Maxillary alveolar ridge augmentation with onlay bone-grafts and immediate endosseous implants Sten Isaksson ~, Per Alberius ~
1Department of Oral Surgery (Head: Prof. S. Isaksson, DMD, hiD), Liinssjukhuset, Halmstad, 2Department of Plastic Surgery (Head: Prof. S. Jacobsson, MD, PhD), MAS MalmS, Sweden.
SUMMARY. Management of the atrophic maxilla can be a taxing surgical problem. One treatment alternative is to use autogenous bone transplants and immediate titanium fixture implantation. Despite the extensive literature on routine implant treatment of the edentulous jaws, only very few reports have dealt with the outcome of bone graft reconstructive surgery as part of the dental implant restoration. This study presents the treatment and healing results of 8 consecutive patients, who, over a period of 2 years and 8 months, were treated using onlay iliac bone grafts to atrophic maxillary alveolar ridges with immediate implant insertion. The patients were followed for 32-64 months. 83 % of the fixtures (n = 46) were welMntegrated. Two fixtures in each of 2 patients were lost due to traumatic bonegraft fractures. Palpatory bone-graft volume and prosthetic function were, with the exception of 1 patient, good. Radiological examination demonstrated preservation of the major part of the vertical dimension of the grafted bone. Patient's assessment was of good aesthetics and intraoral function; 2 patients had minor phonetic problems. In conclusion, similar success to routine maxillary implant treatment can be achieved in the event of extreme maxillary bone deficiency, by bone grafting and immediate fixture insertion. KEY WORDS: Endosseous implants (Br~nemark fixtures) - Atrophy of maxilla - Onlay bone-graft.
INTRODUCTION Placement of endosseous dental implants as introduced by Br~nemark, has been used for over 20 years and has proved to be a valuable method of treating partly and totally edentulous jaws. For example, Adell et al. (1981) reported a success rate of 91% in routine mandibular implants and 81% in maxillary implants over a period of 5-9 years, and van Steenberghe (1989) found, in a multicentre evaluation, a survival rate of 87% and 92% for the upper and lower jaws respectively, after 6--36 months following prosthetic reconstruction in partial edentulous patients. However, in extreme maxillary alveolar bone deficiency, transplantation of autogeneics bone grafts is desirable to attain optimal functional restoration. In 1980, Breine and Brdmemark published their experienc e with two such reconstructive procedures. In 18 patients (14 maxillae and 4 mandibles) tibial cancellous bone chips in combination with titanium implants were used. The titanium fixtures were gnserted in the jaw bone and, thereafter, the harvested bone was modelled around the fixtures during the same procedure. Rapid graft resorption and insufficient bone volume restitution were observed, although restoration of the biomechanical capacity of the jaw bone was achieved. The second procedure, which was a two-stage operation, was performed on 9 patients (8 maxillae and 1 mandible). A preformed tibial composite bone graft was constructed holding the titanium implants. A second stage was carried out
after a healing period of 3-6 months when the preformed graft with its implants was transferred and secured with additional implants to the jaw. Even this procedure resulted in a considerable graft resorption. In 5 out of 8 maxillae, the major part of the grafts was preserved and less than 50% of originally inserted fixtures remained integrated after 1-8 years following bridge construction. Furthermore, Keller et al. (1987) reported, using an immediate onlay autogeneics iliac bone graft technique, 83 % integration in 12 implants inserted in 2 patients at 2 and 24 months, respectively, after fixed tissue-integrated prosthetic treatment and similar success was reported by Kahnberg et al. (1989). A Swedish multicentre study reported a success rate of 83% (71 fixtures) in grafted maxillae (Albrektsson et al., 1988), while an international review claimed a survival rate of 66 % (112 fixtures; Albrektsson 1988) over an observation time of 1-5 years. However, no details of the surgical procedure was given in the latter two reports. This retrospective study presents our observations on the use of titanium implants in conjunction with iliac cortico-cancellous bone grafts positioned along the alveolar ridge. MATERIAL AND METHODS Patients
Eight patients with extremely atrophic edentulous maxillae were studied (Table 1). The first operation
Ridge augmentation with immediate endosseous implants
3
Table I - Summary of the features of the patients
'Follow-up Age period Teeth present Patients Sex (yrs) (months) (Int.nomencl.)
Edentulous period, maxilla (yrs)
1 2 3 4 5 6 7 8
4 20 10 30 30 4 10 16
M F F F M M M M
44 51 44 54 67 46 70 68
64 63 52 52 50 33 33 32
16-14, 43-33, 36 46-35 44-34 43-32 43-35 44-34 46, 43, 33 35 Mand. Imp1.
was performed in February 1986 and, thereafter, remaining patients were treated consecutively until October 1988. Clinical examination and preoperative radiographs, including CT-scans, demonstrated lack of osseous support and precluded treatment without bone grafting. All patients were healthy except for two having problem with duodenal ulcers. Apart from 1 patient (no. 2) all were heavy smokers.
Fig. 2 - Photograph of a bone graft fixed to the alveolus by titanium implants; fixture mounts still in situ.
Surgery
Bone was harvested from the right iliac crest. A 5 cm incision was made, starting 1 cm posteriorly to the anterior superior iliac spine (not to damage the lateral superficial branch of the femoral nerve) and running parallel to the iliac crest. A 4-5 cm bony lid, encompassing the iliac crest and attached only to the inner periosteum, was tilted medially. Two blocks of approximately 4 x 1 x 1 cm were harvested. The inner cortical layer of the iliac bone was left intact. An intraoral approach to the maxilla was made by using a horseshoe incision along the sulcus from the region of the upper right first molar to the upper left first molar. The alveolar crest was revealed by raising a palatally pedicled mucoperiosteal flap. Bone irregularities at the recipient site were removed using rongeur forceps.
I~
~
-
---~.-~~
~
~!,~,'
Fig, 1- Diagrammetric representation of the orientation of the two autogenous bone grafts prior to their fixation to the alveolus.
