title: Effects of Preheated Composite on Micro leakage-An in-vitro Study.
abstract: BACKGROUND
  Resin composites have been the pinnacle of direct esthetic restorations ever since its discovery. However, it comes with its own disadvantages. Post-operative sensitivity and marginal discoloration frequently occur due to polymerization shrinkage and micro leakage, which is the major cause of failure in resin composite restorations.
  
  
  OBJECTIVE
  To evaluate the effects of preheated composite at different temperatures on microleakage.
  
  
  METHODS
  A total of 60 extracted non-carious human premolars were collected and class 1 cavity (1.5x4x 3mm) was prepared in each and were randomly divided into three groups. Group 1 (n=20) was filled with microhybrid resin composite (Heraeus Charisma Smile) at room temperature. Group 2 (n=20) was filled with the same resin composite which was preheated to 50°C and Group 3 (n=20) was filled with resin composite preheated to 60°C. Teeth were subjected to a thermocycling regime (500X, 5 - 55°C), followed by a dye infiltration by immersing in basic fuschin for 24 hours. The tooth was sectioned longitudinally and the extent or absence of micro-leakage was determined by the amount of dye penetration along the resin composite-tooth interface using a confocal microscope.
  
  
  RESULTS
  There was minor micro-leakage detected at the occlusal margin of the control tooth specimen. The sample with preheated composite restoration at 50°C showed an intact tooth-restoration interface with no micro leakage. However, the preheated composite at 60°C showed large amount of microleakage.
  
  
  CONCLUSIONS
  Under the current limitation of the study, preheated composite at 50°C showed the least micro-leakage.
authors: Student, Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospitals , Chennai, India .
authors: Joshua Ng Chor
authors: JN
authors: Yang
authors: Senior Lecturer, Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospitals , Chennai, India .
authors: James David
authors: JD
authors: Raj
authors: Reader, Department of Oral and Maxillofacial Pathology, Saveetha Dental College and Hospitals , Chennai, India .
authors: Herald
authors: H
authors: Sherlin
keywords: Bonding; Class 1 restoration; Marginal integrity; Microhybrid composite