Bone Tissue Reactions Research Articles

Enhancement of adhesion strength and in-vivo evaluation of electrodeposited calcium phosphate/chitosan biocoatings on titanium substrate

Chitosan/calcium phosphate nanocomposites are widely used as a biocompatible coatings for titanium bioimplants in the fields of dentistry and orthopedics to enhance the integration between the implants and the hard bone. However, the poor adhesion strength between the coating and the metal substrate was found to be one of the major problems in the clinical application of these implants. In the current study, we reported the formation of Ca/P coating on titanium (Ti) substrate using electrodeposition. The key factor of the bath ingredients is the change of chitosan's solvent from a commonly used acetic acid to acrylic acid in the electrolyte. The structural analysis including X-ray diffraction (XRD), Raman spectroscopy, and attenuated total reflectance (ATR) confirmed the formation of three phases of Ca/P octacalcium phosphate (OCP), dicalcium phosphate dihydrate (DCPD) brushite, and hydroxyapatite (HA). The bond strength was performed by the tape test (ASTM D3359-09) which showed that nearly 65% of the coatings were removed in the case of using 2, 4, and 6% (v/v) acetic acid as chitosan solvent, while only 5% of the coatings were removed when high concentrations (4 and 6%) of acrylic acid is used in addition to increasing of the surface wettability. Furthermore, the morphology and thickness of the calcium phosphate layer coated on the surface of Ti metal were inspected by scanning electron microscopy (SEM). Finally, an in vivo application was conducted on the optimized coating by surgically placing the coated and control discs into rats’ clavicular bones for 2-weeks healing period. Then biomechanical evaluation was performed to verify the effect of treatment on the interface resistance to shear force, and histological analysis was performed to evaluate the bone tissue reactions to coated discs. The results showed that using acrylic acid instead of acetic acid to dissolve chitosan before in-situ electrodeposition might be an innovative approach to enhance the adhesion strength between chitosan/calcium phosphate-based coatings and titanium metal to be used in orthopedic and dental implant technology.

Bone and Soft Tissue Reaction to Co(II)/Cr(III) Ions Stimulation in a Murine Calvaria Model: A Pioneering in vivo Study.

Metal ions released during wear and corrosion of the artificial knee/hip joints are considered to contribute to aseptic implant failure. However, there are few convincing in vivo studies that demonstrate the effects of metal ions on bone and soft tissue. This study examined the in vivo effects of Co(II)/Cr(III) ions on mouse calvaria and the supra-calvaria soft tissue in an original mouse model. With the implantation of a helmet-like structure, we set up a subcutaneous cavity on the calvaria in which Co(II) Chloride or Cr(III) Chloride solutions were administered respectively. A layer of interface membrane formed on the calvaria along with the implantation of the helmet. The administered Cr(III) ions accumulated in the interface membranes while Co(II) disseminated into the circulation. Accumulated Cr(III) and related products induced local massive macrophage infiltration and skewed the bone metabolic balance. At last, we revealed that lymphocyte aggregates, which are the pathologic hallmark of human periprosthetic tissue, could be caused by either Co(II) or Cr(III) stimulation. These in vivo results may shed light on the effects and pathogenic mechanism of the Co(II)/Cr(III) ions released from the joint prosthesis. STATEMENT OF SIGNIFICANCE: Macrophage infiltration and lymphocyte aggregates are hallmarks of human joint periprosthetic tissue. We chronically administered Co(II)/Cr(III) ions on mouse calvaria and reproduced these two histopathologic hallmarks on mouse tissue based on an implanted helmet-like structure. Our results reveal that Cr(III) ions are locally accumulated and are effective in inducing macrophage infiltration and they can be phagocytosed and stored. However, the lymphocytes aggregates could be induced by both Co(II), Cr(III) and other unspecific inflammatory stimuli.

