High-translucency Monolithic Zirconia Research Articles

Color match of high translucency monolithic zirconia restorations with different thicknesses and backgrounds.

To assess the effects of ceramic thickness and background type on the color match of high translucency monolithic zirconia restorations. Fifty A2 shade high translucency zirconia disk specimens with five different thicknesses (0.7, 0.9, 1.1, 1.4, 1.6 mm) were placed on 12 backgrounds: A1, A2, A3, A3.5, B1, and B2 shade composite resin, A3 shade zirconia, nonprecious gold-colored alloy, nickel-chromium alloy, amalgam, and A2 and A3 shade tooth. Color measurements were performed to determine the specimens' CIELab values. CIEDE2000 formula was used to determine ΔE00 color differences between specimens and A2 VITA classical shade (target). The ΔE00 values were compared with perceptibility (0.8) and acceptability (1.8) thresholds to assess color matches. Data were analyzed using repeated measures ANOVA, Bonferroni, and 1-sample t tests (P < .05). Mean ΔE00 values ranged between 1.3 and 5.7. Ceramic thickness, background type, and their interaction significantly affected the ΔE00 (P < .001). Ceramic thicknesses of ≥1.1 mm with the A2 or A3 shade tooth background showed 0.8 < ΔE00 ≤ 1.8 producing acceptable color matches. High translucency monolithic zirconia restorations with a minimum thickness of 1.1 mm on tooth backgrounds could create acceptable color matches; however, with other backgrounds tested, they could not. Ceramic thickness and background type affect the color of high translucency monolithic zirconia restorations. A minimum zirconia thickness of 1.1 mm and normal color tooth structures, as a background, are essential for achieving the acceptable color match of these restorations.

Effect of Ceramic Thickness and Cement Type on the Color Match of High-Translucency Monolithic Zirconia Restorations.

To find proper ceramic thickness-cement combinations for color matching of high-translucency monolithic zirconia restorations. A total of 300 A2-shade high-translucency zirconia disk specimens of six different thicknesses (0.7, 0.9, 1.1, 1.4, 1.6, and 1.8 mm) were cemented to A3.5-shade composite resin backgrounds with five different cements: Temp-Bond, Zinc Phosphate, RelyX Unicem 2, PANAVIA SA Cement Plus, and GC Gold Label 1. Color measurements were conducted before and after cementation to determine the specimens' CIE L*a*b* values. ΔE00 values were calculated for specimens to assess color differences between before cementation and after cementation (ΔE1), between the A2 VITA classical shade (target) and specimens before cementation (ΔE2), and between the target and specimens after cementation (ΔE3). The ΔE3 values were compared with an acceptability threshold (ΔE00 = 1.8) to evaluate color matches. Data were analyzed using two-way analysis of variance, Bonferroni, and one-sample t tests (P < .05). Mean ΔE3 values ranged between 1.0 and 3.4. Ceramic thickness, cement type, and their interaction affected the ΔE3 (P < .001). Temp-Bond with ceramic thickness of ≥ 1.1 mm and Zinc Phosphate with ceramic thickness of ≥ 0.9 showed color matches, but RelyX, PANAVIA SA, and GC did not show color matches with any tested ceramic thickness. Opaque cements with sufficient ceramic thicknesses created color matches for high-translucency monolithic zirconia restorations on A3.5-shade backgrounds.

Evaluation of color properties of newly generation high translucent monolithic zirconia in different thickness with UV aging process

Evaluation of color properties of newly generation high translucent monolithic zirconia in different thickness with UV aging process

Marginal Adaptation of Monolithic High-Translucency Versus Porcelain-Veneered Zirconia Crowns.

To compare the marginal adaptation of monolithic high-translucency zirconia crowns and porcelain-veneered zirconia crowns. A master die was scanned to design and produce 10 porcelain-veneered zirconia copings for layering (PVZ group) and 10 monolithic high-translucency zirconia crowns (HTZ group). The mean vertical marginal gap in both groups was measured from eight predetermined points using a digital microscope. The mean marginal gap in the PVZ group (39.62 ± 18.98 μm) was significantly higher than in the HTZ group (23.54 ± 7.57 μm) (P < .05). High-translucency monolithic zirconia crowns had better marginal fit than porcelain-veneered zirconia crowns. Both groups exhibited clinically acceptable marginal discrepancies.