Fig. 3 - Photograph of bone grafts in situ, showing good adaptation to the shape of the alveolus. The iliac bone blocks were trimmed to fit the alveolar ridge and placed with their cortical layer inferiorly (Fig. 1). The blocks met in the midline and were fixed to the grossly atrophied maxilla with the titanium implants only (Figs. 2 and 3). In 1 patient (no. 5) the bone blocks were placed infero-buccally to the residual ridge in order to improve a poor sagittal relation of the jaws. The Br~nemark implant system was applied according to the recommended technique. Only standard fixtures were used. Care was taken not to countersink beyond the cortical layer of the graft. The wound was closed with continuous 4-0 sutures. Preoperatively, the patients were given Benzylpenicillin (3 g) and Metronidazole (0"5 g) intravenously and then prescribed continued oral medication for 1 week. Postoperative strategy included permission to wear the relined original denture after 3 weeks. After problems with bone-graft fractures in 2 patients, an acrylic occlusal mandibular splint was produced (see Discussion), which was worn during sleep. The fixtures were unloaded until the abutment operation. The abutment operations were performed after a 6-9 months healing period and, subsequently, a fixed prosthesis was constructed (Table 2, Figs. 4 and 5). All patients were followed regularly (twice a year) and given a strict oral hygiene programme. Most patients demonstrated excellent cooperation. Implant stability was assessed manually and by a surgical instrument in
4
Journal of Cranio-Maxillo-Facia1 Surgery
Table 2 - Number and length of implants inserted and complications before and after prosthodontic treatment
Patients
Implants ( n o ) Length(mm)
2 3 4 5 6 7
2:10, 2:13 3:13, 3 : 15 5:15, 1:18 2:10, 4:13 2: 13, 3: 15, 2:20 3 : 13, 3:15 3:13, 1:18, 1:20
8
1:10, 3:15, 2:18
1
Surgical complications (months)
Fistula R2 (15) Extr. L1, L3 (7) Extr. L4 (3) Graft fracture " Extr. L2, L3 (6) Extr. L1 (7)
Completion of prosthodontic treatment after fixture installation (months)
Prosthodontic treatmentx
Prosthodontic complications (months)
Remaining implants (of total)
14 10 10 8 22 7 9
ISP ISP ISP ISP ISP ISP TISP
Extr. RI, L1 (16) --TMJ-disturbance xx ----
2(4) 6 (6) 6(6) 4 (6) 6 (7) 6 (6) 3 (5)
9
ISP
--
5(6)
L = Left implant; R = Right implant; xISP = implant-supported prosthesis; TISP = tissue- and implant-supported prosthesis; xxclicking and pain already noted preoperatively.
RESULTS
Treatment completed. Fixed implant-supported prosthesis in position in a patient with maxillary onlay bone-graft.
Fig. 4 -
Radiograph showing bone-graft with endosseous implants and fixed prosthesis in position 1 year after completion of prosthodontic treatment. One fixture (R3) partly penetrates the maxillary sinus. Clinical examination reveals complete stability of all implants.
Fig. 5 -
an effort to provoke implant movement. The integration of the implants was evaluated by clinical and radiographic examinations directly after the abutment operation and annually thereafter. The patient's assessment concerning aesthetics, phonetics and intraoral function were evaluated by a questionnaire and by direct questioning.
The procedure described was performed on 8 consecutive patients over a period of 2 years and 8 months (Table 1). Only moderate discomfort during the first postoperative week was reported and none complained of severe pain or any major swelling. All wounds healed uneventfully. Only 1 of the 46 implants revealed signs of early peri-implant infection and clinically detectable mobility and this was subsequently removed 3 months post-installation due to tenderness. Postoperative pain from the iliac bone donor site was moderate and only 1 patient had any neurological disturbance; i.e. an area of temporary paraesthesia on the lateral aspect of the thigh. Average hospitalization was 3 days (range: 2-5 days). By the time of the abutment operation, 6-9 months post fixture insertion, 40 implants (87 %) were found to be clinically stable without any detectable mobility. In 1 patient (no. 7) 2 implants were removed due to traumatic fracture of the bone-graft (Table 2) and in 3 patients (nos. 4, 5, 8) a total of 4 implants were removed because of non-integration. The peri-implant soft tissue was free from visible inflammation. In general, the radiographs disclosed no or negligible peri-implant radiolucency around clinically stable fixtures. Seven patients had restorations with fixed dentures (Table 2). One patient (no. 7) was provided with a removable denture (overdenture) because of non-integration of 2 out of 5 fixtures. One year and 4 months after completion of the prosthodontic treatment, 1 patient (no. 1) lost his bridgework following an accidental bone-graft fracture (Table 2). A peri-implant infection with a buccal fistula was revealed in another patient (no. 3) 5 months after completion of the prosthodontic treatment. The infection was localized to the soft tissues; no signs of bone resorption was evident on the periapical radiographs. The fistula was successfully treated with local gingival adjustment. At the latest joint evaluation, all remaining implants revealed a stable anchorage without detectable mobility and the palpable bone graft volume was found to be excellent in 6 out of 8 patients. Two patients exhibited less preservation of bone graft volume as
Ridge augmentation with immediate endosseous implants Table 3 - Patient's assessment of treatment
Patients
Aesthetics
Phonetics
Intraoral functional disturbance
1 2 3 4 5 6 7 8
Unacceptable x Good Satisfactory Good Good Good Good Good
~ Lisp Good Good Good Good Good Lisp
x None None None None None None None
x Present fixtures not loaded
evaluated by clinical examination and radiography. Excellent prosthetic function was attained in all but 1 patient. In 2 patients moderate inflammation around 3 implants was observed, which was successfully treated by supervised oral hygiene. Radiographic examination showed only minor evidence of vertical bone loss. Registered bone resorption (as evidenced by the ratio between the mean vertical dimension centrally of the 2 grafts for 2 subsequent radiographic examinations) between the abutment operation and the final follow-up ranged from 0.9 to 1.0. Assessment of the resorption occurring between the fixture and abutment operations, though, ranged from 0"7~3"9. The patient's evaluation was of good aesthetics. Two patients had some minor phonetic difficulties. All patients reported excellent intraoral functional restoration (Table 3). DISCUSSION AND CONCLUSIONS The management of the atrophic maxillary ridge is a challenging surgical problem for which various solutions have been suggested. Previous attempts to augment the extremely resorbed maxilla or mandible have not been completely successful. Most long-term studies, using autogeneics or allogeneic bone material, have been discouraging (Canzona et al., 1976; Baker et al., 1979; Breine and Brgmemark, 1980; Davies, 1980). As in fracture healing, the incorporation of a bone graft depends on the capability of the periosteum, the perivascular cells of the bone marrow stroma and the preexisting osteoprogenitor cells in its environment. Three mechanisms have been proposed to, explain the success of bone grafts (Mulliken et al., 1980). First, fresh autografts, particularly cancellous bone and periosteal grafts, have been shown to retain living cells that participate in the osteogenic response around the transplant (Ham et al., 1952; Ray et al., 1963 ; Basset, 1972). Second, the grafted bone may act as a scaffold for bone regeneration (osteoconduction) while parallel gradual resorption takes place. The healing proceeds as osteoblasts migrate from adjacent living bone. Third, mesenchymal cells may, by a stimulating factor, differentiate into cells exhibiting osteogenic ability (Urist and Strates, 1972; Sampath et al., 1987). In the present context all these mechanisms supposedly participated to incorporate
