Abstract
This study assessed the use of composite autogenous bone and deproteinized bovine bone (DBB) for repairing alveolar cleft compared with autogenous bone alone in terms of clinical outcomes and patient morbidity. 30 patients with a mean age of 10.2 ± 1.7 years were randomly divided into two groups. Group I used autogenous cancellous bone graft harvested from the anterior iliac crests by the conventional trapdoor approach. Group II used a composite of DBB and autogenous cancellous bone harvested by a trephine bone collector; the proportion of 1:1 by volume was used. The bone graft quantities of both groups decreased with time. Their average changes were not statistically different over 24 months after grafting. The canines of both groups could spontaneously or orthodontically erupt through the grafting areas. Patients in group II recovered from uncomfortable walking significantly faster than those in group I ( p < 0.05) and their duration of hospital stay was significantly shorter than those in group I ( p < 0.05). The average operation time, intra-operative blood loss and postoperative pain were less in group II than in group I ( p > 0.05).
Alveolar bone grafting is an important procedure in the treatment of cleft lip and palate. Various sources of autogenous bone are used, but an anterior iliac crest is considered the gold standard for grafting. Its resorption rate seems to be high within the first year after grafting . Some studies suggest that this results from its endochondral origin or the lack of scaffolds for osteoconduction mechanisms. The conventional cancellous bone harvesting technique is commonly performed using the trap door approach. This technique provides a large amount of cancellous bone graft and maintains the contour of the crest, the growth centre of the hip, but some studies report retardation of the growth of the crest after the operation in growing children. It may interfere with the abdominal organs and cause a large scar. Other disadvantages include moderate to severe postoperative pain, gait disturbance and extended hospital stays.
The use of xenograft or alloplastic materials, instead of autogenous bone, has been widely accepted for many years. These materials include tricalcium phosphate, hydroxyapatite, deproteinized bovine bone (DBB) and synthetic polymers. DBB can be prepared by chemical treatment, low temperature sintering and high temperature sintering. Bio-Oss (Geistlich Pharma AG, Wolhusen, Switzerland), one of the most commonly used DBB in periodontal and implant surgery , was prepared by chemical treatment. The cost is high, particularly if a large amount of the commercial bone graft is required. The National Metal and Materials Technology Center of Thailand (MTEC) has developed DBB as a grafting material, obtained by sintering bovine bone at 1200 °C to eliminate proteins and lipids, which are antigenic organic matter. It acts as a scaffold consisting of interconnecting pore systems; the pore size is 200–500 μm and the available particle sizes are 0.25–1 mm. In vivo , it showed osteoconductive behaviour that enhanced bone formation in rabbit calvariums. The average new bone formation for DBB alone in a 10 mm 2 defect in 12 weeks was 25 ± 12% compared with 35 ± 5% for an autogenous bone chip ( p > 0.05) .
Several studies have tried to increase the grafting success rate by combining autogenous bone with DBB in various ratios. The proportions of 1:1 and 1:2 were found to obtain maximum new bone formation when compared with 1:4. The latest in vivo study demonstrated that 8 weeks after grafting with autogenous bone combined with DBB (MTEC), the proportions of 1:1 and 1:2 gained more new bone formation (21 ± 6% and 23 ± 6%, respectively) than 1:4 (10 ± 2%), DBB alone (14 ± 3%), or the critical size defect (11 ± 9%), but less than the autogenous bone group (30 ± 17%).
The aim of the present study was to evaluate the clinical and radiographic results of alveolar cleft bone grafting using the composite of autogenous bone from the iliac crest and DBB and to comparing these results with autogenous bone alone over a 24-month follow-up period.
Materials and methods
The study was conducted from November 2004 to June 2007 at the Dental Hospital, Prince of Songkla University in accordance with the regulations of the Faculty board ethics committee. ASA class I patients, aged 9–12 years, with residual alveolar clefts were included in the study. Patients who had bleeding disorders, bone and metabolic diseases, and were not available for 2-year follow-up were excluded from the study. 30 patients were enroled in the study; 10 boys and 20 girls with an average age of 10.2 ± 1.7 years. 22 patients had unilateral alveolar clefts and 8 had bilateral alveolar clefts. Secondary alveolar bone grafting was performed by two oral surgeons using the same surgical technique. The patients were randomly divided into two groups and were unaware of the technique used. In group I, the cancellous bone graft was harvested from the anterior iliac crests by the conventional trap door technique. In group II, the cancellous bone was harvested from the anterior iliac crests using a trephine bone collector (Medicon, Tuttlingen, Germany; diameter 8.0 mm) and mixed with DBB (MTEC, Pathumthani, Thailand), with a particle size of 0.25 mm in the ratio of 1:1 by volume ( Fig. 1 ). The bone grafts for both groups were compressed in 5 ml syringes and the volumes were measured prior to filling the alveolar cleft defects. In both groups, the alveolar cleft sites were grafted and closed using the gingival advancement flap technique. Analgesics (acetaminophen and meperidine) and antibiotics (intravenous cephalosporin) were prescribed according to the standard protocol.
