Xenogeneic Grafts Research Articles

How we do it—the use of peritoneal patches for reconstruction of vena cava inferior and portal vein in hepatopancreatobiliary surgery

PurposeExtended resections in hepatopancreatobiliary (HPB) surgery frequently require vascular resection to obtain tumor clearance. The use of alloplastic grafts may increase postoperative morbidity due to septic or thrombotic complications. The use of suitable autologous venous interponates (internal jugular vein, great saphenous vein) is frequently associated with additional incisions. The aim of this study was to report on our experience with venous reconstruction using the introperative easily available parietal peritoneum, focusing on key technical aspects.MethodsAll patients who underwent HPB resections with venous reconstruction using peritoneal patches at our department between January 2017 and November 2021 were included in this retrospective analysis with median follow-up of 2 months (IQR: 1–8 months). We focused on technical aspects of the procedure and evaluated vascular patency and perioperative morbidity.ResultsParietal peritoneum patches (PPPs) were applied for reconstruction of the inferior vena cava (IVC) (13 patients) and portal vein (PV) (4 patients) during major hepatic (n = 14) or pancreatic (n = 2) resections. There were no cases of postoperative bleeding due to anastomotic leakage. Following PV reconstruction, two patients showed postoperative vascular stenosis after severe pancreatitis with postoperative pancreatic fistula and bile leakage, respectively. In patients with reconstruction of the IVC, no relevant perioperative vascular complications occurred.ConclusionsThe use of a peritoneal patch for reconstruction of the IVC in HPB surgery is a feasible, effective, and low-cost alternative to alloplastic, xenogenous, or venous grafts. The graft can be easily harvested and tailored to the required size. More evidence is still needed to confirm the safety of this procedure for the portal vein regarding long-term results.

Bovine-derived xenograft is a viable bone graft substitute in multilevel, instrumented, spinal fusion.

To evaluate radiological outcomes following the use of xenogeneic bone graft substitute (BGS) in patients undergoing multisegmental spinal fusion. Data exists for single level and short segment fusions, there presently is a paucity of data on fusion rate after bone augmentation with BGS in multisegmental posterior spinal fusion (PSF). The leading concern is pseudarthrosis, which often leads to a loss of correction after PSF. Therefore, the bone graft is an essential aspect of PSF. We retrospectively analysed the radiological data of a consecutive cohort of patients who had been treated for adolescent idiopathic scoliosis (AIS) via multisegmental spinal fusion, in whom a bovine derived BGS had been used and had a complete dataset of 24 months follow-up. The Cobb angle of the main curve was measured pre-operatively and then at 6, 12 and 24 months post-operatively. Loosening of the screws was recorded at the same post-operative time points. After applying inclusion and exclusion criteria, 28 patients were included. We found no significant change of the cobb angle from the main curve as well as the cobb angle from the thoracic kyphosis during the 24 months of follow up. No patient showed a lack of bony fusion. There was 1 revision surgery, which was due to trauma. In this cohort, all patients showed successful bone fusion during a 24-month follow-up. Additionally, there was no change in the Cobb angle during the 2-year post-operative period. Our data indicates that the use of bovine-derived BGS supports bone fusion after multisegmental posterior instrumented fusion of the spine.

Development of an acellular nerve cap xenograft for neuroma prevention.

