Clinical wear and quality assessment of monolithic and lithium disilicate layered zirconia restorations

BACKGROUND

Wear and quality assessments of translucent monolithic zirconia and CAD-on^® restorations were performed.

METHODS

Forty 3-unit posterior fixed partial denture (FPD) in 18 patients (age:18-50 years) were made from translucent monolithic zirconia (tm) (Zenostar T) and zirconia-frameworked, lithium disilicate layered (c) (CAD-on), materials in a split-mouth design. Restorations were digitally fabricated and their internal and marginal adaptations were measured before cementation followed by luting (Multilink Speed). Clinical evaluations were made by modified United States Public Health Service criteria at baseline, 6, 12, and 24-months. Wear of the restorations and the antagonists were digitally evaluated after optical scanning of stone casts at 1st week and 24 m through a software (Cerec 4.4). Statistical analysis was made (analysis of variance, Shapiro-Wilk, Friedman and Wilcoxon tests (SPSS 20)) at α = 0.05 significance level.

RESULTS

At 24 m, all restorations were clinically acceptable. Insignificant differences were found between tm and c restorations (P > 0.05). Mean internal and marginal adaptation of c restorations were significantly better (145 µm (premolar)-174 µm (molar)) than tm (190 µm (premolar)-207 µm (molar)) (P < 0.05). C restorations significantly caused more wear (0.3 ± 0.1 mm) than tm (0.1 ± 0.07 mm) on the antagonistic dentition (P < 0.05).

CONCLUSIONS

Translucent monolithic zirconia restorations caused less wear and antagonist wear than CAD-on restorations. CAD-on restorations exhibited higher internal and marginal adaptation.

Colour agreement between try-in paste and resin cement: effect of background on zirconia-reinforced lithium silicate

PURPOSE

To investigate colour agreement between different shades of Panavia V5 resin cement and their try-in pastes under zirconia-reinforced lithium silicate ceramics.

METHODS

Forty-four zirconia-reinforced lithium silicate ceramic specimens were prepared at 0.8 ± 0.01 mm thickness. Composite resin tooth-shaded background specimens were obtained in two shades. Resin cement specimens were fabricated at 0.1-mm thickness. Colour difference values (ΔE) between Aquagel and both the try-in paste and resin cement were calculated using the CIE-Lab system. The CIEDE2000 (ΔE00) colour formula was used to determine colour differences. The three-way ANOVA test and a multiple comparisons test were used for statistical analysis (α = 0.05).

RESULTS

A statistically significant difference was found between the ΔE00 values obtained from the cement shade colour measurements for all specimens (P < 0.05). According to the three-way ANOVA test, lower ΔE00 values were observed in the try-in paste group compared to the resin cement group. The ΔE00 values were significantly affected by the cement shade and tooth-shaded background (P < 0.05).

CONCLUSIONS

The colour agreement between the try-in pastes and the corresponding resin cement differed, and the try-in pastes could not mask the dark dental background as much as the corresponding resin cement.