title: Wear of resin composites and primary enamel and their applicability to full crown restoration of primary molars.
abstract: OBJECTIVE
  To determine whether resin composites are appropriate for full crown restoration of primary molars by evaluating their wear characteristics. Specifically, the wear properties of resin composite specimens and the opposing enamel surfaces were characterized by means of impacting-sliding wear testing.
  
  
  METHODS
  Three types of light-cured resin composites (Estelite Sigma quick, Litefill IIP, and Metafil C), one type of chemical-cured resin composite (Clearfil FII), and a hybrid composite (Estenia C&B) were tested in this study. The enamel sample was used as the control. The hemispherically prepared specimens were subjected to impacting-sliding wear testing against the flattened enamel of primary molars. The worn surfaces were examined by laser scanning microscopy and scanning electron microscopy. The volumetric loss was estimated by using micro-CT images. The areas of worn enamel surfaces were measured by 3D color laser microscopy. On most of the worn enamel surfaces, cracks appeared. Scatter plot analyses between their width and depth were carried out. Data for each specimen were statistically analyzed by multiple comparisons among the means of treatment by Bonferroni's method (P< 0.01).
  
  
  RESULTS
  Clearfil showed significantly higher surface area wear, volumetric loss, and worn enamel surface area than did the other resin composites and the control enamel (P< 0.01). There was no significant difference among the worn surface areas ofEstelite, Litefill, Metafil, and Estenia (P< 0.01). The control enamel showed significantly lower worn surface area than did the resin composites (P< 0.01). There was no significant difference in volumetric loss and worn enamel surface areas among Estelite, Litefill, Metafil, Estenia, and the control enamel (P< 0.01). Cracks larger than that on the control enamel were seen on the worn enamel surface opposing Estenia.
authors.affiliation: Division of Development Oral Health Science, Graduate School, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. kan978.dohs@tmd.ac.jp
authors.forename: Kanae
authors.initials: K
authors.lastname: Wada
authors.forename: Michiyo
authors.initials: M
authors.lastname: Miyashin
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Nango
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Takagi
mesh_terms: D003188:Composite Resins / Q000009:adverse effects / Q000737:chemistry; D003442:Crowns; D003743:Dental Enamel / Q000473:pathology*; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008963:Molar; D057085:Tooth Wear / Q000209:etiology*; D014094:Tooth, Deciduous
chemical_list: D003188:Composite Resins