Neuroma formation following limb amputation is a prevalent and debilitating condition that can deeply affect quality of life and productivity. Several approaches exist to prevent or treat neuromas; however, no approach is either consistently reliable or surgically facile, with high rates of neuroma occurrence and/or recurrence. The present study describes the development and testing of a xenogeneic nerve cap graft made from decellularized porcine nerve. The grafts were tested in vitro for cellular removal, cytotoxicity, mechanical properties, and morphological characteristics. The grafts were then tested in rat sciatic nerve gap reconstruction and nerve amputation models for 8 weeks. Gross morphology, electrophysiology, and histopathology assessments were performed to determine the ability of the grafts to limit pathologic nerve regrowth. In vitro testing showed well decellularized and demyelinated nerve cap graft structures without any cytotoxicity from residual reagents. The grafts had a proximal socket for the proximal nerve stump and longitudinally oriented internal pores. Mechanical and surgical handling properties suggested suitability for implantation as a nerve graft. Following 8 weeks in vivo, the grafts were well integrated with the proximal and distal nerve segments without evidence of fibrotic adhesions to the surrounding tissues or bulbous outgrowth of the nerve. Electrophysiology revealed absence of nerve conduction within the remodeled nerve cap grafts and significant downstream muscle atrophy. Histologic evaluation showed well organized but limited axonal regrowth within the grafts without fibrous overgrowth or neuromatous hypercellularity. These results provide proof of concept for a novel xenograft-based approach to neuroma prevention.

Alveolar Ridge Preservation after Tooth Extraction and Replacement with Fibre-reinforced Composite Bridge in a Young Patient: A Case Report

Alveolar ridge preservation is a surgical procedure aimed to preserve the alveolar bone after tooth extraction to eliminate or reduce the need for bone augmentation during implant placement. It includes the use of membrane that is either being used alone or in combination with a bone replacement graft. This case report describes the technique of alveolar ridge preservation after tooth extraction using a xenogenic bone graft combined with a resorbable collagen membrane, and the fabrication of an anterior fibre-reinforced composite (FRC) bridge in an 18-year-old male patient. This treatment allows him to have a good preservation of the volume and architecture of the alveolar ridge as well as soft tissues and temporarily replace a missing anterior tooth until a definitive restoration can be achieved.

Доклиническая оценка эффективности и безопасности нового костнопластического материала ксеногенного происхождения, содержащего в своем объеме ванкомицин и меропенем

Bone xenomatrix is an available material for plasty due to its availability and possible significant modification. The purpose was comparative evaluation of the efficacy and safety of xenogenic bone graft material impregnated with antibiotics, vancomycin or meropenem, in an experiment on a model of long bone defect healing in rabbits. Methods The study was performed on 28 male rabbits aged from 8 months to 1.2 years. All animals were modeled with a cavity defect of the right and left distal femoral metaphysis measuring 4 × 4 × 6 mm. Bone matrix blocks of the same size were implanted into the defect cavity. Animals of group 1 (n = 8, control) were implanted with a free “clean” bone block. Animals of group 2 (n = 10) with a bone block saturated with vancomycin. Animals of group 3 (n = 10) with a bone block impregnated with meropenem. To assess the effectiveness and safety of the material, clinical, radiological, pathomorphological, histological, and laboratory methods were used. Results X-ray signs of substitution of the studied materials in the defect in animals of group 1 were noted by 182 days, in group 2 – by 84 days, in group 3 – about 182 days. In each group, there was a complication, arthrosis of the knee joint (one animal in each group). According to the histological study, it was found that in groups 2 and 3, a complete elimination of xenomaterial in the middle part of the defect and its replacement with trabecular bone was noted by 182 days after implantation. The severity of irritating action of the materials in the animals of groups 2 and 3 did not exceed the control value. The laboratory blood tests in the animals of groups 2 and 3 also did not reveal significant differences with group 1. Conclusion The developed osteoplastic materials based on bovine bone xenomatrix, impregnated with vancomycin or meropenem, have acceptable safety and efficacy characteristics.

Influence of Xenogeneic and Alloplastic Carriers for Bone Augmentation on Human Unrestricted Somatic Stem Cells.

