J Oral Maxillofac 49:1277-1287.
Surg
1991
Autogenous Mandibular Bone Grafts and Osseoin tegra ted Implants for Reconstruction of the Severely Atrophied Maxilla: A Preliminary
Report
JOHN JENSEN, DDS,* AND STEEN SINDET-PEDERSEN,
DDS*
The purpose of this study is to present results obtained with a new procedure for reconstruction of the severely atrophied maxillary alveolar ridge that involves the use of intramembranous corticocancellous bone grafts obtained from the mandibular symphysis fixed to the residual bone by endosseous implants, A total of 107 implants were installed in grafted regions in 26 patients. The follow-up period ranged from 6 to 32 months, with a mean of 16 months. In partially edentulous patients the bone grafts were fixed with implants to the residual bone as 1) onlay graft to the alveolar ridge (8 implants in 4 patients); 2) grafts to the nasal and/or sinus floor after a transoral exposure and elevation of the mucosa of the maxillary sinus and/or the nasal mucosa (33 implants in 11 patients); or 3) a combination of these two (5 implants in 2 patients). In totally edentulous patients, implants and grafts were used as a combination of grafting to both the alveolar ridge and nasal and/or sinus floor sites (61 implants in 9 patients). One hundred of 107 implants showed normal clinical and radiologic healing, whereas 7 implants in 4 patients (6.5%) were lost prior to loading. Seventeen patients have had the implants and bone grafts loaded by a prosthodontic reconstruction from 6 to 26 months (mean, 14 months) without loss of any implants. Postoperative marginal resorption of the onlay bone graft of less than 15% was observed. These findings suggest, that the previously observed rapid resorption of endochondral iliac crest onlay bone grafts and the number of lost implants can be significantly reduced if bone from the mandibular symphysis firmly anchored with titanium implants is used.
surgeon and the prosthodontist. Conventional surgical treatment with alveolar augmentation or vestibuloplasty procedures provides only limited improvement in complete denture retention and stability. Also, treatment of some of these patients with osseointegrated implants alone is impossible because of the lack of bone into which implants can be anchored. ’ Reconstruction using particulate bone or corticocancellous onlay bone blocks in combination with implants installed into the residual maxilla has previously been reported and results from these studies using endochondral bone as grafting material indi-
Totally and partially edentulous patients with advanced maxillary alveolar resorption and/or increased pneumatization of the maxillary sinus have always presented a treatment challenge for both the
* Staff, Department of Oral and Maxillofacial Surgery, Aarhus University Hospital, Aarhus, Denmark. Address correspondence and reprint requests to Dr Jensen: Department of Oral and Maxillofacial Surgery, Aarhus University Hospital, Norrebrogade. DK-8000 Aarhus C, Denmark. 0 1991 geons
American
Association
of Oral
and Maxillofacial
Sur-
0278-2391/9114912-0004$3.00/O
1277
1278 cate an implant survival from 25% to 86% and a significant degree of marginal bone graft resorption. l-5 A sinus lift technique combined with iliac crest bone grafting to the sinus floor also has been used for reconstruction of atrophied maxillary alveolar ridges. This technique was first described by Boyne and James in 1980,6 and was primarily performed in patients with reduced interarch space to allow a later reduction of the bony tuberosity to increase interarch space. Three of these patients later received blade implants in the grafted regions. Also, a technique has been presented in which patients with severely atrophic posterior maxillas and pneumatization of the maxillary sinus were reconstructed using a sinus lift technique and mandibular bone obtained from the ascending ramus packed around the installed implants.7 There is experimental evidence that intramembranous bone grafts from the calvarium and zygoma placed as onlay grafts maintain more of their volume and show less postoperative resorption compared with endochondral bone taken from the iliac crests9 Furthermore, studies have indicated that intramembranous onlay bone grafts in the rabbit are more rapidly vascularized than endochondral grafts. These findings may explain the observed differences in graft survival for the two types of bone.” It has also been hypothesized that the graft architecture, which correlates with bone origin, could account for these differences in resorption of onlay bone grafts. ’ ’ Promising clinical results have been obtained in secondary reconstruction of the alveolar process in cleft palate patients by using intramembranous bone grafts taken from the mandibular symphysis. This method was first described in 1980 by Bosker and van Dijk. ‘* Sindet-Pedersen and Enemark later reported on 26 of 28 patients with 0% to 25% resorption of the graft assessed using occlusal radiographs after a median postoperative follow-up period of 8 months. l3 Three later comparative studies on reconstruction of alveolar clefts with mandibular symphyseal bone grafts versus iliac crest or rib bone grafts showed less resorption and less morbidity among patients who received mandibular bone grafts. 14-16 These clinical and experimental studies using intramembranous bone as an autograft for augmentation purposes have had promising results. Therefore, we began using reconstruction procedures in patients with severe atrophy of the maxillary alveolar ridge and/or increased pneumatization of the maxillary sinus involving mandibular bone grafts fixed with osseointegrated implants. The purpose of
IMPLANTS AND MANDIBULAR
BONE GRAFTS
this report is to describe the course of the first 26 patients treated by this method. Materials and Methods Of the 26 patients treated, 9 were totally edentulous in the maxilla and had demonstrated difficulties wearing a conventional maxillary denture owing to poor retention. The other 17 patients were partially edentulous in the maxilla and presented with either a severe loss of maxillary alveolar bone and/or increased pneumatization of the maxillary sinus (Fig 1). Twelve patients were females and 14 were males. The age of patients ranged from 17 to 76 years, with a mean age of 49 years. Only one patient was totally edentulous; all other patients had a partial dentition in the anterior region of the mandible. All the patients who were partially edentulous in the maxilla had a natural mandibular dentition from at least first premolar to first premolar. The mean postoperative follow-up time was 16 months, with a range from 6 to 32 months.
