Biomedical subjects

J M Bouler

Publications and source records attributed to J M Bouler.

27 records · Page 2Linked to original sources

PubMed1999

Macroporous calcium phosphate ceramic: a prospective study of 106 cases in lumbar spinal fusion.

Macroporous biphasic calcium phosphate (MBCP, Triosite) is well known for its safety, absence of allergenicity, and excellent bone-bonding capacity, and it has been widely used as a bone graft substitute in orthopaedic, ENT, and dental surgery. This study investigates the clinical performance of this synthetic porous ceramic in a series of 106 patients, mainly with degenerative spine aetiologies (95/106) and with a minimum follow-up of 2 years. All patients were treated with posterior correction involving the semi-rigid New Orleans instrumentation. Spinal fusion was always performed using MBCP granules mixed with autogenous bone chips and bone marrow obtained from the local spine. Fusion of the spine was confirmed for 100 patients, and 6 non-unions were observed (3 resulting from primary spondylolisthesis). This study shows that MBCP provides suitable results in spinal fusion involving a semi-rigid instrumentation. Because the indication of degenerative spine is not very favorable to fusion, this technique appears to be a good alternative to autografts and could decrease patient morbidity resulting from iliac bone grafting.

Adolescent↗

PubMed1998

Apatite precipitation after incubation of biphasic calcium-phosphate ceramic in various solutions: influence of seed species and proteins.

The dissolution-precipitation process for calcium-phosphate ceramics in contact with biological fluid was studied by incubating blocks of biphasic calcium phosphate composed of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) in different solutions: ionic simulated body fluid (SBF) without protein or SBF that contained various proteins and macromolecules separately (fibronectin, vitronectin, albumin, and poly-L-glutamic acid). Transmission electron microscopy studies revealed that apatite-precipitated microcrystals appeared around ceramic crystals as a result of secondary nucleation; microcrystals were in continuity with the lattice planes of the HA crystals but in a different direction from that of beta-TCP; the size of the precipitates was smaller when fibronectin, vitronectin, and poly-(L-glutamic acid) were present in SBF as compared to SBF without protein; and fibronectin and vitronectin initiated crystal nucleation in the void spaces between the ceramic crystals.

Apatites↗

PubMed1997

Osteoclastic resorption of biphasic calcium phosphate ceramic in vitro.

Neonatal rabbit bone cells were cultured for 1 and 4 days on biphasic calcium phosphate ceramic specimens to study the osteoclastic resorption of the ceramic. Scanning electron microscopic studies after removal of stromal cells with pronase E and EDTA revealed many osteoclast-associated lacunae on the ceramic surface. The degraded crystals inside the lacunae appeared to have been dissolved by acids. Cellular degradation of the ceramic was clearly due to the extracellular process characteristic of osteoclastic resorption.

Animals↗

PubMed1997

Adaptive crystal formation in normal and pathological calcifications in synthetic calcium phosphate and related biomaterials.

Mineralization and crystal deposition are natural phenomena widely distributed in biological systems from protozoa to mammals. In mammals, normal and pathological calcifications are observed in bones, teeth, and soft tissues or cartilage. We review studies on the adaptive apatite crystal formation in enamel compared with those in other calcified tissues (e.g., dentin, bone, and fish enameloids) and in pathological calcifications, demonstrating the adaptation of these crystals (in terms of crystallinity and orientation) to specific tissues that vary in functions or vary in normal or diseased conditions. The roles of minor elements, such as carbonate, magnesium, fluoride, hydrogen phosphate, pyrophosphate, and strontium ions, on the formation and transformation of biologically relevant calcium phosphates are summarized. Another adaptative process of crystals in biology concerns the recent development of calcium phosphate ceramics and other related biomaterials for bone graft. Bone graft materials are available as alternatives to autogeneous bone for repair, substitution, or augmentation. This paper discusses the adaptive crystal formation in mineralized tissues induced by calcium phosphate and related bone graft biomaterials during bone repair.

Animals↗

PubMed1997

Osteoclastic resorption of calcium phosphate ceramics with different hydroxyapatite/beta-tricalcium phosphate ratios.

To study the influence of calcium phosphate ceramic solubility on osteoclastic resorption, neonatal rabbit bone cells were cultured for 2 days on hydroxyapatite (HA), beta-tricalcium phosphate (beta-TCP) and two types of biphasic calcium phosphate (BCP) with HA/beta-TCP ratios of 25/75 and 75/25. Solubility was regulated by varying the ratio of less-soluble HA and more-soluble beta-TCP. After removal of stromal cells by pronase E treatment, ceramic surfaces were observed by scanning electron microscopy. Osteoclasts resorbed BCP most extensively, with an HA/beta-TCP ratio of 25/75, producing typical lobulated, zig-zag track-like resorption lacunae. On pure beta-TCP, which had the highest solubility in acid, osteoclasts formed smaller discontinuous island-like lacunae. The resorption pattern may have been modified by the large number of calcium ions released into the acidic microenvironment at the osteoclast-ceramic interface. No resorption lacunae were found on the other specimens. The extent of osteoclastic resorption of calcium phosphate ceramics might, to a certain degree, be proportional to solubility, although this was not the case when solubility was very high. It would appear that ceramic solubility influences osteoclast resorption activity.