5
the iliac bone grafts into the recipient site, although the first two appear to exert the major influence. Past experience with titanium implants (Adell et al., 1981; Albrektsson et al., 1988) indicates that most failures become evident within the first year. Most non-integrations are discovered at the time of the abutment procedure. Supposedly, this would also apply to implants inserted into grafted bone. Therefore, it seems reasonable not to make any prognostic assessment for at least 1 year of wearing a bridge, but thereafter a rather well-founded individual prognosis seems justified. With this in mind, this study was undertaken to summarize our experience with our first 8 patients treated with an onlay bone-graft technique with immediate titanium implant insertion, and to assess to what extent the technique is beneficial to patients with advanced alveolar atrophy in the maxilla. In general, we conclude that the technique presented may be used routinely for such patients as the onlays healed successfully, permanent bridge stability was accomplished, and only minor postoperative morbidity was observed. The fact that 2 patients fractured their bone grafts is, however, worth considering. All our patients had either retained their own lower front teeth or a fixed prosthetic implant constructed for the anterior mandibular region (Table 1). Consequently, prophylactic prevention of traumatic biting on the bone graft was essential, and, therefore, we constructed an acrylic occlusal mandibular splint to be worn during the entire healing period. The splint, which was used by 5 patients, occludes against the maxillary tuberosity and thus impedes unfavourable chewing forces on the graft. The recommended interval of 6 months between the fixture installation and the subsequent abutment operation is normally sufficient in non-grafted patients (Adell et al., 1987), but probably, this period is somewhat short after bone grafting. We selected an interval of 9 months to allow some extra time for graft incorporation but short enough not to neglect the theoretical advantage of implants providing a bonepreserving stimulus in the same manner as the presence of healthy teeth preserve alveolar bone. The bone graft volume, as evaluated by palpation and radiography, was quite excellent in 6 out of the 8 patients. We used fresh autogenous bone-graft transplants since their osteogenic potential is known to be the best available and, additionally, the iliac bone grafts comprised both a compact and a cancellous bone compartment giving improved conditions for graft fixation. Cancellous bone alone does not provide sufficient rigidity and there are reports of frequent complete resorption of cancellous autografts (Heiple et al., 1963; Brgmemark et al., 1975). Furthermore, rigid fixation, in this study accomplished by the titanium implants, will reduce the process of resorption of the graft (Phillips and Rahn, 1988; LaTrenta et al., 1989). Hence, the length of implanted fixtures must be sufficient to provide immediate stability by anchoring the graft rigidly to the recipient site. The placement of the bone graft with its cancellous rather than its cortical surface in contact
6
Journal of Cranio-Maxillo-Facial Surgery
with the maxillary bone seems advantageous in the maintenance of the bone graft volume. Such strategy was experimentally supported by Thompson and Casson (1970) and Knize (1974) and, furthermore, these authors reported that a bone graft with its cancellous surface in contact with soft tissue was revascularized more rapidly but underwent greater volume loss in the long run. Partial resorption of autogeneic bone grafts generally occurs, often amounting to half of the original size (Kdrlof et al., 1973). Theoretically, the use of tobacco might negatively influence graft incorporation, and thereby volumetric preservation, by disturbing effective revascularization of the graft. Despite the majority of our patients being heavy smokers graft resorption was moderate and the results favourable. Loss of onlay graft volume over time is not a linear process but most pronounced soon after its insertion (Lin et al., 1990). Consequently, the most intensive volumetric loss would have taken place before the abutment operation. Despite the bone resorption registered we found that the remaining mass of bone at the termination of the present investigation was substantial and constituted an effective support for the prosthodontic appliances. One limitation of the surgical method used, apart from the risk of graft fracture as discussed above, is the restricted possibility of correcting sagittal discrepancy between the jaws. In 1 patient (no. 5) the sagittal relationship was found to be unfavourable and the graft had to be positioned infero-buccally to the residual ridge to compensate for the class III relationship between the mandible and the maxilla. However, only limited preoperative correction of the sagittal dimension is possible by the present technique. Previously, the results of techniques for advancementosteotomy have been presented (Farrell et al., 1976; Freihofer, 1989). Sailer (1989) recently reported a onestage method in which 3 separate iliac bone grafts were sandwiched into the osteotomy line (on the floors of the nasal cavity and the maxillary sinuses) after a Le Fort I down-fracture. Graft fixation was by means of fixture installation similarly to the technique used here. Preferably, this method is indicated when advancement of the maxilla to a more favourable position is planned, and further, the method facilitates postoperative denture adjustment as the alveolar ridge retains its preoperative anatomical configuration. In conclusion, the use of alveolar ridge augmentation by iliac bone onlays has evolved as a safe, wellaccepted procedure with low morbidity. Our results, showing 83 % integration of the implants, are comparable even to non-grafted maxillary cases reported. It may be used in patients in whom a more complicated procedure is neither necessary nor feasible.
