Influence of polymerization properties of 4-META/MMA-based resin on the activity of fibroblast growth factor-2.

Dental adhesive resins based on 4-methacryloxyethyl trimellitate anhydride (4-META)/methyl methacrylate (MMA) have been utilized for root-end filling and the bonding of fractured roots. To increase the success rate of these treatments, it would be beneficial to promote the healing of surrounding tissue by applying growth factors. In this study, the influences of the polymerization properties of 4-META/MMA-based resins on the activity of fibroblast growth factor-2 (FGF-2) were evaluated in vitro. The temperature increase caused by the heat generation during polymerization of the 4-META/MMA-based resin was insufficient to change the structure and function of FGF-2. Unpolymerized monomers released from the cured 4-META/MMA-based resin had no negative influences on the ability of FGF-2 to promote the proliferation of osteoblast-like cells. These findings suggest that it is possible to use FGF-2 in combination with 4-META/MMA-based resins.

Effectiveness of non-biodegradable poly(2-hydroxyethyl methacrylate)-based hydrogel particles as a fibroblast growth factor-2 releasing carrier.

OBJECTIVES: Dental resin-based restorative materials are used in a variety of dental treatment modalities such as root-end filling, perforation sealing, and adhesion of fractured roots. However, the prognosis after such treatments is not necessarily favorable because they fail to promote healing of the surrounding alveolar tissue. In the present study, non-biodegradable poly-2-hydroxyethyl methacrylate (polyHEMA)-based hydrogel particles were fabricated as a carrier vehicle for drug delivery that is applied to dental resins. METHODS: The loading and release characteristics of bovine serum albumin (BSA) and fibroblast growth factor-2 (FGF-2) from the polyHEMA-based hydrogel particles were evaluated over time in culture. The hydrogel particles were immersed into an aqueous FITC-labeled BSA solution and were observed using confocal laser scanning microscopy (CLSM). To determine the activity of the FGF-2 released from the particles, the proliferation of osteoblast-like cells cultured with eluates collected from the particles for up to 14 days was determined. RESULTS: CLSM revealed that BSA was adsorbed to the surface of the hydrogel particles. A sustained release of BSA and FGF-2 from the particles was detected for up to 14 days. The eluates from the FGF-2-loaded particles increased the proliferation of the osteoblast-like cells, suggesting that the activity of FGF-2 was maintained for at least 2 weeks within the particles. SIGNIFICANCE: These polyHEMA-based non-degradable hydrogel particles may be useful tools that can be applied to dental restorative materials to achieve sustained delivery of drugs that promote tissue regeneration.

Development of sustained antimicrobial-release systems using poly(2-hydroxyethyl methacrylate)/trimethylolpropane trimethacrylate hydrogels.

Reconstructive materials with sustained antimicrobial effects could be useful for preventing infectious diseases in an environment containing indigenous bacteria or fungi such as the oral cavity. With the objective of applying a non-biodegradable hydrogel to resin-based materials as a reservoir for water-soluble antimicrobials, novel hydrogels consisting of 2-hydroxyethyl methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPT) were fabricated. Cetylpyridinium chloride (CPC) was loaded into five hydrogels comprising different ratios of HEMA/TMPT, and their ability to release as well as to be recharged with CPC was examined in vitro. A polyHEMA/TMPT hydrogel comprising 50% HEMA/50% TMPT could be effectively loaded and recharged with CPC by immersion into a CPC solution, demonstrating the longest release of CPC, above the concentration required to inhibit bacteria and fungi. The binding of CPC to the hydrogels was mainly through hydrophobic interaction. Loading of CPC into a hydrogel by mixing CPC powder with the HEMA/TMPT monomer before polymerization resulted in marked extension of the initial CPC-release period. The CPC-pre-mixed hydrogel was confirmed to exhibit antibacterial activity by agar diffusion tests. It is possible to achieve a sustained release system for antimicrobials by pre-mix loading and recharging CPC into a 50% HEMA/50% TMPT hydrogel.

