Abstract
Objectives: This study evaluated the percentages of continuous margins (%CM) and fracture strength (FS) of crowns made out from blocs of leucite-reinforced ceramic (IPS Empress CAD) and luted with a representative self-adhesive cement (RelyX Unicem) under four contaminating agents: saliva, water, blood, a haemostatic solution containing aluminium chloride (pH= 0.8) and a control group with no contamination. Study Design: %CM at both tooth-cement (TC) and cement-crown (CC) interfaces were determined before and after a fatigue test consisting of 600’000 chewing loads and 1’500 temperature cycles changing from 5º C to 50º C. Load to fracture was recorded on fatigued specimens. Kruskal-Wallis test was used to compare %CM and FS between the five groups with a level of confidence of 95%. Results: At the TC interface, no significant differences in marginal adaptation before loading could be detected between groups. After loading, a significant marginal degradation was observed in the group contaminated with aluminium chloride (52 ± 22 %CM) in respect to the other groups. No significant differences in %CM could be detected between the groups contaminated with saliva, water, blood and the control. At the CC interface, no significant differences in marginal adaptation were observed between the groups. The FS on loaded specimens was around 1637N, with no significant differences between groups as well. Conclusions: An adverse interaction of the highly acidic haemostatic agent with either dentin or the self-adhesive cement could explain the specimens’ marginal degradation. The self-adhesive cement tested in this study was no sensitive to moisture contamination either with saliva, water or blood. Key words:Marginal adaptation, RelyX Unicem, contamination, all-ceramic crowns.
Highlights
Resin-based cements are currently used for the luting of all types of indirect restorations, including all ceramic crowns (ACC), due to their improved mechanical properties, bond strength and higher aesthetics compared to conventional luting agents like zinc phosphate, glass ionomer and polycarboxylate cements [1,2]
At the CC interface there were significant differences before loading (p=0.048) and the lowest scores of marginal adaptation were observed in the groups contaminated with aluminium chloride and saliva
The results of the present study could show that while water, blood and saliva had no negative effect on the marginal adaptation, degradation was evident when the tooth surface was contaminated with the gingival retraction material containing aluminium chloride
Summary
Resin-based cements are currently used for the luting of all types of indirect restorations, including all ceramic crowns (ACC), due to their improved mechanical properties, bond strength and higher aesthetics compared to conventional luting agents like zinc phosphate, glass ionomer and polycarboxylate cements [1,2]. The effect of surface contamination due to provisional cements on bond strength has been assessed in previous studies [13,14]. There is no information available on the effect of different contaminating factors on the marginal adaptation and fracture strength of ACC luted with self-adhesive cements. It is known from previous studies that hemostatic solutions, due to their high acidity, can interfere with the bonding mechanism of self-etching adhesives [15]. The aim of the present study was to investigate how and to what extent different contaminating agents influence the sealing ability of a self-adhesive cement used for luting ACC. Fracture strength of previously fatigued ACC luted with RelyX Unicem
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