The mechanical behavior of high-translucent monolithic zirconia after adjustment and finishing procedures and artificial aging

Statement of problemHow occlusal adjustments and finishing of high-translucent monolithic zirconia restorations affect their mechanical behavior is unclear. PurposeThe purpose of this in vitro study was to investigate the effect of grinding, finishing, and hydrothermal degradation on the roughness, flexural strength, and reliability of fully stabilized zirconia (FSZ) and partially stabilized zirconia (PSZ) for monolithic restorations. Material and methodsSpecimens of PSZ and FSZ were divided into 5 groups: control (Ctrl); those ground by using coarse diamond rotary instrument (Gr); those that underwent grinding, polishing (diamond rubber), and glazing (GrPolGl); those that underwent grinding and glazing (GrGl); and those that underwent grinding and polishing (GrPol). These groups were subdivided into nonaged and hydrothermally aged in autoclave (134 °C, 200 kPa). Three-point bend tests (flexural strength [FS]) were performed (n=30), and roughness (Ra) was measured by using a contact profilometer (n=30). The Weibull moduli were obtained from the FS data. The intergroup FS was analyzed by the Kruskal-Wallis test and Student-Newman-Keuls method, and the intragroup FS, Mann-Whitney tests (α=.05). ResultsThe median FS for PSZ (MPa) for the aforementioned groups is as follows: Gr (1147.8)=GrPol (1210.3)>GrPolGl (815.6)>GrGl (569.7)=Ctrl (583.0). The FS for FSZ (MPa) for the aforementioned groups is as follows: GrPolGl (404.2)=GrGl (427.0)<Ctrl (484.8)=Gr (435.9)=GrPol (443.7). Grinding led to high roughness values. The Weibull modulus was most influenced by glaze treatment. ConclusionsMonolithic zirconia exhibited a different mechanical behavior after adjustment procedures and hydrothermal aging. Grinding increased the roughness, and polishing reduced the roughness of the ground surface. FS improvement by finishing depended on the type of zirconia. Glazing smoothened the surface but tended to decrease the FS. Aging of PSZ improved the FS except in the control and glazed groups, whereas FSZ was not affected by aging, except in the GrGl group.

The effect of restoration thickness and resin cement shade on the color and translucency of a high-translucency monolithic zirconia

Statement of problemInformation regarding the influence of cements and material thickness on the final color of monolithic zirconia restorations is lacking. PurposeThe purpose of this in vitro study was to examine the effect of varying resin cement colors and material thicknesses on the color and translucency of a high-translucency monolithic zirconia and to compare these effects with those reported in similar studies that examined other dental zirconia materials. Material and methodsKatana High Translucent (Kuraray) was used as a monolithic zirconia material. A total of 80 disk specimens (10 mm in diameter) were made in 4 different thicknesses of 0.5 mm, 1 mm, 1.5 mm, and 2 mm (n=20 per thickness). The color of the specimens (Commission Internationale de l'Eclairage [CIE] L*, a*, b* values) before cementation was measured using a spectrophotometer. Specimens within each thickness were further divided into 2 groups: transparent (n=10) and opaque (n=10). A transparent or opaque self-etch adhesive resin cement (Panavia V5) was then applied to each specimen. After cementation, the color was measured again. The translucency parameter (TP) and ΔE were calculated and evaluated with the color measurements by using descriptive statistics, correlation analysis, single specimen t test, 2-way ANOVA, and the Tukey Honestly Significant Difference (HSD) test. ResultsStatistically significant (P<.001) changes were found with the increasing thicknesses of the high-translucency zirconia specimens. The TP, L*, and b* values decreased, whereas the a* values increased. In both the transparent and opaque groups, statistically significant (P<.001) increases in L*, a*, and b* values and a significant decrease in TP were found with cementation. The lowest ΔE value (1.19 for 2 mm) was observed for monolithic zirconia-clear cement. The highest ΔE value (8.05 for the 0.5 mm) was observed for the monolithic zirconia and opaque cement combination. ConclusionsMaterial thickness and cement color affected the color and translucency of high-translucent monolithic zirconia, with effects similar to those observed with other monolithic zirconia materials.