Intramedullary bone tissue reaction of ion-releasing resin-modified glass-ionomer restoration versus two calcium silicate-based cements: an animal study

This comparative study was conducted to assess the intramedullary bone tissue reaction of an ion-releasing resin modified glass-ionomer cement with claimed bioactivity (ACTIVA bioactive resin) restorative material versus Mineral Trioxide Aggregate High Plasticity (MTA HP) and bioceramic putty iRoot BP Plus. Fifty-six adult male Wistar rats were assigned into 4 equal groups (14 rats each). A surgical intramedullary bi-lateral tibial bone defects were performed in rats of the control group I (GI) and left without any treatment to be considered as controls (n = 28). The rats of groups II, III and IV were handled as group I except that the tibial bone defects were filled with ACTIVA, MTA HP and iRoot BP, respectively. In all groups, rats were euthanized after one month and specimens were processed to histological investigation, SEM examination and EDX elemental analysis. In addition, semi-quantitative histomorphometric scoring system was conducted for the following parameters; new bone formation, inflammatory response, angiogenesis, granulation tissue, osteoblasts and osteoclasts. The clinical follow-up outcome of this study revealed the recovery of rats after 4 days post-surgical procedure. It was observed that the animal subjects returned to their routine activities, e.g., walking, grooming and eating. The rats showed normal chewing efficiency without any weight loss or postoperative complications. Histologically, the control group sections showed scanty, very thin, new bone trabeculae of immature woven type located mostly at the peripheral part of the tibial bone defects. These defects exhibited greater amount of thick bands of typically organized granulation tissue with central and peripheral orientation. Meanwhile, bone defects of ACTIVA group showed an empty space surrounded by thick, newly formed, immature woven bone trabeculae. Moreover, bone defects of MTA HP group were partially filled with thick newly formed woven bone trabeculae with wide marrow spaces presented centrally and at the periphery with little amount of mature granulation tissue at the central part. The iRoot BP Plus group section exhibited an observable woven bone formation of normal trabecular structures with narrow marrow spaces presented centrally and at the periphery showed lesser amount of well-organized/mature granulation tissue formation. Kruskal Wallis test revealed total significant differences between the control, ACTIVA, MTAHP and iRoot BP Plus groups (p < 0.05). Meanwhile, Mann–Whitney U test showed significant difference between control and ACTIVA groups, Control and MTA HP groups, control and iRoot BP Plus groups. ACTIVA and MTA HP groups, ACTIVA and iRoot BP Plus (p ˂ 0.05) with no significant difference between MTA HP and iRoot BP Plus (p > 0.05). The elemental analysis outcome showed that the lesions of the control group specimens were filled with recently created trabecular bone with limited marrow spaces. EDX tests (Ca and P analysis) indicated a lower degree of mineralization. Lower amounts of Ca and P was expressed in the mapping analysis compared with other test groups. Calcium silicate-based cements induce more bone formation when compared to an ion-releasing resin modified glass-ionomer restoration with claimed bioactivity. Moreover, the bio-inductive properties of the three tested materials are likely the same. Clinical significance: bioactive resin composite can be used as a retrograde filling.

Increased Peri-implant Bone Formation Around Simultaneously Grafted Hydrophilic Microrough Titanium Implants: An Exploratory Human Histometric Analysis in Four Patients.

This pilot case series histologically and histometrically investigated the influence of implant surface hydrophilicity on early osseointegration and peri-implant bone formation around simultaneously grafted immediate implants. Hydrophilic test (SLAactive) or hydrophobic control (SLA) implants were immediately placed in maxillary molar extraction sites and simultaneously grafted with mineralized cancellous bone allograft (MCBA). Core biopsy samples were obtained at 3 weeks postplacement and histometrically compared for bone-to-implant contact, quantity of graft material, new bone formation, tissue reaction, and inflammatory scores. Test implants showed a more pronounced implant-bone apposition, peri-implant bone formation, and bone aggregate than control implants. Trabecular bone formation and maturation were also qualitatively advanced around test implants. These results indicate that the combination of implant surface and bone graft may affect periimplant bone formation.

