reconstruction of residual alveolar cleft defects with one-stage mandibular bone grafts and...

J Oral Maxillofac Surg 56:460-466. 1998

Reconstruction of Residual Alveolar Cleft Defects with One-Stage Mandibular Bone

Grafts and Osseointegrated Implants John Jensen, DDS, * Steen Sindet-Pedersen, DDS, Dr Med Sci, f

and Hans Enema&, DDS#

Purpose: This study evaluates a treatment regimen for reconstruction of residual maxillary alveolar cleft defects consisting of mandibular bone grafting and immediate implant installation.

Patients and Methods: Sixteen cleft patients (five female and 11 male) had residual cleft defects of the alveolar ridge reconstructed with bone grafts from the mandibular symphyseal region. The bone graft was pretapped at the donor site before fixation in the residual ridge with Bdnemark implants. Twenty implants were installed according to this concept. The period of observation ranged from 36 to 69 months, with a mean of 48 months after implant installation.

Results: Five patients developed wound dehisccnses that resulted in total or partial bone graft sequestration. Two implants were lost, one due to sequestration and the other due to mobility at the abutment procedure; 18 implants were still well functioning at the end of the observation period. However, all patients showed significant periimplant bone resorption after this one-stage treatment.

Conclusion: Because of the observed complication rate, the one-stage procedure may not be optimal for reconstructing residual cleft defects.

Because of the high and predictable success rates reported for osseointegrated implant systems, this treatment has become routine clinical practice for restoring edentulism.ix2 In addition to the significant role that implants have gained in the restoration of form and function in the edentulous and partially edentulous patient, the principles of osseointegration have, in addition, been applied to a variety of other clinical situations, including use as a point of anchorage for orthodontic tooth movement, extraoral fixation for prosthetic reconstruction of soft tissue defects, and reconstruction of irradiated jaws as part of the functional rehabilitation of head and neck cancer patients.3-5

In 1987, Keller et al6 published a report about the use of combined bone grafting and installation of

*Staff, Department of Oral and Maxillofacial Surgery, Royal Dental

College, Aarhus University and Aarhus University Hospital, Aarhus,

Denmark.

tProfessor and Chairman, Department of Oral and Maxillofacial

Surgery, Royal Dental College, Aarhus University and Aarhus Univer-

sity Hospital, Aarhus, Denmark.

*Director, Aarhus Cleft Palate Institute, Aarhus, Denmark.

Address correspondence and reprint requests to Dr Jensen:

Department of Oral and Maxillofacial Surgery, Aarhus University

Hospital, Norrebrogade, DK-8000, Aarhus, Denmark.

o 1998 American Association of Oral and Maxiliofacloi Surgeons

0278.2391,‘98/5604-0004$3.00/O

osseointegrated implants for reconstruction of maxillary alveolar defects and atrophy. In this material, a patient with a unilateral maxillary cleft lip-palate deformity who was reconstructed according to this principle was included. This report represented the first such application of osseointegration for the management of cleft deformities. Since that time, only a few reports have dealt with this subject, mainly presenting anecdotal information7-l1

Even after successful closure of the alveolar cleft accomplished by secondary bone grafting in child- hood, a residual alveolar ridge defect can be present in adult cleft patients. Based on our experience with the use of mandibular bone grafts for reconstruction of alveolar clefts and their use as an onlay/inlay in combination with osseointegrated implants for reconstruction of the severely atrophied maxilla,12-14 we commenced reconstruction of alveolar ridge defects in cleft patients according to these principles. The aim of the study was to evaluate the treatment results of osseointegrated implants installed simultaneously with bone grafts from the mandibular symphysis applied to augment residual horizontal or vertical alveolar ridge deficiency in alveolar cleft patients.

Patients and Methods

Sixteen consecutive patients (5 females and 11 males; age 15 to 38 years; mean age, 19 years) with

460

JENSEN, SINDET-PEDERSEN, AND ENEMARK 461

alveolar cleft defects were included. Fourteen of the patients had unilateral clefts, and two had bilateral clefts of the maxillary alveolus; two of the unilateral cleft cases required two implants to restore the edentulous space, whereas the remaining 12 received only one implant. Accordingly, these patients had a total of 20 implants installed with lengths ranging from 10 to 20 mm (10 mm:l; 13 mm:l; 15 mm:12; 18 mm:3; 20 mm:3).