Effects of ultrasonic scaling on the optical properties and surface characteristics of highly translucent CAD/CAM ceramic restorative materials: An in vitro study

Abstract Esthetic restorations using highly translucent ceramics powered by chairside digital dentistry are becoming popular. The purpose of this in vitro study was to investigate the impact of ultrasonic scaling on the optical and surface properties of highly translucent ceramic materials for digital dentistry. A resin nanoceramic (Lava Ultimate; LU), dual-network ceramic (Vita Enamic; VE), feldspathic ceramic (Vitablocs Mark II; VM), lithium disilicate ceramic (IPS e.max CAD; EX), and high-translucency monolithic zirconia (Rainbow Shine-T; MZ) were evaluated. All specimens were subjected to ultrasonic scaling, and the following data were obtained before and after scaling: color change (Δ E 00 ), translucency parameter, surface gloss, surface roughness, and superficial topography. One-way analysis of variance (ANOVA), repeated-measures ANOVA, and two-way ANOVA were used for intergroup comparisons (all α = 0.05). The mean Δ E 00 values were 0.243, 0.48, 1.591, 0.143, and 4.466 for LU, VE, VM, EX, and MZ, respectively, with statistically significant differences among the materials. With regard to Commission Internationale de l'Eclairage (CIE) L* , a* , and b* values, VE, VM, and MZ showed significantly decreased L* values relative to the baseline values. Moreover, MZ showed a significantly increased a* value and a significantly decreased b* value after scaling. Ultrasonic scaling also resulted in significant changes in the surface gloss of the LU, VE, VM, and MZ specimens. Micrographs showed scrapes and surface deterioration after scaling. For all materials, the translucency parameter and the surface roughness showed no significant differences between specimens that were subjected to scaling and those that were not. These findings suggest that ultrasonic scaling MARKEDLY affects the optical properties and surface characteristics of highly translucent computer-aided design and computer-aided manufacturing (CAD/CAM) ceramics. The findings can aid restorative dentists in the selection of appropriate materials and motivate periodontists for performing scaling procedures with due consideration of restorations in esthetically demanding areas.

Choice of resin cement shades for a high-translucency zirconia product to mask dark, discolored or metal substrates

PURPOSEThe aim was to study the masking ability of high-translucency monolithic zirconia and provide guidance in selecting resin luting cements in order to mask discolored substrates.MATERIALS AND METHODS160 high-translucency zirconia specimens were divided into 32 groups depending on their thickness and shades. Using five shades of try-in paste, the specimens were luted onto the sub strates (Co-Cr, precious-metal, opaque porcelain-sintered Co-Cr, opaque porcelain-sintered precious-metal, and 5M3-shade zirconia). All CIELAB color parameters were measured and statistically analyzed.RESULTSZirconia shade and thickness and try-in paste shade affected CIELAB color parameters (P=.000) in different substrates groups, and there were interactions among these factors (P=.000). All five try-in paste shades can be chosen to achieve ΔE values of zirconia with 1.2 – 1.5 mm for masking dark-tooth-like 5M3-shade and zirconia with 1.5 mm for masking precious-metal groups < 2.6. Only suitable try-in paste shades were used, can ΔE values that less than 2.6 be achieved when applied translucent monolithic zirconia with 0.7–1.0 mm for masking dark-tooth-like 5M3-shade and zirconia with 0.7 – 1.2 mm for masking precious-metal groups.CONCLUSIONChoosing suitable resin cement shades is necessary for high-translucency monolithic zirconia to achieve ideal masking ability (ΔE < 2.6) on the dark-tooth.

Influence of polymerization time on properties of dual-curing cements in combination with high translucency monolithic zirconia

PurposeThe aim of this in vitro study was to assess conversion degree (DC), micro-hardness (MH) and bond strength of two dual-curing resin cements employed under translucent monolithic zirconia irradiated with different time protocols. Methods84 square shaped samples of 1mm thickness were prepared from high translucency zirconia blocks and divided into two groups (n=24) according to the cement employed: (1) Rely-X Ultimate; (2) Panavia SA. Each group was further divided into 3 subgroups (n=8) according to the irradiation time: (a) no light; (b) 20s; (c) 120s. Light curing was performed 60s after the sample was placed on the diamond support of a FT-IR spectrophotometer with a high power multiLED lamp. Final DC% were calculated after 10min. After 24h, Vickers Test on the cement layer was performed. The same protocol was used to lute composite cylinders in order to evaluate microshear bond-strength test. ANOVA and Bonferroni tests were performed to find differences between MH and bond-strength to zirconia, while for DC% the Scheirer–Ray–Hare two-way test was used. ResultsThe two cements reached higher DC% in subgroup (b) and (c). As concern MH, statistics showed an increase in curing time was able to improve MH significantly. Bond-strength was not affected by irradiation time only for Panavia SA. ConclusionsThe first null hypothesis has to be rejected since DC% and MH of the dual-cements tested were influenced by the curing time. The second null hypothesis is partially rejected since the bond strength was influenced by the curing time only for Rely-X Ultimate.

