جستجوی مقالات مرتبط با کلیدواژه « xenograft » در نشریات گروه « پزشکی »

 Xenograft bone substitutes can be obtained from different animals and processed using various methods. The present in vivo study evaluated bone regeneration after using three types of xenografts with different sources in critical-sized bone defects in rabbit calvaria.

 Four 8-mm defects were created in calvaria of 14 New Zealand and white male rabbits. Three out of four defects were filled with xenografts of bovine, camel, and ostrich sources. The fourth defect was left unfilled as the control group. Seven rabbits were sacrificed after eight weeks and seven others after 12 weeks. Micro-CT imaging and histologic evaluation were further performed on dissected calvarias.

 After 8 and 12 weeks, the highest and lowest percentages of new bone formation were observed in the camel (27.71% and 41.92%) and control (11.33% and 15.96%) groups, respectively. In the case of residual material, the ostrich group had the most value after eight weeks (53%), while after 12 weeks, it was highest in the camel group (37%). Micro-CT findings were consistent with histologic results.

 Although all three xenografts can be good choices for treating bone defects, camel-sourced xenograft seemed to be better than the other two groups. The origin and processing procedures of xenografts affected their final characteristics, which should be considered for clinical use.

Dental implants are now the best treatment method to replace missing teeth. However, complications may necessitate further therapeutic interventions because of anatomic limitations and mistakes during surgical procedures. In this case report, a nasopalatine duct cyst (NPDC) due to implant placement was studied. After clinical and radiographic evaluation, unilocular radiolucency with disturbance to the nasopalatine canal was observed. Following that, flap elevation was performed. Subsequently, the cyst was enucleated, and the bone defect was filled with xenograft and further covered with a resorbable membrane. Histopathology results confirmed NPDC as the definite diagnosis. After six months, the defect was completely resolved.

This study compared the effect of various grafting materials on the area and volume of minerals attached to dental implants.

In this animal study, 13 dogs were divided into three groups according to the time of sacrificing (2 months, 4 months, or 6 months). The implants were placed in oversized osteotomies, and the residual defects were filled with autograft, bovine bone graft (Cerabone), or a synthetic substitute (Osteon II). At the designated intervals, the dogs were sacrificed and the segmented implants underwent micro‑computed tomography analysis. The bone‑implant area (BIA) and bone‑implant volume (BIV) of bone and graft material were calculated in the region of interest around the implant. The data were analyzed by two‑way analysis of variance (ANOVA) at P < 0.05.

There was no significant difference in BIA and BIV between the healing intervals for any of the grafting materials (P > 0.05). ANOVA exhibited comparable BIA and BIV between the grafting materials at 2 and 4 months after surgery (P > 0.05), although a significant difference was observed after 6 months (P < 0.05). Pairwise comparisons revealed that BIA was significantly greater in the autograft‑stabilized than the synthetic‑grafted sites (P = 0.035). The samples augmented with autograft also showed significantly higher BIV than those treated by the xenogenic (P = 0.017) or synthetic (P = 0.002) particles.

All graft materials showed comparable performance in providing mineral support for implants up to 4 months after surgery. At the long‑term (6‑month) interval, autogenous bone demonstrated significant superiority over xenogenic and synthetic substitutes concerning the bone area and volume around the implant.

Xenograft and allograft bone substitutes are widely used to replace the missing bone in defects. Since removing the packaging of these grafts can nullify their sterilization, this study aimed to evaluate the sterility and bioactivity changes of an allograft and a xenograft following uncapping/recap.

Two types of commercial allograft and xenograft vials were unpacked and further exposed to operating room air, where implant surgery was performed for one second, ten minutes, and one hour. After three repetitions, samples were analyzed using microbiological tests and scanning electron microscopy (SEM) with energy dispersive x-ray analysis (EDX) for sterility and bioactivity evaluation.

None of the bone graft samples showed microbial growth or bioactivity-negative changes after seven days of unpacking the vials.