FIGURE bone loss Maxillary cant bone
1. A, Pneumatization of left maxillary sinus with and only minimal increase in interarch distance. B, edentulous patient with pneumatized sinuses, signifiloss, and increased interarch distance.
JENSEN AND SINDET-PEDERSEN
Preoperatively, all patients were subjected to thorough medical and radiographic examinations. Lateral cephalograms and panoramic radiographs were taken, in addition to routine intraoral periapical radiographs. The patients received all available information concerning the surgical procedure before the operation. All patients with a totally edentulous maxilla and eight patients with a partially edentulous maxilla were treated under general anesthesia. The other nine patients were treated under local anesthesia and oral sedation (diazepam). Prophylactic antibiotic treatment was initiated at the time of surgery and continued for 7 days postoperatively. Those patients who underwent a sinus or nasal lift procedure were also given decongestant nose drops. After the abutment placement procedure, 6 months postoperatively, the prosthodontic treatment was performed. Clinical and radiologic examinations were performed 3 and 6 months after prosthodontic treatment was completed and every 6 months thereafter. At the 6-month and 1 year time points, bridgework and dolder bars were removed from the implants and each implant was examined for mobility and peri-implant tissue condition. At the donor site, all teeth were examined for pulp vitality, periodontal condition, and radiologically examined for root resorption. Surgical
Technique
The reconstruction procedure was dependent on the region of edentulousness and the amount and shape of the residual maxillary bone. In partially edentulous patients, the prepared mandibular bone grafts were fixed with implants to the residual maxillary bone as 1) onlay bone grafts to the residual alveolar ridge (8 implants in 4 patients) (Fig 2); 2) inlay bone grafts to the sinus floor after elevation of the mucosa of the maxillary sinus (33 implants in 11 patients) (Fig 3); or 3) a combination of onlay and sinus bone grafts (5 implants in 2 patients) (Fig 4). In totally edentulous patients, a combination of onlay and sinus bone grafts was used (61 implants in 9 patients) (Fig 5) (Table 1). A nasal lift procedure was performed in all totally edentulous patients to ensure sufficient bone height in the anterior region. The donor site on the mandibular symphysis was exposed through a transoral approach. Holes for implant placement were drilled and tapped prior to procurement of the bone graft (Fig 6). In totally edentulous patients who received an onlay bone graft, the alveolar crest was surgically exposed by a vestibular incision approximately 1 cm from the at-
1279
FIGURE 2. View of partially edentulous patient reconstructed with an onlay bone graft fixed by four implants.
tached/unattached mucosal margin, with relieving incisions towards the alveolar crest in the second molar regions. In partially edentulous patients who received onlay bone grafts, similar vestibular and posterior relieving incisions were used, whereas in dentate regions, the relieving incisions were made at least one tooth away from the edentulous region. In partially edentulous patients who received bone grafts after a sinus lift, the alveolar crest and antral wall was exposed by means of an incision placed palatally to the crest of the ridge with relieving in-
FIGURE 3. An inlay bone graft fixed with two implants after a sinus lift procedure.
1280
IMPLANTS AND MANDIBULAR
BONE GRAFTS
Table 1. Number of Patients and Implants Placed According to Type of Bone Graft Variable Partially edentulous Onlay graft Sinus graft Onlay and sinus graft Totally edentulous Onlay and sinus graft Totals
Patients
-
Implants
-
4 11 2
8 33 5
9 26
61 107
Mucosal flaps were mobilized to wound closure in all cases where grafting was performed. All patients liquid diet for 10 days after surgery.
secure a tight alveolar onlay were kept on a Totally eden-
FIGURE 4. This partially edentulous patient received four implants for reconstruction of the right side of the maxilla. The most anterior implant was installed in the residual bone, whereas the second implant fixed onlay and sinus bone grafts (arrow). A sinus bone graft also was fixed by the two posterior implants.
cisions in the vestibule and at the mesial aspect edentulous area. In all of the bony palate was of the residual alveolar prepared.
in the second molar region of the tooth adjacent to the patients, minimal exposure performed. After exposure ridge, implant sites were
FIGURE 5. A totally edentulous maxilla reconstructed lay and sinus bone grafts fixed by eight implants.
by on-
FIGURE 6. Exposed mandibular symphysis showing bone grafts prepared before the reconstruction procedure (A), and preparation of implant sites (B).
1281
JENSEN AND SINDET-PEDERSEN
tulous patients who received onlay grafts were not allowed to wear their dentures during the healing period of 6 months. One month postoperatively, partially edentulous patients started wearing their dentures, which were relieved in the operated areas. A second-stage abutment procedure was performed 6 months after surgery. In seven patients, free gingival grafts were simultaneously placed to secure attached mucosa around 35 implants, all of which involved cases of alveolar onlay grafts (Fig 7).
Results In the 26 consecutive patients, 107 implants were installed in the maxilla using onlay, sinus, or a combination of onlay/sinus bone graft techniques. One maxillary edentulous patient had mandibular prognathism; therefore, he was restored by an overdenture to compensate for the discrepancy in the maxillomandibular relationship. Another patient with a totally edentulous maxilla had Parkinson’s disease and was also restored with an overdenture. Because
FIGURE 7. This patient had unattached gingiva at the implant sites (A). At the time of the abutment procedure, free gingival grafts from the palate were simultaneously placed to secure attached mucosa around the implants (B). Clinical appearance after 2 weeks (C) and after bridge connection (D).
