A study about early osteoconductivity of porous alloplastic carbonapatite and anorganic bovine xenograft in canine maixlliary augmentation model

Evaluation of Osteosynthesis in CaO-SiO2-P2O5-B2O3 Glass-ceramics by Posterolateral Fusion of Rabbit Lumbar vertebrae / 대한척추외과학회지

STUDY DESIGN: A comparative in vivo study between ceramics with different compositions. OBJECTIVES: To compare the biodegradation and osteoconduction properties of CaO-SiO2- P2O5- B2O3 glass-ceramics and Cerabone(R)-AW. Summary of Literature Review: Bioglass ceramics can be used as bone graft substitutes. However, no study has been undertaken to investigate the possibility of CaO-S i O2-P2O5-B2O3 glass-ceramics as a bone graft substitute. MATERIALS AND METHODS: Porous CSPB2 implants (44.07% CaO, 40.28% SiO2, 8.1% P2O5 and 5.0% B2O3), porous CSPB3 implants (43.76% CaO, 43.41% SiO2, 4.05% P2O5 and 7.5% B2O3) and porous Cerabone(R)-AW were prepared by the polymer sponge method. Single-level posterolateral spinal fusions were performed on sixty New Zealand white male rabbits. The animals were divided into four groups (9 of autograft, 17 per 3 kind of porous implant group) according to the implant material used: autograft, CSPB2, CSPB3 and Cerabone(R)-AW. Radiographs were performed every two weeks. All animals were sacrificed 12 weeks after surgery. Manual palpation and uniaxial tensile strength were determined. The proportion of the area occupied by the ceramics in the final compared to the initial radiographs was calculated. Decalcified and undecalcified histological sections were evaluated by light microscopy. RESULTS: Fifty one rabbits were evaluated. The union rates were 100 (9 out of 9), 80 (8 out of 8), 81.1 (9 out of 11) and 90.9% (10 out of 11) in the autograft, Cerabone(R)-AW, CSPB2 and CSPB3 groups, respectively. The proportion of the area occupied by Cerabone(R)-AW (90.8 % +/- 14.0) was significantly higher than for CSPB2 (73.1% +/- 11.5) and CSPB3 (73.5% +/- 10.0)(p=0.0011). The mean values of the tensile strengths of Cerabone(R)-AW (214. +/- 57.3N), CSPB2 (214. +/- 57.3 N) and CSPB3 (217 +/- 70.1 N) were not significantly different (p>0.05). CONCLUSION: CSPB2 and CSPB3 had similar tensile strengths and fusion rates of the fusion masses as those of Cerabone(R)-AW; however, they degraded more rapidly than Cerabone(R)-AW. These findings suggest that CSPB2 and CSPB3 grafts can be used as a more ideal new bone graft substitutes than Cerabone(R)-AW.

Finite element analysis of cylinder type implant placed into regenerated bone with type IV bone quality

Stress transfer to the surrounding tissues is one of the factors involved in the design of dental implants. Unfortunately, insufficient data are available for stress transfer within the regenerated bone surrounding dental implants. The purpose of this study was to investigate the concentration of stresses within the regenerated bone surrounding the implant using three-dimensional finite element stress analysis method. Stress magnitude and contours within the regenerated bone were calculated. The 3.75*10-mm implant (3i, USA) was used for this study and was assumed to be 100% osseointegrated, and was placed in mandibular bone and restored with a cast gold crown. Using ANSYS software revision 6.0, a program was written to generate a model simulating a cylindrical block section of the mandible 20 mm in height and 10 mm in diameter. The present study used a fine grid model incorporating elements between 165,148 and 253,604 and nodal points between 31,616 and 48,877. This study was simulated loads of 200N at the central fossa (A), at the outside point of the central fossa with resin filling into screw hole (B), and at the buccal cusp (C), in a vertical and 30degree lateral loading, respectively. The results were as follows; 1. In case the regenerated bone (bone quality type IV) was surrounded by bone quality type I and II, stresses were increased from loading point A to C in vertical loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, concentrated on the top of the cylindrical collar loading point B and C in vertical loading. And, In case the regenerated bone (bone quality type IV) was surrounded by bone quality type III, stresses were increase from loading point A to C in vertical loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, B and C in vertical loading. 2. In case the regenerated bone (bone quality type IV) was surrounded by bone quality type I and II, stresses were decreased from loading point A to C in lateral loading. Stresses according to the depth of regenerated bone were concentrated on the top of the cylindrical collar in loading point A and B, distributed along the implant evenly in loading point C in lateral loading. And, In case the regenerated bone (bone quality type IV) was surrounded by bone quality type III, stresses were decreased from loading point A to C in lateral loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, B and C in lateral loading. In summary, these data indicate that both bone quality surrounding the regenerated bone adjacent to implant fixture and load direction applied on the prosthesis could influence concentration of stress within the regenerated bone surrounding the cylindrical type implant fixture.

