Calcium phosphate (CaP) biomaterials currently in use for bone repair, substitution, augmentation, and regeneration include hydroxyapatite of synthetic or biologic origin, beta-tricalcium phosphate (β-TCP), and biphasic calcium phosphate. They are available as granules, porous blocks, CaP/polymer composites, cements, and as coatings on orthopedic and dental implants. Experimental CaP biomaterials include CO₃- and F-substituted apatites, Mg- and Zn-substituted β-TCP, and CaP glasses. This paper gives a brief review of the different types of CaP biomaterials available and their properties, such as bioactivity, osteoconductivity, and osteoinductivity.

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It has been shown that mucosal application of chemokines with protein antigen (Ag) successfully induces mucosal and systemic antibody (Ab) responses, as well as CD4⁺ T cell responses. We examined whether plasmids expressing lymphotaction (LTN) and/or macrophage chemoattractant proteine-1 (MCP-1) cDNA (pLTN and pMCP-1) exhibit nasal adjuvanticity when administered with protein Ag. When either pLTN or pMCP-1 was employed as a nasal adjuvant in mice, OVA-specific IgG Ab responses were seen in plasma ; however, both failed to induce OVA-specific secretory IgA (S-IgA) Abs in external secretions except anti-OVA IgG and IgA Abs in nasal washes of mice given pLTN. However, mice nasally immunized with a combination of pLTN and pMCP-1 showed OVA-specific S-IgA Ab responses in both saliva and fecal extracts. Further, that combination of chemokines used as a nasal adjuvant induced the highest levels of CD4⁺ T cell proliferative and Th2-type cytokine responses in cervical lymph nodes (CLN), as compared with a single chemokine nasal administration. In addition, a significantly increased number of CD11c⁺ dendritic cells (DCs) which expressed co-stimulatory molecules such as MHC II, CD40 and CD86 noted in the nasopharyngeal-associated lymphoreticular tissue (NALT) of mice given pLTN and pMCP-1. These results show that a combination of pLTN and pMCP-1 given as a nasal adjuvant induces optimal mucosal S-IgA Ab responses in submandibular glands, which are mediated by increased number of DCs in the NALT and Th2-type CD4⁺ T cells in the CLN.

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This study examined the influence of carbon chain length of fluorinated alkyl acrylate on bacterial adhesion to the surface of test specimens. Perfluorobutylethyl acrylate (C4F), perfluorohexylethyl acrylate (C6F), perfluorooctylethyl acrylate (C8F), and perfluorodecylethyl acrylate (C10F) were used as fluorinated alkyl acrylate monomers. All specimens with the fluoro-monomer added exhibited significantly higher water-shedding and oil-shedding surface characteristics when compared to control (MMA/PMMA). Furthermore, contact angle for droplets of water and dodecane on the fluoromonomer-added specimens increased with carbon chain length of the perfluoroalkyl groups. Bacterial adhesion was significantly suppressed on the fluoromonomer-added specimens, both the saliva-uncoated and -coated specimens. In addition, the number of Candida albicans adhering to both the saliva-uncoated and -coated fluoromonomer-added specimens decreased with an increase in perfluoroalkyl carbon chain length. The results suggest that the application of fluorinated alkyl acrylate to denture base resin can modify the surface characteristics, and that fluorinated alkyl acrylate with long carbon chains of C8F and C10F successfully inhibit bacterial adherence to the resin surface.

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A new selective medium, designated GCHB, was developed for the isolation of Actinobacillus actinomycetemcomitans from clinical specimens. A sole inhibitory substrate was used, bacitracin at 100 u/ml. All serotypes (a to g) of A. actinomycetemcomitans strains grew well on the medium. The average growth recovery of A. actinomycetemcomitans on GCHB medium was 89.1% of that on nonselective blood medium. Growth of Haemophilus aphrophilus was significantly inhibited on the medium with an average recovery of 0.01%. The proportion of contaminating bacteria among total cultivable bacteria from clinical samples on GCHB was one to ten times lower than that on TSBV.

