Abstract
Composite resin and metallic posts are the materials most employed for reconstruction of teeth presenting partial or total destruction of crowns. Resin-based cements have been widely used for cementation of ceramic crowns. The success of cementation depends on the achievement of adequate cement curing.ObjectivesTo evaluate the microhardness of Variolink® II (Ivoclar Vivadent, Schaan, Liechtenstein), used for cementing ceramic crowns onto three different coronal substrate preparations (dentin, metal, and composite resin), after 7 days and 3 months of water storage. The evaluation was performed along the cement line in the cervical, medium and occlusal thirds on the buccal and lingual aspects, and on the occlusal surface. Material and MethodsThirty molars were distributed in three groups (N=10) according to the type of coronal substrate: Group D- the prepared surfaces were kept in dentin; Groups M (metal) and R (resin)- the crowns were sectioned at the level of the cementoenamel junction and restored with metallic cast posts or resin build-up cores, respectively. The crowns were fabricated in ceramic IPS e.max® Press (Ivoclar Vivadent, Schaan, Liechtenstein) and luted with Variolink II. After 7 days of water storage, 5 specimens of each group were sectioned in buccolingual direction for microhardness measurements. The other specimens (N=5) were kept stored in deionized water at 37ºC for three months, followed by sectioning and microhardness measurements. ResultsData were first analyzed by three-way ANOVA that did not reveal significant differences between thirds and occlusal surface (p=0.231). Two-way ANOVA showed significant effect of substrates (p<0.001) and the Tukey test revealed that microhardness was significantly lower when crowns were cemented on resin cores and tested after 7 days of water storage (p=0.007). ConclusionThe type of material employed for coronal reconstruction of preparations for prosthetic purposes may influence the cement properties.
Highlights
Treated teeth presenting partial or total destruction of crowns require reconstruction to create a core to provide mechanical conditions IRU WKH LQGLUHFW UHVWRUDWLRQ WR EH ¿[HG DQG UHPDLQ in function for a long period
Considering the lack of information in the OLWHUDWXUH RQ WKH SRVVLEOH LQÀXHQFH RI WKH W\SH of material used as coronal reconstruction on the physical properties of the cement used for luting ceramic crowns, this study evaluated the microhardness of the resin cement Variolink® II along the cement line in the cervical, medium and occlusal thirds on the buccal and lingual aspects, and on the occlusal surface, when used for luting ceramic crowns on different substrates, after 7 days and 3 months of water storage
When the substrate is hydrated dentin, the permeability might be more relevant and harmful than the chemical incompatibility in relation to metal and composite resin substrates22. 7KLV RFFXUV EHFDXVH WKH ÀXLG WUDQVXGDWLRQ WKURXJK the adhesive may result in water accumulation at the interface between adhesive and cement, FDXVLQJ VLJQL¿FDQW UHGXFWLRQV LQ ERQG VWUHQJWK 7KLV water accumulation is originated from the hydrated dentin, and the negative effect of this permeability on the adhesive resistance of resin cements was FRQ¿UPHG E\ in vitro studies27
Summary
Treated teeth presenting partial or total destruction of crowns require reconstruction to create a core to provide mechanical conditions IRU WKH LQGLUHFW UHVWRUDWLRQ WR EH ¿[HG DQG UHPDLQ in function for a long period. Resin-based cements have been widely employed for cementation of metaloceramic or ceramic crowns due to their adhesive capacity to both tooth structure and restoration, combined with esthetic and mechanical properties. Considering the lack of information in the OLWHUDWXUH RQ WKH SRVVLEOH LQÀXHQFH RI WKH W\SH of material used as coronal reconstruction on the physical properties of the cement used for luting ceramic crowns, this study evaluated the microhardness of the resin cement Variolink® II along the cement line in the cervical, medium and occlusal thirds on the buccal and lingual aspects, and on the occlusal surface, when used for luting ceramic crowns on different substrates (dentin, metal, and composite resin), after 7 days and 3 months of water storage. The null hypotheses tested were that microhardness would not be LQÀXHQFHG E\ WKH UHJLRQ RI SUHSDUHG VXUIDFHV coronal substrate, and water storage
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