Acknowledgements We thank L. Kristersson, DMD, PhD, and J. E. Blomqvist, DMD for their participation in some of the operations and R. Loukota, FDSRCS, FRCS (Ed) for help with language revision.
References Adell, R., U. Lekholm, B. Rockier, P-I. Brgmemark : A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int. J. Oral Surg. 10 (1981) 387 Adell, R., U. Lekholm, P-L Brhnemark : Surgical procedures. In: Brfinemark P-I., G. A. Zarb, T. Albrektsson (eds) : Tissueintegrated prostheses. Osseointegration in clinical dentistry. Quintessence Publishing Co Inc, Chicago. 1987, p. 211 Albrektsson, T. : A multicenter report on osseointegrated oral implants. J. Prosthet. Dent. 60 (1988) 75 Albrektsson, T., E. Dahl, L. Enbom et al: Osseointegrated oral implants. A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants. J. Periodontol. 59 (1988) 287 Baker, R. D., B. C. Terry, W. H. Davis, P. W. Cannole : Longterm results of alveolar ridge augmentation. J. Oral Surg. 37 (1979) 486 Bassett, C. A. L. : Clinical implications of cell function in bone grafting. Clin. Orthop. 87 (1972) 49 Breine, U., P-L Brdmemark: Reconstruction of alveolar bone. An experimental and clinical study of immediate and preformed autologous bone grafts in combination with osseointegrated implants. Scand. J. Plast. Reconstr. Surg. 14 (1980) 23 Brdmemark, P-L, J. Lindstr6m, O. Hall~n, U. Breine, P. H. Jeppson, A, Ohman : Reconstruction of the defective mandible. Scand. J. Plast. Reconstr. Surg. 9 (1975) 116 Canzona, J., N. G. Grand, Y. P. Waterhouse, D. M. Laskin: Autogenous bone grafts in augmentation of edentulous canine mandible. J. Oral Surg. 34 (1976) 879 Davis, W. H. : Rib graft augmentation to the superior border of the mandible. In: Starshak T. J., B. Sanders, (eds) Preprosthetic oral and maxillofacial surgery. CV Mosby Company, St Louis, 1980, p. 218 Farrell, C. D., J. N. Kent, L. R. Guerra. : One-stage interpositional bone grafting and vestibuloplasty of the atrophic maxilla. J. Oral Surg. 34 (1976) 901 Freihofer, H. P. M. : Stability after osteotomy of the edentulous maxilla. J. Cranio-Max. Fac. Surg. 17 (1989) 306 Ham, A., S. Gordon. : The origin of bone that forms in association with cancellous chips transplanted into muscle. Br. J. Plast. Surg. 5 (1952) 154 Heiple, K. G., S. W. Chase, C. H. Hernon. : A comparative study of the healing process following different types of bone transplantation. J. Bone Joint Surg. 45A (1963) 1593 Kahnberg, K. E., E. Nystr6m, L. Bartholdsson: Combined use of bone grafts and Br~nemark fixtures in the treatment of severely resorbed maxillae. Int. J. Oral Maxillofac. Implants 4 (1989) 297 Keller, E. E., N. B. van Roekel, R. P. Desjardins, D. E. Tolman ." Prosthetic-surgical reconstruction of the severely resorbed maxilla with iliac bone grafting and tissue-integrated prostheses. Int. J. Oral Maxillofac. Implants. 2 (1987) 155 Knize, D. M: The influence of periosteum and calcitonin on onlay bone graft survival. A roentgenographic study. Plast. Reconstr. Surg. 53 (1974) 190 K6rlof, B., B. Nylkn, K. A. Ritz: Bone grafting of skull defects: A report on 55 cases. Plast. Reconstr. Surg. 52 (1973) 378 LaTrenta, G. S., 3. G. McCarthy, A. S. Breitbart, M. May, H. A. Sissons: The role of rigid fixation in bone-graft augmentatio n of the craniofacial skeleton. Plast. Reconstr. Surg. 84 (1989) 578 Lin, K. Y., S. P. Bartlett, M. J. Yaremchuk, M. Fallon, R. F. Grossman, L. A. Whitaker: The effect of rigid fixation on the survival of onlay bone grafts: An experimental study. Plast. Reconstr. Surg. 86 (1990) 449 Mulliken, J. B., J. Glowacki : Induced osteogenesis for repair and construction in the craniofacial region. Plast. Reconstr. Surg. 65 (1980) 553 Phillips, J. H., B. A. Rahn: Fixation effects on membranous and enchondral onlay bone-graft resorption. Plast. Reconstr. Surg. 82 (1988) 872 Ray, R. D., T. Y. Saber: Bone grafts: Cellular survival versus induction. J. Bone. Joint. Surg. 45A (1963) 337 Sailer, H. F. : A new method of inserting endosseous implants in totally atrophic maxillae. J. Cranio-Max-Fac. Surg. 17 (1989) 299
Ridge augmentation with immediate endosseous implants Sampath, T. K., N. Muthukumaran, A. H. Reddi: Isolation of
osteogenin, an extracellular matrix-associated protein, by heparin affinity chromatography. Proc. Natl. Acad. Sci. USA 84 (1987) 7109 Steenberghe, D. van: A retrospective multicenter evaluation of the survival rate of osseointegrated fixtures supporting fixed partial prostheses in the treatment of partial edentulism. J. Prosthet. Dent. 61 (1989) 217 Thompson, N., J. A. Casson: Experimental onlay bone grafts to the jaws. A preliminary study in dogs. Plast. Reconstr. Surg. 46 (1970) 341 Urist, M. R., B. S. Strates : Bone morphogenetic protein. J. Dent. Res. 50 (1972) 1392, suppl 6
S. Isaksson, DMD, MD Department of Oral Surgery L~inssjukhuset S-301 85 Halmstad Sweden. Paper received 27 May 1991 Accepted 12 September 1991
7
1Department of Oral Surgery (Head: Prof. S. Isaksson, DMD, hiD), Liinssjukhuset, Halmstad, 2Department of Plastic Surgery (Head: Prof. S. Jacobsson, MD, PhD), MAS MalmS, Sweden.
