PREPARATION OF GLASS-IONOMER CEMENT USING N-ACRYLOYL-SUBSTITUTED AMINO-ACID MONOMERS - EVALUATION OF PHYSICAL-PROPERTIES

Objectives. The objectives of this study were (1) to develop polyacid formulations through the incorporation of amino acid-derived monomers with carboxylic acid groups at various distances away from the polymer backbone to allow for greater flexibility, less rigid ionic cluster f ormation and improved solubility, and (2) to test selected physical an d handling properties of experimental ionomers with a conventional gla ss ionomer as a control. Methods. The polycarboxylic acids prepared an d used in the glass ionomer formulation in this study included N-acryl oylglutamic acid (AGA) and N-acryloyl-6-aminocaproic acid (AACA)- modi fied acrylic acid-itaconic acid copolymers, where the acrylic acid:ita conic acid:amino acid monomers were combined in different proportions. The characterization and purity of the monomers were determined by FT IR and their melting points. The characterization of synthesized polym ers included molecular weight and relative viscosity determinations. T he compressive strengths, diametral tensile strengths, flexural streng ths and fracture toughness of the experimental ionomers and a commerci ally available ionomer (control) were measured after storage in water, at 37 degrees C for 1 h or 7 d. The working times and setting times o f the experimental ionomers were compared to the control specimens. Se parate analysis of variance and Tukey's tests were used to study the s tatistical significance of the physical strength parameters as a funct ion of materials and storage times. Results. Significant increases (p < 0.001) in diametral tensile, compressive, flexural strengths and fra cture toughness were observed in the AGA co-polymers, while significan t increases were observed in diametral and flexural strengths in the A ACA co-polymers compared to the control Fuji II. The working and setti ng times of all except one experimental ionomer studied were comparabl e to the controls. Significance. The use of amino acid-modified acryli c monomers to produce water soluble copolymers of acrylic-itaconic aci d offers a new route of discovery to produce chemical-cured glass iono mers with improved physical properties. The spacer chain length, the h ydrophobicity of the chains, the molecular weight and viscosity of the polymer ail played important roles in determining the physical proper ties of the material.