Onlay Block Grafts Research Articles

Immunological aspects of fresh‐frozen allogeneic bone grafting for lateral ridge augmentation

To present some immunological aspects of fresh-frozen allogeneic bone grafting for lateral bone augmentation, based on the quantitative evaluation of IL-10, IL-1β, IFN- γ and TNF- α in patients sera. Thirty-three partially or totally edentulous patients received fresh-frozen allogeneic bone (AL - 20 patients) or autologous bone onlay block grafts (AT - 13 patients) prior to oral implant placement. Blood samples were collected from each patient at various time-points during a 6month-period (baseline, 14, 30, 90 and 180days postoperatively). Quantitative evaluation of IL-10, IL-1β, IFN- γ and TNF- α was performed by enzyme linked immunosorbent assay (ELISA). For all evaluated markers and at all evaluated periods, inter-group comparisons showed no statistically significant differences between the groups, while the observed values were within normal levels. For AL-treated patients, intra-group evaluation showed statistically significant increase of TNF-α from baseline to 90 (P<0.001) and 180 (P<0.01) days, and from 14 to 90 (P<0.01) and 180 (P<0.05) days. IFN- γ showed intercalated results, with a decrease from baseline to 14days (P<0.05), and increase from 14 to 90days (P<0.001) and 180 (P<0.05) days. No differences between the periods of evaluation were found for the AT group. AL grafting for lateral bone augmentation, similar to AT grafting, does not seem to challenge the immune system significantly.

Stability Evaluation of Implants Integrated in Grafted and Nongrafted Maxillary Bone: A Clinical Study from Implant Placement to Abutment Connection

Clinical studies have shown a higher degree of implant failures in grafted bone compared with normal nongrafted maxillary bone. Additionally, a prolonged time for integration of titanium implants in grafted block bone has been shown by means of resonance frequency analysis (RFA). The aim of this prospective study was to compare the stability of implants placed in particulate bone, onlay block bone, interpositional bone, and nongrafted maxillary bone during the early phase of osseointegration using RFA and implant failure. Thirty-five patients with edentulism in the maxilla were included in the study. In all, 260 Astra Tech TiOblast implants (Astra Tech AB, Mölndal, Sweden) were installed. Twenty-five of these patients had severe maxillary atrophy and were treated with iliac bone grafts 5 to 6 months prior to implant placement, 19 with lateral onlay block grafts on one side (group A, 38 implants) and particulate bone for lateral augmentation on the other (group B, 38 implants). These 19 patients also got bilateral sinus floor augmentation with particulate bone (group C, 76 implants). Six patients had an unfavorable sagittal relation between the jaws and underwent a LeFort I operation with interpositional bone blocks grafted to the nasal and sinus floors (group D, 48 implants). The remaining 10 patients could be treated with implants without bone augmentation and served as control (group E, 60 implants). RFA was performed at implant placement and abutment connection 6 months later and an implant stability quotient (ISQ) value was given for each implant. Four implants (1.5%) were found mobile at abutment connection and removed (two in group A and two in group D). RFA showed a slight increase in stability from installation to abutment connection but the differences were not statistically significant in any of the groups (Wilcoxon signed rank test for comparison of paired data). Implants installed in group D had a significantly lower ISQ value at both measurements compared with the other groups (Wilcoxon Rank Sum test for comparisons of independent samples, p = .05). It is concluded that TiO(2)-blasted implants placed in nongrafted and grafted maxillary bone using a two-staged protocol show similar stability during the early phase of osseointegration. Patients reconstructed with interpositional bone graft after a LeFort I osteotomy showed lower implant stability values than nongrafted patients and other grafting techniques.

Cone Beam Computed Tomographic Evaluation of a Maxillary Alveolar Ridge Reconstruction With Iliac Crest Graft and Implants

The present article discusses an atrophic maxilla reconstruction with iliac crest bone block and particulate grafts and dental implants. Onlay block grafts were used to restore bone volume of the anterior maxilla, whereas bilateral sinus floor augmentation was performed using a particulate graft. Ten months after the grafting surgery, 9 dental implants were placed to rehabilitate the case. Results of a 7-year follow-up were obtained clinically and by cone beam computed tomographic images.

Fate of autologous and fresh‐frozen allogeneic block bone grafts used for ridge augmentation. A CBCT‐based analysis

To evaluate dimensional changes in autologous (AT) and fresh-frozen allogeneic (AL) block bone grafts 6months after alveolar ridge augmentation. Twenty-six partially or totally edentulous patients treated either with fresh-frozen AL bone or AT bone onlay block grafts prior to implant placement (13 patients in each group), were included in this analysis. Patients received CBCT (i-CAT Classic) examinations prior to surgery and 14days and 6months after grafting. Differences in alveolar ridge area among the various observation times were evaluated by planimetric measurements on two-dimensional CBCT images of the grafted regions. Nineteen grafted blocks from each group were evaluated. Significant increase in alveolar ridge dimensions, allowing implant placement, was obtained with both types of grafts 6months after grafting; no significant differences in alveolar ridge area were observed between the groups at the various observation times. However, graft resorption in the AL group was significantly larger compared to that in the AT group at 6months. Larger bone graft resorption was seen in patients treated with fresh-frozen AL bone than in those treated with AT bone 6months following alveolar ridge augmentation.