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In fura-2-loaded human gingival fibroblasts, 1-50 μM MnCl₂ evoked an increase in intracellular Ca²⁺ concentrations ([Ca²⁺]_i) in a dose-dependent manner. This increase was abolished in the absence of extracellular Ca²⁺. MnCl₂ induced an increase in [Ca²⁺]_i provoked prostaglandin E₂ release in human gingival fibroblasts in time- and dose-dependent manners. MnCl₂ failed to evoke prostaglandin E₂ release in the absence of extracellular Ca²⁺. A protein kinase C activator and a tyrosine kinase inhibitor inhibited the increase in [Ca²⁺]_i induced by MnCl₂. These results suggest that Mn²⁺ evokes Ca²⁺ entry and prostaglandin E₂ release in human gingival fibroblasts, which are regulated by protein kinase C and tyrosine kinase activities.

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During the isolation of Actinobacillus actinomycetemcomitans from periodontal pockets, a serologically untypeable strain, designated NUM-Aa 4039, was observed. Biochemical and serological identification and PCR-based analysis confirmed that NUM-Aa 4039 was a strain of A. actinomycetemcomitans. An antigen from NUM-Aa 4039 did not react with a to e serotype-specific antibodies in double-immunodiffusion experiments. DNA from the strain could not be amplified by PCR using specific PCR DNA primer of a to f serotype-specific O-polysaccharide gene cluster. The antigen was extracted from whole cells by autoclaving and purified by ion-exchange and gel filtration chromatography. The molecular weight was approximately 180,000. The new antigen was composed of glucose, rhamnose and N-acetyl-glucosamine. Double immunodiffusion and ELISA experiments with antigens and antibodies showed that the antigen had individual antigen determinant. I propose that untyped strain be assigned to a new A. actinomycetemcomitans serotype, designated serotype g.

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The rickets rat is a rat model of metabolic bone disease that displays deficient calcification of bone throughout the body. By placing an implant in the tibia of the rickets rat, the present research sought to : measure bone contact ratio with regard to bone healing around the implant as a result of differences in surface properties, examine crystallization of apatite using a micro X-ray diffraction and compare the compatibility of various implants. Bone contact ratio 4 weeks after implant placement was greater with a sandblasted implant (control group, 68.8±22.8% ; rickets group, 46.9±19.4%) than an anodic oxidation implant (control group, 64.7±20.7% ; rickets group, 36.6±17.9%). Similarly, 8 weeks after implant placement contact was greater with a sandblasted implant (control group, 80.2±12.9% ; rickets group, 61.1±18.1%) than an anodic oxidation implant (control group, 74.0±18.3% ; rickets group, 52.4±16.6%). Four and 8 weeks after implant placement, micro X-ray diffraction indicated a greater total amount of crystals for the sandblasted implant than the anodic oxidation implant in both the control and the rickets groups, and apatite with good crystallinity was detected.

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Human bone marrow-derived mesenchymal stem cells (hMSC) have the ability to differentiate into osteoblasts and are thought to be useful for bone regeneration. Although the commitment of hMSC differentiation into osteoblasts has been studied, the molecular-based mechanisms, especially the gene expression profile, are poorly understood. In this study, to identify the genes involved in the differentiation of hMSC into osteoblasts, hMSC were cultured with osteogenic induction medium and gene expression changes were examined using the Affymetrix GeneChip analysis system. Osteomodulin mRNA levels were elevated during the differentiation process and those gene expression changes were successfully confirmed by endpoint reverse transcription/polymerase chain reaction (PCR) and real-time PCR. Thus, gene expression profiling of in vitro differentiation cultures of hMSC using GeneChip analysis will be useful for defining the lineage-specific differentiation of hMSC into osteoblasts. Because osteomodulin is found in hard tissues and plays an important role in collagen fibrillogenesis, cellular growth, differentiation, and migration, elevation of osteomodulin transcription may be involved in the differentiation process of hMSC into osteoblasts.

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