1282 of her poor manual dexterity, oral hygiene with a conventional bridge was expected to be difficult. All other patients in this study were restored with or prepared for restoration with a fixed prosthesis. Four patients are ready for the abutment connection, and four patients have had only the bridge in function from 1 to 4 months. Seventeen patients have had the implants and bone grafts loaded by a prosthodontic reconstruction for periods varying from 6 to 26 months, with a mean of 14 months. All totally edentulous patients and 7 partially edentulous patients were treated under general anesthesia and hospitalized from 1 to 4 days postoperatively, with a mean of 2 days. Ten partially edentulous patients were treated under local anesthesia and oral sedation, and were discharged the day of surgery.
IMPLANTS AND MANDIBULAR
BONE GRAFTS
Seven implants (6.5%) have been removed. One patient who was totally edentulous in the maxilla did not follow the recommendations of not wearing the denture during the healing period, and subsequently a wound dehiscence developed after 1 week. This was treated by conservative management. Two months postoperatively, 2 implants and the bone graft were removed because of fracture of the residual bone. At the time of removal it was found that the implants had integrated with the bone graft. The distribution of the remaining implants allowed a fixed bridge to be constructed (Fig 8). Another totally edentulous patient sustained a fracture of the residual ridge around 2 implants intraoperatively and despite treatment of this fracture with osteosynthesis screws, the implants were found not to be integrated at the abutment place-
FIGURE 8, Two anterior implants and the bone graft were removed because of fracture of the residual bone. This was induced by premature loading from a denture (AJ). However, the distribution of the remaining implants allowed the construction of a fixed bridge. Clinical (C) and radiologic (D) appearance 2 years postoperatively.
JENSEN AND SINDET-PEDERSEN
1283
FIGURE 9. A, An osteosynthesis screw was inserted for treatment of a fracture of the residual ridge around two implants (arrow). The implants were not integrated at the abutment procedure and were therefore removed. B, A dolder bar was constructed on the remaining six implants. C, Clinical appearance of the overdenture 1 year after the initial operation.
ment procedure and therefore, they were removed. Following their removal, the patient functioned well with an overdenture supported by the six remaining implants (Fig 9). A third totally edentulous patient had one implant removed, which had been placed into a bone graft in the maxillary sinus, because it was mobile at the time of the second-stage procedure. The bone graft was stable and supported a second implant. Reconstruction was completed with the remaining seven implants. One partially edentulous patient treated by a combination of onlay/sinus bone graft secured by
two implants presented with wound dehiscence 2 weeks postoperatively. At 5 weeks postoperatively, sequestration of the onlay bone graft started and eventually the entire graft was exposed. Therefore, the decision was made to remove the implants along with the onlay graft. Bone ingrowth into the apical perforations of the implants was evident at the time of removal of the implants and graft, thus indicating survival of the sinus portion of the bone graft (Fig IO). The patient was prepared for conventional implant treatment. In all other patients, healing of implants and bone grafts has been uneventful. In those patients who have had implants loaded
1284
IMPLANTS AND MANDIBULAR
BONE GRAFTS
erated after 1 year. However, no soft-tissue profile changes were apparent (Fig 12). Discussion
FIGURE 10. A, Sequestration of onlay bone graft around two implants. B, Radiographs indicates that implants were integrated in the sinus bone graft.
from 6 to 26 months, and especially those who received onlay bone grafts, it was estimated that a postoperative marginal bone resorption of less than 15% of the height of the onlay bone graft has occurred. This figure was obtained by comparing immediate postoperative and follow-up radiographs and using the implants as a reference. This situation seems to stabilize 1 year postoperatively, without further progression of the resorption (Fig 11). The mandibular donor site did not present a management problem in any of the patients. No damage to teeth or roots was observed. A slight sensory disturbance was initially observed in five patients, but this recovered spontaneously in all cases during the following 6 months. In the patients older than 60 years, radiographic examination revealed that only two thirds of the donor site bone had regen-
It is well known that there is a prognostic difference for conventional implant treatment between the mandible and the maxilla, with better results in the mandible. “,i8 The relative loose structure of the bone in the maxilla has been suggested as a decisive factor for the higher incidence of lost implants. It has been theorized that the insufficient stabilization of implants in the alveolar bone of the maxilla at the installation procedure demands more restrictive guidelines for decreased loading during the healing period. ‘9-2’ Accordingly, the totally edentulous patients in this study were not allowed to use the upper denture for the entire healing period of 6 months, and this may have influenced the results achieved. In reports from previous studies where endochondral bone grafts and implants have been used for reconstruction of the severely atrophied maxillary alveolar ridge, consistently good results have not occurred,‘~5~18 and grafted jaws still remain a special treatment challenge. The use of an intramembranous bone donor site may provide a better solution to this problem. Using prepared mandibular bone grafts fixed to the residual maxillary alveolar bone by screw-type implants functioning as a rigid fixation, a primary stabilization of both grafts and implants is achieved. This has been described as a decisive factor for healing of bone grafts.** By obtaining mandibular symphyseal bone there also is easier access to the donor site as compared with the iliac crest. Drilling and tapping is performed at the donor site, and therefore, a shorter exposure period of the bone graft is necessary. During the development of this treatment method, instruments were developed to facilitate the surgery. Curettes that protect the delicate membrane during the sinus/nasal lift procedure, a template that determines the minimal necessary size and shape of the bone grafts and maintains parallelism of the implant sites, and a bone graft holder are instruments that reduce operating time (Fig 13). Wound dehiscence at the onlay graft site has earlier been described as a decisive factor for implant and graft survival. 1,354In the present study, dehiscence was noted in two patients among the first 10 operated on. These patients had the implants and grafts removed. Careful patient instruction concerning postsurgical behavior is necessary to achieve maximal patient compliance. In contrast to reconstruction procedures using
JENSEN AND SINDET-PEDERSEN
1285
FIGURE 11. Preoperative, postoperative, and 18 to 30 months postoperative radiographic appearance of four patients (A to D) showing the amount of marginal resorption following an onlay bone graft. The average marginal resorption was between 10% and 15%.
the iliac crest as donor site, hospitalization is reduced or avoided. The morbidity at the donor site of the mandible as compared with the iliac crest23 was limited to a reversible hypoesthesia in five cases. In
patients over 60 years old, it was noticed radiographically that complete bony regeneration at the donor site did not occur within 1 year after surgery, but this had no clinical implications.
