Papers by Keyword: Rabbit

Abstract: The histomorphometry of the rabbit bone tissue from the lower jaw was done. Authors hypothesized that local enhancement with biphasic calcium phosphate ceramic materials in the femur trochanter major area increase the trabecular bone volume outside the implantation zone in vivo. Twenty-two California female rabbits were included in this study and were divided into four groups. Four healthy rabbits composed a control group (A group), while other eighteen underwent ovariectomy. Bone defects were created in femur trochanter major region. Sham surgery group (B group) consisted of four female rabbits with osteoporosis and bone defect, but no biomaterials were implanted. In C group (seven rabbits) created defects were filled with granules of biphasic calcium phosphate ceramic (hydroxyapatite (HAP) and tricalcium phosphate (TCP) 30/70); in D group (seven rabbits) defects were filled with the same granules (HAP/TCP 30/70) together with strontium (5% by mass). Twenty-two bone samples were taken from lower jaw premolar region. Trabecular bone area was measured using Image Pro Plus 7 program, where three equal fields (0.975 mm²) of view were at random chosen in all bone samples. Results have shown that the trabecular bone area in A group was 0.201 mm² (0.176-0.233), which is statistically significantly higher (p <0.0001) than in B group 0.127 mm² (0.118 – 0.149), C group 0.136 mm² (0.108 – 0.166) and D group 0.135 mm² (0.126 – 0.164), respectively. Statistically significant differences between B, C and D groups were not found (p > 0.05).

Abstract: Magnesium alloys have shown potential as biodegradable metallic materials for oral and maxillofacial surgery applications due to their degradability. Biodegradable magnesium are advantageous over existing biodegradable materials such as polymers, ceramics and bioactive glasses in load-bearing applications where sufficient strength and Young’s modulus close to that of the bone are required.

Abstract: Variety of different bone substitutive materials are synthetized to improve bone healing potentials in pathological bone conditions. Physiologically active molecules within biomaterials, can initiate expression level of biomarkers, regulating bone remodeling. Aim of our study was to analyze bone healing process in bone defects followed by implantation with 5% strontium substituted hydroxyapatite (HAP) /tricalcium phosphate (TCP) 70/30 granules (group A) or HAP/TCP biphasic ceramic granules without strontium substitution (group B), or sham surgery affected bone (group C) in osteoporotic rabbits’ femur. Tissue samples from contralateral intact left leg were used for evaluation of systemic effects after surgery. Changes of bone volume were measured and appearance of OPG, NFkB-105, OC, COL-1, BMP-2/4, MMP-2, TIMP-2, IL-1 and IL-10-positive osteocytes in osteoporotic rabbits’ bone defect were evaluated. No statistical difference between groups of trabecular bone volume was detected. All analyzed markers showed higher appearance of positive osteocytes in groups A and B with comparison to control left leg (p<0.05). Only NFkB105-positive cells showed important difference between sham surgery affected leg and control one (p=0.034). Numerous OPG-positive cells appeared in group A, while moderate number of them was found in groups B and C (p=0.025; p=0.027). Numerous to abundant OC-positive osteocytes were detected in group A, while moderate in group C (p=0.034). Statistical difference of rest biomarkers between groups was not detected. We concluded that implantation of biomaterials in osteoporotic bone improves local bone regenerative properties. However, the notable increase of OPG-containing cells proves the increase of osteoclastogenesis suppression and gives the evidence for renew of bone functionality.

Abstract: Investigation of biomechanical properties of the rabbit bone tissue from a corner of the lower jaw was done. Experimental osteoporosis was induced by ovariectomy and following injections of methylprednisolone. The defects in the greater trochanter region was created and filled with granules of a hydroxyapatite and tricalcium phosphate (HAP/TCP 30/70) or HAP/TCP 30/70 together with 5% strontium ranelate. After 3 month animals were euthanased, squared samples have been cut out from a corner of the lower jaw and tested on a bend. Results of research show, that the corner of a lower jaw in rabbit becomes more rigid after filling of defects in the greater trochanter region with granules of a hydroxyapatite and tricalcium phosphate (HAP/TCP 30/70) or granules together with strontium ranelate. The ultimate strain for the bone tissue in the 2^nd and 3^rd group is less, than for control group. Thus, local uses calcium – phosphatic bioceramic material around the greater trochanter region improves biomechanical parameters of a bone tissue in the lower jaw of animals.

