Clinical and Histologic Observations of Sites Implanted With Intraoral Autologous Bone Grafts or Allografts. 15 Human Case Reports

The cases reported in this paper were treated at 7 different clinical centers and present clinical and histologic observations from 15 patients and 21 human biopsies. The biopsies were taken from extraction sockets or dental implant sites which were grafted with either autologous intra-oral bone (6 sites), demineralized freeze-dried bone (DFDBA) (7 sites), or mineralized freeze-dried bone (MFDBA) (7 sites), or a combination of autologous bone, DFDBA and a barrier membrane (1 site). Six sites were grafted with DFDBA and augmented with expanded polytetrafluoroethylene (ePTFE) barrier membranes. Biopsies for histological evaluation were taken 4 to 13 months after implantation. A bone scoring system of 0 to 4 was used to evaluate the sections for dead implanted particles or the presence of vital bone. A bone score of 3 indicated the presence of dead implant material, blood vessels, islands of cartilage, osteoblasts, and new bone formation. A score of 4 indicated total replacement of the implanted material by the host bone. The average bone score for sites which received autologous bone was 2.33; for DFDBA sites, 0.98; and MFDBA was 0.18. The over-riding histologic characteristic of sites implanted with DFDBA or MFDBA was retention of non-vital graft particles within fibrous connective tissue. Biopsies taken adjacent to the host bed demonstrated incorporation of the allografts (osteoconduction). Sites grafted with autologous bone chips also demonstrated non-vital bone chips surrounded by vital host bone (osteoconduction). Sites which received barrier membranes did not appear to improve or impair bone healing of the augmented sites. Autologous bone chips harvested from within the oral cavity as well as allografts may serve as biologic fillers, but do not apparently contribute to osteoinduction. Autologous bone will eventually be resorbed and replaced by the host. DFDBA and MFDBA are resorbed very slowly and apparently do not contribute to osteoinduction. Allografts apparently are not resorbed by osteoclasts and therefore their continued use around dental implants is questioned. J Periodontol 1996;67:1025–1033.     

Demineralization of the Contacting Surfaces in Autologous Onlay Bone Grafts Improves Bone Formation and Bone Consolidation

Background: Autologous bone grafts are usually well consolidated after 4 to 5 months but can be incompletely interlocked with the native bone. This study investigated the effect of acid demineralization of the graft–bed interface on graft consolidation. Methods: Onlay bone grafts were performed on the calvaria of 36 guinea pigs. Half of the animals had the graft–bed contacting surfaces demineralized with 50% citric acid (pH 1.0) for 3 minutes (test group). The other half received no demineralization (control group). The bone grafts were immobilized by a resorbable membrane glued to the recipient bed with cyanoacrylate. After 7, 30, and 90 days, specimens (n = 6) were obtained for light microscopy. Data from qualitative analysis and computerized histomorphometry were statistically processed at a significance level of 5%. Results: Osteogenesis was not seen at the interface after 7 days. After 30 days, the test group showed 34.39% ± 13.4% of the interface area filled with mineralized tissue, compared to 17.14% ± 8.6% in the control group (P = 0.026). After 90 days, the mean percentages of mineralized tissue at the interface in the test and control specimens were 54.00% ± 11.23% and 38.65% ± 7.76% (P = 0.041), respectively. Within groups, a higher percentage of the area filled with mineralized tissue was seen at 90 days compared to 30 days (P = 0.004 for control and 0.041 for test). Conclusions: Demineralization of the contacting surfaces between autologous bone graft and bone bed improved new bone formation and bone consolidation. These data need to be confirmed in humans.     