Alloplastic and xenogeneic bone grafting materials are frequently used for bone augmentation. The effect of these materials on precursor cells for bone augmentation is yet to be determined. The aim of this study was to ascertain, in vitro, how augmentation materials influence the growth rates and viability of human unrestricted somatic stem cells. The biocompatibility of two xenogeneic and one alloplastic bone graft was tested using human unrestricted somatic stem cells (USSCs). Proliferation, growth, survival and attachment of unrestricted somatic stem cells were monitored after 24 h, 48 h and 7 days. Furthermore, cell shape and morphology were evaluated by SEM. Scaffolds were assessed for their physical properties by Micro-CT imaging. USSCs showed distinct proliferation on the different carriers. Greatest proliferation was observed on the xenogeneic carriers along with improved viability of the cells. Pore sizes of the scaffolds varied significantly, with the xenogeneic materials providing greater pore sizes than the synthetic inorganic material. Unrestricted somatic stem cells in combination with a bovine collagenous bone block seem to be very compatible. A scaffold’s surface morphology, pore size and bioactive characteristics influence the proliferation, attachment and viability of USSCs.

Histologic Evaluation of the Effect of Mecsina Hemostopper on Bone Regeneration for Critical-Size Defects.

Acceleration of the bone healing period and/or increasing the quality of newly formed bone still have great importance in the field of oral and maxillofacial surgery. The aim of this study was to evaluate the effect of isolated liquid Mecsina (herbal extract) and its combination with xenogeneic graft material (bovine bone graft) on bone regeneration. Full-thickness critical-size defects with 10-mm diameter and 2-mm depth were created on the calvarial bone region in 28 Sprague Dawley male rats. Four groups were generated: Mecsina Hemostopper, Mecsina Hemostopper + graft group, only graft group, and empty control group. On the 28th day following surgery, all animals were sacrificed. The calvarial samples were evaluated both histopathologically and histomorphometrically. According to the histopathologic evaluation result, vascular proliferation was significantly higher in the groups in which Mecsina Hemostopper was used as a single material or in combination with graft material (P < .05). Histomorphometric evaluation showed that trabecular and osteoid thickness were significantly higher in all Mecsina application groups (P < .05). Mecsina Hemostopper was found to be an effective agent in increasing cell proliferation and providing more qualified bone formation. The combination of Mecsina and xenogeneic bone graft was found to be one of the most effective augmentation options for critical-size defects in rats. Mecsina Hemostopper could be used to get more qualified bone formation clinically, but more clinical research is needed in the future.

Maxillary Sinus Floor Augmentation with Two Different Inorganic Bovine Bone Grafts: an Experimental Study in Rabbits.

To compare the sequential healing of maxillary sinuses grafted with two different xenogeneic bone substitutes processed at either a low (300°C) or high (1200°C) temperature. A sinus augmentation procedure was performed bilaterally in 20 rabbits and two different xenogeneic bone grafts were randomly used to fill the elevated spaces. Healing was studied after 2 and 10 weeks, in 10 rabbits during each period. After 2 weeks of healing, very small amounts of new bone were observed in both groups, and were mainly confined to close to the sinus bone walls and osteotomy edges. After 10 weeks of healing, new bone was found in all regions, with higher percentages in those close to the bone walls and to the osteotomy. In this period of healing, the proportion of new bone in the 300°C group was 20.0% ± 4.3%, and in the 1200°C group it was 17.2% ± 4.3% (P = 0.162). In the 1200°C group, translucent, dark fog-like shadows in regions of the grafts were hiding portions of new bone (interpenetrating bone network). Both biomaterials provided conditions that allowed bone growth within the elevated space, confirming that both biomaterials are suitable to be used as a graft for sinus floor augmentation.