SUMMARY. Management of the atrophic maxilla can be a taxing surgical problem. One treatment alternative is to use autogenous bone transplants and immediate titanium fixture implantation. Despite the extensive literature on routine implant treatment of the edentulous jaws, only very few reports have dealt with the outcome of bone graft reconstructive surgery as part of the dental implant restoration. This study presents the treatment and healing results of 8 consecutive patients, who, over a period of 2 years and 8 months, were treated using onlay iliac bone grafts to atrophic maxillary alveolar ridges with immediate implant insertion. The patients were followed for 32-64 months. 83 % of the fixtures (n = 46) were welMntegrated. Two fixtures in each of 2 patients were lost due to traumatic bonegraft fractures. Palpatory bone-graft volume and prosthetic function were, with the exception of 1 patient, good. Radiological examination demonstrated preservation of the major part of the vertical dimension of the grafted bone. Patient's assessment was of good aesthetics and intraoral function; 2 patients had minor phonetic problems. In conclusion, similar success to routine maxillary implant treatment can be achieved in the event of extreme maxillary bone deficiency, by bone grafting and immediate fixture insertion. KEY WORDS: Endosseous implants (Br~nemark fixtures) - Atrophy of maxilla - Onlay bone-graft.
INTRODUCTION Placement of endosseous dental implants as introduced by Br~nemark, has been used for over 20 years and has proved to be a valuable method of treating partly and totally edentulous jaws. For example, Adell et al. (1981) reported a success rate of 91% in routine mandibular implants and 81% in maxillary implants over a period of 5-9 years, and van Steenberghe (1989) found, in a multicentre evaluation, a survival rate of 87% and 92% for the upper and lower jaws respectively, after 6--36 months following prosthetic reconstruction in partial edentulous patients. However, in extreme maxillary alveolar bone deficiency, transplantation of autogeneics bone grafts is desirable to attain optimal functional restoration. In 1980, Breine and Brdmemark published their experienc e with two such reconstructive procedures. In 18 patients (14 maxillae and 4 mandibles) tibial cancellous bone chips in combination with titanium implants were used. The titanium fixtures were gnserted in the jaw bone and, thereafter, the harvested bone was modelled around the fixtures during the same procedure. Rapid graft resorption and insufficient bone volume restitution were observed, although restoration of the biomechanical capacity of the jaw bone was achieved. The second procedure, which was a two-stage operation, was performed on 9 patients (8 maxillae and 1 mandible). A preformed tibial composite bone graft was constructed holding the titanium implants. A second stage was carried out
after a healing period of 3-6 months when the preformed graft with its implants was transferred and secured with additional implants to the jaw. Even this procedure resulted in a considerable graft resorption. In 5 out of 8 maxillae, the major part of the grafts was preserved and less than 50% of originally inserted fixtures remained integrated after 1-8 years following bridge construction. Furthermore, Keller et al. (1987) reported, using an immediate onlay autogeneics iliac bone graft technique, 83 % integration in 12 implants inserted in 2 patients at 2 and 24 months, respectively, after fixed tissue-integrated prosthetic treatment and similar success was reported by Kahnberg et al. (1989). A Swedish multicentre study reported a success rate of 83% (71 fixtures) in grafted maxillae (Albrektsson et al., 1988), while an international review claimed a survival rate of 66 % (112 fixtures; Albrektsson 1988) over an observation time of 1-5 years. However, no details of the surgical procedure was given in the latter two reports. This retrospective study presents our observations on the use of titanium implants in conjunction with iliac cortico-cancellous bone grafts positioned along the alveolar ridge. MATERIAL AND METHODS Patients
Eight patients with extremely atrophic edentulous maxillae were studied (Table 1). The first operation
Ridge augmentation with immediate endosseous implants
3
Table I - Summary of the features of the patients
'Follow-up Age period Teeth present Patients Sex (yrs) (months) (Int.nomencl.)
Edentulous period, maxilla (yrs)
1 2 3 4 5 6 7 8
4 20 10 30 30 4 10 16
M F F F M M M M
44 51 44 54 67 46 70 68
64 63 52 52 50 33 33 32
16-14, 43-33, 36 46-35 44-34 43-32 43-35 44-34 46, 43, 33 35 Mand. Imp1.
was performed in February 1986 and, thereafter, remaining patients were treated consecutively until October 1988. Clinical examination and preoperative radiographs, including CT-scans, demonstrated lack of osseous support and precluded treatment without bone grafting. All patients were healthy except for two having problem with duodenal ulcers. Apart from 1 patient (no. 2) all were heavy smokers.
Fig. 2 - Photograph of a bone graft fixed to the alveolus by titanium implants; fixture mounts still in situ.
Surgery
Bone was harvested from the right iliac crest. A 5 cm incision was made, starting 1 cm posteriorly to the anterior superior iliac spine (not to damage the lateral superficial branch of the femoral nerve) and running parallel to the iliac crest. A 4-5 cm bony lid, encompassing the iliac crest and attached only to the inner periosteum, was tilted medially. Two blocks of approximately 4 x 1 x 1 cm were harvested. The inner cortical layer of the iliac bone was left intact. An intraoral approach to the maxilla was made by using a horseshoe incision along the sulcus from the region of the upper right first molar to the upper left first molar. The alveolar crest was revealed by raising a palatally pedicled mucoperiosteal flap. Bone irregularities at the recipient site were removed using rongeur forceps.
I~
~
-
---~.-~~
~
~!,~,'
Fig, 1- Diagrammetric representation of the orientation of the two autogenous bone grafts prior to their fixation to the alveolus.