EXPERIMENTAL ASSESSMENT OF THE BONE CAVITY HEATING AT DIFFERENT SPEEDS DURING PREPARATION FOR DENTAL IMPLANTATION

The objective of the study was to evaluate the level of bone tissue heating experimentally during various high-speed and slow-speed protocols for the preparation of the bone cavity for dental implantation. Materials and Methods: 8 samples of skeletonized veal ribs (length 10.00–12.00 cm and thickness 1.50–2.00 cm) were dissected, four cuts were made according to different speed protocols at a distance of 1.00–1.50 cm from each other. The duration of each manipulation was 15 s. The Lindemann guide drill with a diameter of 2.20 mm (apex diameter – 1.70 mm) and length of 35.00 mm (with a limiter) was used for work without any cooling of the operating field. The following preparation parameters were applied: 1000 rpm, 300 rpm, 100 rpm, and 50 rpm; in all cases, the torque of the surgical drill was 35 N×cm. Bone tissue temperature was measured with an electronic contact thermometer before and immediately after manipulation. Results: Measurements showed that heating of bone tissue was observed in almost all applied protocols of bone tissue preparation. This fact can represent a danger to the patient by increasing the risk of developing localized osteomyelitis of the alveolar ridge due to trauma. This, in turn, can increase the risk of the installed dental implant disintegration or the development of fiber integration. During 15 seconds of preparation at a speed of 1000 rpm, the bone tissue heated up the most; the average temperature increase was 5.64 ± 2.23 °С (М = 4.60 °С), the value – from 3.00 to 10.30 °С. At the speed of 300 rpm, heating was less – by 3.79 ± 1.76 °C (M = 3.80 °C), the values were in the range of 1.10–6.40 °C. At the speed of 100 rpm, the heating of the bone canal was 2.99 ± 1.36 °С (М = 2.65 °С), in the range of values within 1.10–5.20 °С. During preparation at the speed of 50 rpm, the heating of bone tissue was minimal – 2.06 ± 0.66 °С (М = 1.95 °С), the value was recorded in the range of 1.00–3.20 °С. Considering that in most experimental studies, the time of preparation of bone tissue (or its model) was longer – 1 min, while in our study such prolongation of interaction with bone tissue was impractical (the bone cavity was fully prepared in 15 s) and the interaction of the cutter with the surrounding tissue was minimized, a decision was made to create a mathematical regression model of the thermal reaction of bone tissue during such treatment. The application of the created regression mathematical model of bone tissue heating during preparation without cooling for 1 min showed that the use of surgical drills at the speed of 1000 rpm and torque of 35 N×cm could lead to critical heating in 62.50% of cases, at the speed of 300 rpm min and a torque of 35 N×cm – in 50.00% of cases, at a speed of 100 rpm and torque of 35 N×cm – in 25.00%. The use of the speed of 50 rpm and torque of 35 N×cm without water cooling did not impose the risk of critical heating of bone tissue. Conclusions: the experimental data on the bone tissue heating when using different speeds during preparation without cooling the operating field were obtained. The safest method used was the scheme of 50 rpm with a torque of 35 N×cm.

Bone and Soft Tissue Reaction to Co(II)/Cr(III) Ions Stimulation in a New Murine Calvaria Model: A Pioneering in Vivo Study

Bone and Soft Tissue Reaction to Co(II)/Cr(III) Ions Stimulation in a New Murine Calvaria Model: A Pioneering in Vivo Study

Физиологические механизмы действия витамина D в тканях и органах полости рта и возможность его применения в профилактической стоматологии (обзор литературы)

Vitamin D has a variety of effects on oral tissues and organs. Cholecalciferol is involved in the processes of formation of enamel and dentin, metabolism of jaw bone tissue, local immunity and antitumor reactions. The functional features of the vitamin D effects reveal the possibility of dental pathology prevention. Objective. To study the literature data on the effect of vitamin D on oral tissues and organs and the possibility of using vitamin D as a drug in the prevention of dental diseases. Materials and methods. The review and analysis of literary sources was carried out by keywords on the electronic resources of the Scopus, Web of Science, MedLine, The Cochrane Library, RSCI databases. Russian and foreign sources were used. The literature review was conducted between August 2021 and March 2022. Results. Randomized studies prove that receptors for vitamin D (colecalciferol) are found on the surface of almost all cells, which explains the pleiotropic effect of vitamin D on the human body. Colecalciferol is involved in the formation of substitutive dentin in the foci of demineralization. The active metabolite of vitamin D has an antitumor effect on the oral tissues, anti-inflammatory and antimicrobial action in periodontal disease. Colecalciferol influences osseointegration during implantation, the processes of osteogenesis and osteolysis during orthodontic treatment. Conclusion. Vitamin D has effects on various tissues and organs of the oral cavity, which gives the possibility to include cholecalciferol in clinical guidelines for dental diseases prophylaxis.

