title: Hardness Evaluation of Composite Resins Cured with QTH and LED.
abstract: Background and aims. Today light cured composites are widely used. Physical and mechanical properties of composites are related to the degree of conversion. Light curing unit (LCU) is an important factor for composite polymerization. Aim of this study is evaluation of composite resins hardness using halogen and LED light curing units. Materials and methods. In this study, 30 samples of Filtek Z250 and C-Fill composite resins were provided. Samples were light cured with Ultralume2, Valo and Astralis7. Vickers hardness number (VHN) was measured in 0, 1, 2 mm depth.
  
  
  METHODS
  Data were analysed by SPSS software and compared with each other by T-test, one-way and two-way ANOVA and Post-hoc Tukey test. Results. In Filtek Z250, at top surface, VHN of Ultralume2 was higher than VHN of Valo (P = 0.02) and Astralis7 (P =0.04), but in depth of 1, 2 mm, VHN of Ultralume2 and Astralis7 were almost the same and both LCUs were more than Valo which the difference between Ultralume2 and Valo was significant in depth of 1mm (0.05) and 2mm (0.02). In C-Fill composite, at top surface, Astralis7 showed higher VHN, but in depth of 2 mm, performance of all devices were rather simi-lar. Conclusion. In Z250, which contains camphorquinone initiator, light cure LED Ultra-lume2 with narrow wavelength showed higher hardness number than Valo. In C-fill, in top surface, Astralis7 with more exposure time, resulted higher VHN. But In depth of 2 mm, various light curing devices had rather similar hardness number.
authors.affiliation: Dental Materials Research Center, Department of Operative Dentistry, School of Dentistry, Babol University of Medical Science, Babol, Iran.
authors.forename: Behnaz
authors.initials: B
authors.lastname: Esmaeili
authors.affiliation: Dental Materials Research Center, Department of Operative Dentistry, School of Dentistry, Babol University of Medical Science, Babol, Iran.
authors.forename: Hengameh
authors.initials: H
authors.lastname: Safarcherati
authors.affiliation: General Practitioner, Private Practice, Golestan Province, Iran.
authors.forename: Assila
authors.initials: A
authors.lastname: Vaezi
keywords: composite resins; curing lights; dental, hardness