EVALUATION OF THE EFFICIENCY OF SINUS LIFTING TECHNIQUES

Right after teeth extraction in posterior regions, there is a following process that consists of physiological resorption and nonfunctional atrophy of the remained alveolar bone ridge. That also impacts the quality on the quality and quantity of the remained bone tissue, what later makes the implant incorporation and the prosthetic restoration much harder and complicated than usual it is. In the posterior region of the upper jaw additional complication of the prosthetic restoration process causes the existing of paranasal sinus that is located right in the body of the upper jaw maxilla. It’s post extraction pneumatization reduces the height of bone tissue what causes difficulties in dental implants placement. The aim of this survey is to evaluate the clinical outcome and the efficiency of the most often used sinus lifting techniques. Were analyzed totally 78 published studies that were done in the last 12 years. The study is made on narrative review of published articles that were investigating the related subject. Research was done by using the most common data bases: NCBI (US National Library of Medicine), Emedicine, PubMEd, Webmd. By using the open method for sinus lifting there needs to be formed lateral window in the bone tissue first by elevating the mucoperiosteal flap on the vestibular surface of the maxillary alveolar ridge and after that creating iatrogenic fenestration on the cortical lamina without perforating the sinus membrane. After the sinus membrane is being separated, the following step is augmentation. For this step are used four different types of bone substituent: autogenous, allogeneic, xenogeneic bone graft and synthetic alloplastic materials. The closed method for sinus lifting is performed after previous created place for the future implant in the residual alveolar bone ridge in the maxilla, after that with special instruments a perforation is being made in the bone floor of the maxillary sinus and carefully elevating the sinus membrane up for a few millimeters. In the created space a bone graft material is being placed and at the same time a dental implant is being applied. From the gathered results, both of the techniques are considered to be effective, in all of the followed cases the implant placements were successful with high rate of postoperative osseointegration, the healing period was without complications and also successful. There was no prosthetic failure in any case. From this survey the final conclusion is that both of the techniques are successful when it comes to sinus lifting. Very important is to have a qualitative imaging like computed tomography or roentgen before placing the implants to be able to estimate the bone volume and height. If the residual bone height is less than 5 mm the survival rate of the future implants is not guaranteed.

Efficacy of concentrated growth factor versus collagen membrane in reconstructive surgical therapy of peri-implantitis: 3-year results of a randomized clinical trial

ObjectivesTo compare the 3-year clinical and radiographic outcomes of two different reconstructive surgical management of peri-implantitis using a bone substitute in combination with either concentrated growth factor (CGF) or collagen membrane (CM).Material and methodsFifty-one patients who had at least one implant presenting peri-implantitis with an intrabony defect were filled with a xenogenic bone grafting material and covered either CGF or CM. Clinical and radiographic assessments were carried out at baseline and postoperative years 1 and 3. Three different composite outcomes were defined to evaluate treatment success at a 3-year follow-up. The effects of possible prognostic indicators on treatment success were identified by using multilevel regression analysis.ResultsThe changes in probing depth (PD) and radiographic vertical defect depth (VDD) between baseline and year 1 and baseline and year 3 presented significantly greater decreases for the CM group in comparison with the CGF group (p < 0.05). No significant differences between the two treatment modalities were demonstrated regarding treatment success outcomes. History of periodontitis, VDD at baseline, and the number of intrabony defect walls revealed significant impacts on treatment success (p = 0.033; OR = 3.50, p = 0.039; OR = 0.975, and p = 0.024; OR = 7.0 and p = 0.019;OR = 6.0, respectively).ConclusionsCM in combination with a bone substitute seems to have slightly better outcomes compared to the CGF membranes in reconstructive surgical therapy of peri-implantitis. The history of periodontitis, baseline VDD, and peri-implant bone defect configuration could be possible predictors influencing treatment success.Trial registrationClinicalTrials.gov NCT04769609.Clinical relevanceFor the reconstruction of peri-implant bone defects, using a bone substitute in combination with a collagen membrane may show more favorable outcomes.

Clinical Reference Strategy for the Selection of Treatment Materials for Maxillofacial Bone Transplantation: A Systematic Review and Network Meta-Analysis.

Bone graft materials have mixed effects of bone repair in the field of oral maxillofacial surgery. The qualitative analyses performed by previous studies imply that autogenous odontogenic materials and autogenous bone have similar effects on bone repair in clinical jaw bone transplantation. This retrospective systematic assessment and network meta-analysis aimed to analyze the best effect of clinical application of autogenous odontogenic materials and autogenous, allogeneic, and xenogeneic bone grafts in bone defect repair. A systematic review was performed by searching the PubMed, Cochrane Library, and other journal databases using selected keywords and Medical Subject Headings search terms. 10 Papers (n = 466) that met the inclusion criteria were selected. The assessment of heterogeneity did not reveal any overall statistical difference or heterogeneity (P = 0.051 > 0.05), whereas the comparison between autogenous and allogeneic bone grafts revealed local heterogeneity (P = 0.071 < 0.1). Risk of bias revealed nine unclear studies and one high-risk study. The overall consistency was good (P = 0.065 > 0.05), and the local inconsistency test did not reveal any inconsistency. The publication bias was good. The confidence regarding the ranking of bone graft materials after GRADE classification was moderate. The effects on bone repair in the descending order were as follows: autogenous odontogenic materials, xenogeneic bone, autogenous bone, and allogeneic bone. This result indicates that the autogenous odontogenic materials displayed stronger effects on bone repair compared to other bone graft materials. Autogenous odontogenic materials have broad development prospects in oral maxillofacial surgery.

Production of a Low-Cost, Off-the-Shelf, Decellularized Cartilage Xenograft for Tissue Regeneration.

Reconstruction of cartilaginous deformities is a well-established surgical challenge with high levels of unpredictability and complication. Because of the morbidity associated with autologous cartilage grafting, combined with its limited supply and the significant expense of commercially decellularized allografts, increasing efforts have sought to produce an acellular, nonimmunogenic cartilage xenograft. We have developed and validated a novel protocol for high throughput decellularization of ovine costal cartilage with immediate translational potential for preclinical investigation of novel strategies for cartilaginous reconstruction. Floating ribs were isolated from freshly slaughtered rack of lamb and after cleaning, the ribs were either minced into 2-mm cubes or zested into 1-mm flakes. Tissue was then decellularized via a protocol consisting of 4 freeze/thaw cycles, digestion with trypsin, incubation in hyperosmolar and hypoosmolar salt solutions, with incubation in 1% Tween following both the hyperosmolar and hypoosmolar steps, a 48-hour incubation in nucleases, DNA elution via EDTA, and 2 terminal sterilization steps. Protocol success was evaluated via histologic analysis with hematoxylin and eosin, DAPI, and safranin-O staining, as well as DNA quantification. Histologic analysis of the decellularized tissue revealed a significant reduction in nuclei as evidenced by hematoxylin and eosin and DAPI staining (P < 0.01). Safranin-O staining demonstrated a depletion of glycosaminoglycan content in the decellularized cartilage but with preservation of tissue architecture. Unprocessed lamb cartilage contained 421 ± 60 ng DNA/mg of lyophilized tissue, whereas decellularized zested and minced costal cartilage contained 27 ± 2 ng DNA/mg lyophilized tissue (P < 0.0001) and 24 ± 2.3 ng DNA/mg lyophilized tissue (p < 0.0001), respectively, well below the threshold of 50 ng accepted as evidence of suitable decellularization. In comparison, commercial allograft cartilage contained 17 ± 5 ng DNA/mg of lyophilized tissue. We have developed a novel protocol for the decellularization of xenogeneic cartilage graft. This structurally stable, low immunogenicity decellularized cartilage can be produced at low cost in large quantities for use in preclinical investigation.

The Innate Cellular Immune Response in Xenotransplantation.