Animals↗

PubMed1997

Fourier-transform infrared spectroscopy study of an organic-mineral composite for bone and dental substitute materials.

A new injectable biomaterial for bone and dental surgery is a composite consisting of a polymer as a matrix and bioactive calcium phosphate (CaP) ceramics as fillers. The stability of the polymer is essential in the production of a ready-to-use injectable sterilized biomaterial. The purpose of this study was to detect possible polymer degradation which may have been caused by the interaction with the fillers using Fourier transform infrared spectroscopy. Composites containing CaP fillers (biphasic calcium phosphate, hydroxyapatite and peroxidized hydroxyapatite) and polymer (hydroxypropyl methyl cellulose) were prepared. To investigate the properties of the polymer, the inorganic and organic phases of the composite were separated using several extraction methods. The difficulty in separating the organic (polymer) from the mineral (CaP fillers) phases in the composite investigated in this study suggested the presence of strong interactions between the two phases. Spectra of extracted polymers showed new absorption bands of low intensities and indications that some chemical modifications of the original polymers have occurred. Results also indicated that the filler composition has an effect on the integrity of the polymer.

Journal Article↗

PubMed1996

Macroporous biphasic calcium phosphate ceramics: influence of five synthesis parameters on compressive strength.

Compressive strength measurements were conducted on 32 macroporous biphasic calcium phosphate (MBCP) samples to evaluate the influences and interactions of five synthesis factors: chemical composition, percentage of macropores, mean size of macropores, isostatic compaction pressure, and sintering temperature. These parameters were varied simultaneously between two limit levels. Experiments used a factorial design method (FDM) allowing optimization of the number of samples as well as statistical analysis of results. FDM showed that compressive strength, in a defined experimental area, can be described by a first-order polynomial equation in which the percentage of macroporosity and sintering temperature are the major influences. This study leads up to an isoresponse line diagram that will allow the manufacture of some classes of MBCP with fitted compressive strength.

Bone Substitutes↗

PubMed1996

Biodegradation of synthetic biphasic calcium phosphate by human monocytes in vitro: a morphological study.

Biodegradation processes (both intra- and extracellular) occur immediately after implantation of calcium phosphate (CaP) ceramics. Monocytes and macrophages, among the first cells to appear in wound healing, are largely implicated in phagocytosis and may be involved in CaP degradation because of their sensitivity to secreted cytokines. We tested the behaviour of human monocytes placed on the surface of hydroxyapatite (HA) and biphasic calcium phosphate (BCP) tablets in the presence of vitamin D3 (VD3) and interferon gamma (INF gamma). After short-term culture (6 days), morphological events were observed in histological and scanning electron microscopy studies, and degradation lacunae were characterized. There were cell prints but no pits on the HA surface, but pits appeared near cells on the BCP surface. Preincubation of biomaterial in culture medium was essential. Variations in cell morphology were observed in different culture types. In the presence of VD3, degradation was greater than in the control, and cells were more polarized and rounded. With INF gamma, cells were extensively spread out on the sample surface, and the biomaterial seemed to be extracted from the surface by cells. Thus, monocytes are clearly influenced by soluble factors (vitamins, cytokines) and could be key cells in initiating the degradation of biomaterial.

Biodegradation, Environmental↗

PubMedDate not supplied

Macroporous biphasic calcium phosphate ceramics: influence of macropore diameter and macroporosity percentage on bone ingrowth.

A total of 60 cylindrical 6 x 6 mm samples of a macroporous biphasic calcium phosphate (MBCP) ceramic were implanted into a distal femoral site in 30 rabbits. These samples represented six kinds of implants with two different macropore diameters and three different macroporosity percentages. Analysis of backscattered electron images of implant surfaces analysed by a factorial design method showed that implants with 565 microm pore size provided more abundant newly formed bone both in peripheral and deep pores than those with 300 microm pore size. No significant differences were found between implants with 40 and 50% macroporosity, suggesting that the influence of macropore size on bone ingrowth was greater than that of macroporosity percentage. MBCP implants with 565 microm pore diameter and 40% macroporosity represented the optimal association for homogeneous and abundant bone ingrowth.

Animals↗