Fig. 3 - Photograph of bone grafts in situ, showing good adaptation to the shape of the alveolus. The iliac bone blocks were trimmed to fit the alveolar ridge and placed with their cortical layer inferiorly (Fig. 1). The blocks met in the midline and were fixed to the grossly atrophied maxilla with the titanium implants only (Figs. 2 and 3). In 1 patient (no. 5) the bone blocks were placed infero-buccally to the residual ridge in order to improve a poor sagittal relation of the jaws. The Br~nemark implant system was applied according to the recommended technique. Only standard fixtures were used. Care was taken not to countersink beyond the cortical layer of the graft. The wound was closed with continuous 4-0 sutures. Preoperatively, the patients were given Benzylpenicillin (3 g) and Metronidazole (0"5 g) intravenously and then prescribed continued oral medication for 1 week. Postoperative strategy included permission to wear the relined original denture after 3 weeks. After problems with bone-graft fractures in 2 patients, an acrylic occlusal mandibular splint was produced (see Discussion), which was worn during sleep. The fixtures were unloaded until the abutment operation. The abutment operations were performed after a 6-9 months healing period and, subsequently, a fixed prosthesis was constructed (Table 2, Figs. 4 and 5). All patients were followed regularly (twice a year) and given a strict oral hygiene programme. Most patients demonstrated excellent cooperation. Implant stability was assessed manually and by a surgical instrument in
4
Journal of Cranio-Maxillo-Facia1 Surgery
Table 2 - Number and length of implants inserted and complications before and after prosthodontic treatment
Patients
Implants ( n o ) Length(mm)
2 3 4 5 6 7
2:10, 2:13 3:13, 3 : 15 5:15, 1:18 2:10, 4:13 2: 13, 3: 15, 2:20 3 : 13, 3:15 3:13, 1:18, 1:20
8
1:10, 3:15, 2:18
1
Surgical complications (months)
Fistula R2 (15) Extr. L1, L3 (7) Extr. L4 (3) Graft fracture " Extr. L2, L3 (6) Extr. L1 (7)
Completion of prosthodontic treatment after fixture installation (months)
Prosthodontic treatmentx
Prosthodontic complications (months)
Remaining implants (of total)
14 10 10 8 22 7 9
ISP ISP ISP ISP ISP ISP TISP
Extr. RI, L1 (16) --TMJ-disturbance xx ----
2(4) 6 (6) 6(6) 4 (6) 6 (7) 6 (6) 3 (5)
9
ISP
--
5(6)
L = Left implant; R = Right implant; xISP = implant-supported prosthesis; TISP = tissue- and implant-supported prosthesis; xxclicking and pain already noted preoperatively.
RESULTS
Treatment completed. Fixed implant-supported prosthesis in position in a patient with maxillary onlay bone-graft.
Fig. 4 -
Radiograph showing bone-graft with endosseous implants and fixed prosthesis in position 1 year after completion of prosthodontic treatment. One fixture (R3) partly penetrates the maxillary sinus. Clinical examination reveals complete stability of all implants.
Fig. 5 -
an effort to provoke implant movement. The integration of the implants was evaluated by clinical and radiographic examinations directly after the abutment operation and annually thereafter. The patient's assessment concerning aesthetics, phonetics and intraoral function were evaluated by a questionnaire and by direct questioning.
The procedure described was performed on 8 consecutive patients over a period of 2 years and 8 months (Table 1). Only moderate discomfort during the first postoperative week was reported and none complained of severe pain or any major swelling. All wounds healed uneventfully. Only 1 of the 46 implants revealed signs of early peri-implant infection and clinically detectable mobility and this was subsequently removed 3 months post-installation due to tenderness. Postoperative pain from the iliac bone donor site was moderate and only 1 patient had any neurological disturbance; i.e. an area of temporary paraesthesia on the lateral aspect of the thigh. Average hospitalization was 3 days (range: 2-5 days). By the time of the abutment operation, 6-9 months post fixture insertion, 40 implants (87 %) were found to be clinically stable without any detectable mobility. In 1 patient (no. 7) 2 implants were removed due to traumatic fracture of the bone-graft (Table 2) and in 3 patients (nos. 4, 5, 8) a total of 4 implants were removed because of non-integration. The peri-implant soft tissue was free from visible inflammation. In general, the radiographs disclosed no or negligible peri-implant radiolucency around clinically stable fixtures. Seven patients had restorations with fixed dentures (Table 2). One patient (no. 7) was provided with a removable denture (overdenture) because of non-integration of 2 out of 5 fixtures. One year and 4 months after completion of the prosthodontic treatment, 1 patient (no. 1) lost his bridgework following an accidental bone-graft fracture (Table 2). A peri-implant infection with a buccal fistula was revealed in another patient (no. 3) 5 months after completion of the prosthodontic treatment. The infection was localized to the soft tissues; no signs of bone resorption was evident on the periapical radiographs. The fistula was successfully treated with local gingival adjustment. At the latest joint evaluation, all remaining implants revealed a stable anchorage without detectable mobility and the palpable bone graft volume was found to be excellent in 6 out of 8 patients. Two patients exhibited less preservation of bone graft volume as
Ridge augmentation with immediate endosseous implants Table 3 - Patient's assessment of treatment
Patients
Aesthetics
Phonetics
Intraoral functional disturbance
1 2 3 4 5 6 7 8
Unacceptable x Good Satisfactory Good Good Good Good Good
~ Lisp Good Good Good Good Good Lisp
x None None None None None None None
x Present fixtures not loaded
evaluated by clinical examination and radiography. Excellent prosthetic function was attained in all but 1 patient. In 2 patients moderate inflammation around 3 implants was observed, which was successfully treated by supervised oral hygiene. Radiographic examination showed only minor evidence of vertical bone loss. Registered bone resorption (as evidenced by the ratio between the mean vertical dimension centrally of the 2 grafts for 2 subsequent radiographic examinations) between the abutment operation and the final follow-up ranged from 0.9 to 1.0. Assessment of the resorption occurring between the fixture and abutment operations, though, ranged from 0"7~3"9. The patient's evaluation was of good aesthetics. Two patients had some minor phonetic difficulties. All patients reported excellent intraoral functional restoration (Table 3). DISCUSSION AND CONCLUSIONS The management of the atrophic maxillary ridge is a challenging surgical problem for which various solutions have been suggested. Previous attempts to augment the extremely resorbed maxilla or mandible have not been completely successful. Most long-term studies, using autogeneics or allogeneic bone material, have been discouraging (Canzona et al., 1976; Baker et al., 1979; Breine and Brgmemark, 1980; Davies, 1980). As in fracture healing, the incorporation of a bone graft depends on the capability of the periosteum, the perivascular cells of the bone marrow stroma and the preexisting osteoprogenitor cells in its environment. Three mechanisms have been proposed to, explain the success of bone grafts (Mulliken et al., 1980). First, fresh autografts, particularly cancellous bone and periosteal grafts, have been shown to retain living cells that participate in the osteogenic response around the transplant (Ham et al., 1952; Ray et al., 1963 ; Basset, 1972). Second, the grafted bone may act as a scaffold for bone regeneration (osteoconduction) while parallel gradual resorption takes place. The healing proceeds as osteoblasts migrate from adjacent living bone. Third, mesenchymal cells may, by a stimulating factor, differentiate into cells exhibiting osteogenic ability (Urist and Strates, 1972; Sampath et al., 1987). In the present context all these mechanisms supposedly participated to incorporate
