Particulate Xenograft Research Articles

Horizontal Bone Augmentation Using Autogenous Block Grafts and Particulate Xenograft in the Severe Atrophic Maxillary Anterior Ridges: A Cone-Beam Computerized Tomography Case Series

The aim of the present study was to use cone-beam computerized tomography (CBCT) to assess horizontal bone augmentation using block grafts, harvested from either the iliac crest (IC) or mandibular ramus (MR) combined with particulate xenograft and a collagen membrane for in the severe maxillary anterior ridge defects (cases Class III-IV according to Cadwood and Howell's classification). Fourteen healthy partially edentulous patients requiring extensive horizontal bone reconstruction in the anterior maxilla were selected for the study. Nineteen onlay block grafts (from IC or MR) were placed. The amount of horizontal bone gain was recorded by CBCT at 3 levels (5, 7, and 11 mm from the residual ridge) and at the time of bone grafting as well as the time of implant placement (≈5 months). Both block donor sites provided enough ridge width for proper implant placement. Nonetheless, IC had significantly greater ridge width gain than MR (Student t test) (4.93 mm vs 3.23 mm). This was further confirmed by nonparametric Mann-Whitney test (P = .007). Moreover, mean pristine ridge and grafted ridge values showed a direct association (Spearman coefficient of correlation = .336). A combination of block graft, obtained from the IC or MR, combined with particulate xenograft then covered with an absorbable collagen membrane is a predictable technique for augmenting anterior maxillary horizontal ridge deficiency.

Alterations in Bone Quality After Socket Preservation with Grafting Materials: A Systematic Review

While the ability of various grafting materials to preserve extraction socket morphology has been adequately reviewed, the quality of the grafted bone in the socket is not as well understood. This systematic review aimed to compare the proportion of vital bone and connective tissue between grafted and naturally healed sockets. An electronic search of five databases (from 1965 to November 2011) and a hand search of peer-reviewed journals for relevant articles were performed. Human clinical trials that compared histologic components of soft and hard tissues in augmented sockets and naturally healed sites, with at least five samples per group, were included. Eight studies (five randomized controlled trials and three controlled clinical trials) were included. The mean percentages of vital bone and connective tissue in natural healing sockets were 38.5% ± 13.4% and 58.3% ± 10.6%, respectively. Limited evidence (one to two articles for each material) implied that vital bone fraction was not different with demineralized allografts and autografts and increased by 6.2% to 23.5% with alloplasts in comparison to nongrafted sites. Four studies investigating the effect of xenografts were available, with equivocal results. The difference in the mean percentage of vital bone ranged from -22.2% (decrease) to 9.8% (increase). Connective tissue content decreased with the use of the aforementioned bone substitutes. Considerable residual hydroxyapatite and xenograft particles (15% to 36%) remained at a mean of 5.6 months after socket augmentation procedures. Based on a limited number of prospective comparative studies, the use of grafting materials for socket augmentation might change the proportion of vital bone in comparison to sockets allowed to heal without grafting. Whether these changes in bone quality will influence implant success and peri-implant tissue stability remains unknown.

Horizontal Augmentation of Thin Maxillary Ridge With Bovine Particulate Xenograft Is Stable During 500 Days of Follow-Up: Preliminary Results of 12 Consecutive Patients

The purpose of our evaluation was to determine the stability of the horizontal augmentation of the anterior maxilla using particulate bovine xenograft under a membrane. The hypothesis to be tested was that bovine particulate graft material is effective for augmenting the narrow ridge of the anterior maxilla and can maintain its augmentation dimension within 1 mm over time. A consecutive series of 12 patients who received a bovine particulate graft were evaluated in a retrospective manner. Using a standardized method, their cone beam scans were measured for width at 3 vertical locations preoperatively (T0), immediately after the augmentation (T1), 3 to 6 months after augmentation and before implant placement (T2), immediately after implant placement (T3), and at the longest postoperative point (T4). One examiner, who was not involved in the surgical procedures, measured all the radiographs. The intraexaminer error approximated 0.2 mm in all areas of measurements. A linear mixed effects model was used to determine the stability of the augmentation over time. The most coronal aspect of the crest had the least width augmentation. The midway region and apical region had the greatest width changes (P < .001). Within the sample size, there were no statistically significant differences in width changes over time after augmentation was performed. Within the limitations of this sample, horizontal ridge augmentation using bovine particulate material under a membrane was stable over time in the anterior maxilla.

