title: Timing for composite resin placement on mineral trioxide aggregate.
abstract: BACKGROUND
  The aim of this study was to investigate the proper time to restore composite resin over mineral trioxide aggregate (MTA).
  
  
  METHODS
  Thirty-five samples of MTA blocks were divided into 7 groups with 3 different times (10 minutes, 1 day, and 7 days) selected for restoring the composite resin over MTA with and without bonding resin, and a control group was included for comparison. After 21 days, the distances between MTA and the composite resin or between MTA and the bonding agent on sectioned planes along the long axis were measured using a scanning electron microscope (×2,000 magnification). The hardness of the MTA near the composite resin was presented as the Vickers microhardness.
  
  
  RESULTS
  There were no gaps at the interface in the 10-minute groups, the 1-day group with a bonding agent, and the 7-day group with a bonding agent. The groups without a bonding agent at 1 and 7 days presented a separation or gap at the interface. The value of the Vickers microhardness in the 1-day groups was significantly decreased compared with those of the other groups regardless of the presence or absence of a bonding agent.
  
  
  CONCLUSIONS
  These findings suggest that composite resin with a bonding agent over MTA can be restored almost immediately after MTA mixing during a single visit.
authors: Department of Cariology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors: Masaki
authors: M
authors: Tsujimoto
authors: Yasuhisa
authors: Y
authors: Tsujimoto
authors: Atsushi
authors: A
authors: Ookubo
authors: Takanobu
authors: T
authors: Shiraishi
authors: Ikuya
authors: I
authors: Watanabe
authors: Shizuka
authors: S
authors: Yamada
authors: Yoshihiko
authors: Y
authors: Hayashi
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000379:methods; D004338:Drug Combinations; D006244:Hardness; D006801:Humans; D006813:Humidity; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D003188:Composite Resins; D003764:Dental Materials; D004338:Drug Combinations; C095452:Megabond; C472989:Megabond self-etching primer; D008689:Methacrylates; D010087:Oxides; D011109:Polymethacrylic Acids; D019279:Resin Cements; D012387:Root Canal Filling Materials; D017640:Silicates; C541508:clearfil majesty; C086631:mineral trioxide aggregate; C061083:Lumicon
keywords: Composite resin; Vickers microhardness; mineral trioxide aggregate; moist curing; scanning electron microscope