Оценка использования биодеградируемых имплантов на основе оксида магния в сравнении с титановыми аналогами. Экспериментальное исследование

The issues of improving surgical implants used in treating patients with traumatological and orthopedic profiles continue to remain relevant. The development of a material not inferior in its elastic-strength properties to metal and that does not require further removal remains a reason for studying new samples that are inert during resorption. The purpose of this study was to experimentally explore and compare the bone tissue reaction to the introduction of titanium and magnesium oxide implants, as well as to study the state of magnesium oxide structures at different times after implantation. The material for the study was an implant based on magnesium oxide manufactured by the «MAGNEZIX» company. We operated on 30 rabbits based on the experimental laboratory of the Main Military Clinical Hospital named after academician N.N. Burdenko Russian Defense Ministry. The main group consisted of 10 rabbits, which were injected with a biodegradable screw made of a material based on magnesium oxide. The control group included 10 rabbits, which were injected with a titanium screw. In addition, another group of rabbits was studied. It included 10 young subjects who were injected with an implant based on magnesium oxide into the growth zone. Subjects were removed from the experiment one at a time at various stages. Then X-ray and histological assessment of the paraimplant zone were performed. As a result, the experiment showed that biomaterials based on magnesium oxide are bioinert, do not cause an inflammation reaction or osteolysis of the surrounding tissue, do not lead to the release of gas and the formation of a pathological cavity. During the introduction of magnesium-containing implants to young subjects, no pathological changes in bone tissue, deformities or stunting in the growth of the studied individuals were detected. Based on the obtained experimental data gathered for 6 months, it should be concluded that the material based on magnesium oxide is very promising and suitable for use in traumatology and orthopedics.

Дослідження остеорегенераційної активності окістя нижньощелепних кісток, уражених кістами різного ґенезу

In response to the prolonged increasing influence of the radicular cyst, there is an adaptive compensatory reaction of the adjacent bone tissue and periosteum located in the area of damage. However, in the available professional literature there is no data on the activity of the marker of osteoregeneration-alkaline phosphatase in the periosteum of the mandible, which is in the growth zone of osteoblastoclastoma. The purpose of the study: to study in a comparative aspect osteoregenerative activity of the periosteum of the mandibular bones affected by radicular cyst and cystic form of osteoblastoclastoma by using the histochemical method. Histochemical studies were performed in 10 patients with large radicular cysts (d&gt;3.0 cm) located on the mandibles – 1st clinical group, and in 9 patients with cystic forms of osteoblastoclastomas, localized on the mandibles - 2nd clinical group. Determination of alkaline phosphatase in periosteal tissues of the mandible was performed by the method of simultaneous azo combination according to Kaplow. Prepared samples of histochemicals were studied under a light microscope, the received images were photographed. Digitized images of histochemicals were analyzed using the computer program ImageJ. The accumulation of alkaline phosphatase in the periosteum of the mandibular areas affected by osteoblastoclastomas is less intense compared to the process of synthesis of this enzyme in the periosteum of the mandible, which is affected by radicular cysts of large size. Osteoregenerative potential of periosteum of mandibular bones affected by radicular cysts is much greater than in the periosteum located in the growth zone of the cystic form of osteoblastoclastoma.

Early mature bone formation using a bioactive membrane in dogs

The purpose of study was to compare the amounts of mature bone formation between a new bioactive collagen membrane (BCM) and a conventional collagen membrane (CCM) when used in a canine model of dental guided bone and tissue regeneration (GBR). GBR surgery was performed in 36 skeletally mature (9-14kg / 20-30lb) Beagle dogs using a split mouth design. The implant site was prepared with a titanium implant in the tooth socket and remaining void filled with a granulated bone substitute. The collagen membranes were trimmed and placed over the implant, and the gingiva closed around the treatment site. Animals were sacrificed (n=6 each group) at 4, 8, and 12 weeks after implant placement. Bone formation and tissue reactions were measured by micro-CT and histomorphometry. The study was approved by the institutional Animal Ethics committee. Bone volume in sites treated with both collagen membranes was significantly greater than controls at 12 weeks. However, the BCM displayed comparatively more bone formation at the early time point of 4 weeks than the CCM. Further, histological assessment of sites treated with the bioactive membrane revealed that mature cortical bone formation occurred as early as 8 weeks, which was likely due to the minimal inflammatory reaction observed and retention of the bioactive barrier structure. The new bioactive collagen membrane induces early mature bone formation in a canine model of dental GBR.