Xenograft Bone Inclusion Improves Incorporation of Hydroxyapatite Cement Into Cancellous Defects

Hydroxyapatite cement (HAC) is biocompatible and osteoconductive, but its slow resorption limits new bone formation. The purpose of this investigation was to determine the effects of adding partially demineralized xenograft cortical bone in an established animal model. Eight 6-month-old female New Zealand white rabbits were used. Drill-hole defects (8.0 mm long, 5.0 mm diameter) were prepared and filled with either HAC alone or HAC mixed with processed xenograft bone particles from young pigs (XBC) at a volumetric ratio of approximately 25%. The particles were approximately 5 mm long and 1 mm diameter and were extensively washed, demineralized in dilute hydrochloric acid, and rewashed. Microcomputed tomography scanning and histology were performed after 10 weeks. New bone and inflammatory/immune response were graded on a 0 to 3 scale and calcein labeling was quantified as percent area new bone. Statistical analyses were by Student's t tests. XBC showed significantly more new bone formation than HAC throughout the defect (P < 0.05). XBC also showed significantly more inflammatory/immune response than HAC (P < 0.05). The three-dimensional microcomputed tomography reconstructions showed that the HAC was basically inert, whereas the XBC took on an appearance suggestive of more extensive incorporation. Adding xenograft to HAC creates a bioactive composite that is more rapidly incorporated, resorbed, and replaced by new bone. The presence of processed xenograft particles creates a vigorous inflammatory response, but there may be some benefit to the resorption rate of the HAC as a result of the infiltration of cells. Future research should focus on the longer-term incorporation and remodeling of XBC.

Clinical and Histologic Evaluation of a Granular Bovine Bone Biomaterial Used as an Adjunct to GTR With a Bioresorbable Bovine Pericardium Collagen Membrane in the Treatment of Intrabony Defects

The aim of the present study is to evaluate the clinical and histologic healing of deep intrabony defects treated with guided tissue regeneration (GTR) with a collagen membrane from bovine pericardium and implantation of granular bovine bone biomaterial. Thirty patients with one deep, combined 1- and 2-wall intrabony defect exhibiting a probing depth ≥6 mm and an associated intrabony defect ≥3 mm were treated with GTR with a bioresorbable collagen membrane from bovine pericardium and adjunct implantation of a granular bovine bone biomaterial. The clinical results were evaluated 1 and 3 years after surgery. In addition, five teeth fulfilling the inclusion criteria but scheduled for extraction because of advanced periodontitis or restorative considerations were treated similarly and then extracted along with a portion of their surrounding periodontal tissues for histologic evaluation 6 months after surgery. Healing was uneventful in all patients. Significant clinical improvements were observed at 1 and 3 years postoperatively (P <0.01; probing depth averaged 4.4 ± 1.6 and 4.7 ± 1.4 mm and clinical attachment level gain was 3.9 ± 1.4 and 3.5 ± 1.3 mm, respectively). The histologic evaluation revealed formation of new cellular cementum and new periodontal ligament in four of the five cases. In general, the xenograft particles seemed to be mostly embedded in connective tissue without any evidence of new bone formation. GTR treatment of intrabony defects with the collagen membrane from bovine pericardium and adjunct implantation of the new bovine bone biomaterial may result in significant clinical improvements that can be maintained over a period of 3 years, and regeneration of cementum and periodontal ligament, but without bone formation.

