Influence of TRY-in paste contamination on immediate and delayed dentin sealing

Full ceramic restorations have gained popularity due to increasing esthetic demands of patients. Resin cements are used for cementing full ceramic restorations for their superior esthetic and adhesive properties. The colour of the cement is vital in terms of esthetic of full ceramic restoration. Try in pastes are used for colour matching of cement to final restoration, yet it can contaminate tooth-restoration surfaces. Thus, cleaning of the try-in paste or preventing the contamination with the try in paste before cementation is crucial for the success of restoration. Immediate dentin sealing (IDS) is the process of applying bonding agent on dentin surface immediately after preperation. Exposed dentin surface can be coated and dentin tubules can be obstructed prior to the contamination with impression material or temporary cement. It's advocated that full ceramic bond strength can be increased with IDS. There is no study on the influence of try in paste contamination on bond strength of full ceramic restorations to dentin surfaces treated with IDS. The aim of the present study is to evaluate try in paste contamination on shear bond strength of ceramics to the dentin surfaces treated with IDS or delayed dentin sealing (DDS). In the current study, freshly extracted 3rd molars were divided into 3 groups randomly as IDS, control and contamination groups (n=10). Dentin surface treatments were completed. Standardized cylindrical ceramic specimens were luted using a resin cement. After cementation, specimens were aged with thermal cycling and subjected to shear bond test. Results were statistically analyzed using Kruskal Wallis and Mann Whitney U post hoc tests. Bonding surfaces were examined by SEM. After SEM examination, a group of specimens, that were only contaminated with try in paste and cleaned as in the test groups were subjected to EDS analysis. The contamination group resulted in a significant decrease in bond strength (5,84±4,4 MPa) values compared to the IDS (11,45±4,4 MPa) and the control groups (10,29±2,5 MPa). No statistically significant difference was detected between the IDS group and the control group. (p>0,05) SEM examination revealed the remnants of try-in pastes in and around the dentin tubules. Detection of Ca, O, Si, Al and Zn using EDS from tubule openings showed the existance of try in paste. Within the limitations of this study it can be concluded that try in paste contamination decreases the bond strength of ceramic on dentin surfaces.