Histological Evaluation of Bioceramic Sealer Effect in Animal Model after Exposure to Gamma Radiation

Purpose: This study was carried out to evaluate the bone tissue reactions to TotalFill Bioceramic (BC) and Zinc oxide eugenol (ZOE) sealers in gamma-irradiated rats. Materials and methods: In this study, round osseous bone defects were produced in the tibia of 48 male Albino rats (weighing120–150g). Group 1: 9 control non-irradiated rats, Group 2: 9 control irradiated rats, and Group 3: 30 irradiated rats in which the surgical cavities were filled with TotalFill sealer in the right tibia and ZOE in the left tibia. The assigned animals were euthanized on 7, 14, and 28 days. For histopathological examination, tissue sections stained with H & E were examined by a light microscope. Results: At 7 days, the inflammatory response of all studied groups (1, 2, and 3) showed no significant differences (p-0.092). The inflammatory response significantly decreased from 14 to 28 days in all groups, virtually disappeared in the non-irradiated group whilst intense inflammatory infiltrate was still observed in 40% of ZOE group samples with a significant difference between TotalFill vs. ZOE sealer (p- < 0.009). Bone tissue at 14 days showed severe resorption in many areas in irradiated animals that reversed at 28 days. In group 3 treated with TotalFill sealer, fiber condensation was observed in surgical cavity at 14 days which was replaced by trabeculae of bone tissue at 28 days while this event was focal in ZOE sealer. Conclusion: TotalFill sealer proved to be more compatible and has some repair potential than ZOE sealer in irradiated animals

過大埋入トルクで撤去されたHA インプラント周囲の骨組織反応とHA の剥離

過大埋入トルクで撤去されたHA インプラント周囲の骨組織反応とHA の剥離

Preservation of Bone Tissue Quality during the Usage of Synthetic Bioactive Calcium Phosphate Mineral Coating for Prevention of Metallic Construction Migration

This work is devoted to studying the reaction of bone tissue to installed titanium implants, which are bioinert in comparison with other metals used in traumatological and orthopedic practice, but which have a negative effect on bone tissue in the implant-to-bone area. In order to increase the affinity of the implant surface with bone tissue, it was proposed to use synthetic bioactive calcium phosphate mineral coating by applying it on titanium implants, which ultimately will make it possible to maintain the quality of the bone tissue around the implant after osteosynthesis or prosthetics. During the comparative research an in vivo experiment was conducted in which quality change of peri-implant zone of bone tissue when using titanium implants with synthetic bioactive calcium phosphate mineral coating and titanium implants without bioactive coating was analyzed. To analyze the results of the study, we used the X-ray computed tomography method, for a detailed assessment of the X-ray density and bone mineral density of the peri-implant zone. According to the results of the experiment, it was concluded that the reaction of bone tissue to synthetic bioactive calcium phosphate mineral coating of titanium implants was reduced, what ensures the preservation of bone tissue quality in the postoperative period at a high level.

Bone tissue response to an MTA-based endodontic sealer, and the effect of the addition of calcium aluminate and silver particles.

To evaluate bone tissue reactions in rats to an MTA-based endodontic sealer with and without the addition of various concentrations of C3A or C3A+Ag. Bone tissue reactions were evaluated in 45 Wistar rats after 7, 30 and 90days (n=5 per period). Three surgical cavities were prepared on the right femur and filled with 0.2 mL MTA Fillapex, MTA Fillapex+C3A and C3A+Ag at various concentrations: AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany), EndoSequence BC (Brasseler USA, Savannah, GA, USA) or no sealer (negative control). By the end of each experimental period, animals were randomly euthanized. The samples were histologically processed and analysed using a light microscope. The presence of inflammatory cells, fibres and hard tissue barrier formation was evaluated. Data were analysed statistically using nonparametric tests to compare the differences between groups. Multiple groups were compared using the Kruskal-Wallis and Mann-Whitney U-tests with a Bonferroni correction at P=0.05. The inflammatory response significantly decreased from 30 to 90days (P<0.05). Fibre condensation was similar amongst the groups at 07 and 30days after intervention (P>0.05). At 90days, however, fibres were absent in most specimens of EndoSequence BC Sealer, AH Plus, MTA Fillapex and the control group, whilst they were still observed in samples of the modified sealers (P<0.05). At 90 days, all specimens of AH Plus, EndoSequence BC Sealer and control group had complete formation of hard tissue barrier. In the MTA Fillapex group, as well as in the modified sealers groups, partial deposition of mineralized tissue was noticed. The hypothesis tested that the incorporation of C3A and C3A+Ag particles to MTA Fillapex would improve bone tissue repair was partially accepted, since modified MTA Fillapex did not have the same repair potential as the commercial bioceramic material.

