title: The effects of cavity size and incremental technique on micro-tensile bond strength of resin composite in Class I cavities.
abstract: OBJECTIVE
  The purpose of this study was to investigate if incremental-filling technique and cavity size would affect the bond strength of resin composite.
  
  
  METHODS
  Two sizes of Class I cavities were prepared in bovine dentin (large cavities: pi x (5/2)2 x 5 mm3; small cavity: pi x (3/2)2 x 3 mm3). Light-cure resin composite (Clearfil Photocore) with a self-etching primer adhesive (Clearfil SE Bond) was placed into the cavities by bulk filling (C-factor=5) or incremental filling (two layers, C-factor=3) and light-cured. As a control, 3 or 5mm thick resin composite was bonded to the flat dentin surface. After 24h storage in 37 degrees C water, the micro-tensile bond strength was measured at a crosshead speed of 1mm/min. The results obtained were statistically analyzed using two-way ANOVA and t-test at a significance level of P=0.05.
  
  
  RESULTS
  The results obtained showed that there was no significant difference among the filling techniques in small cavities (P>0.05). However, in large cavities, bulk filling presented the lowest bond strength (P<0.05).
  
  
  CONCLUSIONS
  Not only the filling technique affected the bonding strength to the cavity floor, but the cavity size was also an influential factor in Class I cavities.
authors.affiliation: Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo 113-8549, Japan. hezhd0122@yahoo.co.jp
authors.forename: Zhengdi
authors.initials: Z
authors.lastname: He
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shimada
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
mesh_terms: D000269:Adhesives / Q000737:chemistry / Q000528:radiation effects; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000145:classification / Q000379:methods*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry / Q000528:radiation effects; D008027:Light; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011092:Polyethylene Glycols / Q000737:chemistry / Q000528:radiation effects; D011109:Polymethacrylic Acids / Q000737:chemistry / Q000528:radiation effects; D019279:Resin Cements / Q000737:chemistry / Q000528:radiation effects; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000269:Adhesives; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D011109:Polymethacrylic Acids; D019279:Resin Cements; D014867:Water; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate