Influence of Bulk-Fill Composite Resins Placing Characteristics on Compressive Properties

Objectives: Clinician's directly affects the quality of dental restorations. Studies have determined the longevity of such restorations. The placement characteristics and the outcome of mechanical properties of bulk-fill restorations have not been explored. The objectives of this study were to identify characteristic parameters during placement of bulk-fill composite resins in the simulated oral cavity and to relate them to compressive properties of bulk fill composite resin restorations

Methods: A mannequin jaw was equipped with miniature pressure transducer at all the first, second permanent molars. Cylindrical molds containing preparations analog to Cl I cavities were located above each pressure transducer. Four experienced dentists restored these cylinders with either of materials: 3M-ESPE (Filtek Bulk Fill) or Vivadent-Ivoclar (Tetric EvoCeram).
Five fillings from each material manufacturer were placed at four quadrants of a mannequin jaw. Force vs. time was acquired during placement. Then, all specimens were loaded by a loading machine in compression. Statistics: Mixed Model Analysis was applied to the data.

Results: The force-time data showed characteristic patterns with peaks loads. The choice of material was not found to affect the placement characteristics. Less time was needed to accomplish this procedure in the mandible compared to the maxilla and in the left side compared to the right side (p<0.029). The mean force, the number of peaks and mean peak loads exerted during placement in the left side were smaller than on the right (p=0.01, p=0.021, p=0.03, respectively). Filtek Bulk-Fill showed higher compressive stiffness compared to Tetric EvoCeram (p<0.005). No correlations were found between placement parameters and mechanical properties.

Conclusions: The Bulk-Fill mechanical properties were not affected by placement technique