title: Effects of pH on the microhardness of resin-based restorative materials.
abstract: This study determined the effect of pH on the microhardness of commonly used resin-based restorative materials which included a resin composite (Esthet-X, Dentsply), a new generation compomer (Dyract Extra, Dentsply) and a giomer (Beautifil, Shofu). Fifty-four specimens (3-mm wide x 3-mm long x 2-mm deep) were made for each material. The specimens were divided into six equal groups and conditioned in the following solutions at 37 degrees C for one week: 0.3% citric acid at pH 2.5, sodium hydroxide-buffered citric acid at pH 3, 4, 5, 6 and 7. After conditioning, the specimens were subjected to hardness testing using a digital microhardness tester (load 500gf; dwell time 15 seconds). Data was analyzed using one-way ANOVA and Scheffe's test at a significance level of 0.05. The effects of pH on the microhardness of resin-based restoratives were material dependent. The compomer and giomer materials were more affected by acids of low pH than the composite material that was evaluated.
authors.affiliation: Department of Preventive Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore. rashid@nus.edu.sg
authors.forename: M A
authors.initials: MA
authors.lastname: Mohamed-Tahir
authors.forename: Hui Yian
authors.initials: HY
authors.lastname: Tan
authors.forename: An Anson Sheng
authors.initials: AA
authors.lastname: Woo
authors.forename: Adrian U J
authors.initials: AU
authors.lastname: Yap
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D019343:Citric Acid / Q000737:chemistry; D020770:Compomers / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D006244:Hardness; D006863:Hydrogen-Ion Concentration; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; C470433:Beautifil composite resin; D020770:Compomers; D003188:Composite Resins; C088486:Dyract; C466112:Esthet-X; C015897:glass ionomer; D019343:Citric Acid; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide