxillofacial Surgery
but it seems prudent to counsel patients against vigorous sports for 6 weeks. We have shown in this preliminary report that the mandibular lower border graft is a successful way of augmenting edentulous spaces. The procedure has a low morbidity and acceptability by patient is good. We now advocate this technique as the procedure of choice for augmentation of deficient anterior alveolar ridges where the edentulous space is between one and six teeth. REFERENCES 1. Tolman DE. Reconstructive procedures with endosseous implants in grafted bone: a review of the literature. Int J Oral Maxillofac Implants 1995; 10: 275–294. 2. Collins TA. Onlay bone grafting in combination with Branemark implants. Oral Maxillofac Clin North Am 1991; 3: 893–902. 3. Sindet-Pedersen S, Enemark H. Reconstruction of alveolar clefts with mandibular or iliac crest bone grafts: a comparative study. J Oral Maxillofac Surg 1990; 48: 554–558. 4. Misch CM, Misch CE, Resnik RR, Ismail YH. 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. 5. Hoppenreijs TJM, Nijdam ES, Freihofer HPM. The chin as a donor site in early secondary osteoplasty: a retrospective clinical and radiological evaluation. J Craniomaxillofac Surg 1992; 20: 119–124.
6. Rubens BC, West RA. Ptosis of the chin and lip incompetence: consequences of lost mentalis muscle support. J Oral Maxillofac Surg 1989; 47: 359–366. 7. Misch CM. Comparison of intraoral donor sites for onlay grafting prior to implant placement. Int J Oral Maxillofac Implants 1997; 12: 767–776. 8. Nkenke E, Schultze-Mosgau S, Radespiel-Troger M, Kloss F, Neukam FW. Morbidity of harvesting of chin grafts: a prospective study. Clin Oral Implants Res 2001; 12: 495–502.
The Authors C. J. Cotter MB, FDSRCS Lecturer A. Maher BDS, MB Lecturer C. Gallagher MB, FDSRCS, FFDRCS Registrar D. Sleeman FDSRCS, FRCS, FFDRCS Professor and Head of Department, Oral and Maxillofacial Surgery, Department of Dental Surgery, University Dental Hospital, Cork, Ireland Correspondence and requests for offprints to: Dr C. J. Corter MB, FDSRCS, Lecturer, Oral and Maxillofacial Surgery, Department of Dental Surgery, University Dental Hospital, Cork, Ireland. Tel: +353 21 454 5100; Fax: +353 21 454 5539 Accepted 10 June 2002