title: Micro-CT evaluation of internal adaptation in resin fillings with different dentin adhesives.
abstract: OBJECTIVE
  The purpose of present study was to evaluate the internal adaptation of composite restorations using different adhesive systems.
  
  
  METHODS
  Typical class I cavities were prepared in 32 human third molars. The teeth were divided into the following four groups: 3-step etch-and-rinse, 2-step etch-and-rinse, 2-step self-etch and 1-step self-etch system were used. After the dentin adhesives were applied, composite resins were filled and light-cured in two layers. Then, silver nitrate solution was infiltrated, and all of the samples were scanned by micro-CT before and after thermo-mechanical load cycling. For each image, the length to which silver nitrate infiltrated, as a percentage of the whole pulpal floor length, was calculated (%SP). To evaluate the internal adaptation using conventional method, the samples were cut into 3 pieces by two sectioning at an interval of 1 mm in the middle of the cavity and they were dyed with Rhodamine-B. The cross sections of the specimens were examined by stereomicroscope. The lengths of the parts where actual leakage was shown were measured and calculated as a percentage of real leakage (%RP). The values for %SP and %RP were compared.
  
  
  RESULTS
  After thermo-mechanical loading, all specimens showed significantly increased %SP compared to before thermo-mechanical loading and 1-step self-etch system had the highest %SP (p < 0.05). There was a tendency for %SP and %RP to show similar microleakage percentage depending on its sectioning.
  
  
  CONCLUSIONS
  After thermo-mechanical load cycling, there were differences in internal adaptation among the groups using different adhesive systems.
authors: Department of Conservative Dentistry, Kangbuk Samsung Hospital, Seoul, Korea.
authors: Seung-Hoon
authors: SH
authors: Han
authors: Department of Conservative Dentistry, Oral Science Research Center, Yonsei University College of Dentistry, Seoul, Korea.
authors: Sung-Ho
authors: SH
authors: Park
keywords: Dentin adhesive; Internal adaptation; Micro-CT; Microleakage