Evaluation of the Long-Term Results of Rat Cranial Bone Repair Using a Particular Xenograft

Bone defects that cannot be healed completely are termed critical-sized defects and can be used to test bone grafts for medicine, dentistry, and periodontology. The aim of the present study was to detect the effects of a xenograft (Unilab Surgibone) on bone building in experimentally created parietal bone defects in rats. Standardized parietal bone defects were created in 16 rats, and each defect had a circular morphology 6 mm in diameter. The right defect sites were filled with porous particle material, and the left site was used as control. After the 3rd, 6th, and 12th months, rats were killed and tissue samples obtained from the related site of the cranium. Subsequently, histological sections were taken and stained with different stains for evaluation under light microscope. The rate of bone formation was assessed using a semiquantitative method. These results showed that dense collagenous tissue was observed in the control area during the third month, whereas xenograft particles were surrounded by a fibrous tissue layer at the implantation site. Osteoclast-like cells were also observed. There was also no significant bone repair at other observation periods. It can be concluded that the material used had no evidence of resorption and does not enhance bone formation. However, it seems biocompatible, osteoconductive, and could be used in a limited manner as a material for filling osseous defects in clinical practice.

The bone-healing effect of a xenograft in a rat calvarial defect model

Bone grafts have been widely used to fill osseous defects in medicine, dentistry, and periodontology. The purpose of this study was to investigate the effects of a xenograft (Unilab Surgibone) on experimentally created parietal bone defects in rats. To this end, 14 rats were employed in the present study and in each of them, 5-mm-diameter defects were created on the parietal bone. The right defect sites were filled with the xenograft material, while the left sites were used as control. After 30 days, the rats were sacrificed and tissue samples were retrieved from the defect sites of the cranium. Dense collagenous tissue was observed in the control area, whereas the xenograft particles were surrounded by a fibrous tissue layer at the implantation site. Based on the findings obtained, it could be concluded that the investigated xenograft seemed biocompatible and could be proposed as a potential material for filling osseous defects.

Natural Bovine Anorganic Apatite and Collagen Presents Osteoconductivity and Contribute to Bone Repair of Rat Calvaria Critical Size Defect

The aim of this study was verify the biological efficacy of the use of a xenograft for bone loss therapy. Blood clot, particulate autogenous bone or anorganic bovine xenograft filled critical size defects (CSD) in rat calvaria (8mm diameter). After 0, 7, 30 and 90 days the animals were killed and macroscopic, radiographic and histopathological analysis were conducted. Although no treatment promoted the total closure of bone defect, autogenous bone group had better bone repair after 90 days, followed by xenograft group that exhibited direct bone neoformation onto, and around, the particles confirming its osteoconductivity. In conclusion, the xenograft tested in vivo showed biocompatibility, biodegradability and osteoconductive properties in rat calvaria CSD.

Use of Engineered Bone for Sinus Augmentation

Tissue-engineered bone grafts represent an appealing alternative for maxillary sinus augmentation because they eliminate the significant drawbacks associated with extra- and intraoral bone-harvesting procedures. In the present case series, we document the outcomes of sinus augmentation surgery using tissue-engineered bone grafts. Three patients requiring bilateral sinus augmentation received tissue-engineered bone grafts combined with xenograft prior to implant placement. Implants were placed and loaded 6 and 12 months postaugmentation, respectively. Radiographs were taken and clinical examinations were performed preoperatively and at 4, 6, 12, and 18 months postaugmentation. Biopsies were obtained at 4 and 6 months postaugmentation. Standardized orthopantomograms were used to measure the posterior maxilla bone height. None of the patients experienced untoward complications during or following the therapeutic procedures. Ten implants were inserted into the augmented sinuses and loaded. Biopsies revealed a lack of inflammation or pathology; newly formed fibrous bone with osteoblastic activity and xenograft particles was evident. Compared to 4 months postaugmentation, augmented tissue was more mature at 6 months. The postoperative (18 months) bone height in augmented areas was significantly greater than the preoperative height (P <0.0001), representing an approximately 4.5-fold increase in bone height. Sinus augmentation using tissue-engineered bone grafts was successful in all three cases, permitting the subsequent insertion and loading of dental implants. The present cases demonstrated the feasibility of using engineered bone for sinus augmentation. Controlled clinical trials will be required to evaluate this new and evolving treatment modality.