Gap Formation After Adhesive Cementation of Fibre Reinforced Composite Post

Objectives: Object of this study was evaluation of the polymerization stress in the form of gaps created after fibre composite post cementation with two resin composite cements. Methods: 20 FRC Postec posts (Ivoclar Vivadent, Liechtenstein) were cemented, 10 with Variolink II (Ivoclar Vivadent, Liechtenstein) which uses total etching pretreatment and 10 with Panavia F (Kuraray Co. Ltd, Japan) which uses self etching pretreatment. Both cements were cured by LE Demetron I (Kerr, Danbury, CT) with intensity output of 800 mW/cm2. Sections 2 mm thick were made for the entire post length. Coronal, middle and apical sections were inserted in methyl blue for 30 seconds and, after drying, appearance of gap between dentin and cement was studied under the stereomicroscope - Olympus system SZX-12 (Olympus Optical Co., Germany). After images were taken by digital camera they were transferred into personal computer and processed using DP.Soft 3.3 program for digital image analysis. Data obtained was then statistically analyzed using Friedman ANOVA test and represented in percentages. Results: There was no statistically significant difference between types of cement (p<0.0001), however trend of decreasing gap size from coronal towards apex was statistically significant for Variolink II. The largest gap appeared in the coronal layer (24.6 % for Panavia F and 33.3 % for Variolink II) due to highest polymerization stress in the best polymerized section. In the apical section, presence of gap is smallest (15.4 % for Panavia F and 15.6 % for Variolink II), probably because of insufficient polymerization. Conclusion: Resin composite cements used in combination with total etching pretreatment exhibited higher incidence of gap formation compared to cement which used self etching pretreatment. Use of soft start polymerization mode could probably decrease polymerization stress during adhesive cementation of esthetic intracanal posts.