Evaluation of Biodegradation and Osteosynthesis in CaO-SiO2-B2O3 Glass-ceramics by Posterolateral Fusion of Rabbit Lumbar vertebrae / 대한정형외과학회잡지

PURPOSE: To compare the biodegradation and osteoconduction properties of CaO-SiO2-B2O3 glass-ceramics (CS10B), hydroxyapatite(HA), and tricalcium phosphate (TCP). MATERIALS AND METHODS: Porous CS10B implants were prepared by the polymer sponge method. Single-level posterolateral spinal fusions were performed on thirty rabbits. The animals were divided into three groups by implant material: HA, TCP and CS10B. Radiographs were performed every two weeks. All animals were sacrificed 12 weeks after surgery. The proportion of the area occupied by the ceramicsin the final over the initial radiographs was calculated. Uniaxial tensile strength was determined from 7 cases in each group. RESULTS: The proportion of the area occupied by HA (88.7+/-16.1%) was significantly higher than the others (p<0.05), and the proportion of the area occupied by CS10B (28.2+/-9.3%) was significantly lower than those of HA and TCP (37+/-9.6%) (p<0.05). The mean values of the tensile strengths of HA (191.4+/-33.5 N) and CS10B (182.7+/-19.9 N) were significantly higher (p<0.05) than those of TCP (141.1+/-28.2 N). CONCLUSION: CS10B had similar tensile strengths of the fusion masses as HA, however, it degraded more rapidly than HA or TCP. These findings suggest CS10B grafts as possible bone replacement materials.

Porous Beta-Calcium Pyrophosphate as a Bone Graft Substitute in a Canine Bone Defect Model / 대한정형외과학회잡지

PURPOSE: To evaluate the possibility of using porous beta-calcium pyrophosphate (beta-CPP) as a bone graft substitute by comparing its osteoconduction and degradation with porous hydroxyapatite (HA). MATERIALS AND METHODS: Porous HA and porous beta-CPP were implanted in the proximal tibia of 7 dogs. Two animals were sacrificed at 8weeks and 5 animals were sacrificed at 20 weeks after surgery. Radiographs and histologic sections were evaluated. RESULTS: The mean period required for the radiolucent zone to disappear was 7.1+/-1.1 weeks in HA and 6.4+/-1.1 weeks in beta-CPP. By serial radiography, resorption was more prominent in porous beta-CPP than in porous HA at 8 weeks (p=0.04) and at 20 weeks. The proportion of bony tissue in the pore was 16.8% in HA and 29.7% in -CPP. The proportion of pores with bony tissue was 70.2% in HA and 62.5% in beta-CPP at 8 weeks. CONCLUSION: In beta-CPP, the new bone growth was as vigorous as in HA, but the degradation was more rapid than in HA. These results suggest that beta-CPP is a more ideal new bone graft substitute.

Evaluation of Osseointegration in Dense Ceramics Using Rabbit's External Fixation Model / 대한정형외과연구학회지

PURPOSE: To evaluate the osseointegration of different dense ceramics. MATERIALS AND METHODS: Twenty-eight New Zealand white male rabbits were divided into 4 groups by implant materials: Cerabone(R)-AW, CaO-SiO2- B2O3 glass ceramics (CS10B), CaO-SiO2- B2O3 glass (CS5B glass) and Cerabone(R)- A W + A l2O3 glass ceramics. We implanted the dense ceramics into the tibia of rabbits with external fixator and checked the radiographs every 4 weeks. The union rate, histology and SEM were evaluated 8 weeks after surgery. RESULTS: The union rates were 85.7% (6 of 7) in Cerabone(R)-AW, 85.7% (6 of 7) in CS10B, 71.4% (5 of 7) in CS5B glass and 28.6% (2 of 7) in Cerabone(R)-AW+Al2O3 by simple radiographs. The union rates of Cerabone (R)-AW and CS10B were statistically higher than that of Cerabone(R)-AW+Al2O3 (p=0.031). Histologically, the Cerabone(R)-AW had fused with tibia without biodegradation, CS10B, CS5B glass had fused with tibia in some portion but resorbed in others. Cerabone(R)-AW+Al2O3 had not fused with bony tissue. CONCLUSION: We confirmed the osseointegration and insolubility of Cerabone(R)-AW. We also confirmed the osseointegration and partial solubility of CaO-SiO2-B2O3 glass ceramics. These findings suggest that Cerabone (R)-AW can be used as an insoluble artificial bone and CaO-SiO2-B2O3 glass ceramics as biodegradable bone replacement materials.

