title: An in vitro evaluation of microleakage in class V preparations restored with Hybrid versus Silorane composites.
abstract: OBJECTIVE
  To compare the difference in microleakage values using conventional and new low-shrink Silorane composites using the dye penetration method.
  
  
  BACKGROUND
  With improvement in adhesive technology, problems associated with composites have been largely overcome. However, microleakage due to polymerization shrinkage still remains a challenge. New Silorane-based composites are alleged to have less than 1% polymerization shrinkage, which would potentially decrease the microleakage, and hence, resolve this longstanding issue.
  
  
  METHODS
  The teeth were randomly divided into three groups (A,B, and C). Group A was restored with conventional composite (Valux(™) Plus), with a total-etch protocol, Group B was restored with conventional composite, with a self-etch protocol, and group C were restored with a silorane-based composite (Filtek TMP90). Thermocycling at 200 cycles between 5 and 55°C ± 2°C with a dwell time of 60 seconds was conducted. The teeth were stained with methylene blue dye and then sectioned and viewed under a dissection microscope, afer which the microleakage was evaluated.
  
  
  RESULTS
  The interexaminer reliability was evaluated using the kappa score, which was acceptable (61 - 78%). The total-etch group performed statistically and significantly better (P < 0.001) at the occlusal margin and was marginally and statistically significant (P = 0.05) at the gingival margin compared to the self-etch conventional and Silorane groups.
  
  
  CONCLUSIONS
  The Silorane composite did not perform better than the conventional composites, however, it may have its uses and requires further research.
authors.affiliation: Operative Dentistry, Section of Dentistry, The Aga Khan University, Hospital and Medical College, Karachi, Pakistan.
authors.forename: Fahad
authors.initials: F
authors.lastname: Umer
authors.forename: Farah
authors.initials: F
authors.lastname: Naz
authors.forename: Farhan Raza
authors.initials: FR
authors.lastname: Khan