Despite the positive results of this study, future studies and more analysis considering influential factors are required. Also, disinfection and air exchange must still be observed during biomaterial application and bone grafting procedures.

Living organ, tissue, or cell transplantation from one species to another is known to as xenotransplantation. The history of xenotransplantation is just as ancient as that of allogeneic transplantation. Early attempts were attempted when it was uncertain exactly, on an immunologic level, causes organ rejection. With the emergence of potent immunosuppressive medicines and concurrent advancements in the field of genetic engineering, a new perspective on the role of xenotransplantation as a tactic to resolve the disparity between the number of applicants on the waitlist and the available organs has developed. Although a xenotransplantation clinical trial involving human subjects appears to be theoretically viable, it requires a stringent regulatory framework on both a national and international level to ensure both the individuals' and the public's safety. Several scientists in the United States urged the FDA to prohibit cross-species transplantation research until ethical concerns and health risks are addressed at the public conference on xenotransplantation that was held in January 1998. Clinical studies that are being conducted cautiously and with precision were approved by the FDA as suitable. ARMBA and the roles of the relevant governmental organisations and healthcare institutions are the focus of the present rules regulating the conduct of xenotransplantation clinical trials in Korea. In accordance with the standards of the international guidelines, Korea is prepared to perform a clinical experiment involving xenotransplantation on humans. In accordance with the ARMBA and other relevant laws and regulations, the appropriate governmental authorities would work together to control the xenotransplant clinical study.

Objectives:

 This study aimed to assess and compare the results of sterility and residual solvent testing in a newly developed antler-derived xenograft versus a bovine-derived xenograft.

Methods:

 First, test and control samples were prepared using thermal and chemical procedures, involving immersion in deionized water for 24 hours, drying, boiling in sterile water, chemical treatment with chloroform and methanol, and heating at 650°C in a furnace. Next, they were sterilized via gamma radiation at 25 kGy. The sterility test was then performed based on the ISO 11737-2:2019 standard, using the direct inoculation method. Finally, residual solvent testing was carried out via gas chromatography-mass spectrometry.

Results :

The sterility test showed no evidence of bacterial or fungal growth in any of the samples during 14 days of incubation. Also, residual solvent testing indicated no sign of residual solvents in the samples.

Conclusion:

 Antler-derived xenograft was safe to use in terms of the sterility and removal of residual solvents. Further studies should be carried out regarding other important laboratory tests as well as the animal and clinical studies.

The aim of the study was to evaluate osteopromotive ability of human tooth powder and compare it to a bovine xenograft, a synthetic material and the DFDBA allograft.

This was an in vitro study. 30 teeth without caries, inflammation, infection, which have been extracted due to orthodontic reasons, have been gathered. The crowns were removed and they were treated with pulpectomy and then grinded to a powder with particles less than 500 microns. Osteoblast-like cells of MG-63 was cultured with tooth powder, Cerabone, DFDBA and Osteon II. Cell proliferation was assessed by MTT test in 24 and 72 hours. The Alizarin red test was done after 3 and 5 days. To assess the osteoblastic activity, amount of Alkaline Phosphatase was measured in 24, 48 and 72 hours. The results were analyzed by one-way ANOVO analysis.

According to the MTT test, all of the materials had a higher proliferation rate than the control group in 24 hours. In 72 hours, DFDBA with concentrations of 40 and 80 mg/ml had the lowest cell proliferation rate. DFDBA and the positive control group was able to create calcified nodules by Alizarin red test. In 48 and 72 hours, DFDBA with concentration of 40 mg/ml had the lowest alkaline phosphatase activity. In 72 hours, bovine xenograft had the highest alkaline phosphatase level and the synthetic material and tooth powder were after that.

Tooth powder was able to increase cell proliferation in comparison with the bovine xenograft, the synthetic graft and the DFDBA. However, its osteopromotive ability was less than the osteogenic materials.