Aging resistance, mechanical properties and translucency of different yttria-stabilized zirconia ceramics for monolithic dental crown applications

ObjectivesThe dental market moves towards high-translucency monolithic zirconia dental crowns, which are usually placed either with – or without – a thin glaze layer. The microstructural features and the mechanical performances of these materials are still controversial, as well as their susceptibility to aging. This paper aims at studying these aspects in the current generation of zirconia dental crowns showing different degrees of translucency. MethodsFour different commercial zirconia materials were investigated, including one standard ‘full-strength’ 3Y-TZP and three grades with improved translucency. The microstructural features (phase composition and assemblage, grain size) were carefully studied, as well as mechanical properties (biaxial bending strength and indentation toughness), translucency and aging behavior (in autoclave at 134°C). Aging was conducted on crowns with and without glaze to better represent clinical uses. ResultsImportant differences are found in terms of microstructures among the materials in terms of cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. We show that higher cubic phase content leads to better translucency and stability in water steam, but at the expense of strength and toughness. A compromise is always inevitable between translucency and aging resistance on one side and mechanical properties on the other side. Significance-Even so called ‘high translucent’ zirconia ceramics tested in this work should be considered as medium translucency materials.-Aging occurs in standard state-of-the-art dental zirconia and glazing does not fully avoid this issue. However, aging did not compromise strength even after prolonged duration.-Aging is null in the ‘highly translucent’ zirconia grades but at the expense of strength, which is then comparable to glass-ceramics.

Effect of grinding and polishing on roughness and strength of zirconia

Statement of problemThe clinical applications of high-translucency monolithic zirconia restorations have increased. Chairside and laboratory adjustments of these restorations are inevitable, which may lead to increased roughness and reduced strength. The influence of grinding and polishing on high-translucency zirconia has not been investigated. PurposeThe purpose of this in vitro study was to compare the roughness averages (Ra) of ground and polished zirconia and investigate whether roughness influenced strength after aging. Material and methodsHigh-translucency zirconia disks were milled, sintered, and glazed according to the manufacturer’s recommendations. Specimens were randomized to 4 equal groups. Group G received only grinding; groups GPB and GPK received grinding and polishing with different polishing systems; and group C was the (unground) control group. All specimens were subjected to hydrothermal aging in an autoclave at 134°C at 200 kPa for 3 hours. Roughness average was measured using a 3-dimensional (3D) optical interferometer at baseline (Ra1), after grinding and polishing (Ra2), and after aging (Ra3). A biaxial flexural strength test was performed at a rate of 0.5 mm/min. Statistical analyses were performed using commercial software (α=.05). ResultsGroup G showed a significantly higher mean value of Ra3 (1.96 ±0.32 μm) than polished and glazed groups (P<.001), which showed no statistically significant difference among them (GPB, 1.12 ±0.31 µm; GPK, 0.88 ±0.31 µm; C: 0.87 ±0.25 μm) (P>.05). Compared with baseline, the roughness of groups G and GPB increased significantly after surface treatments and after aging, whereas aging did not significantly influence the roughness of groups GPK or C. Group G showed the lowest mean value of biaxial flexural strength (879.01 ±157.99 MPa), and the highest value was achieved by group C (962.40 ±113.84 MPa); no statistically significant differences were found among groups (P>.05). Additionally, no significant correlation was detected between the Ra and flexural strength of zirconia. ConclusionsGrinding increased the roughness of zirconia restorations, whereas proper polishing resulted in smoothness comparable with glazed surfaces. The results provide no evidence that grinding and polishing affect the flexural strength of zirconia after aging.