SURGICAL TECHNIQUE

All patients were treated under general anesthesia. After submucosal infiltration of a local anesthetic (lidocaine 1% with l:lOO,OOO epinephrine) in the anterior labial vestibule and palatal mucosa adjacent to the cleft area, a standard full-thickness trapezoidal mucoperiosteal flap pedicled to the palate was raised (Fig 1A). The vestibular incision was begun approxi- mately 1 cm superior to the mucogingival junction and extended horizontally from the midline of the tooth immediately anterior to the repaired cleft to the midline of the tooth immediately posterior to the defect. Converging vertical incisions were then continued to the mesiopalatal and distopalatal aspect, respec- tively, of the teeth adjacent to the edentulous region. Care was taken to preserve a collar of attached gingiva around the necks of the teeth adjacent to the cleft to reduce the risk of surgically induced gingival recession on these teeth. A periosteal elevator was used to reflect the flap and expose the maxillary alveolar crest in the intended implant site. The flap was retracted from the surgical field with a single 4-O Vicryl suture for the duration of the surgical procedure. The residual alveolar crest was drilled and tapped for implant placement and bony reconstruction.

Attention was then directed to the mandibular symphysis. After infiltration of the local anesthetic, an anterior labial vestibular incision was made approxi- mately 3 mm apical to the mucogingival junction, extending from canine to canine. The exposed symphysis was prepared and tapped to receive a conventional Bdnemark implant as described by Jensen and Sindet- Pedersen.ls This was done before bone harvest, as it was possible to achieve greater stability during the preparation procedure with the graft attached to the recipient site. A window of bone was outlined around the circumference of the implant preparation with the aid of a tapered fissure surgical bur under saline irrigation (Fig 1B). The graft was removed with the aid of a thin osteotome. This approach gave access to the intramedullary bone, and additional cancellous bone chips were harvested for purposes of optimizing osseous contour at the recipient site. When more than one implant was required to restore the edentulous cleft space, a stainless steel template (OSW Leibinger,

Freiburg, Germany) corresponding to the size of the residual alveolar cleft defect was used to determine the area of bone to be harvested from the symphysis and facilitate parallelism of the implants while ensur- ing maintenance of optimal interimplant distance.14 The prepared bone graft was then applied to the edentulous cleft site and modified appropriately with a stainless steel reduction bur until it could be placed passively. Thickness of bone in the implant area of the bone graft was measured with a calliper (Vernier gauge). The graft was then stabilized by the installed Branemark implant(s).

After placement of the implant(s) and cover screw(s), a bone reduction bur was used to remove all sharp edges from the grafted symphyseal bone, reduc- ing the risk of ischemic necrosis of the soft tissue flap. Cancellous bone was used to obliterate all open areas between the graft and alveolar ridge and restore the anatomic form of the area (Fig lC-1E).

The soft tissue flap was reapproximated to the surgical site and secured with multiple 4-O Vicryl horizontal mattress sutures. A prefabricated palatal acrylic stent was fitted and secured with 26gauge stainless steel interdental wires. The stent protected the surgical site from the trauma of occlusion and minimized hematoma formation, which could compro- mise healing of the grafted bone. It was removed on the seventh postoperative day. Prophylactic antibiotic treatment (usually penicillin) was initiated at the time of surgery and continued for 7 days postoperatively.

After the abutment placement procedure 6 months postoperatively, prosthodontic treatment was commenced. Implant mobility and peri-implant tissue condition were assessed 3 and 6 months after prosthodontic treatment was completed and thereafter at 12-month intervals. Lateral cephalograms and pan- oramic and intraoral radiographs were used to evaluate the condition of the bony support of the implants before and after surgery and at the abutment placement procedure. Thereafter, only intraoral radiographs were taken annually. Using the design of the implant as a reference (top plateau, excluding the external hexagon and the treads) on the intraoral radiographs, the resorption of the height (thickness) of the bone graft was determined as the mean of resorption mesially and distally to each of the 18 remaining implants (a total of 36 sites) (Fig 2). Measurements were done 1 and 2 years after the abutment placement procedure.

