title: Comparison of Surface Hardness of Various Shades of Twinky Star Colored Compomer Light-cured with QTH and LED Units.
abstract: BACKGROUND
  Colored compomers are a group of restorative materials that were introduced in 2002 to repair primary teeth, and they provide attractive color and ease of use in pediatric dentistry. The aim of this study was to evaluate the effect of QTH and LED light-curing units on the surface hardness of different colors of Twinky Star compomers.
  
  
  METHODS
  In this experimental study, a composite resin (Z250, 3M, and USA), an ionosit compomer (DMG, Germany) with A3 shade and 8 different Twinky Star colored compomer (Voco, Germany) samples were used. In all, 100 samples were prepared with 10 samples in each group, i.e., 10 Z250 composite resin, 10 ionosit compomers, and 10 Twinky Star compomer samples of each color. The samples were prepared in a 4×4-mm Teflon mold. Half of the samples were light-cured with QTH and the other half with LED units. Then, the surface microhardness was measured by Vickers hardness test. The data were analyzed with IBM-SPSS version 22, using the t-test and ANOVA.
  
  
  RESULTS
  Two-way ANOVA showed that the mean surface hardness of the compomer samples cured with the QTH unit was significantly higher than that cured with the LED unit (p < 0.001). In each curing unit, surface hardness of some materials exhibited significant differences with the highest hardness being observed in the Z250 composite resin (650.35 ± 56.320) and the lowest hardness being detected in the ionosit compomers (461.10 ± 96.170). One-way ANOVA also showed that, among the different colors of the Twinky Star compomer, the lowest hardness with both units (QTH and LED) was observed in the gold color (214.32 ± 22.026 and 175.116 ± 15.918, respectively).
  
  
  CONCLUSIONS
  The colored compomer and the type of light-curing unit affected the microhardnesses of the surfaces. Different colors of Twinky Star compomers exhibited different surface microhardnesses.
authors.affiliation: DDS. Assistant Professor, Department of Pedodontics, Faculty of Dentistry, Babol University of Medical science, Babol, Iran.
authors.forename: Effat
authors.initials: E
authors.lastname: Khodadadi
authors.affiliation: Ph.D., Assistant Professor, Department of Biostatistics and Epidemiology, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Soraya
authors.initials: S
authors.lastname: Khafri
authors.affiliation: Postgraduate Student, Department of Pedodontics, Faculty of Dentistry, Babol University of Medical Science, Babol, Iran.
authors.forename: Mahdiyeh
authors.initials: M
authors.lastname: Aziznezhad
keywords: Colored compomer; LED; QTH; Surface hardness