Comparison of Osteosyntheses in Various Types of Porous Calcium Phosphate Compounds: An Experimental Study by Posterolateral Fusion of Rabbits' Lumbar Vertebrae / 대한척추외과학회지

PURPOSE: The purpose of the present study was to compare the osteoconduction in porous bodies made of various compositions of calcium phosphate compounds and other porous artificial bones. MATERIALS AND METHODS: Single-level posterolateral spinal fusions were performed on ninety rabbits. The animals were divided into nine groups by graft materials: autograft (positive control), implantation of HA, TCP, CPP, HA/TCP composite, TCP/CPP composite, Lubboc(R) and Calcium sulfate pellet (CSP), no-graft after decortication (negative control). Serial radiography, serum calcium and phosphorus levels were checked. All animals were sacrificed 12 weeks after surgery and the fusion masses were compared by manual palpation, uniaxial tensile strength measurement and histological evaluation. RESULTS: Autografted and CPP implanted groups showed significantly higher fusion ratio than TCP, TCP/CPP composite, and no-graft groups. Meanwhile, HA and HA/TCP groups showed no significant difference with other groups in fusion ratio. From the radiological examination, TCP and CPP groups seemed to show more rapid absorption of implant than HA group. The mean values of tensile strength of autografted and CPP group were significantly larger than those of TCP, TCP/CPP composite, and no-graft groups. The result of direct inspection and microscopic examination showed the TCP-contained implants lost their porous structure, whereas the other implants did not. On the light microscopy, both HA and CPP groups showed more abundant new bone growth into the pores than TCP-contained groups, but the pore size of CPP became larger than that of the HA, which manifested more rapid absorption of CPP in the living body. CONCLUSION: The porous CPP implant is considered to be more desirable bone graft substitute because it has satisfactory osteoconductive ablility and better biodegradation than porous HA. And the maintenance of porous structure is considered to be indispensable for osteoconduction.

Differences in Osteoconduction at Porous Hydroxyapatite according to Pore Geometry / 대한정형외과학회잡지

PURPOSE: To assess the histological response and the reinforcing effects of bone ingrowth within porous hydroxyapatite implants depending on pore geometry. MATERIALS AND METHODS: Three types of porous hydroxyapatite (cylindrical, sponge and cross type) were prepared. Forty-two white rabbits were divided into 3 groups and 5x5x7 mm-sized porous hydroxyapatite block was inserted through the medial cortical window of a proximal tibia. Histomorphological changes were examined using light and scanning electron microscopy. Biomechanical compression test was performed using material test machine. RESULTS: At four weeks after implantation, the implants showed different histological changes depending on pore geometry. In cylindrical type porous hydroxyapatite, new bone was arranged in a concentric pattern around vessel similar to osteon. In sponge and cross type, irregular lamellar bone pattern was found. At 8 weeks, evidence of remodelling of new bone and bone marrow formation within porous hydroxyapatite was found. In biomechanical study, ultimate compressive strength significantly increased in all three implants after 8 weeks of implantation compared to preimplantation. CONCLUSIONS: In cylindrical type porous hydroxyapatite, new bone was arranged in a concentric pattern around vessel, and compressive strength was highest. Sponge type porous hydroxyapatite showed irregular lamellar bone pattern and was rather flexible and ductile. Cross type porous hydroxyapatite showed borderline pattern of both cylindrical and sponge type porous hydroxyapatite.

Effects of Pore Size on Osteoconduction at the Porous Hydroxyapatite / 대한정형외과학회잡지

PURPOSE: Porous hydroxyapatite is resorbable and osteoconductive, so it is slowly replaced by ingrowing new bone. Optimal pore geometry for osteoconduction, however, has not been determined yet. The objective of this investigation was to assess both the histological response and the reinforcing effects of bone ingrowth within the porous hydroxyapatite implants depending on pore size. MATERIALS AND METHODS: Four kinds of cylindrical types (50, 100, 300, 500 micrometer) of porous hydrox-yapatite were prepared. Fifty-six white rabbits were divided into 4 groups and porous hydroxyapatite block was inserted through the medial cortical window of a proximal tibia. Histomorphological changes were examined using light microscopy and scanning electron microscopy. Biomechanical compression test was performed using a material test machine. RESULTS: Hydroxyapatite implants appeared to have no early adverse effects, such as inflammation and foreign body reaction. Osteoconduction through the pores was found in all four implants and new bone was found on the surface of pores with no histologically demonstrable intervening nonosseous tissue. At four weeks after implantation, new bone was arranged in a concentric pattern around the vessel, similar to osteon. New bone formation through pores was most evident at 300 micrometer-sized type. At 8 weeks, active osteoconduction was also found at 50 micrometer-sized type. Evidence of bone marrow formation within porous hydroxyapatite was found. In a biomechanical study, ultimate compression strength significantly increased in the 300 micrometer-sized type, after 8 weeks implantation compared to preimplantation. CONCLUSIONS: Porous hydroxyapatite implanted into rabbit tibia showed biological fixation and osteointegration. A pore size of 300 micrometer was most effective for bone ingrowth. Osteoconduction also took place in 50 micrometer-sized cylindrical pores.