5
the iliac bone grafts into the recipient site, although the first two appear to exert the major influence. Past experience with titanium implants (Adell et al., 1981; Albrektsson et al., 1988) indicates that most failures become evident within the first year. Most non-integrations are discovered at the time of the abutment procedure. Supposedly, this would also apply to implants inserted into grafted bone. Therefore, it seems reasonable not to make any prognostic assessment for at least 1 year of wearing a bridge, but thereafter a rather well-founded individual prognosis seems justified. With this in mind, this study was undertaken to summarize our experience with our first 8 patients treated with an onlay bone-graft technique with immediate titanium implant insertion, and to assess to what extent the technique is beneficial to patients with advanced alveolar atrophy in the maxilla. In general, we conclude that the technique presented may be used routinely for such patients as the onlays healed successfully, permanent bridge stability was accomplished, and only minor postoperative morbidity was observed. The fact that 2 patients fractured their bone grafts is, however, worth considering. All our patients had either retained their own lower front teeth or a fixed prosthetic implant constructed for the anterior mandibular region (Table 1). Consequently, prophylactic prevention of traumatic biting on the bone graft was essential, and, therefore, we constructed an acrylic occlusal mandibular splint to be worn during the entire healing period. The splint, which was used by 5 patients, occludes against the maxillary tuberosity and thus impedes unfavourable chewing forces on the graft. The recommended interval of 6 months between the fixture installation and the subsequent abutment operation is normally sufficient in non-grafted patients (Adell et al., 1987), but probably, this period is somewhat short after bone grafting. We selected an interval of 9 months to allow some extra time for graft incorporation but short enough not to neglect the theoretical advantage of implants providing a bonepreserving stimulus in the same manner as the presence of healthy teeth preserve alveolar bone. The bone graft volume, as evaluated by palpation and radiography, was quite excellent in 6 out of the 8 patients. We used fresh autogenous bone-graft transplants since their osteogenic potential is known to be the best available and, additionally, the iliac bone grafts comprised both a compact and a cancellous bone compartment giving improved conditions for graft fixation. Cancellous bone alone does not provide sufficient rigidity and there are reports of frequent complete resorption of cancellous autografts (Heiple et al., 1963; Brgmemark et al., 1975). Furthermore, rigid fixation, in this study accomplished by the titanium implants, will reduce the process of resorption of the graft (Phillips and Rahn, 1988; LaTrenta et al., 1989). Hence, the length of implanted fixtures must be sufficient to provide immediate stability by anchoring the graft rigidly to the recipient site. The placement of the bone graft with its cancellous rather than its cortical surface in contact
6
Journal of Cranio-Maxillo-Facial Surgery
with the maxillary bone seems advantageous in the maintenance of the bone graft volume. Such strategy was experimentally supported by Thompson and Casson (1970) and Knize (1974) and, furthermore, these authors reported that a bone graft with its cancellous surface in contact with soft tissue was revascularized more rapidly but underwent greater volume loss in the long run. Partial resorption of autogeneic bone grafts generally occurs, often amounting to half of the original size (Kdrlof et al., 1973). Theoretically, the use of tobacco might negatively influence graft incorporation, and thereby volumetric preservation, by disturbing effective revascularization of the graft. Despite the majority of our patients being heavy smokers graft resorption was moderate and the results favourable. Loss of onlay graft volume over time is not a linear process but most pronounced soon after its insertion (Lin et al., 1990). Consequently, the most intensive volumetric loss would have taken place before the abutment operation. Despite the bone resorption registered we found that the remaining mass of bone at the termination of the present investigation was substantial and constituted an effective support for the prosthodontic appliances. One limitation of the surgical method used, apart from the risk of graft fracture as discussed above, is the restricted possibility of correcting sagittal discrepancy between the jaws. In 1 patient (no. 5) the sagittal relationship was found to be unfavourable and the graft had to be positioned infero-buccally to the residual ridge to compensate for the class III relationship between the mandible and the maxilla. However, only limited preoperative correction of the sagittal dimension is possible by the present technique. Previously, the results of techniques for advancementosteotomy have been presented (Farrell et al., 1976; Freihofer, 1989). Sailer (1989) recently reported a onestage method in which 3 separate iliac bone grafts were sandwiched into the osteotomy line (on the floors of the nasal cavity and the maxillary sinuses) after a Le Fort I down-fracture. Graft fixation was by means of fixture installation similarly to the technique used here. Preferably, this method is indicated when advancement of the maxilla to a more favourable position is planned, and further, the method facilitates postoperative denture adjustment as the alveolar ridge retains its preoperative anatomical configuration. In conclusion, the use of alveolar ridge augmentation by iliac bone onlays has evolved as a safe, wellaccepted procedure with low morbidity. Our results, showing 83 % integration of the implants, are comparable even to non-grafted maxillary cases reported. It may be used in patients in whom a more complicated procedure is neither necessary nor feasible.