1286
FIGURE 12. Radiograph showing decreased bone regeneration in the donor site of an elderly patient.
IMPLANTS AND MANDIBULAR
BONE GRAFTS
There is a limited amount of bone in the mandibular symphysis; however, it is our experience that if the patient has a dentition from canine to canine, the volume of bone in the symphysis allows reconstruction of a totally edentulous maxilla. The follow-up in this study is limited as in other studies dealing with this subject.3,4,18 At this time, only 6.5% of the implants in this study have been removed, and it is worthwhile to note that so far no implants have been lost after loading. Marginal bone resorption of onlay bone grafts has been estimated to be less than 15% (1 to 2 mm), and this resorption is comparable with results from studies on conventional implant treatment.” Based on these results, it is reasonable to assume that the
FIGURE 13. A, Curettes that protect the delicate membrane during the sinus/nasal lift procedure. B, A template is placed on the mandibular bone to assure the correct size and shape of bone grafts and parallelism of the implant sites. C, A bone graft holder secures the graft in place during implant installation.
1287
JENSEN AND SINDET-PEDERSEN
previously observed resorption of endochondral bone grafts and the number of lost implants can be significantly reduced if intramembranous bone grafts obtained from the mandibular symphysis firmly anchored with screw-type implants are used for reconstruction of the severely atrophied maxillary alveolar ridge.
12. 13.
14.
References 15. 1. Breine U, Br%nemark PI: Reconstruction of alveolar jaw bone. Stand J Plast Reconstr Surg 14:23, 1980 2. B&remark PI, Zarb GA, Albrektsson T (eds): TissueIntegrated Prostheses. Osseointegration in Clinical Dentistry. Chicago, IL, Quintessence, 1985 3. Keller EE, Van Roekel NB, Desjardins RP, et al: Prostheticsurgical reconstruction of the severely resorbed maxilla with iliac bone grafting and tissue-integrated prostheses. Int J Oral Maxillofac Implants 2: 155, 1987 4. Kahnberg K-E, Nystrom E, Bartholdsson L: Combined use of bone grafts and B&remark fixtures in the treatment of severely resorbed maxillae. Int J Oral Maxillofac Implants 4~297, 1989 5. Jensen J, Krantz Simonsen E, Sindet-Pedersen S: Reconstruction of the severely resorbed maxilla with bone grafting and osseointegrated implants: A preliminary report. J Oral Maxillofac Surg 48:27, 1990 6. Bovne PJ. James RA: Graftina of the maxillarv sinus floor with autogenous marrow aid bone. J Oral Surg 38:613, 1980 7. Wood RM, Moore DL: Grafting of the maxillary sinus with intraorally harvested autogenous bone prior to implant placement. J Oral Maxillofac Implants 3:209, 1988 8. Smith JD, Abramson M: Membraneous vs. endochondral bone autografts. Arch Otolaryngol99:203, 1974 9. Zins JE, Whitaker LA: Membraneous vs. endochondral bone autografts: Implications for craniofacial reconstruction. Surg Forum 30:521, 1979 10. Kusiak JF, Zins JE, Whitaker LA: Early revascularization of membraneous bone. Plast Reconstr Surg 76:510, 1985 11. Hardesty RA, Marsh JL: Craniofacial onlay bone grafting: A
16.
17. 18.
19.
20.
21.
22.
23.
prospective evaluation of graft morphology, orientation, and embryonic origin. Plast Reconstr Surg 86:5, 1990 Bosker H, van Dijk L: Het bottransplantaat uit de mandibula voor herstel van de gnatho-palatoschisis. Ned Tijdschr Tand heelk 87:383, 1980 Sindet-Pedersen S, Enemark H: Mandibular bone grafts for reconstruction of alveolar clefts. J Oral Maxillofac Surg 46:533, 1988 Koole R, Bosker H, van der Dussen FN: Late secondary autogenous bone grafting in cleft patients comparing mandibular (ectomesenchymal) and iliac crest (mesenchymal) grafts. J Craniomaxillofac Surg 17:28, 1989 Sindet-Pedersen S, Enemark H: Reconstruction of alveolar clefts with mandibular or iliac crest bone grafts: A comparative study. J Oral Maxillofac Surg 48:554, 1990 Borstlap WA, Heidbuchel KLWN, Freihofer HPM, et al: Early secondary bone grafting of alveolar cleft defects: A comparison between chin and rib grafts. J Craniomaxillofat Surg 18:201, 1990 Adell R, Lekholm U, Rockier B, et al: A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 10:387, 1981 Albrektsson T, Dahl E, Enbom L, et al: Osseointegrated oral implants: A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants. J Periodontol 591287, 1988 Johansson C, Albrektsson T: Integration of screw implants in the rabbit: A I-yr follow-up of removal torque of titanium implants. J Oral Maxillofac Implants 2:69, 1987 Albrektsson T, Br%nemark P-I, Hansson H-A, et al: Osseointegrated titanium implants. Requirements for ensuring a long-lasting direct bone anchorage in man. Acta Orthop Stand 52: 155, 1981 Branemark P-I, Albrektsson T: Endosteal dental implants in the treatment of the edentulous jaw, in Fonseca RJ, Davis WH (eds): Reconstructive preprosthetic oral and maxillofacial surgery. Philadelphia, PA, Saunders, 1986, pp 210221 Lin KY, Bartlett SP, Yaremchuk MJ, et al: The effect of rigid fixation on the survival of onlay bone grafts: An experimental study. Plast Reconstr Surg 86449, 1990 Marx RE, Morales MJ: Morbidity from bone harvest in major jaw reconstruction. J Oral Maxillofac Surg 46:196, 1988
Surg
1991
Autogenous Mandibular Bone Grafts and Osseoin tegra ted Implants for Reconstruction of the Severely Atrophied Maxilla: A Preliminary
Report
JOHN JENSEN, DDS,* AND STEEN SINDET-PEDERSEN,
DDS*