Degradation and interaction with bone of magnesium alloy WE43 implants: A long-term follow-up in vivo rat tibia study.

The aim of this in vivo study was to examine the degradation and biocompatibility of the WE43 magnesium alloy containing magnesium yttrium, rare earth elements, and zirconium over a one-year long-term follow-up period. Additionally, we compared anodized WE43 implants with monolithic ones and clarified the effect of the anodization. WE43 cylindrical implants with and without anodization (length, 10 mm; diameter, 0.3 mm) were transplanted into the rat tibia. In both groups, the development of corrosion and the change in implant volume were evaluated by in vivo micro-computed tomography until 12 months, and the bone tissue reaction was observed histologically. In the monolithic WE43 implants, hydrogen gas was evident until 14 days and the volume loss was 36.3% after 12 months. In the anodized WE43 implants, the development of hydrogen gas was inhibited and the volume loss was 27.7% after 12 months. The anodized WE43 implants showed a significantly slower corrosion process in the early phase. Therefore, these implants may require a prolonged period to degrade completely and may even resist complete degradation. At one year post surgery, bone maturation progressed and lamellar bone structure developed around the implant in both groups. In conclusion, the WE43 implants showed good long-term stability and biocompatibility in bone tissue.

Comparison of the removal torque and a histomorphometric evaluation of the RBM treated implants with the RBM followed by laser treated implants: an experimental study in rabbits.

BackgroundIn the osseointegration of dental implants, the implant surface properties have been reported to be some of the most important critical factors. The effect of implant’s surfaces created by resorbable blast media (RBM) followed by laser ablation on bone tissue reactions was examined using the removal torque test and histomorphometric analysis.MethodsTwo types of dental implants, RBM-laser implants (experimental group) and RBM implants (control group) (CSM implant system, Daegu, Korea; L=6 mm, diameter=3.75 mm) were placed into the right and left distal femoral metaphysis of 17 adult rabbits. Six weeks after placement, removal torque was measured and histomorphometric analysis was performed.ResultsThe mean removal torque was 24.0±10.2 Ncm and 46.6±16.4 Ncm for the control and test specimens, respectively. The experimental RBM-laser implants had significantly higher removal torque values than the control RBM implants (p=0.013). The mean values of total and cortical bone to implant contact (BIC) were respectively 46.3±10.8% and 65.3±12.5% for the experimental group, and 41.9±18.5% and 57.6±10.6% for the control group. The experimental RBM-laser implants showed a higher degree of total and cortical BIC compared with RBM implants, but there was no statistical significance (p=0.482, 0.225).ConclusionThe removal torque and BIC of the test group were higher than those of the control group. In this study, the surface treatment created by RBM treatment followed by laser ablation appears to have a potential in improving bone tissue reactions of dental implants.

Bone tissue reaction, setting time, solubility, and pH of root repair materials.

This study aims to compare the bone tissue reaction, setting time, solubility, and pH of NeoMTA Plus, Biodentine (BD), and MTA Angelus (MTA-A). Initial and final setting times (n = 7) and solubility up to 7days (n = 11) were evaluated in accordance with ASTM C266-15 and ANSI/ADA Specification No. 57, respectively. pH (n = 10) was measured up to 28days. Bone tissue reactions in 48 rats' femur were histologically analyzed after 7, 30, and 90days. ANOVA and Tukey's tests compared setting time, solubility, and pH data; bone reactions data were compared by Kruskal-Wallis and Dunn's tests. NeoMTA Plus had longer initial and final setting times than MTA-A and BD (P < 0.05). At 7days, BD showed the highest solubility, similar to NeoMTA Plus (P > 0.05) and different from MTA-A (P < 0.05). NeoMTA Plus had a progressive mass loss over time; at 7days, it was significantly different from the initial mass (P < 0.05). BD showed higher pH in the periods assessed when compared to the other materials (P < 0.05). Bone tissue repair had no differences between groups in each experimental period (P > 0.05). All groups presented no difference from 30 to 90days (P > 0.05) and had better bone repair at 90days than at 7days (P < 0.05). NeoMTA Plus, BD, and MTA-A showed satisfactory setting time, high mass loss, alkaline pH, and allowed bone repair. Calcium silicate-based cements are indicated for multiple clinical situations. NeoMTA Plus and BD showed satisfactory physical-chemical and biological properties, being considered as alternatives to MTA-A, as root repair materials for clinical use.