Mechanism of detoxification of the cationic antibacterial monomer 12-methacryloyloxydodecylpyridiniumbromide (MDPB) by N-acetyl cysteine.

OBJECTIVES: The protective effects of N-acetyl cysteine (NAC) against cytotoxicity induced by conventional dental resin monomers have been widely documented. However, its effectiveness to detoxify cationic antibacterial monomers has not yet been elucidated. The aim of the present study was to investigate the possible protective effects of NAC against the cytotoxicity of 12-methacryloyloxydodecylpyridiniumbromide (MDPB) and explore the role of adduct formation in NAC-directed detoxification. METHODS: The influences of NAC on the cytotoxicity of MDPB were studied in mouse osteoblast-like MC3T3-E1 cells using the MTT assay. Ultra-performance liquid chromatography (UPLC) and liquid chromatography-mass spectrometry (LC-MS) analysis were performed to investigate the possible chemical reaction between NAC and MDPB. RESULTS: While only slight reduction in the cytotoxicity of MDPB by NAC was observed immediately after mixing with MDPB, remarkable protection against MDPB-induced cell death was detected when the mixture was tested after 24h of pre-incubation. UPLC and LC-MS analysis revealed that chemical binding of MDPB and NAC occurred under neutral conditions after 24h of pre-incubation. SIGNIFICANCE: Our findings suggest that NAC reduces the toxicity of the cationic antibacterial monomer MDPB, and adduct formation is partially responsible for the detoxification ability of NAC against MDPB-induced cell damage.

Assessment of bactericidal effects of quaternary ammonium-based antibacterial monomers in combination with colloidal platinum nanoparticles.

Pretreatment of dentin using colloidal platinum nanoparticles (CPtN) can enhance the bond strength of dentin adhesives. However, the combination of CPtN, which is negatively charged, with cationic monomer-containing adhesive may reduce the antibacterial activity of the original material. Thus, the purpose of this study was to assess the effect of CPtN on the bactericidal activity of two cationic antibacterial monomers, 12-methacryloyloxydodecylpyridinium bromide (MDPB) and methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB). The rapid killing effects of the two monomers against planktonic or attached Streptococcus mutans in the presence or absence of CPtN were examined by viable cell counts. The measurement of minimum inhibitory and bactericidal concentrations demonstrated that CPtN up to 2.5 mM has no antibacterial activity. In the absence of CPtN, rapid killing of both planktonic and attached Streptococcus mutans were achieved by the two cationic monomers. Combination with 0.1 mM CPtN did not reduce the bactericidal effects of the two monomers, indicating that CPtN may be used as a pretreatment with antibacterial adhesives.

Proliferation and differentiation potential of pluripotent mesenchymal precursor C2C12 cells on resin-based restorative materials.

This study investigated the proliferation and differentiation potential of pluripotent mesenchymal cells on three resin-based restoratives using a typical pluripotent mesenchymal precursor cell line, C2C12. C2C12 cells were cultured for 3-21 days on cured specimens of a Bis-GMA/TEGDMA-based composite resin (APX; Clearfil AP-X), a 4-META/MMA-based resin cement (SB; Superbond C&B) or a HEMA-containing resin modified glass-ionomer (LC; Fuji Ionomer Type II LC). To examine the influences on differentiation potential, alkaline phosphatase (ALP) activity of the cells cultured on each material was determined. On APX and SB, cells adhered and proliferated well, and no significant influences on ALP activity were observed. In contrast, poor cell proliferation and significant suppression of ALP activity were observed for cells cultured on LC, similar to those cultured on a zinc oxide EBA cement used as a control material. Bis-GMA/TEGDMA-based composite resin and 4-META/MMA-based resin exhibited better biocompatibility for C2C12 cells than HEMA-containing resin modified glass-ionomer, suggesting a potential advantage of the former two resins to show smaller influences on regeneration of periapical or periodontal tissue.