Background and Aim: 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). Materials and Methods: 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. Result: 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. Conclusion: 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.

Objective: Osteon has been introduced as a bone substitute material. It is biphasic calcium phosphate (BCP) that use in dentistry. The aim of the present study was to evaluate the effect of Osteon on the proliferation, cell viability and differentiation of saos-2 cells in vitro. Also it was compared with cerasorb bone graft.Materials and Methods: Two different bone grafts materials, Osteon and cerasorb, were used to evaluate the effect on proliferation and differentiation rate of saos-2 cells. On day 15 the cell proliferation and cell viability was measured by MTT assay. For determination of differentiation, alkaline phosphatase and alizarin red test was used.Results: Osteon and cerasorb groups showed significantly higher alkaline phosphatase activity and cell differentiation. Cell viability of both bone grafts was significantly lower than control group and cell proliferation was higher in Osteon group. Osteon has more suitable biological property compare to cerasorb.Conclusions: The results of the present study showed that Osteon and cersorb bone grafts allow proliferation and differentiation of saos-2 cells in vitro.

Background and Aim: Several reports have been published on the successful application of various bone substitute materials (BSM). Appropriate physiologic and histologic characteristics and reactions of these materials against host cells are critically important. In this study, the biocompatibility of a new bone substitute material has been evaluated. Methods and Materials: In this experimental In vitro study, the biocompatibility of silicate calcium phosphate, Bio-Oss and Osteon were compared by evaluation of cell viability and differentiation rate of human osteoblast-like cell line (SaOS-2). No graft material was used in the control group. Cell viability rate was evaluated by MTT test after 1, 3 and 14 days of incubation. Inverted Light Microscope and SEM were utilized for evaluation of cell morphology. MTT and cell morphology were analyzed by ANOVA test in all groups. Results: Cell viability of the control group equaled 0. 453± 0. 016, while in the test groups it equaled 0. 453± 0. 016 for Bio-Oss, 0. 439± 0. 011 for Osteon and 0. 425± 0. 026 for silicate calcium phosphate. There was no significant difference between the control and the test groups. Spindle form was the dominant SaOS-2 cell morphology in all groups. Conclusion: This study showed that calcium silicate phosphate has appropriate biocompatibility comparable with that of Bio-Oss and Osteon.

Bone structure has been widely studied in mammals, however, Osteon structure in sheep has received relatively little attention, especially in terms of its location on the forelimbs and hindlimbs. The aim of this study was to investigate the histometric characteristics and mineral composition of the metacarpus and metatarsus of adult Sanjabi sheep. Metacarpal and metatarsal bones were collected from five adult Sanjabi sheep (n = 10). Morphometric measurements were performed on computed tomographic scan images. Histometric parameters were measured on histological sections. The mineral composition of the bone samples was detected using the X-ray fluorescence method. The diameter of the Haversian canal in the right metatarsus was significantly greater than that in the other bones. The smallest diameter of the Haversian canal was observed for the right metacarpus. The diameter and area of the Osteons in the right metacarpal were significantly greater than those in the other bones. The amount of essential mineral elements was not significantly different among bones. Aluminum and lead were significantly greater in the left metatarsus. The highest amount of copper was observed in the left metacarpus. These results indicated that there was a greater load on the right limb. This compensatory mechanism might be used to put more weight on the right forelimb and reduce the pressure caused by the weight of the rumen on the left forelimb. However, to prove this hypothesis, more detailed and extensive studies are needed in the future.

A two dimensional finite element model for the human Haversian cortical bone is represented. The interstitial bone tissue, the Osteons and the cement line were modeled as the matrix, the fibers and the interface, respectively. This was due to similarities between fiber-ceramic composite materials and the human Haversian cortical bone. The stress intensity factor in the microcrack tips vicinity was computed using the linear elastic fracture mechanics theory and assuming a plane strain condition. It was therefore possible to study the effect of microstructure and mechanical properties of Haversian cortical bone on microcrack propagation trajectory. The results indicated that this effect was limited to the vicinity of the Osteon. If both Osteon and cement line were assumed to be softer than the interstitial tissue, the stress intensity factor was increased when the crack distance to the Osteon reduced. The stress intensity factor decreased if both Osteon and cement line were assumed to be stiffer than the interstitial tissue. The resulting simulation indicated that the effect of existence of Osteon on the stress intensity factor was no significance, if both the interstitial tissue and cement line were assumed either stiffer or softer than the Osteon. Microcrack trajectory was observed to deviate from the Osteon under tensile loading; indicating an independence from the mechanical properties of various tissues. In fact, the microcrack adopts a trajectory between the Osteons, thereby increasing the necessary absorbed energy for fracture. This results in an increase in the human Haversian cortical bone toughness. The result of this finite element modeling has been confirmed by through evaluation and comparison made with experimental results.

Introduction: This study was designed to determine the effect of Osteon II mineralized bone powder on the surface microhardness of two retrofilling materials: Mineral trioxide aggregate (MTA) and Biodentine (BD). Methods and Materials: Each retrograde material was mixed and carried into 30 sterile custom-made plastic cylinders. Half of the samples in each group were exposed to Osteon II. All cylinders were submerged in simulated tissue fluid and incubated at 37° C and 100% relative humidity for 7 days. Surface microhardness values of each study group was attained using Vicker’ s microhardness test. The data were analyzed statistically using two-way ANOVA and independent t test at a significance level of 0. 05. Results: In all the setting conditions, BD had significantly greater surface microhardness than MTA (P<0. 001). Surface microhardness of both materials was significantly reduced in the presence of Osteon II (P=0. 006 for BD and P<0. 001 for MTA). Conclusion: Mineralized bone graft materials negatively affect surface microhardness of both MTA and BD. In presence of Osteon II, BD had the highest surface microhardness.

Introduction: During periapical surgery, using of bone products in large endodontic lesions, is a treatment option that could affect the properties of the retro-filling endodontic material. The aim of present study was to evaluate the effect of Osteon II bone powder on the surface microhardness of calcium-enriched mixture (CEM) and mineral trioxide aggregate (MTA). Methods and Materials: Each material was mixed and carried into 40 sterile custom-made plastic cylinders. Half of the samples in each group were exposed to Osteon II. All cylinders were submerged in simulated tissue fluid and incubated at 37° C and 100% relative humidity for 7 days. Surface microhardness values of each study group was attained using Vickers microhardness test. The data were analyzed statistically using two-way ANOVA and independent t-test at a significance level of 0. 05. Results: The highest and lowest microhardness values were recorded in the MTA/without Osteon and MTA/with Osteon groups, respectively. Irrespective of the presence or absence of bone powder, the overall microhardness of CEM cement and MTA was not significantly different. In the MTA group, the presence of the powder resulted in a significant decrease (P<0. 05) of the microhardness; however, its effect on CEM cement was not significant (P>0. 05). Conclusion: Under the limitations of the present in vitro study, the presence of Osteon bone powder had no negative effect on the microhardness of CEM cement, contrary to its effect on MTA.

Microcracks development in cortical bone occurs when the tissue is subjected to cyclic and fatigue loading. This phenomenon reduces the fracturer resistance of bone. The underlying mechanisms governing bone fracture, however, require a more thorough study. To this effect a two-dimensional micromechanical fiber - ceramic matrix composite material model for the tissue is presented in this paper. Here, the interstitial tissue was modeled as a matrix and the Osteon was modeled as a fiber, followed by the implementation of the linear elastic fracture mechanics theory. The solution for the edge dislocations, as a Green's functions, was adopted to formulate a system of singular integral equations for the radial microcracks in the matrix in vicinity of the Osteon. The effects of microstructural morphology and heterogeneity of haversian cortical bone upon the fracture behavior was investigated by computing the stress intensity factor near the microcracks tips. The results indicated that interaction between Osteon and microcracks was limited to the vicinity of the Osteon. Furthermore, analysis of the microcrack interactions was an indication of the effects of microcrack configuration upon Stress Intensity Factor in shape of either stress amplification or stress shielding.

A two-dimensional model has been prepared to analyze the fracture micromechanics of haversian cortical bone. The interstitial bone has been presented as a matrix and the Osteon as a fiber. The justification for such substitutions could be made through similarities between fiber-ceramic composite materials and the human haversian cortical bone. The linear elastic fracture mechanics theory is adopted and the solution for the edge dislocations, as a Green's functions, is used to formulate a system of singular integral equations for the arbitrarily oriented microcrack in the matrix in vicinity of an Osteon. The problem is solved for various models and the corresponding stress intensity factors are computed. It is also possible to study the effect of microstructural morphology and heterogeneity of the haversian cortical bone upon the fracture behavior. The results indicate that this effect is limited to vicinity of the Osteon. The Osteonal effect upon the microcrack could lead to increase or decrease of the stress intensity factor at microcrack tips. This effect is, however, related to mismatch between material properties of tissues and the location of microcrack with respect to the Osteon.

Varieties within the genomic region of 1p36.12 have already been linked with osteoporosis in genome-wide association studies (GWASs), even though the functional implications behind these non-coding variants remain uncertain. We highlighted rs6426749 as a probable causative variant for Osteon at 1p36.12 predicated on comprehensive genomic analyses and epigenetic evaluations. For sampling, fifty (50) patients with osteoporosis were admitted to Baghdad Teaching Hospital, and 40 healthy subjects were performed in Baghdad Teaching Hospital/Bone Density Screening Unit/ Baghdad - Iraq between September 2020 January 2021. We used nested PCR of the Genome-wide association studies of the primers designed by the primer3 program. For rs6426749 G/C genotyping, The results of osteoporosis patients (women) and the healthy group was studied according to bone mineral density. The results showed a significant difference between the two study groups in bone mineral density and body mass index. The mean of patient groups was mean±SD (0.6824±0.08285), and control groups were mean±SD (1.066±0.06876). Then we divided the patients into three groups according to their age, and from the age of 30 to 44, they were called pre-menopause, from the age of 45 to 55, they were called Menopause, and from the age of 56 to 70, they were called Post menopause, and we compared these three groups with the control. The results showed that there was statistically significant P-Value <0.0001 differences.