The purpose of this study is to present results obtained with a new procedure for reconstruction of the severely atrophied maxillary alveolar ridge that involves the use of intramembranous corticocancellous bone grafts obtained from the mandibular symphysis fixed to the residual bone by endosseous implants, A total of 107 implants were installed in grafted regions in 26 patients. The follow-up period ranged from 6 to 32 months, with a mean of 16 months. In partially edentulous patients the bone grafts were fixed with implants to the residual bone as 1) onlay graft to the alveolar ridge (8 implants in 4 patients); 2) grafts to the nasal and/or sinus floor after a transoral exposure and elevation of the mucosa of the maxillary sinus and/or the nasal mucosa (33 implants in 11 patients); or 3) a combination of these two (5 implants in 2 patients). In totally edentulous patients, implants and grafts were used as a combination of grafting to both the alveolar ridge and nasal and/or sinus floor sites (61 implants in 9 patients). One hundred of 107 implants showed normal clinical and radiologic healing, whereas 7 implants in 4 patients (6.5%) were lost prior to loading. Seventeen patients have had the implants and bone grafts loaded by a prosthodontic reconstruction from 6 to 26 months (mean, 14 months) without loss of any implants. Postoperative marginal resorption of the onlay bone graft of less than 15% was observed. These findings suggest, that the previously observed rapid resorption of endochondral iliac crest onlay bone grafts and the number of lost implants can be significantly reduced if bone from the mandibular symphysis firmly anchored with titanium implants is used.
surgeon and the prosthodontist. Conventional surgical treatment with alveolar augmentation or vestibuloplasty procedures provides only limited improvement in complete denture retention and stability. Also, treatment of some of these patients with osseointegrated implants alone is impossible because of the lack of bone into which implants can be anchored. ’ Reconstruction using particulate bone or corticocancellous onlay bone blocks in combination with implants installed into the residual maxilla has previously been reported and results from these studies using endochondral bone as grafting material indi-
Totally and partially edentulous patients with advanced maxillary alveolar resorption and/or increased pneumatization of the maxillary sinus have always presented a treatment challenge for both the
* Staff, Department of Oral and Maxillofacial Surgery, Aarhus University Hospital, Aarhus, Denmark. Address correspondence and reprint requests to Dr Jensen: Department of Oral and Maxillofacial Surgery, Aarhus University Hospital, Norrebrogade. DK-8000 Aarhus C, Denmark. 0 1991 geons
American
Association
of Oral
and Maxillofacial
Sur-
0278-2391/9114912-0004$3.00/O
1277
1278 cate an implant survival from 25% to 86% and a significant degree of marginal bone graft resorption. l-5 A sinus lift technique combined with iliac crest bone grafting to the sinus floor also has been used for reconstruction of atrophied maxillary alveolar ridges. This technique was first described by Boyne and James in 1980,6 and was primarily performed in patients with reduced interarch space to allow a later reduction of the bony tuberosity to increase interarch space. Three of these patients later received blade implants in the grafted regions. Also, a technique has been presented in which patients with severely atrophic posterior maxillas and pneumatization of the maxillary sinus were reconstructed using a sinus lift technique and mandibular bone obtained from the ascending ramus packed around the installed implants.7 There is experimental evidence that intramembranous bone grafts from the calvarium and zygoma placed as onlay grafts maintain more of their volume and show less postoperative resorption compared with endochondral bone taken from the iliac crests9 Furthermore, studies have indicated that intramembranous onlay bone grafts in the rabbit are more rapidly vascularized than endochondral grafts. These findings may explain the observed differences in graft survival for the two types of bone.” It has also been hypothesized that the graft architecture, which correlates with bone origin, could account for these differences in resorption of onlay bone grafts. ’ ’ Promising clinical results have been obtained in secondary reconstruction of the alveolar process in cleft palate patients by using intramembranous bone grafts taken from the mandibular symphysis. This method was first described in 1980 by Bosker and van Dijk. ‘* Sindet-Pedersen and Enemark later reported on 26 of 28 patients with 0% to 25% resorption of the graft assessed using occlusal radiographs after a median postoperative follow-up period of 8 months. l3 Three later comparative studies on reconstruction of alveolar clefts with mandibular symphyseal bone grafts versus iliac crest or rib bone grafts showed less resorption and less morbidity among patients who received mandibular bone grafts. 14-16 These clinical and experimental studies using intramembranous bone as an autograft for augmentation purposes have had promising results. Therefore, we began using reconstruction procedures in patients with severe atrophy of the maxillary alveolar ridge and/or increased pneumatization of the maxillary sinus involving mandibular bone grafts fixed with osseointegrated implants. The purpose of
IMPLANTS AND MANDIBULAR
BONE GRAFTS
this report is to describe the course of the first 26 patients treated by this method. Materials and Methods Of the 26 patients treated, 9 were totally edentulous in the maxilla and had demonstrated difficulties wearing a conventional maxillary denture owing to poor retention. The other 17 patients were partially edentulous in the maxilla and presented with either a severe loss of maxillary alveolar bone and/or increased pneumatization of the maxillary sinus (Fig 1). Twelve patients were females and 14 were males. The age of patients ranged from 17 to 76 years, with a mean age of 49 years. Only one patient was totally edentulous; all other patients had a partial dentition in the anterior region of the mandible. All the patients who were partially edentulous in the maxilla had a natural mandibular dentition from at least first premolar to first premolar. The mean postoperative follow-up time was 16 months, with a range from 6 to 32 months.
