Key Engineering Materials Vols. 309-311

Abstract: Six patients underwent arthroplasty of the trapeziometacarpal joint of the thumb with our ball-and socket type ceramic prosthesis for the osteoarthritis of Eaton stage 3 or 4. Our prosthesis was made of alumina ceramic and high-density polyethylene. Pain and dislocation or subluxation of the trapeziometacarpal joint were found in all of the patients preoperatively and these symptoms were relieved completely after surgery. The % total active motion of the trapeziometacarpal joint and metacarpophalangeal + interphalangeal joints, the % grip strength and % pinch strength improved postoperatively. The trapeziometacarpal joint function according to Eaton’s criteria after surgery was excellent of 5 patients and good of 1 patient.

Abstract: We innovated a new technique and hydroxyapatite material “HA Block” in order to decrease complications such as pulmonary embolization and correct kyphosis due to osteoporosis. A cadaveric study of vertebroplasty was attempted to confirm accurate the efficacy for three materials in terms of restoration of vertebral height, strength and stiffness after packing HA Block as compared with Polymethylmethacrylate Cement (PMMA) and alpha-tri-calcium phosphate cement (Biopex-R) in cadaveric study. By using thoracolumber spines derived from elderly human cadavers, two kinds of vertebral fracture models: Flat and Wedge were made on MTS 858 Mini. Restoration rate after packing each material was best for HA Block. The strength of HA Block was somewhat lower than PMMA and Biopex-R. It is suggested that HA Block had moderate and optimal strength to reduce stress to adjuscent vertebra and was enable to correct kyphosis in osteoporotic spine.

Abstract: We have successfully treated osteoporotic spine fractures for about three years, by using transpedicular kyphoplasty with hydroxyapatite blocks (HA Block: PENTAX) (refer with: Fig. 1), The 13 patients, four men and nine women, ranged from 61 to 86 years in age (mean, 73 years). The mean Visual Analogue Scale (VAS) was 8.5 points before operation, improved to 2.7 points on the next day of operation, and improved significantly to 1.8 points at the final evaluation. The mean deformity rate (Anterior height / Posterior height x 100) was 66.3% before operation, but improved to 91.7% immediately after operation. At the time of follow-up, this rate was 78.6%, indicating that the correction loss was 13.1%. This procedure caused none of serious complications such as neurological disorder and pulmonary infarction. Kyphoplasty with HA blocks may be safe and effective in the treatment of chronic vertebral fractures.

Abstract: I have been able to recognize a new pathogenesis of arthrosis. According to this pathogenesis, I have developed a new treatment to drain the joint fluid from the lesional bone marrow. This new treatment is referred to as “Core Drainage.” The benefits of my “Core Drainage” method were effective for late stage arthrosis and resulted in almost immediate pain relief. This is a minimally invasive procedure that does not require bed rest post-operatively. Patients are able to bear weight immediately. Core Drainage can prevent progression of arthrosis and can even cure arthrosis at an early stage. With this technique, degenerated and worn joint cartilage was regenerated, and joint effusion and contracture were almost eliminated. The Core Drainage method greatly enhances the patient’s quality of life.

Abstract: Calcium phosphate bioceramics and bovine bone xenograft with or without sintering are more or less used in orthopaedics or in maxillofacial surgery. In this study we compare in a rat femoral epiphysis model after 3 weeks of implantation the bone in growth at the expense of granules of same size of micro macro porous biphasic calcium phosphate MBCP, sintered bovine bone and unsintered BioOss.

Abstract: After culture expansion of mesenchymal stem cells (MSCs) from a few milliliter of fresh patient’s bone marrow, we applied the MSCs on alumina ceramic ankle prosthesis and further cultured in an osteogenic medium for 2 weeks. After the culture, the MSCs differentiated into osteoblasts, which fabricated bone matrix on the surface of ceramic prosthesis. The expansion of MSCs followed by osteogenic differentiation was done using the commercially available medium with some chemicals and patient’s own serum. The MSCs well proliferated and differentiated into osteoblasts, even the MSCs were from old aged (more than 70 years old) patients. The tissue engineered ceramic prostheses were implanted into osteoarthritic patients. Typical X-ray findings showed that radiodense areas began to appear around the cell-seeded areas on the prosthesis about 2 to 3 months after the operation. These findings confirmed the importance of tissue engineering approach for early bone fixation and the approach can be done using small number of bone marrow cells and patient’s own serum without adding animal-derived products.

Abstract: This study demonstrates the use of human dentine derived hydroxyapatite (DHA) as an easily prepared graft material in 23 dogs and 5 cats with various orthopaedic problems. Results of these cases were evaluated clinically and radiographically. This study reveals that DHA can be used safely in animals and is an effective graft material.

Abstract: Hydroxyapatite (HA) implants were used as grafting materials to fill some of the root resections in three patients. Two of the patients had previous root resections without implant insertion. Being implanted to the resection sites, the porous structure of HA serves as a framework for vascular and soft tissue ingrowth. Previous reports on the utilization of three phase nuclear bone scintigraphy (NBS) to evaluate the degree of fibrovascular ingrowth into HA dental implants after surgery are scarce. Three cases are described in which bone scintigraphy was performed at 6 months after implant insertion. The images revealed technetium-99m methylenediphosphonate (99mTc-MDP) uptake at dental implant sites consistent with vascularization and osteoconduction. The current results strongly indicate that osseointegration is complete. This study demonstrates that NBS is a valuable test in the follow up of osseointegration rate at implantation sites and HA is found to be a good biomaterial for grafting purposes showing high osseointegration rates.

Abstract: This study evaluated the effects of mixture of fibrin-fibronectin sealant system(FFSS) and calcium carbonate(CC) in periodontal intrabony defects. Thirty six sites with two or three wall intrabony defect were used. 14 defects treated with periodontal flap surgery were assigned as the control group. 11 defects treated with CC implantation were designed as experimental group 1 and 11 defects, treated with CC and FFSS implantation as experimental group 2. The control and experimental groups all achieved statistically significant improvements in probing depth and clinical attachment level from the baseline (P<0.01). In mean postsurgery probing depth and gingival recession reduction, there were no statiscally significant differences between the experimental groups and the controls. However, mean postsurgery clinical attachment levels of both experimental groups improved significantly more than that of the controls. As a result, we suggest that mixture of FFSS and CC can be used effectively in intrabony defect as osteoconductive materials.

Abstract: The objective of this paper is to theoretically investigate the stress distribution in a tooth model due to expansion or contraction of the filler material. Finite element calculations were carried out to determine the stresses and deformations in a model of the tooth. The tooth was modelled to consist of two concentric cylinders, an inner cylinder of 7 mm diameter dentine and an outer layer of 1 mm thick enamel. The two cylinders were assumed to be rigidly fixed at the bottom end and the top end was free. Different sizes of occlusal cavities (2, 4 and 7 mm) as well as mesial-occlusal and mesial-occlusal-distal were simulated through removal of dentine from the centre. The fillings were subjected to an internal pressure of 1 MPa and a chewing pressure of 1 MPa. Since the cylinders were rigidly fixed at one end, the inner part of the cavity (dentine) tended to bend outwards, thus compressing the outer (enamel) layer. This behaviour, coupled with a strong mismatch of the elastic moduli of dentine and enamel, leads to widely different distributions of stress in the tooth as the cavity sizes and filling types are varied. The radial deformations were of the order of microns, most of it occurring in the softer dentine. The maximum stresses occur in the stiffer enamel layer when a chewing pressure is applied, without a chewing pressure the stresses are more evenly distributed.