Statistical analysis was performed using SPSS (Chi- cago, IL). Analysis of variance (ANOVA) was performed to test whether all three groups (periopera- tive, 1 year postoperative, and 2 years postoperative) were subgroups of the same total population. If there were significant differences (5% level), a contrast

462 RESIDUAL ALVEOLAR CLEFT DEFECTS

FIGURE 1. Reconstruction of a single-tooth defect with mandibular bone graft and an implant. A, Trape&dal incisions are performed to raise a oalatal oedicled full-thickness mucooeriosteal flap. B, After exposure of the mandibular symphysis, an imp’lant site is prepared for a single-implant reconstruction. Thereafter, a bone block with a size corresponding to the recipient area in the maxilla is outlined with a

fissure bur and delivered with the aid of a curved chisel. C, After the bone graft is fixed to the residual ridge with an implant, all sharp edges are removed, and bone chips are packed to restore the shape of the area. D, Radiographic appearance of the patient showing a large defect in both the horizontal and the vertical dimension. E, Intraoral radiograph taken immediately after reconstruction with a mandibular bone graft fixed to the residual ridge with an implant.

procedure was performed to test the subgroups two vitality, periodontal condition, and radiologically exam-

and two using Scheffe’s method to compensate for the ined for root resorption and periapical pathology. The

multiple comparisons. period of observation ranged from 36 to 69 months,

At the donor site, all teeth were examined for pulp with a mean of 48 months after implant installation.

JENSEN, SINDET-PEDERSEN, AND ENEMARK 463

FIGURE 2. Radiographs showing bone resorption. A, The marginal bone resorption in this case was 2 mm, a mean of the measurement performed mesial and distal to the implant. 6, In this patient, the bone resorption was 2.5 mm (left) and 3.0 mm [right).

Results

Twenty Brinemark implants with lengths from 10 to 20 mm were installed in 16 patients with residual cleft defects. The thickness of bone in the implant region of the graft ranged from 3.5 to 15 mm, with a mean of 4.0 mm. One patient’s jaw was reconstructed with a 15-mm implant totally surrounded by a bone graft that was fixed to the residual ridge by an osteosynthesis plate.

Five patients developed wound dehiscence that resulted in total or partial bone graft sequestration. Wound dehiscence was primarily managed conserva- tively with chlorhexidine (0.1%) irrigation three times a day until healing of the involved area had taken place. In one of the cases of dehiscence, an area of cementurn on an adjacent lateral incisor tooth remained exposed after healing was completed (Fig 3). Two patients developed total bone graft sequestration around two implants. This was treated by removal of the necrotic fragment. One patient had the terminal coronal threads of the implant exposed, necessitating modification of the implant with a high-speed bur to remove the threads (Fig 4). This was then managed in the prosthetic phase of treatment by construction of a modified abutment collar. In the other patient, it was necessary to remove the implant because of mobility; the site was regrafted with symphyseal bone 2 months later and another implant was placed simultaneously. A cosmetic appearance of Cera-one crowns was nega- tively affected in two of three patients with partial bone sequestration due to gingival recession.

In one patient, with a previous bilateral cleft, the premaxilla was reconstructed with an onlay bone graft fixed with two implants. At the abutment procedure, one implant was mobile and therefore removed. Three months later, a new implant was installed.

Fifteen patients in this study have been restored with single-unit fixed crowns, and one of the patients with two implants placed in the edentulous cleft region had the crowns fused together (Fig 5). The implants and bone grafts have been loaded for periods ranging from 30 to 63 months, with a mean of 42 months.

ANOVA analysis showed that there were statisti- cally significant differences between the three subgroups (P = .016). Subsequent multiple contrast analy-

FIGURE 3. The left canine region was reconstructed with a bone graft and an implant. Because of dehiscense in the primary healing phase,

cementum on the adjacent lateral incisor remained exposed.


FlGURi 4. Patient with partial loss of the bone graft. A, Partial bone graft sequestration resulting in loss of bone on the facial aspect of the implant in the right lateral incisal region. 6, Clinical appearance after modification of the implant by removal of exposed threads with a high-speed bur. A modified abutment collar was constructed to support

the ceramic crown.

sis showed that there were significant differences between the initial height of the bone 1 year (P = ,049) and 2 years postoperatively (P = ,040). However, there was no statistical difference between the bone

FIGURE 5. A, Even after sufficient cleft closure, there is a residual defect in the alveolar ridge in the left lateral incisal region. B, Clinical appearance 2 years after recohstruction with a bone graft and an implant

height 1 year postoperatively and 2 years postoperatively (P = .997) (Figs 6, 7).

The mandibular donor site did not presept a management problem in any of the patients. No damage to teeth or roots was observed, and 6-month follow-up radiographs of the donor site did not show any periapical pathology. Furthermore, no soft tissue pro- file changes were apparent. A slight disturbance of sensation within the region of innervation of the mental nerve was recorded in four patients; however, this recovered spontaneously in all cases during the following 6 months.