Bone Subdestructive Kryoapplicaton in the Experiment

Relevance. Trend of modern surgery in the implementation of new methods of treatment is to develop all phases of the proposed method of treatment in an experimental model. In this paper, comparative studies have been performed in laboratory animals, aimed at studying the bone tissue reaction at subdestruktion cryotherapy.&#x0D; Purpose. Identify the optimal exposure of the refrigerant to achieve kryoregenerative action ultralow temperatures.&#x0D; Materials and methods. An experimental study was conducted on rabbits "Chinchilla" by cryotherapy in the cavity osteoperforation with different exposure refrigerant (liquid nitrogen). After 10 days after the removal of the animal from an experiment conducted morphological study.&#x0D; Results. It was found that the exposure of 3 seconds is observed active regeneration, while kryoosteonekrosis observed during long-term exposure. The experimental results allow differentiated recommend them for use in clinical practice.&#x0D; Conclusion. Light microscopy kryoregeneration with a three-second exposure shows the refrigerant is very active calcification regenerate. Primary callus composed of fibrous tissue and retikulofibrosis. Reclaimed presented osteoblasts chain. The proposed regime is advisable to apply cryotherapy with degenerative diseases of the bone in order to increase osteoreparative properties of bone.

Biodegradation of Pure Magnesium and Bone Tissue Reaction in Rabbit Femur 1 Year Results of 3D Micro-CT Monitoring and Histological Observation

Pure magnesium and its alloys are biocompatible and biodegradable. In cardiovascular surgery, they have been experimentally applied for short-term use as tiny devices. Many studies have been performed on rats and mice using X-ray imaging and CT scanning. However, these small animals have a low radiation resistance and the lethal exposure dosage is small. In orthopedic surgery, fracture fixation using magnesium materials has high potential applicability. Although long-term stable fixation is required, few long-term animal studies have been performed. Therefore, many unclear issues still remain. Accordingly a long-term animal study was performed on Dutch rabbits to investigate the biodegradation of pure magnesium. Specimens implanted into rabbit femurs showed a volume reduction of 40–50% at 52 weeks. Bone resorption was observed in cancellous bone, and new bone formation and direct contact were partially observed. No magnesium hydroxide was observed in the surrounding area.

Osteogenic Potential of Oxycellulose – A Molecular-Biological and Histological Study in Rats

Oxidized cellulose is a polysaccharide substance formed by the oxidation of cellulose. Depending on the amount used, oxycellulose is completely absorbable and can be used as hemostatic agents in general and dental surgery for hemostatic purposes. Each procedure on the bone also carries the risk of bleeding, but still not much is known about the bone tissue reaction on this material. Due to this fact, the aim of this study was to evaluate the tissue reaction and osteogenic potential of the natural oxycellulose material RESORBA-CELL® standard by its implantation into rat cranial bone defects. The materials were evaluated using an established rat cranial defect model in 22 animals. One bone defect with a diameter of 5 mm was created per animal. The defects were filled with oxycellulose and left to heal for 4 weeks. Twelve samples (n=6 oxycellulose; n=6 untreated control lesions) were processed for histological evaluation. The remaining 10 samples were processed for mRNA expression analysis of genes coding for growth factors and osteogenic differentiation using quantitative RT-PCR. In oxycellulose treated bone lesions significant reduced mRNA levels of Runx2, Bglap and COL1A1 were found. The expression reached 74%, 73% and 47% of the mRNA quantity of the untreated bone, respectively. In the histological sections, the bone defects were completely filled with connective tissue / bone marrow with embedded foam cells after four weeks. In contrast to the controls, the tested material do not induced early bone healing. The residual bone seems to be rather absorbed. In conclusion, the study has shown that the RESORBA-CELL® oxidized cellulose has no osteogenic potential, but it still can be considered as a useful wound dressing in the dental surgery.