Biomedical subjects

G J Meijer

Publications and source records attributed to G J Meijer.

21 records · Page 2Linked to original sources

PubMed1996

Polyactive as a bone-filler in a beagle dog model.

Calcification is a crucial step in the bone-bonding mechanism of PEO/PBT hydrogel copolymers (Polyactive, a new generation of bone-fillers. A beagle dog study was conducted to determine whether the preoperative presence of a calcium phosphate layer (precalcification) on a PEO/PBT 80/20 copolymer would further increase the bone-bonding rate. Standard bone cavities were filled with either precalcified or nonprecalcified porous cylindric PEO/PBT 80/20 implants, or hydroxyapatite granules held together with PEO/PBT 70/30, or were left unfilled. A significantly higher percentage of mineralized component was present in the cavities filled with the precalcified PEO/PBT 80/20 copolymer than in the control defects. As a result of swelling by fluid-uptake, the press-fit inserted copolymer implants showed a significant reduction in pore size, thus preventing optimal bone ingrowth. Both precalcification of the copolymer and underfilling of the defect, to create space for the copolymer to increase in diameter, stimulate postoperative calcification and bone ingrowth in PEO/PBT 80/20 copolymers.

Alveolectomy↗

PubMed1995

The influence of a flexible coating on the bone stress around dental implants.

The influence of a three-layered flexible coating of Polyactive on bone stress distribution was investigated by three-dimensional finite element models of mandibular bone, in which a titanium implant (coated or uncoated) was located. Polyactive is a system of poly(ethylene oxide) poly(butylene terephthalate) segmented co-polymers with bone-bonding capacity. In the case of sagittal and transversal loading, the use of a Polyactive coating reduced both the minimum principal stress in the bone and the compressive radial stress at the bone-implant interface. However, it raised the maximum principal and the tensile radial stress. In the case of vertical loading, the application of a flexible coating reduced the compressive radial stress at the bone-implant interface around the neck of the implant by a factor of 6.6 and the tensile radial stress by a factor of 3.6. Variations in composition and thickness of the coating did not affect the results significantly.

Alveolar Process↗

PubMed1995

Observations of the bone activity adjacent to unloaded dental implants coated with Polyactive or HA.

In addition to bone-bonding biomaterials such as calcium phosphate ceramics and Bioglass/glass ceramics, an elastomeric poly(ethylene oxide) poly(butylene terephthalate) (PEO/PBT) segmented block co-polymer (Polyactive) was recently introduced. In contrast to ceramic biomaterials, Polyactive is a flexible material. In a previous three-dimensional finite element analysis study, it was stated that application of a flexible Polyactive coating simulates the function of the periodontal ligament. The topic of this investigation was to compare the bone-bonding capacity of Polyactive-coated titanium implants with hydroxylapatite (HA) coated implants. The implants were inserted bilaterally in the edentulous part of the mandibular bone of 12 goats. After 3 weeks, the implants were in close contact with the cortical bone, but no cortical bone reaction or remodelling was observed. After 9 weeks, an extensive bone reaction was seen around the HA and Polyactive-coated implants and contact was frequently encountered between newly formed bone and the implants. Within the surface of the Polyactive coating, a considerable amount of calcification was present. After 25 weeks, cortical remodelling was still apparent. A striking finding was the apparent association between osteon formation and calcification within the surface of the Polyactive layer. Back-scatter analysis of the non-decalcified Polyactive bone interface showed the presence of a calcium phosphate layer in the implant material that apparently formed a continuity with the mineral matrix of bone, suggesting bone-bonding. In general, it was observed that the bone reactions to HA and Polyactive were comparable. A swelling of the coating, just beneath the cortical layer (champagne-cork effect) was often seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