Porosity Accretion in Composite Materials by Material, Technique and Operator

Objectives: To investigate porosity accretion during composite placement according type of composite resin, technique of application, and operator.
Methods: Three different nanohybrid composite resins were used: IPS Empress Direct shade A1 (EDA1), IPS Empress Direct shade Opal (EDOP), Miris 2 shade NR (M2NR). The composite resins were applied onto a glass slide with dimensions of 8 mm length x 4 mm width x 1 mm thickness (n=30) according to two different application methods: composite instrument (CI) and composite instrument in conjunction with artists’ sable brush (CIB), and five different operators (residents of Advanced Operative Dentistry Program at USC). High-resolution digital images were obtained from each specimen using at 7360x4912 pixels. ImageJ software was utilized to process and analyze the images and presented a quantification of the amount of porosity accrued as a percent area. The data was submitted to Kruskal-Wallis statistical analysis followed by Mann-Whitney U post-hoc test at α=0.05.
Results: M2NR showed the least amount of porosity (0.66±0.58), whereas EDOP showed the largest amount of porosity (3.75±2.31) compared to that of the other composites, being EDA1 intermediate located (1.26±0.73) (P<.0001). The use of a sable brush after composite placement only slightly improved porosity formation, but no statiscal differences were observed (P=.721). No statistical differences were observed among different operators (P=.955).
Conclusions: Different nanohybrid composites with different filler content and composition resulted in significant differences in porosity accretion.