Assessment of consistency and compressive strength of glass ionomer reinforced by different amount of hydroxyapatite

Abstract

ABSTRACT:
Background: Glass ionomers have good biocompatibility and the ability to adhere to both enamel and dentin. However, they have certain demerits, mainly low tensile and compressive strengths. Therefore, this study was done to assess consistency and compressive strength of glass ionomer reinforced by different amount of hydroxyapatite.
Materials and Methods: In this study hydroxyapatite materials were added to glass ionomer cement at different ratios, 10%, 15%, 20%, 25% and 30% (by weight). The standard consistency test described in America dental association (ADA) specification No. 8 was used, so that all new base materials could be conveniently mixed and the results would be of comparable value and the compressive strength test described by British standard specification for zinc polycarboxylate cement was used in this study.
Results: Different consistencies of materials produced a disc of varying sizes. The amount of the powder (in milligram)
was mixed with 0.5 ml of liquid to produce a consistency giving a disc of 3 cm±1mm in diameter were 500 mg for
glass monomer cement, 450 mg for glass ionomer cement reinforced by 10%, 5% and 30% of hydroxyapatite and
350 mg for glass ionomer cement reinforced by 20% and 25% of hydroxapatite. The results showed that the glass
ionomer cement reinforced by hydroxyapatite has higher compressive strength than conventional glass ionomer.
Conclusion: The addition of hydroxyapatite to conventional glass ionomer requires less powder to liquid ratio. Addition of hydroxyapatite to glass ionomer cement increased its compressive strength.
Key words: Consistency, compressive, Glass ionomer, Hydroxyapatite. (J Bagh Coll Dentistry 2008; 20(1) 16-20)