Use of resorbable screws for autogenous onlay block graft fixation: a histological analysis in rabbits

Use of resorbable screws for autogenous onlay block graft fixation: a histological analysis in rabbits

Bone Remodeling in Onlay Beta-Tricalcium Phosphate and Coral Grafts to Rat Calvaria: Microcomputerized Tomography Analysis

This study was conducted to establish the efficiency of microcomputerized tomography (micro-CT) in detection of trabecular bone remodeling of onlay grafts in a rodent calvaria model, and to compare bone remodeling after onlay grafts with beta-tricalcium phosphate (TCP) or coral calcium carbonate. Ten rats received calvarial onlay blocks-5 with TCP and 5 with coral calcium carbonate. The grafts were fixed with a titanium miniplate screw and were covered with a collagen resorbable membrane. Three months after surgery, the calvaria were segmented, and a serial 3-dimensional micro-CT scan of the calvarium and grafted bone block at 16-micrometer resolution was performed. Image analysis software was used to calculate the percentage of newly formed bone from the total block size. Newly formed bone was present adjacent to the calvarium and screw in all specimens. The mean area of newly formed bone of the total block size ranged from 34.67%-38.34% in the TCP blocks, and from 32.41%-34.72% in the coral blocks. In the TCP blocks, bone remodeling was found to be slightly higher than in the coral blocks. Micro-CT appears to be a precise, reproducible, specimen-nondestructive method of analysis of bone formation in onlay block grafts to rat calvaria.

The efficacy of a double‐layer collagen membrane technique for overlaying block grafts in a rabbit calvarium model

To analyze the outcomes of a single- and a double-layered collagen membrane on the efficacy of onlay block grafts in terms of bone resorption and augmentation. A total of 36 New Zealand white rabbits were used in this study. Calvarial bone blocks were obtained from one side of the parietal bone and fixed on the contaralateral side. The onlay grafts were covered with either no (C group), one (M1 group), or two (M2 group) layers of a non-cross-linked collagen membrane (BioGide((R))). After 2, 4, and 6 months of healing, rabbits were sacrificed and explanted specimens were prepared for histologic and histomorphometric analysis. At each period, the overall pattern of graft bone resorption and membrane biodegradation were examined histologically, and the sustained external form of grafted bone (%) and the remaining mineralized bone volume (%) were measured histomorphometrically. The M1 and M2 groups exhibited decreased bone resorption compared with the C group at all periods. The M2 group had less graft resorption and a higher bone density of the grafted bone than the M1 group. In the M1 group, the collagen membrane was degraded partially or completely by 4 months and was absent at 6 months. Conversely, for the M2 group, the membrane body was retained up to 6 months. Our results demonstrated that the collagen membrane used here can reduce graft bone resorption. Furthermore, the double-layer technique using non-cross-linked collagen membranes (BioGide((R))) can enhance the efficacy of the onlay block bone graft technique in terms of both bone resorption and augmentation compared with a single-layer collagen membrane.

Reconstruction of the Severely Resorbed Maxilla with Autogenous Bone, Platelet-Rich Plasma, and Implants: 1 -Year Results of a Controlled Prospective 5-Year Study

Prosthetic treatment of the edentulous maxilla may require bone augmentation to enable placement and integration of dental implants. This constitutes a complex healing situation, and resorption of the grafted bone and failure of the implants often occur. The application of autogenous platelet-rich plasma (PRP) has been suggested to improve incorporation and preservation of bone grafts. The aim of this controlled clinical study was to evaluate whether PRP in conjunction with grafting of particulated autogenous bone to the maxilla could improve the integration and clinical function of dental implants. An additional aim was to compare block bone grafts without PRP with PRP-treated particulated bone. Nineteen consecutive patients were included in the study and treated with iliac bone grafts and dental implants in the maxilla according to a split-mouth design. In the anterior maxilla, particulated bone mixed with PRP (test) was compared with onlay block grafts without additional PRP (control). In the posterior maxilla, particulated bone grafts with (test) or without (control) PRP were placed as sinus inlay grafts. After 6 months of healing, 152 implants (8 implants/patient) (TiOblast, Astra Tech AB, Mölndal, Sweden) were placed. Test (PRP; 76 implants) and non-PRP (76 implants) sides were evaluated and compared by implant survival rate, marginal bone level, and implant stability using resonance frequency analysis (RFA) during 1 year in function. Two control implants in control sites in two patients were lost at abutment connection. After 1 year in function, no further implants were lost, giving an overall survival rate of 98.7%. The marginal bone level measurements showed no significant differences, although there was a tendency toward less resorption on PRP sides. RFA measurements showed statistically significantly higher implant stability quotient values for PRP sites at abutment connection in the anterior but not in the posterior regions. The present clinical study showed that a high implant survival rate and stable marginal bone conditions can be achieved after 1 year of loading in the maxilla following autogenous bone grafting whether or not PRP is used. RFA measurements revealed differences at abutment connection, which could be explained by the type of graft rather than as an effect of PRP. Although no obvious positive effects of PRP on bone graft healing could be demonstrated, the handling of the particulated bone grafts was improved.