title: The influence of elastic modulus of base material on the marginal adaptation of direct composite restoration.
abstract: This study compared the marginal adaptation of direct composites under base materials with different elastic moduli. MOD cavities were prepared in 30 teeth. The cervical margin was placed 1 mm above the cementoenamel junction (CEJ) in one side and 1 mm below the CEJ in dentin in the other. The teeth were randomly divided into the following six groups (five teeth each) according to the base materials used: No base (Group 1), experimental flowable composite (Group 2), Helioflow (Ivoclar Vivadent) (Group 3), Tetric Flow (Group 4), Heliomolar HB (Ivoclar Vivadent) (Group 5) and Fuji II LC (Group 6). In Group 1, after etching the cavity enamel with 35% phosphoric acid, the cavities were primed and bonded with AdheSE, then filled with Tetric Ceram according to the manufacturer's instructions. In the other groups, after placing the base materials (1 mm thick) into the cavity, the cavity was filled with Tetric Ceram using the same methods as in Group 1. After storing the specimens in distilled water for seven days, they were finished and polished. Using stereomicroscopy at 150x magnification, marginal adaptation of the specimens was determined and the percentage of the imperfect margin (IM%) in the pre-loaded specimens was calculated. A mechanical load was applied using a custom-made Chewing simulator. All specimens were submitted to 600,000 load cycles at 49N with a frequency of 2Hz. The IM% in the post-load specimens was calculated. Repeated measured one-way ANOVA with Tukey was applied to compare the IM% in the six groups at the 95% confidence level. The results of statistical analysis indicated that the IM% was Group 3, 4, 6 < or = 2 < or = 5 < or = 1.
authors.affiliation: Yonsei University, Conservative Dentistry, Seoul, Republic of Korea.
authors.forename: Oh-Hyun
authors.initials: OH
authors.lastname: Kwon
authors.forename: Do-Hyun
authors.initials: DH
authors.lastname: Kim
authors.forename: Sung-Ho
authors.initials: SH
authors.lastname: Park
mesh_terms: D000134:Acid Etching, Dental; D000180:Acrylic Resins / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000145:classification; D003743:Dental Enamel / Q000473:pathology; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D003804:Dentin / Q000473:pathology; D055119:Elastic Modulus; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; C489662:AdheSE cement; D003188:Composite Resins; D003764:Dental Materials; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; C470818:Heliomolar Flow; C478050:Heliomolar HB; D010756:Phosphoric Acids; D019279:Resin Cements; D012117:Resins, Synthetic; C121818:Tetric ceram; C111840:flowable hybrid composite; C452226:tetric flow composite resin; D014867:Water; C030242:phosphoric acid