Abstract: The heart function suppression during a long-term anestesia should be considered in implant placement surgery. The aim of this study is to determine the effect of propofol and isoflurane combination as a long-term anesthesia on the heart size using radiography vertebrae heart size (VHS) method. Rabbits were injected by propofol 12.5 mg/kg body weight intravenously as an induction and inhaled by 1.0 ml/minutes rate ofisoflurane in facemasked for next 12 hours. Thorax cardiogram in right lateral (RL) and dorsoventral (DV) view were obtained and compared according to duration of anesthesia at 0 hr, 4 hrs, 8 hrs, and 12 hrs. The result showed that heart size on RL view are 7.67±0.50v, 6.67±0.16v, 7±0.00v, and 7.53±0.23v, respectively, while the values on DV view are 7.33±0.23v, 7.06±0.30v, 7±0.2v, and 7.33±0.35v, respectively. The heart size on RL view was decreased after 4 hrs and increased after at 8 to 12hrs significantly (P<0.05) compared to DV view. As the conclusion, propofol and isoflurane combination as a long-term anesthesia had minimal effect on heart size and is a good candidate for long-term biomaterial implant placement procedures.

Abstract: The aim of the present study is to evaluate the in vivo biological behaviour of porous β-CS/PDLGA scaffolds. The scaffolds were implanted in critical-sized femur defects ( 6 ×10 mm) for 4, 12 and 20 weeks with β-TCP scaffolds as the control. The in vivo bone regeneration of the scaffolds were investigated using sequential histological evaluations and Micro-CT technology. Results showed that the β-CS/PDLGA scaffolds could stimulate bone regeneration and degrade progressively at a rate proportionate with the regeneration of new bone as compared with β-TCP scaffolds. The present study suggested the potential application of β-CS/PDLGA scaffolds in hard tissue regeneration.

Abstract: We have developed a new Ti alloy, Ti-15%Zr-4%Nb-4%Ta alloy (Ti-15-4-4) that showed higher biological safety and mechanical properties than the currently used Ti-6%Al-4%V alloy. The purpose of this study is to determine the biological performance of the new alloy. Ti-15-4-4 implants (machined or blasted) were placed in surgically created defects in rabbit femurs. The rabbits were sacrificed after 4, 8, 16, 24 and 48 weeks. Bone mineral density (BMD) and area of newly formed bone around the implants were measured using micro-CT. Results showed that the Ti-15-4-4 alloy is biocompatible and forms new bone around the Ti-15-4-4 implant, regardless of the surface treatment. The BMD and area of newly formed bone around the blasted implant surfaces were significantly greater than those around the machined surfaces. These results indicate that the new Ti-15-4-4 alloy has a potential for use as implants and has the advantage of improved mechanical properties described in earlier studies.

Abstract: This study evaluated the histology results of surgically created bone cavities in the calvaria of rabbits that were subsequently filled with a HA/ß-TCP composite powder developed in Korea (Dentium, Korea). Ten young adult rabbits were used. Four defects were surgically produced in the calvaria of each rabbit. These defects were classified into 4 groups: the control group, no graft materials; experimental group I, normal saline + graft materials; experimental group II, venous blood + graft materials; and experimental group III, graft materials only. The defects were randomly filled with the graft materials. The rabbits were sacrificed with at 1-, 2-, 4-, 6- and 8- weeks after surgery. The histology specimens were prepared using the general method with H & E staining at a 6 ㎛ thickness. Histologically, the degree of new bone formation was similar in all experimental groups. However, for experimental group II, many cells had gathered around the graft materials 1-week after surgery, and new bone formed slightly faster and than in the other groups. No bone formation was observed in the control group. Based on histology findings, the new HA/ß- TCP composite powders appeared to act as a scaffolding material for the regeneration of osseous defects.

Abstract: Calcium phosphate (CaP) hybridized to a whole tendon graft delayed cell repopulation in anterior cruciate ligament (ACL) reconstruction in rabbits. However, a tendon graft masked with an adhesive tape at the intra-articular (IA) portion to prevent CaP hybridization did not delay cell repopulation. Synovial tissues can adhere to the tendon graft and can invade the tendon graft masked at the IA portion. The masking induced an effect similar to that of the unhybridized tendon graft. The CaP hybridized tendon grafts masked at the IA portion showed cell repopulation 2 weeks earlier than the unmasked CaP hybridized tendon grafts.

Abstract: The purpose of this study is to determine the potential of the LEBRA-PXR imaging in investigating the details of newly formed bone around the dental implants. Transmission image observation of the undecalcified specimen at the wavelength of 1.771 Å showed clearly the formation of immaturely calcified new bone around the dental implants which could not be observed in the usual CMR nor conventional X-ray imaging apparatus.