جستجوی مقالات مرتبط با کلیدواژه « bone substitutes » 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.

The use of bone graft materials has significantly increased. Given the inherent variations in structure and functionality between different grafting materials, this evaluated and compared the physical attributes of antler and bovine femur bone substitutes.

  In the present in vitro investigation, the surface morphological architecture of the two bone substitutes with different origins was assessed through scanning electron microscopy. Furthermore, the Brunauer–Emmett–Teller (BET) technique was employed to measure the porosity, specific surface area (SSA), and pore morphology.

  Scanning electron microscopy observations indicated that the surface of the bovine particles appeared smoother, while the antler particles exhibited a rougher surface texture. The BET analysis revealed that both samples exhibited identical pore morphology. The SSA was 15.974 m2 /g in the antler particles compared with 18.404 m2 /g in the bovine sample. The total porosity volume in the antler and bovine femur bone substitutes were 0.2172 cm3 /g and 0.2918 cm3 /g, respectively. Additionally, the antler particles had a porosity percentage of 40%, whereas the bovine femur bone substitute showed a porosity percentage of 43.5%.

 Based on the results of this study, it seems that the two samples of bone grafting materials have comparable physical structures.

This study aimed to investigate the effects of photobiomodulation (PBM) therapy associated with biphasic calcium phosphate on calvaria critical defects in rats.

Forty-eight (90 days old) adult male rats (Rattus norvegicus, Albinus variation, Wistar) received critical defects of 5 mm in diameter, which were made on their skull, and they were randomly assigned into the following groups: C-blood clot, B-biphasic calcium phosphate, L-photobiomodulation therapy, and B + L-biphasic calcium phosphate + photobiomodulation therapy. A low-level a gallium aluminum arsenide (GaAlAs) laser was applied in a single dose during surgery, in a wavelength of 660 nm and total energy density of 45 J/cm2. On 30th and 60thdays, the animals from each group were euthanized. Histological and histomorphometric analyses were performed.

In 30 days, almost all specimens (C, L, B and B + L) showed bone neoformation areas in regions near the borders of the surgical defect. In 60 days, in many specimens (C, L, B, B + L), it was possible to see a narrow neoformed bone structure along almost the whole extension of the surgical defect, though it was thinner than the original calvary bone. Data were recorded as mean ± standard deviation, and after normality was tested, a suitable statistical test was applied (α = 5%). On day 60, there was a statistically significant difference when comparing the proportion of neoformation area between group L (0.52% ± 0.13) and group B + L (0.20% ± 0.08). Group L showed a difference compared with all the groups when we compared the remaining distance between the edges of neoformed bone (C × L, P = 0.0431; B × L, P = 0.0386; L × B + L, P = 0.0352), demonstrating a great defect closure.

Our findings suggest that although biphasic calcium phosphate exerts some osteogenic activity during bone repair, PBM therapy is not able to modulate this process.

Immediate implant placement is a predictable therapeutic option to replace the missing teeth. However, it is technique-sensitive, and requires strict case selection criteria. Tooth extraction triggers the biologic phenomenon of bone resorption, which is not prevented with immediate implant placement. This study aimed to evaluate the influence of deproteinized bovine bone mineral (DBBM) use on vertical bone loss around immediately placed mandibular molar implants.  

In this non-randomized clinical study, 14 patients with immediate molar implants in the lower jaw, restored with screw-retained single crowns were evaluated. The case group (with bone material use) received DBBM in conjunction with implant placement, while no grafting was performed in the control group. The vertical bone level changes were radiographically measured at the mesial and distal implant sides as the distance between the implant shoulder and first implant-bone contact in apical direction. Measurements were made at two time points of six months postoperatively and one year post-functional loading. The acquired data were statistically analyzed using two-way ANOVA.

The mean values for vertical bone loss at the mesial and distal reference points were greater in the control group (without bone replacement material use) than in the case group both six months postoperatively and one year post-functional loading. The difference was statistically significant at both time points (P<0.05).

Within the limitation of this study, it can be concluded that the use of DBBM in immediate implants can reduce vertical bone loss.

The mineral skeleton of corals possesses physical and chemical properties that could resemble the matrix of human bone. It is crucial to evaluate the cytotoxicity of the coral before utilizing it in clinical settings. The present study aimed to assess the cytotoxicity of Madrepora coral on peripheral mononuclear blood (PBM) cells.

Different concentrations (50, 20, 10, 5, 2, 1 and 0.5 mg/ml) of coral powder were prepared. 96-well plate containing PBM cells, culture medium, and different concentrations of the coral powered was incubated in 37° C with 5% CO2 for 24, 48, 72 hours. The cell viability was evaluated using MTT assay.

After 24 h, only 50 mg/ml dose of the coral significantly decreased the viability of PBM cells compared to the control group. After 48 h, 20 mg/ml and 50 mg/ml doses significantly decreased the viability of PBM cells (P < 0.05). After 72 h, the viability of PBM cells was significantly decreased with 10 mg/ml, 20 mg/ml, and 50 mg/ml doses (P < 0.05).

It can be concluded that the Madrepora coral has low toxicity for mononuclear peripheral blood cells in high doses, and it can be a candidate for implantation in human as a bone substitute.

