title: An In-Vitro Comparison of Micro Leakage Between Two Posterior Composites Restored with Different Layering Techniques Using Two Different LED Modes.
abstract: OBJECTIVE
  Composite resins have undergone various advances since their introduction, but their polymerization shrinkage remains a problem. Shrinkage can cause debonding of the restoration and can contribute to postoperative sensitivity, secondary caries, marginal staining and eventual failure of the restoration. So, our aim is to compare the effect of two different placement techniques and two different curing modes in reducing the marginal microleakage of two different composites in Class II cavities, where oblique and horizontal placement techniques and ramp & pulse curing modes of LED are used during the restoration.
  
  
  METHODS
  Standardized slot preparations were prepared in 80 human multi-rooted teeth. The teeth were randomly divided into four groups. Group A and B: Restored with Filtek P60 (3M, ESPE), Group C and D: Restored with Filtek P90 (3M, ESPE). All groups were further divided into sub-groups on basis of placement technique and curing mode. The samples were stored in distilled water, followed by thermocycling and immersed in 2% methylene blue. The samples were sectioned and evaluated for microleakage at the gingival margin with an optical stereomicroscope.
  
  
  RESULTS
  P60 composite when placed in the cavity with oblique incremental technique and cured with ramp mode of LED showed highest mean microleakage. There is no significant difference between horizontal and oblique placement technique (p=0.80); Pulse-curing and the ramp-curing mode (p=0.62).
  
  
  CONCLUSIONS
  In restoring deep class II cavities, the use of a low-shrink composite with the oblique placement technique and ramp curing mode of LED is recommended to overcome the problem of marginal microleakage.
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry & Endodontics, Pacific Dental College & Hospital , Udaipur, India .
authors.forename: Nikhil
authors.initials: N
authors.lastname: Relhan
authors.affiliation: Principal, Professor and Head, Department of Conservative Dentistry & Endodontics, Coorg Institute of Dental Sciences , Virajpet, Coorg, India .
authors.forename: K C
authors.initials: KC
authors.lastname: Ponnappa
authors.affiliation: Post Graduate student, Department of Orthodontics, Manav Rachna Dental College , Faridabad, India .
authors.forename: Ashima
authors.initials: A
authors.lastname: Relhan
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry & Endodontics, Maharana Pratap Dental College & Research Institute , Gwalior, India .
authors.forename: Anurag
authors.initials: A
authors.lastname: Jain
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry & Endodontics, Maharana Pratap Dental College & Research Institute , Gwalior, India .
authors.forename: Priyanka
authors.initials: P
authors.lastname: Gupta
keywords: Polymerization shrinkage; Silorane; Silver amalgam