Discussion

Prosthetic replacement of missing anterior teeth in the maxillary arch of cleft patients has always been considered an important part of their rehabilitation.15J6 In the past, many patients have used partial dentures as orthodontic retainers to avoid relapse after movement of teeth or maxillary segments. Unfor- tunately, this treatment can induce inflammation of the soft tissues and cause a risk of general breakdown of oral health. Accordingly, in reviewing the prosthetic options for treatment of cleft lip and palate patients, Wegscheider et alI7 described the following possibilities: 1) Fixed prosthodontics (crowns, bridges, and Maryland bridges); 2) Removable prostheses (conventional cast partials, overdentures, and full dentures), and 3) Precision prostheses (tippliances with bars, splints, and telescope retainers). These authors reported a 50% failure rate with Maryland bridges tid attributed this to the high frequency of mobile teeth in the maxillary cleft segments. Of 12 fixed bridges placed, seven failed as a result of periodontal disease, marginal defects, or dissolution of cementurn, and all four of the bar-constructions had to be removed because of marginal defects developing as a result of poor access for oral hygiene.

In the late management of secondarily bone-grafted clefts, a higher rate of rehabilitation without the need for bridgework has been shown if the cleft was grafted before canine eruption. 18,19 In this way, most of the patients achieved closure of the dental arch by either orthodontic treatment alone or a combination of orthodontic treatment and minor osteotomies. How- ever, to eliminate a residual edentulous space in 20% to 30% of the patients, it was necessary to restore the dental arch with bridgework.19J0 Ideally, the aim should be to achieve a complete archform in every cleft palate patient without the need for bridges or reqovable prostheses. The success of implants for repiacement of single teeth is well established, and the functional and aesthetic results are certainly com- parable to those achieved with conventional fixed prosthodontics.21J2

JENSEN, SINDET-PEDERSEN, &ND ENEMARK 465

16

12 6

12 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Implant No

FIGURE 6. Height of bone graft in the peri-implant region perioperatively and postoperatively.

We have presented our experience with the irnme- diate use of osseointegrated implants combined with mandibular bone grafts for reconstruction of secondarily bone-grafted alveolar cleft defects. This treatment concept has previously been presented in both experimental and clinical studies,13J4J3-27 but this study represents the first systematic approach to a consecutive series of cleft patients treated in a uni- form way. Despite the fact that a secondary bone grafting procedure was performed successfully in all patients, some degree of bone graft resorption took place. Because there is often a delay of several years between the time of grafting of the alveolar cleft and

m m

8

FIGURE 7. Average height [mm; SD] of bone grafts around all implants in the study.

that of implant placement, the degree of graft resorption may be significant and require an additional graft at the time of implant placement to ensure normaliza- tion of vertical and horizontal dimension of the alveolus. In this way, a more sufficient final cosmetic restoration can be achieved.

It is recommended that implant placement be deferred until completion of skeletal growth; accordingly, the average age of patients at surgery in the current series was 19 years. However, in the current study, there was a high frequency of complications. Despite using a modification of a well-known mucosal flap design for secondary bone grafting of the cleft defectsz8 a high rate of wound dehiscense (25%) was recorded, resulting in total or partial bone sequestration (25%). Extreme stretching of the mucosal flap due to onlay bone grafting combined with placement of a suture line close to the graft could be the main reasons for these complications.

In conventional maxillary implant surgery, there is normally a marginal bone loss of 1.2 mm during the first year of loading and thereafter a stabilization to an annual resorption rate of 0.1 mm.29,30 Authors using immediate bone grafting and implant installation for reconstruction of severe maxillary alveolar ridge atrophy reported a marginal bone loss of 1.5 mm during the first year of loading and thereafter stabilizations1 whereas another author reported an average bone loss of 2.5 mm after 1 year, progressing to almost 5 mm after 3 years.32%33 In the current study, there was also a


high degree of bone resorption; however, marginal resorption around implants abated after a year of functional loading. The use of mandibular (membra- nous) bone as a grafting material could be the reason for this difference in accordance with previously reported findings in an experimental study.3* Further- more, there were no specific soft tissue problems recorded in the current study in areas with exposed threads, which is in accordance with results presented by Lekholm et a1.35

Because of the observed high complication rate, we thi& that the one-stage procedure is not optimal for reconstructing residual cleft defects. Further improve- ment in the results of implant/bone graft reconstruction of cleft patients with residual alveolar ridge defects might be achieved by using a two-stage procedure.

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reconstruction of residual alveolar cleft defects with one-stage mandibular bone grafts and...

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