Clinical assessment
The recordings for intra-operative assessments included duration of the operation (h), bone graft volume (ml) taken from the donor sites, and estimated blood loss (ml) calculated from the total fluid volume in the suction bottle minus the irrigating fluid plus the blood volume in blood-soaked four-by-four gauzes used in the operation. Postoperative assessments included: duration of hospital stay (day); time taken to walk again, with and without assistance (h); and postoperative pain level (using a 10 cm visual analogue scale) over the 7 days after the operation. Wound healing of the donor and recipient sites was observed. Wound complications such as bleeding, infection, dehiscence and neurologic disturbance were recorded. Other rare complications such as hip joint dislocation and abdominal perforation were monitored. Orthodontic treatments began 6 months postoperatively. Spontaneous or orthodontically assisted tooth eruption into the grafted cleft sites was recorded within 24 months after the surgery.
Evaluation of bone graft quantities
Changes to the bone graft quantities during the follow-up period were assessed by intraoral radiographs. The quantities were determined mainly by measuring bone density and bone graft height . In brief, occlusal radiographs were taken by an intraoral radiography machine (Gendex GX 1000; Gendex Corporation, Desplaines, USA) preoperatively, 3 days postoperatively and 1, 3, 6, 12, 18 and 24 months postoperatively with individually similar constant kilovoltage, milliamp and exposure times. A custom-made holder was used to ensure reproducibility of the distance of the film for each patient. Bone density was measurement by optical density (OD); the grey scale or brightness of the entire pixels in the image. For this purpose, an aluminium step wedge was attached to each film to calibrate the radiographic density. Each radiographic image was captured and transferred to a personal computer and analysed by image processing and analysis software (Image Pro Plus 5.0, Media Cybernetics Inc., Silver Spring, USA). By using the software, the preoperative cleft areas were outlined and duplicated for each serial postoperative X-ray. The areas occupied by the erupted teeth were deleted and the OD of each outline was measured. The bone graft height was demonstrated as the percentage of bone coverage of the reference tooth roots.
Statistical analysis
The data were analysed using SPSS version 13(SPSS Inc., Chicago, IL, USA). Descriptive statistics and unpaired t -tests were used to compare the clinical results and bone graft quantities between the two groups, at each time interval, during the follow-up periods. One-way analysis of variance was applied to detect the change in bone quantities for each group during the follow-up periods. Multiple comparisons, using Tukey’s HSD test, were made where variances were homogeneous, otherwise Dunnett T3 was performed. The Mann–Whitney U -test was applied to detect postoperative pain differences between the two groups at each time interval. The Kruskal–Wallis test and Dunn’s multiple comparison test were used to assess the change in postoperative pain for each group during the 7 days after surgery. A p -value <0.05 was considered significant.
Results
All patients tolerated the operation well without anaesthetic complications. The data for all clinical parameters are given in Table 1 . One patient in group I and two patients in group II were excluded from the study due to lack of compliance and loss to follow up. The mean autogenous bone graft volume used in group II could be reduced by adding an equal volume of DBB. There was no significant difference in the operation time and intra-operative blood loss between the two groups. The patients in group II recovered from walking uncomfortably statistically faster than those in group I. The duration of the hospital stay was significantly shorter in group II than in group I.
| Parameters | Group I Autogenous bone alone (mean ± SD) |
Group II Autogenous bone + DBB 1:1 (mean ± SD) |
p |
|---|---|---|---|
| Number of unilateral cleft patients | 11 | 10 | |
| Number of bilateral cleft patients (number of cleft sites) | 3 (6) | 3 (6) | |
| Total cleft sites | 17 | 16 | |
| Bone graft volume (ml) | 2.53 ± 1.07 | 1.22 ± 0.20 * | <0.001 |
| Intra-operative blood loss (ml) | 150 ± 46.30 | 122.5 ± 35.45 | 0.239 |
| Duration of the operation (h) | 2.68 ± 0.61 | 2.29 ± 0.91 | 0.172 |
| Time taken to walk with assistance (h) | 37.88 ± 11.07 | 25.5 ± 6.46 * | 0.006 |
| Time taken to walk without assistance (h) | 67.07 ± 13.86 | 46.63 ± 13.82 * | 0.003 |
| Duration of hospital stay (day) | 5.4 ± 1.12 | 4.23 ± 0.8 * | 0.006 |
* Unpaired t -tests, significant difference from group I at p < 0.05.
The postoperative pain in both groups significantly reduced within 3 days after surgery. The overall pain score was less in group II than in group I, but the results were not statistically significant ( Fig. 2 ).
Regarding complications at the donor site, paresthesia of the skin around the incision lines occurred in one case and pain when walking was reported in three cases in group I. No complications were detected in group II. At the recipient site, wound infection occurred in one patient in each group. Wound dehiscence was detected in one patient in group I and in three in group II. This might be due to excessive bone graft volume packed into the cleft sites, the tension of wound closure and the patient’s oral hygiene. They were healed eventually following wound debridement and antibiotics.
Canine tooth buds presented in 10 cleft sites in group I and 12 cleft sites in group II. Within the 24-month follow-up period, spontaneous eruption of canines had occurred; 5 teeth in group I (50%) and 5 teeth in group II (42%). The tooth eruption had been assisted by orthodontic force in three teeth in group I (30%) and two teeth in group II (17%). The spontaneous eruption of canines was demonstrated by serial occlusal radiographs ( Fig. 3 ). The status of the teeth moved by orthodontic appliances is shown in Fig. 4 .