Xenotransplantation is very attractive strategy for addressing the shortage of donors. While hyper acute rejection (HAR) caused by natural antibodies and complement has been well defined, this is not the case for innate cellular xenogeneic rejection. An increasing body of evidence suggests that innate cellular immune responses contribute to xenogeneic rejection. Various molecular incompatibilities between receptors and their ligands across different species typically have an impact on graft outcome. NK cells are activated by direct interaction as well as by antigen dependent cellular cytotoxicity (ADCC) mechanisms. Macrophages are activated through various mechanisms in xenogeneic conditions. Macrophages recognize CD47 as a “marker of self” through binding to SIRPα. A number of studies have shown that incompatibility of porcine CD47 against human SIRPα contributes to the rejection of xenogeneic target cells by macrophages. Neutrophils are an early responder cell that infiltrates xenogeneic grafts. It has also been reported that neutrophil extracellular traps (NETs) activate macrophages as damage-associated pattern molecules (DAMPs). In this review, we summarize recent insights into innate cellular xenogeneic rejection.

Photooxidation and Pentagalloyl Glucose Cross-Linking Improves the Performance of Decellularized Small-Diameter Vascular Xenograft In Vivo.

Small-diameter vascular grafts have a significant need in peripheral vascular surgery and procedures of coronary artery bypass graft (CABG); however, autografts are not always available, synthetic grafts perform poorly, and allografts and xenografts dilate, calcify, and induce inflammation after implantation. We hypothesized that cross-linking of decellularized xenogeneic vascular grafts would improve the mechanical properties and biocompatibility and reduce inflammation, degradation, and calcification in vivo. To test this hypothesis, the bovine internal mammary artery (BIMA) was decellularized by detergents and ribozymes with sonication and perfusion. Photooxidation and pentagalloyl glucose (PGG) were used to cross-link the collagen and elastin fibers of decellularized xenografts. Modified grafts’ characteristics and biocompatibility were studied in vitro and in vivo; the grafts were implanted as transposition grafts in the subcutaneous of rats and the abdominal aorta of rabbits. The decellularized grafts were cross-linked by photooxidation and PGG, which improved the grafts’ biomechanical properties and biocompatibility, prevented elastic fibers from early degradation, and reduced inflammation and calcification in vivo. Short-term aortic implants in the rabbits showed collagen regeneration and differentiation of host smooth muscle cells. No occlusion and stenosis occurred due to remodeling and stabilization of the neointima. A good patency rate (100%) was maintained. Notably, implantation of non-treated grafts exhibited marked thrombosis, an inflammatory response, calcification, and elastin degeneration. Thus, photooxidation and PGG cross-linking are potential tools for improving grafts’ biological performance within decellularized small-diameter vascular xenografts.

Proteomics Analysis of Aqueous Humor and Rejected Graft in Pig-to-Non-Human Primate Corneal Xenotransplantation.

Although pig-to-non-human primate (NHP) corneal xenotransplantation has shown long-term graft survival, xenogeneic antigen-related immune responses are still stronger than allogeneic antigen-associated responses. Therefore, there is an unmet need to investigate major rejection pathways in corneal xenotransplantation, even with immunosuppression. This study aimed to identify biomarkers in aqueous humor for predicting rejection and to investigate rejection-related pathways in grafts from NHPs transplanted with porcine corneas following the administration of steroids combined with tacrolimus/rituximab. NHPs who had received corneas from wild-type (WT) or α-1,3-galactosyltransferase gene-knockout (GTKO) pigs were divided into groups with or without rejection according to clinical examinations. Liquid chromatography-mass spectrometry (LC-MS) was used to analyze the proteomes of corneal tissues or aqueous humor. The biological functions of differentially expressed proteins (DEPs) were assessed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) for pathways and protein–protein interaction network analysis. Among the 66 DEPs in aqueous humor, complement proteins (C3, C5, and C9) and cholesterol metabolic proteins (APOA1 and APOA2) were related to xenogeneic rejection as biomarkers, and alternative pathways of the complement system seemed to be important in xenogeneic graft rejection. Among the 416 DEPs of the cornea, NF-κB1 and proteosomes (PSMD7, PSMA5, and PSMD3) seemed to be related to xenogeneic graft rejection. Additionally, oxidative phosphorylation and leukocyte activation-related pathways are involved in rejection. Overall, our proteomic approach highlights the important role of NF-κB1, proteosomes, oxidative phosphorylation, and leukocyte activation-related inflammation in the cornea and the relevance of complement pathways of the aqueous humor as a predictive biomarker of xenogeneic rejection.