Reconstruction of Severely Atrophied Alveolar Ridges with Calvarial Onlay Bone Grafts and Dental Implants

Objective: Severely atrophied alveolar ridges are most commonly reconstructed with free autologous bone grafts from the iliac crest. The use of these grafts, however, is frequently associated with bone resorption as possible late complication after implant surgery and prosthetic loading. Other donor sites, especially intraoral donor sites, show limited availability. The aim of this present study was to evaluate the clinical and radiographical outcome of alveolar ridge reconstruction with bone from the calvarium and subsequent implant rehabilitation. Patients and Methods: Reconstruction was performed by using calvarial split grafts in case of severe and complex alveolar ridge defects induced by trauma or bone atrophy. Fifteen patients were treated at 19 different intraoral recipient sites (15 sites in the maxilla, four in the mandible). Autologous block grafts were used for combined vertical and horizontal grafting. After a 3‐month healing period, patients received dental implants. A total of 99 dental implants (OsseoSpeed?, Astra Tech AB, Mölndal, Sweden) were inserted and left to heal in a submerged position for 3 months before the prosthetic implant‐based rehabilitation was performed. Results: No donor site complications occurred during or after surgery. At the intraoral recipient sites two infections occurred, leading to partial loss of the grafts. Implant placement, however, was possible in all cases. Two of 99 implants were lost in two patients prior to prosthetic loading. Patients were followed up clinically and radiographically for an average observation period of 28 months. Implant survival rate and success rates were 97.85 and 95.7%, respectively, and a minimal marginal bone loss was documented. Discussion: The low morbidity at the donor sites and the good marginal bone stability in the reconstructed regions indicate that calvarial bone grafts represent a viable treatment alternative to grafts from the iliac crest.     

Inlay versus Onlay Iliac Bone Grafting in Atrophic Posterior Mandible: A Prospective Controlled Clinical Trial for the Comparison of Two Techniques

Purpose: To compare the efficacy of inlay and onlay bone grafting techniques in terms of vertical bone formation and implant outcomes for correcting atrophic posterior mandibles.
Materials and Methods: Twenty surgical sites were assigned to two treatment groups, inlay and onlay, with iliac crest as donor site. After 3 to 4 months, 43 implants were placed and loaded 4 months later. The median follow up after loading was 18 months.
Results: For the inlay versus onlay group, median bone gain was 4.9 versus 6.5 mm ( p  = .019), median bone resorption was 0.5 versus 2.75 mm ( p  < .001), and median final vertical augmentation was 4.1 versus 4 mm ( p  = .190). The implant survival rate was 100% in both groups, while the implant success rate was 90% versus 86.9% ( p  = .190, not significant). A minor and major complication rate of 20% and 10%, respectively, for both groups was encountered.
Conclusions: Inlay results in less bone resorption and more predictable outcomes, but requires an experienced surgeon. In contrast, onlay results in greater bone resorption and requires a bone block graft oversized in height, but involves a shorter learning curve. Once implant placement has been carried out, the outcomes are similar for both procedures.     

Implants in Reconstructed Bone: A Comparative Study on the Outcome of Straumann® Tissue Level and Bone Level Implants Placed in Vertically Deficient Alveolar Ridges Treated by Means of Autogenous Onlay Bone Grafts

Purpose: To evaluate: (1) the survival rate of Straumann® Tissue Level and Bone Level implants placed in atrophic edentulous jaws previously reconstructed by means of autogenous onlay bone grafts; (2) to compare peri‐implant bone resorption values over time. Materials and Methods: From 2005 to 2010, 50 patients presenting with vertical or tridimensional defects of the edentulous ridges were treated with autogenous bone grafts. Three to 7 months afterward, 192 implants were placed (Group A: 97 Tissue Level implants; Group B: 95 Bone Level implants) in the reconstructed areas. After a further waiting period of 2 to 3 months, patients were rehabilitated with implant‐supported fixed prostheses. The follow‐up ranged from 12 to 68 months after the start of prosthetic loading (mean: 33 months). Results: No implants were removed (survival rate: 100%), but in Group B 13 implants (8 placed in iliac grafts, 2 placed in ramus grafts, and 3 placed in calvarial grafts) presented peri‐implant bone resorption values higher than those proposed by Albrektsson and colleagues. for successful implants: the overall implant success rate was then 100% for Group A and 86.8% for Group B. No prosthetic failures were recorded, thus leading to a 100% prostheses success rate. Conclusion: No significant differences were found between the two types of implants as far as implant survival rate is concerned, but results from this study seem to demonstrate that Tissue Level implants may present better long‐term results in terms of peri‐implant bone maintenance, as compared with Bone Level implants, when placed in reconstructed areas.