FIGURE bone loss Maxillary cant bone
1. A, Pneumatization of left maxillary sinus with and only minimal increase in interarch distance. B, edentulous patient with pneumatized sinuses, signifiloss, and increased interarch distance.
JENSEN AND SINDET-PEDERSEN
Preoperatively, all patients were subjected to thorough medical and radiographic examinations. Lateral cephalograms and panoramic radiographs were taken, in addition to routine intraoral periapical radiographs. The patients received all available information concerning the surgical procedure before the operation. All patients with a totally edentulous maxilla and eight patients with a partially edentulous maxilla were treated under general anesthesia. The other nine patients were treated under local anesthesia and oral sedation (diazepam). Prophylactic antibiotic treatment was initiated at the time of surgery and continued for 7 days postoperatively. Those patients who underwent a sinus or nasal lift procedure were also given decongestant nose drops. After the abutment placement procedure, 6 months postoperatively, the prosthodontic treatment was performed. Clinical and radiologic examinations were performed 3 and 6 months after prosthodontic treatment was completed and every 6 months thereafter. At the 6-month and 1 year time points, bridgework and dolder bars were removed from the implants and each implant was examined for mobility and peri-implant tissue condition. At the donor site, all teeth were examined for pulp vitality, periodontal condition, and radiologically examined for root resorption. Surgical
Technique
The reconstruction procedure was dependent on the region of edentulousness and the amount and shape of the residual maxillary bone. In partially edentulous patients, the prepared mandibular bone grafts were fixed with implants to the residual maxillary bone as 1) onlay bone grafts to the residual alveolar ridge (8 implants in 4 patients) (Fig 2); 2) inlay bone grafts to the sinus floor after elevation of the mucosa of the maxillary sinus (33 implants in 11 patients) (Fig 3); or 3) a combination of onlay and sinus bone grafts (5 implants in 2 patients) (Fig 4). In totally edentulous patients, a combination of onlay and sinus bone grafts was used (61 implants in 9 patients) (Fig 5) (Table 1). A nasal lift procedure was performed in all totally edentulous patients to ensure sufficient bone height in the anterior region. The donor site on the mandibular symphysis was exposed through a transoral approach. Holes for implant placement were drilled and tapped prior to procurement of the bone graft (Fig 6). In totally edentulous patients who received an onlay bone graft, the alveolar crest was surgically exposed by a vestibular incision approximately 1 cm from the at-
1279
FIGURE 2. View of partially edentulous patient reconstructed with an onlay bone graft fixed by four implants.
tached/unattached mucosal margin, with relieving incisions towards the alveolar crest in the second molar regions. In partially edentulous patients who received onlay bone grafts, similar vestibular and posterior relieving incisions were used, whereas in dentate regions, the relieving incisions were made at least one tooth away from the edentulous region. In partially edentulous patients who received bone grafts after a sinus lift, the alveolar crest and antral wall was exposed by means of an incision placed palatally to the crest of the ridge with relieving in-
FIGURE 3. An inlay bone graft fixed with two implants after a sinus lift procedure.
1280
IMPLANTS AND MANDIBULAR
BONE GRAFTS
Table 1. Number of Patients and Implants Placed According to Type of Bone Graft Variable Partially edentulous Onlay graft Sinus graft Onlay and sinus graft Totally edentulous Onlay and sinus graft Totals
Patients
-
Implants
-
4 11 2
8 33 5
9 26
61 107
Mucosal flaps were mobilized to wound closure in all cases where grafting was performed. All patients liquid diet for 10 days after surgery.
secure a tight alveolar onlay were kept on a Totally eden-
FIGURE 4. This partially edentulous patient received four implants for reconstruction of the right side of the maxilla. The most anterior implant was installed in the residual bone, whereas the second implant fixed onlay and sinus bone grafts (arrow). A sinus bone graft also was fixed by the two posterior implants.
cisions in the vestibule and at the mesial aspect edentulous area. In all of the bony palate was of the residual alveolar prepared.
in the second molar region of the tooth adjacent to the patients, minimal exposure performed. After exposure ridge, implant sites were
FIGURE 5. A totally edentulous maxilla reconstructed lay and sinus bone grafts fixed by eight implants.
by on-
FIGURE 6. Exposed mandibular symphysis showing bone grafts prepared before the reconstruction procedure (A), and preparation of implant sites (B).
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tulous patients who received onlay grafts were not allowed to wear their dentures during the healing period of 6 months. One month postoperatively, partially edentulous patients started wearing their dentures, which were relieved in the operated areas. A second-stage abutment procedure was performed 6 months after surgery. In seven patients, free gingival grafts were simultaneously placed to secure attached mucosa around 35 implants, all of which involved cases of alveolar onlay grafts (Fig 7).
Results In the 26 consecutive patients, 107 implants were installed in the maxilla using onlay, sinus, or a combination of onlay/sinus bone graft techniques. One maxillary edentulous patient had mandibular prognathism; therefore, he was restored by an overdenture to compensate for the discrepancy in the maxillomandibular relationship. Another patient with a totally edentulous maxilla had Parkinson’s disease and was also restored with an overdenture. Because
FIGURE 7. This patient had unattached gingiva at the implant sites (A). At the time of the abutment procedure, free gingival grafts from the palate were simultaneously placed to secure attached mucosa around the implants (B). Clinical appearance after 2 weeks (C) and after bridge connection (D).