Complicated Mandible Fracture Treatment with Xenogenic Bone Graft

The problem of filling bone cavities remains relevant in maxillofacial and oral surgery. There is a large selection of osteotropic materials, of various natures, for filling bone defects of different etiologies. The aim of our research was to improve the outcome of surgical treatment in a patient with a complicated mandibular fracture, with the use of a collagenic xenograft during osteosynthesis. In this article, we share our experience of the treatment of a patient with a complicated mandibular angle fracture, in combination with a follicular cyst. The obligate steps of treatment included stabilization of the bone fragments, decreasing the risk of fracture line malposition, using titan mini-plates, and shortening the time of bone regeneration, by filling the bone defect with osteotropic material. This approach allowed us to reduce the rehabilitation period and further prosthetic treatment after 4–5 months, without additional bone grafting manipulations. Thus, the use of collagen osteotropic materials, possessing osteoconductive properties, can improve the treatment of patients with mandibular fractures.

Double Layer Socket Preservation Technique Associated with Xenogenous Bone Graft and Polypropylene Membrane: A Case Report

With the demand for tooth/gum aesthetics in implant-supported rehabilitations, the surgeon, whether an implant specialist or not, increasingly needs to be mindful of proper care for socket preservation following extraction. The paper presented here reports the case of a male patient who manifested dental impairment of the Upper Left First Molar (tooth #26) (in FDI notation); following tomographic analysis and after reaching a consensus with the patient, the decision was made to extract said tooth and preserve the socket for subsequent implant placement. The aim of the case report is to present a clinical case of alveolar ridge preservation through the “Double Layer Socket Preservation” technique, a technique created by Barry Barthee, whereby a xenogenous graft under an xenogenous type III collagen membrane was combined with a polypropylene barrier. Following research and study results on the subject, it was concluded that by applying this technique, the alveolar ridge is greatly preserved and bone volume is maintained, both of which are very important factors for good health of the tissues surrounding the implant and consequent increase in the survival of the implant itself.

Comparison of the effects of three different xenogeneic bone grafts used in sinus augmentation simultaneous with dental implant placement on the survival of the implants and the dimensional changes of the region.

Xenografts can be produced in various particle sizes by using different bone types. Currently, there is no consensus about the ideal type of xenograft for sinus augmentations, and this choice depends on the personal experience of clinicians. This retrospective study aimed to evaluate the effects of three different xenografts used in sinus augmentation simultaneously with implant placement on the survival of the implants and the dimensional changes of the region. One hundred nine sinus augmentations and 164 implants were evaluated in 76 patients. Three different xenografts were used: 41 Gen-Os® (250-1000µm, Corticocancellous; Tecnoss, Giaveno, Turin, Italy), 35 Bio-Oss® (1000-2000µm, Cancellous; Geistlich Biomaterials italia S.r.l., Vicenza, Italy) and 33 Apatos-Cortical® (600-1000µm, Cortical; Tecnoss). The preoperative, postoperative, and follow-up (21±8.8 month) radiographs were evaluated for the dimensional changes and the implant survivals. The data were statistically analyzed. Among the implant failures; 3 (5.6%) in 53 implants in Apatos, 2 (3.6%) in 55 implants in Bio-Oss, 9 (16%) in 56 implants in Gen-Os, and 14 (8.5%) total implant failures were observed. This difference between the groups was statistically significant and was due to the high loss rate in the Gen-Os (P=0.044). There was a mean difference of -1.8±1.5mm between the measured bone heights on postoperative day (14.2±2.4mm) and the last follow-up (12.4±2.5 mm). While the loss of height was not affected due to the graft type (P=0.981), the general 12.6% vertical loss was statistically significant (P<0.0001), also the length of implants placed reduced this loss (P=0.036). Within the limits of this retrospective study, it can be concluded that: 1) The sinus augmentation procedures with thicker particle size grafts achieved higher success rate; and 2) over the time, 12.6% loss may occur in the height of grafted area.