Difference of Bonding Behavior between Four Different Kinds of Hydroxyapatite Plate and Rabbits's Bone / 대한정형외과학회잡지

The change of conditions of hydroxyapatite synthesis can affect not oniy the material properties, but also the body reaction to the hydroxyapatite implants. To find out conditions for preparing more biocompatible hydroxyapatite implants as bone graft substitute. we evaluated the biologic response to the dense synthetic hydroxyapatite implants, made with various synthetic conditions, placed in corticocancellous defects of rabbits' long bone. The hydroxyapatites were synthesized with coprecipitation technique using Ca(NO3) 4H2O and (NH4)2HPO4, made with various Ca/P ratio and aging temperatures. Four kinds of hydroxyapatites were selected to use as implants(HA I: Ca/P ratio 1.5, aging temperature 90degrees C; HA V :1.5 , 30degrees C; HA VI: 1.83, 30degrees C; and HA lX: 1.67, 30degrees C). These hydroxyapatites were pressed and sintered at l300degrees C to fabricate dense plates. Biomechanical test and rnorphological examination were performed using Instron, light microscope and electron microscope. The characteristics of hydroxyapatite powder and sintered body were more significantly affected by siarting Ca/P ratios. The bonding strength of HA IX(1.67, 30degrees C) with bone was grcatest at 4 or 8 weeks after implantation with statistically significant difference(p<0.05). Bonding behavior betweeb HA IX and bone was most excellent in terms of new bone formation and new bone ingrowth into resorbed surface of hydroxyapatite plate.

Health Assessment for Glass Fibre Landfill at Gozan-dong, Inchon / 예방의학회지

In September 1994, residents of Gozan-dong, Incheon City, made a petition to the government about their health problems which might be caused by previous glass fibre landfill nearby "H" company. In February 1995, at regular academic meeting of occupational and environmental medicine, a research team of "D" University presented that they had found glass fibres in groundwater of the area through their survey. They were suspicious of probable association between ingestion of groundwater contaminated with glass fibres and skin tumors among residents. A joint research team was formed and carried out the survey of environment concerning groundwater and its glass fibre existence, and health assessment of residents in the area and industrial workers of "H" company during May to November, 1995. Analysis of groundwater flow system indicates that the flow lines from the glass fibre landfill pass through or terminate at the 6 houses around the landfill. This means that the groundwater of the 6 houses around the glass fibre landfill could be affected by some possible contaminants from the landfill, but the groundwater quality of the other houses was irrelevant to the landfill. The qualitative and quatitative analyses for glass fibres in 54 groundwater samples including those from the nearby 6 houses, were carried out using SEM equipped with EDS, resulting in no evidence for the presence of glass fibres in the waters. Major precipitates, formed in waters while boiling, were identified as calcium carbonates, in particulary, aragonites in needle form. The results of health assessments of 889 residents in Gozan-dong, participated in this study, showed statistically significant differences in past medical histories of skin tumor and respiratory disease between the exposed group (31 persons who inhabited in 6 houses around the landfill) and the control group, but no significant differences in past medical histories of other diseases, such as cancer mortality, current gastroscopic findings, current skin diseases and respiratory diseases, etc. Also, we could not prove any glass fibres in excised specimens of 9 skin tumors in both groups and there were no health problems possibly associated with glass fibres in employees of the "H" company. After all, we could not authenticate the association, raised by prior investigators, between groundwater streams, assumedly contaminated with glass fibres or not, and specific disease morbidities or common disease/symptom prevalences. That is, we could not find any glass fibres in groundwater as the only exposure factor of this study hypothesis, and there were not enough certain evidences such as increasing disease prevalences, for examples, skin, respiratory and gastrointestinal diseases etc, possibly related to glass fibre exposure, in exposed group. As a matter of course, the conditions for confirming causal association, for example, strength of the association, consistency of the association, specificity of the association, temporality of the association and dose-response relationship etc, have not been satisfied. In conclusion, we were not able to certify the hypothesis that contamination of groundwater with glass fibres might cause any hazardous health effects in human who used it for drinking.