1282 of her poor manual dexterity, oral hygiene with a conventional bridge was expected to be difficult. All other patients in this study were restored with or prepared for restoration with a fixed prosthesis. Four patients are ready for the abutment connection, and four patients have had only the bridge in function from 1 to 4 months. Seventeen patients have had the implants and bone grafts loaded by a prosthodontic reconstruction for periods varying from 6 to 26 months, with a mean of 14 months. All totally edentulous patients and 7 partially edentulous patients were treated under general anesthesia and hospitalized from 1 to 4 days postoperatively, with a mean of 2 days. Ten partially edentulous patients were treated under local anesthesia and oral sedation, and were discharged the day of surgery.
IMPLANTS AND MANDIBULAR
BONE GRAFTS
Seven implants (6.5%) have been removed. One patient who was totally edentulous in the maxilla did not follow the recommendations of not wearing the denture during the healing period, and subsequently a wound dehiscence developed after 1 week. This was treated by conservative management. Two months postoperatively, 2 implants and the bone graft were removed because of fracture of the residual bone. At the time of removal it was found that the implants had integrated with the bone graft. The distribution of the remaining implants allowed a fixed bridge to be constructed (Fig 8). Another totally edentulous patient sustained a fracture of the residual ridge around 2 implants intraoperatively and despite treatment of this fracture with osteosynthesis screws, the implants were found not to be integrated at the abutment place-
FIGURE 8, Two anterior implants and the bone graft were removed because of fracture of the residual bone. This was induced by premature loading from a denture (AJ). However, the distribution of the remaining implants allowed the construction of a fixed bridge. Clinical (C) and radiologic (D) appearance 2 years postoperatively.
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FIGURE 9. A, An osteosynthesis screw was inserted for treatment of a fracture of the residual ridge around two implants (arrow). The implants were not integrated at the abutment procedure and were therefore removed. B, A dolder bar was constructed on the remaining six implants. C, Clinical appearance of the overdenture 1 year after the initial operation.
ment procedure and therefore, they were removed. Following their removal, the patient functioned well with an overdenture supported by the six remaining implants (Fig 9). A third totally edentulous patient had one implant removed, which had been placed into a bone graft in the maxillary sinus, because it was mobile at the time of the second-stage procedure. The bone graft was stable and supported a second implant. Reconstruction was completed with the remaining seven implants. One partially edentulous patient treated by a combination of onlay/sinus bone graft secured by
two implants presented with wound dehiscence 2 weeks postoperatively. At 5 weeks postoperatively, sequestration of the onlay bone graft started and eventually the entire graft was exposed. Therefore, the decision was made to remove the implants along with the onlay graft. Bone ingrowth into the apical perforations of the implants was evident at the time of removal of the implants and graft, thus indicating survival of the sinus portion of the bone graft (Fig IO). The patient was prepared for conventional implant treatment. In all other patients, healing of implants and bone grafts has been uneventful. In those patients who have had implants loaded
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erated after 1 year. However, no soft-tissue profile changes were apparent (Fig 12). Discussion
FIGURE 10. A, Sequestration of onlay bone graft around two implants. B, Radiographs indicates that implants were integrated in the sinus bone graft.
from 6 to 26 months, and especially those who received onlay bone grafts, it was estimated that a postoperative marginal bone resorption of less than 15% of the height of the onlay bone graft has occurred. This figure was obtained by comparing immediate postoperative and follow-up radiographs and using the implants as a reference. This situation seems to stabilize 1 year postoperatively, without further progression of the resorption (Fig 11). The mandibular donor site did not present a management problem in any of the patients. No damage to teeth or roots was observed. A slight sensory disturbance was initially observed in five patients, but this recovered spontaneously in all cases during the following 6 months. In the patients older than 60 years, radiographic examination revealed that only two thirds of the donor site bone had regen-
It is well known that there is a prognostic difference for conventional implant treatment between the mandible and the maxilla, with better results in the mandible. “,i8 The relative loose structure of the bone in the maxilla has been suggested as a decisive factor for the higher incidence of lost implants. It has been theorized that the insufficient stabilization of implants in the alveolar bone of the maxilla at the installation procedure demands more restrictive guidelines for decreased loading during the healing period. ‘9-2’ Accordingly, the totally edentulous patients in this study were not allowed to use the upper denture for the entire healing period of 6 months, and this may have influenced the results achieved. In reports from previous studies where endochondral bone grafts and implants have been used for reconstruction of the severely atrophied maxillary alveolar ridge, consistently good results have not occurred,‘~5~18 and grafted jaws still remain a special treatment challenge. The use of an intramembranous bone donor site may provide a better solution to this problem. Using prepared mandibular bone grafts fixed to the residual maxillary alveolar bone by screw-type implants functioning as a rigid fixation, a primary stabilization of both grafts and implants is achieved. This has been described as a decisive factor for healing of bone grafts.** By obtaining mandibular symphyseal bone there also is easier access to the donor site as compared with the iliac crest. Drilling and tapping is performed at the donor site, and therefore, a shorter exposure period of the bone graft is necessary. During the development of this treatment method, instruments were developed to facilitate the surgery. Curettes that protect the delicate membrane during the sinus/nasal lift procedure, a template that determines the minimal necessary size and shape of the bone grafts and maintains parallelism of the implant sites, and a bone graft holder are instruments that reduce operating time (Fig 13). Wound dehiscence at the onlay graft site has earlier been described as a decisive factor for implant and graft survival. 1,354In the present study, dehiscence was noted in two patients among the first 10 operated on. These patients had the implants and grafts removed. Careful patient instruction concerning postsurgical behavior is necessary to achieve maximal patient compliance. In contrast to reconstruction procedures using
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FIGURE 11. Preoperative, postoperative, and 18 to 30 months postoperative radiographic appearance of four patients (A to D) showing the amount of marginal resorption following an onlay bone graft. The average marginal resorption was between 10% and 15%.
the iliac crest as donor site, hospitalization is reduced or avoided. The morbidity at the donor site of the mandible as compared with the iliac crest23 was limited to a reversible hypoesthesia in five cases. In
patients over 60 years old, it was noticed radiographically that complete bony regeneration at the donor site did not occur within 1 year after surgery, but this had no clinical implications.
