Dual-Resinous-Cement: Post Type vs Depth of Polymerization

Objective: The aim of this study was to evaluate the depth al polymerization and the influence of the post type on the polymerization of a dual resinous cement. Methods: Twelve bovine incisors roots, 12mm length, were selected and randomly divided into 4 groups (n=3): G1- glass fiber post (Reforpost - Angelus); G2- carbon fiber bolts (C-post - Bisco); G3- fiber quartz post (Light-post - RTD); G4- polyethylene post (Aesthti-plus - Bisco). After the face-cementation of the posts with a dual resinous cement Rely-X (3M-ESPE), the samples had were transversally severed in five slices with different depths from the coronary limit (mm): P1) 0,0; P2) 2,5; P3) 5,0; P4) 7,5; P5) 10,0. The slices were embedded in acrylic resin and submitted to the knoop hardness test, performed on the cement with a load of 25g for 30s. Results: Data were submitted to ANOVA Tukey test (p<0,05). The knoop hardness results were: G1- P1= 53,5±10,8; P2= 47,9±16,2; P3= 44,6±18,7; P4= 43,8±15,2; P5= 43,2±15,6; G2- P1= 60,9±21,3; P2= 52,0±21,2; P3= 41,9±9,5; P4= 38,9±16,8; P5= 38,4±10,5; G3- P1= 54,1±14,1; P2= 50,6±5,0; P3= 50,1±19,2; P4= 47,9±15,0; P5= 41,2±4,4; G4- P1= 60,9±30,2; P2= 60,2 ±21,5; P3= 47,2±21,0; P4= 45,6±15,1; P5= 38,8±14,9. Conclusion: Irrespective of the limitations of this experiment, it can be concluded that the type of post does not influence in the degree of polymerization of dual resinous cement. However, the increase of the depth reduces the hardness of the resinous cement.