Autogenous bone grafts are considered the gold standard although they have several disadvantages, leading to a search for suitable alternative graft biomaterials. This study evaluates the histological and histomorphometric properties of regenerated bone in defects in rabbits following the application of two commercially available xenografts (Bio-Oss and Osteon).

This animal study was carried out on 14 New Zealand rabbit calvaria. Four 6.5-mm critical-size defect (CSD) models of bone regeneration were formed in each surgical site. The first defect was filled with Bio-Oss, the second with large Osteon (L-Osteon), the third with small Osteon (S-Osteon), and the last one remained unfilled (the control group). The cases were sacrificed. Bone forming properties (amount of new bone formation, inflammation, and foreign body reaction) were observed at 4- and 8-week intervals through histological and histomorphometric examinations. The Friedman test, Kruskal-Wallis test, and Wilcoxon test for multiple comparisons were used for data analysis. The level of statistical significance was set at 0.05.

There was no statistically significant difference for regenerated bone among the four groups (P>0.05). The L-Osteon site showed more inflammation and foreign body reaction compared to the other groups. 

The results of this study showed that Bio-Oss and Osteon appear to be highly biocompatible and osteoconductive and can thus successfully be used as bone substitutes in augmentation procedures.

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.

The most common method of increasing implant stability in the posterior maxilla comprises the reinforcement of bone height using bone grafts in sinus lift surgery. The purpose of the present study was to compare autogenous and allogeneic bone grafts in implant stability after open sinus lift surgery. This split-mouth clinical trial compared the implant stability in 10 patients who needed bilateral open sinus lifts, including 8 men and 2 women. Each side of each patient's jaw was assigned to either case or control groups. Open sinus lift was performed on both sides of the jaw: autogenous bone graft was used on the side considered as the control, while allogeneic bone graft was used on the side assigned to the case group. After four months, the implant stability was evaluated and recorded in each group using the Periotest® system. The mean value related to implant stability was -2.78±2.31 in the control group and -3.19±2.51 in the case group. The values below zero (negative values) indicate an acceptable stability. According to Mann-U-Whitney test, there were no statistically significant differences between the two groups (P>0.05); however, the intragroup analysis using Wilcoxon test showed statistically significant results with regard to implant stability in each group (P<0.05). Based on the results, autogenous and allogeneic bone grafts have similar effects on implant stability after open sinus lift surgery, and both bone grafts provide a suitable implant durability.

Bone loss is one of the hallmarks of periodontitis. Hence, a major focus of research into periodontal regeneration has concentrated on the initiation of Osteogenesis. Osteoinduction requires the differentiation of mesenchymal cells into osteoblasts with subsequent formation of new bone. The present study has been carried out to evaluate periodontal bone regenerationin intrabony defects using osteostimulative oleaginous calcium hydroxide suspension Osteora® (Metacura, Germany) in combination with osteoconductive bone graft Ossifi ™ (Equinox Medical Technologies, Holland). A total of 22 sites in patients within the age range of 25-50 years, with intrabony defects were selected and divided into two groups (Group A and Group B) by using the split-mouth design technique. All the selected sites were assessed with the clinical parameters such as - Plaque Index, Gingival Index, Sulcus Bleeding Index, Periodontal Probing Depth,Clinical Attachment Level, Gingival Recession and radiographic parameter to assess the amount of Defect Fill. Mann-Whitey U-test and Wilcoxon Signed Rank Test has been used to fi nd the signifi cance of study parameters on continuous scale for the comparison between the mesial and distal bone levels. P < 0.05 was considered to be statistically signifi cant. Osteora® in combination with osteoconductive Ossifi ™ showed better regenerative potential and more signifi cant amount of bone fi ll in periodontal intrabony defects than when Ossifi ™ was used alone (P = 0.039). Osteora® can be used as an adjunct to osteoconductive bone grafts, as an osteostimulating agent in the treatment of periodontal intrabony defects.

Bone regeneration in the defects around oral implants using substitutes may improve long-term prognosis of the implant. Hydroxyapatite (HA) is a good candidate for bone substitutes due to its similarity to bone minerals. Nanostructured hydroxyapatite is also expected to have better bioactivity than coarser crystals. The aim of this work was to synthesize and evaluate the bioactivity of HA.
Nanocrystalline HA was synthesized via mechanical activation method. Fourier transform infrared spectroscopy (FTIR) was utilized to identify the functional groups of the prepared HA. Transmission electron microscopy (TEM) technique was utilized to evaluate the shape and size of prepared HA powder. The synthesized powder was soaked in stimulated body fluid (SBF) medium for various periods of time in order to evaluate its bioactivity. The changes of the pH of SBF medium were measured. Atomic absorption analysis (AAS) was used to determine the dissolution of calcium ion in the SBF environment and scanning electron microscopy (SEM) was utilized to evaluate the surface morphology of nanocrystalline HA powder after immersion in SBF.
The prepared HA powder had nano-scale morphological structure with the mean crystallite size of 29 nm in diameter and bone-like composition. The ionic dissolution rate of prepared nanocrystalline HA was higher than that in conventional HA and was similar to that of biological apatite of bone. High bioactivity of prepared nanocrystalline HA powder due to the formation of apatite on its surface was observed.
Prepared nanocrystalline HA could be more useful for treatment of oral bone defects in comparison with conventional HA, and could be more effective as a bone replacement material to promote bone formation.