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FIGURE 12. Radiograph showing decreased bone regeneration in the donor site of an elderly patient.
IMPLANTS AND MANDIBULAR
BONE GRAFTS
There is a limited amount of bone in the mandibular symphysis; however, it is our experience that if the patient has a dentition from canine to canine, the volume of bone in the symphysis allows reconstruction of a totally edentulous maxilla. The follow-up in this study is limited as in other studies dealing with this subject.3,4,18 At this time, only 6.5% of the implants in this study have been removed, and it is worthwhile to note that so far no implants have been lost after loading. Marginal bone resorption of onlay bone grafts has been estimated to be less than 15% (1 to 2 mm), and this resorption is comparable with results from studies on conventional implant treatment.” Based on these results, it is reasonable to assume that the
FIGURE 13. A, Curettes that protect the delicate membrane during the sinus/nasal lift procedure. B, A template is placed on the mandibular bone to assure the correct size and shape of bone grafts and parallelism of the implant sites. C, A bone graft holder secures the graft in place during implant installation.
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previously observed resorption of endochondral bone grafts and the number of lost implants can be significantly reduced if intramembranous bone grafts obtained from the mandibular symphysis firmly anchored with screw-type implants are used for reconstruction of the severely atrophied maxillary alveolar ridge.
12. 13.
14.
References 15. 1. Breine U, Br%nemark PI: Reconstruction of alveolar jaw bone. Stand J Plast Reconstr Surg 14:23, 1980 2. B&remark PI, Zarb GA, Albrektsson T (eds): TissueIntegrated Prostheses. Osseointegration in Clinical Dentistry. Chicago, IL, Quintessence, 1985 3. Keller EE, Van Roekel NB, Desjardins RP, et al: Prostheticsurgical reconstruction of the severely resorbed maxilla with iliac bone grafting and tissue-integrated prostheses. Int J Oral Maxillofac Implants 2: 155, 1987 4. Kahnberg K-E, Nystrom E, Bartholdsson L: Combined use of bone grafts and B&remark fixtures in the treatment of severely resorbed maxillae. Int J Oral Maxillofac Implants 4~297, 1989 5. Jensen J, Krantz Simonsen E, Sindet-Pedersen S: Reconstruction of the severely resorbed maxilla with bone grafting and osseointegrated implants: A preliminary report. J Oral Maxillofac Surg 48:27, 1990 6. Bovne PJ. James RA: Graftina of the maxillarv sinus floor with autogenous marrow aid bone. J Oral Surg 38:613, 1980 7. Wood RM, Moore DL: Grafting of the maxillary sinus with intraorally harvested autogenous bone prior to implant placement. J Oral Maxillofac Implants 3:209, 1988 8. Smith JD, Abramson M: Membraneous vs. endochondral bone autografts. Arch Otolaryngol99:203, 1974 9. Zins JE, Whitaker LA: Membraneous vs. endochondral bone autografts: Implications for craniofacial reconstruction. Surg Forum 30:521, 1979 10. Kusiak JF, Zins JE, Whitaker LA: Early revascularization of membraneous bone. Plast Reconstr Surg 76:510, 1985 11. Hardesty RA, Marsh JL: Craniofacial onlay bone grafting: A
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prospective evaluation of graft morphology, orientation, and embryonic origin. Plast Reconstr Surg 86:5, 1990 Bosker H, van Dijk L: Het bottransplantaat uit de mandibula voor herstel van de gnatho-palatoschisis. Ned Tijdschr Tand heelk 87:383, 1980 Sindet-Pedersen S, Enemark H: Mandibular bone grafts for reconstruction of alveolar clefts. J Oral Maxillofac Surg 46:533, 1988 Koole R, Bosker H, van der Dussen FN: Late secondary autogenous bone grafting in cleft patients comparing mandibular (ectomesenchymal) and iliac crest (mesenchymal) grafts. J Craniomaxillofac Surg 17:28, 1989 Sindet-Pedersen S, Enemark H: Reconstruction of alveolar clefts with mandibular or iliac crest bone grafts: A comparative study. J Oral Maxillofac Surg 48:554, 1990 Borstlap WA, Heidbuchel KLWN, Freihofer HPM, et al: Early secondary bone grafting of alveolar cleft defects: A comparison between chin and rib grafts. J Craniomaxillofat Surg 18:201, 1990 Adell R, Lekholm U, Rockier B, et al: A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 10:387, 1981 Albrektsson T, Dahl E, Enbom L, et al: Osseointegrated oral implants: A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants. J Periodontol 591287, 1988 Johansson C, Albrektsson T: Integration of screw implants in the rabbit: A I-yr follow-up of removal torque of titanium implants. J Oral Maxillofac Implants 2:69, 1987 Albrektsson T, Br%nemark P-I, Hansson H-A, et al: Osseointegrated titanium implants. Requirements for ensuring a long-lasting direct bone anchorage in man. Acta Orthop Stand 52: 155, 1981 Branemark P-I, Albrektsson T: Endosteal dental implants in the treatment of the edentulous jaw, in Fonseca RJ, Davis WH (eds): Reconstructive preprosthetic oral and maxillofacial surgery. Philadelphia, PA, Saunders, 1986, pp 210221 Lin KY, Bartlett SP, Yaremchuk MJ, et al: The effect of rigid fixation on the survival of onlay bone grafts: An experimental study. Plast Reconstr Surg 86449, 1990 Marx RE, Morales MJ: Morbidity from bone harvest in major jaw reconstruction. J Oral Maxillofac Surg 46:196, 1988