Decellularized xenogenic bone graft for repair of segmental bone defect in rabbits.

Bone grafting is a preferred treatment option for the healing of large diaphyseal bone defects and is useful in the management of nonunion, delayed union, and tumor resection. To investigate a decellularization protocol of bovine cancellous bone for xenogenic implantation in radial bone defects in rabbits. Bovine bone scaffolds fabricated with various decellularization protocols viz phosphate buffer saline (PBS), 1% sodium dodecyl sulfate (SDS), and rapid freeze and thaw technique. The manufactured scaffolds were characterized by biomechanical testing, histological staining, and scanning electron microscopy. A 10 mm rabbit radius bone defect was repaired with autograft and SDS treated and rapid freeze and thaw in groups A, B, and C respectively. Healing was evaluated by radiography and histopathology at 0, 30, 60, and 90 days. The grafts were also checked for host tissue reaction and incorporation into the defect. The freeze and thaw group showed complete elimination of all cellular nuclei, regular arrangement of collagen fiber, and no significant difference in tensile strength compared to 1% SDS treated and native groups. The in vivo radiographic and histopathological study showed that the rapid freeze and thaw group had complete bridging of the bone gap defect with new bone formation and they were immunologically less reactive compared to group B. The in vitro and in vivo evaluation of the grafts suggested that freeze and thaw technique was most superior to all other techniques for effective decellularization and augmentation of bone healing with better integration of the graft into the host.

Cone-beam computed tomographic evaluation of dimensional hard tissue changes following alveolar ridge preservation techniques of different bone substitutes: a systematic review and meta-analysis.

PurposeThis study was conducted to evaluate and compare the effects of different graft materials used in alveolar ridge preservation on dimensional hard tissue changes of the alveolar ridge, assessed using cone-beam computed tomography (CBCT) scans.MethodsA systematic electronic search of MEDLINE and the Cochrane Central Register of Controlled Trials and a manual search were conducted from November 2019 until January 2020. Randomized controlled trials were included if they assessed at least 1 variable related to vertical or horizontal hard tissue changes measured using CBCT scans. After a qualitative analysis of the included studies, subgroups were formed according to the graft material used, and a quantitative analysis was performed for 5 outcome variables: changes in vertical alveolar bone height at 2 points (midbuccal and midpalatal/midlingual) and changes in horizontal (buccolingual) alveolar bone width at 3 different levels from the initial crest height (1, 3, and 5 mm).ResultsThe search resulted in 1,582 studies, and after an independent 3-stage screening, 16 studies were selected for qualitative analysis and 9 for quantitative analysis. The meta-analysis showed a significantly (P<0.05) lower reduction of alveolar ridge dimensions for the xenogenic subgroup than in the allogenic subgroup, both vertically at the midbuccal aspect (weighted mean difference [WMD]=−0.20; standard error [SE]=0.26 vs. WMD=−0.90; SE=0.22) as well as horizontally at 1 mm (WMD=−1.32; SE=0.07 vs. WMD=−2.99; SE=0.96) and 3 mm (WMD=−0.78; SE=0.11 vs. WMD=−1.63; SE=0.40) from the initial crest height. No statistical analysis could be performed for the autogenic subgroup because it was not reported in sufficient numbers.ConclusionsLess vertical and horizontal bone reduction was observed when xenogenic graft materials were used than when allogenic graft materials were used; however, the loss of alveolar ridge dimensions could not be completely prevented by any graft material.