Acknowledgements We thank L. Kristersson, DMD, PhD, and J. E. Blomqvist, DMD for their participation in some of the operations and R. Loukota, FDSRCS, FRCS (Ed) for help with language revision.
References Adell, R., U. Lekholm, B. Rockier, P-I. Brgmemark : A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int. J. Oral Surg. 10 (1981) 387 Adell, R., U. Lekholm, P-L Brhnemark : Surgical procedures. In: Brfinemark P-I., G. A. Zarb, T. Albrektsson (eds) : Tissueintegrated prostheses. Osseointegration in clinical dentistry. Quintessence Publishing Co Inc, Chicago. 1987, p. 211 Albrektsson, T. : A multicenter report on osseointegrated oral implants. J. Prosthet. Dent. 60 (1988) 75 Albrektsson, T., E. Dahl, L. Enbom et al: Osseointegrated oral implants. A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants. J. Periodontol. 59 (1988) 287 Baker, R. D., B. C. Terry, W. H. Davis, P. W. Cannole : Longterm results of alveolar ridge augmentation. J. Oral Surg. 37 (1979) 486 Bassett, C. A. L. : Clinical implications of cell function in bone grafting. Clin. Orthop. 87 (1972) 49 Breine, U., P-L Brdmemark: Reconstruction of alveolar bone. An experimental and clinical study of immediate and preformed autologous bone grafts in combination with osseointegrated implants. Scand. J. Plast. Reconstr. Surg. 14 (1980) 23 Brdmemark, P-L, J. Lindstr6m, O. Hall~n, U. Breine, P. H. Jeppson, A, Ohman : Reconstruction of the defective mandible. Scand. J. Plast. Reconstr. Surg. 9 (1975) 116 Canzona, J., N. G. Grand, Y. P. Waterhouse, D. M. Laskin: Autogenous bone grafts in augmentation of edentulous canine mandible. J. Oral Surg. 34 (1976) 879 Davis, W. H. : Rib graft augmentation to the superior border of the mandible. In: Starshak T. J., B. Sanders, (eds) Preprosthetic oral and maxillofacial surgery. CV Mosby Company, St Louis, 1980, p. 218 Farrell, C. D., J. N. Kent, L. R. Guerra. : One-stage interpositional bone grafting and vestibuloplasty of the atrophic maxilla. J. Oral Surg. 34 (1976) 901 Freihofer, H. P. M. : Stability after osteotomy of the edentulous maxilla. J. Cranio-Max. Fac. Surg. 17 (1989) 306 Ham, A., S. Gordon. : The origin of bone that forms in association with cancellous chips transplanted into muscle. Br. J. Plast. Surg. 5 (1952) 154 Heiple, K. G., S. W. Chase, C. H. Hernon. : A comparative study of the healing process following different types of bone transplantation. J. Bone Joint Surg. 45A (1963) 1593 Kahnberg, K. E., E. Nystr6m, L. Bartholdsson: Combined use of bone grafts and Br~nemark fixtures in the treatment of severely resorbed maxillae. Int. J. Oral Maxillofac. Implants 4 (1989) 297 Keller, E. E., N. B. van Roekel, R. P. Desjardins, D. E. Tolman ." Prosthetic-surgical reconstruction of the severely resorbed maxilla with iliac bone grafting and tissue-integrated prostheses. Int. J. Oral Maxillofac. Implants. 2 (1987) 155 Knize, D. M: The influence of periosteum and calcitonin on onlay bone graft survival. A roentgenographic study. Plast. Reconstr. Surg. 53 (1974) 190 K6rlof, B., B. Nylkn, K. A. Ritz: Bone grafting of skull defects: A report on 55 cases. Plast. Reconstr. Surg. 52 (1973) 378 LaTrenta, G. S., 3. G. McCarthy, A. S. Breitbart, M. May, H. A. Sissons: The role of rigid fixation in bone-graft augmentatio n of the craniofacial skeleton. Plast. Reconstr. Surg. 84 (1989) 578 Lin, K. Y., S. P. Bartlett, M. J. Yaremchuk, M. Fallon, R. F. Grossman, L. A. Whitaker: The effect of rigid fixation on the survival of onlay bone grafts: An experimental study. Plast. Reconstr. Surg. 86 (1990) 449 Mulliken, J. B., J. Glowacki : Induced osteogenesis for repair and construction in the craniofacial region. Plast. Reconstr. Surg. 65 (1980) 553 Phillips, J. H., B. A. Rahn: Fixation effects on membranous and enchondral onlay bone-graft resorption. Plast. Reconstr. Surg. 82 (1988) 872 Ray, R. D., T. Y. Saber: Bone grafts: Cellular survival versus induction. J. Bone. Joint. Surg. 45A (1963) 337 Sailer, H. F. : A new method of inserting endosseous implants in totally atrophic maxillae. J. Cranio-Max-Fac. Surg. 17 (1989) 299
Ridge augmentation with immediate endosseous implants Sampath, T. K., N. Muthukumaran, A. H. Reddi: Isolation of
osteogenin, an extracellular matrix-associated protein, by heparin affinity chromatography. Proc. Natl. Acad. Sci. USA 84 (1987) 7109 Steenberghe, D. van: A retrospective multicenter evaluation of the survival rate of osseointegrated fixtures supporting fixed partial prostheses in the treatment of partial edentulism. J. Prosthet. Dent. 61 (1989) 217 Thompson, N., J. A. Casson: Experimental onlay bone grafts to the jaws. A preliminary study in dogs. Plast. Reconstr. Surg. 46 (1970) 341 Urist, M. R., B. S. Strates : Bone morphogenetic protein. J. Dent. Res. 50 (1972) 1392, suppl 6
S. Isaksson, DMD, MD Department of Oral Surgery L~inssjukhuset S-301 85 Halmstad Sweden. Paper received 27 May 1991 Accepted 12 September 1991
7
