Aesthetic properties of a new high-translucent lithiumdisilicate press-ceramic

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machined using Cerec inLab (Sirona, Germany). The copings and discs were veneered with a novel ceramic of matched CTE (50% feldspar/50%leucite) for the fluorcanasite and fluorapatite (e.max Ceram, Ivoclar Vivadent AG) for the lithium disilicate. Ten specimens of each group were placed in an oven preheated to 90 ◦ C. After 30 min, they were removed and quenched in icecold water. The samples were then dried, returned to the oven, reheated to 90 ◦ C for 30 min and cooled to room temperature. The specimens were inspected for crazing using 40× light microscopy with transillumination. If crazing was observed, this would constitute a failure at T = 90 ◦ C. If no failure was observed, the specimens were tested again at increasing temperature increments of 10 ◦ C until failure. Statistical analysis was undertaken using one-way ANOVA with Tukey’s multiple comparison tests. Results: The fluorcanasite, in both disc and crown form, greatly outperformed the lithium disilicate glass-ceramic system (P < 0.05). The fluorcanasite discs had T values ranging from 230–270 ◦ C while the lithium disilicate discs ranged from 190 to 240 ◦ C. With the crown system, the difference was even more noticeable, with a T values of 370–450 ◦ C for the fluorcanasite but only 190–230 ◦ C for the lithium disilicate glass-ceramic system. The T values of fluorcanasite crowns were significantly higher than the other 3 groups (P < 0.05). There was no statistically significance difference between the two lithium disilicate groups. Ceramic

Fluorcanasite/feldspar-leucite disc Lithium disilicate/fluorapatite disc Fluorcanasite/feldspar-leucite crown Lithium disilicate/fluorapatite crown

10

246 ± 13

230–270

10

213 ± 18

190–240

loading on the strength (
), subcritical crack growth (SCG) and lifetime (Lt) of these framework ceramics. Materials and methods: Ninety specimens (sp) (1.2 mm × 4 mm × 20 mm) were fabricated according to the ISO 6872 standard and manufacturer instructions. IA and IZ sp were divided into 6 groups (n = 15) and submitted to: (1) 3-point bending test in artificial saliva at 37 ◦ C (IA3P and IZ3P ); (2) cyclic fatigue test under dry and wet conditions (IAFD , IAFW , IZFD , IZFW ). The initial strength (
) and the number of cycles until fracture were obtained from the 3-point bending and cyclic fatigue test, respectively; and evaluated using the Weibull distribution. The SCG was obtained from the velocity of crack propagation (v) with the stress intensity factor. The Lt was described using the Wöhler diagram (WD). Results: The
values (MPa) ranged from 340 to 560 and from 410 to 660 for IA and IZ, respectively. The Weibull moduli (m = 8) was found similar for both ceramics, and the characteristic mechanical strength (
0 ) of IA and IZ was 550 MPa and 466 MPa, respectively. Based on the
and the calculated fatigue data, using a maximum stress of 150 MPa, an average Lt was estimated as follows: IZFD = , 1.57 × 108 ; IZFW = 1.70 × 107 ; IAFD = 1.75 × 106 ; and IAFW = 8.70 × 105 cycles. SCG was greater for IZ sp when they were tested in water; the presence of zirconia in the IZ resulted in greater mean
and
0 values for IZ than for IA. The WD estimated a probability of failure of only 5% after 20 years (10220000 cycles) for IA and IZ if the maximum applied stress in wet conditions does not exceed to 316 MPa and 264 MPa, respectively. Conclusions: The lifetime under cyclic loading of IZ ceramics decreases significantly in water, which supports the concept of avoiding contact of the IZ material with water. The higher KImax needed to promote subcritical crack growth in the IZ samples indicates that zirconia-reinforced ceramics are less prone to failure due to fatigue under cyclic loading conditions.

10

418 ± 24

370–450

doi:10.1016/j.dental.2009.01.085

10

205 ± 14

190–230

Aesthetic properties of a new high-translucent lithiumdisilicate press-ceramic

n

Mean T range T ± S.D. (◦ C) (◦ C)

Conclusions: The fluorcanasite system with its matched veneering ceramic vastly outperformed the lithium disilicate glass-ceramic system regarding thermal shock resistance. doi:10.1016/j.dental.2009.01.084 Strength, subcritical crack growth and lifetime of glassinfiltrated alumina-based ceramics S.M. Salazar Marocho 1 , A. Studart 2 , M.A. Bottino 1 , A. DellaBona 3 1

São Paulo State University, São Paulo, Brazil ETH Zurich, Switzerland 3 University of Passo Fundo, Passo Fundo, Brazil 2

Objectives: The objective of this study was to evaluate (1) the influence of the microstructure and chemical composition on the flexural strength and fatigue of glass-infiltrated aluminabased (IA- In-Ceram Alumina) and zirconia-reinforced (IZIn-Ceram Zirconia) ceramics; and (2) the effect of the cyclic

R. Watzke ∗ , A. Peschke, J.F. Roulet Dental Clinic R & D, Ivoclar Vivadent AG, Schaan, FL, Liechtenstein Objectives: The aim of the clinical study was to evaluate the aesthetic properties of the new high-translucent lithiumdisilicate ceramic e.max press HT used as restoration material for defect-oriented tooth preparations. Materials and methods: 53 full-ceramic restorations made of e.max press with a new high translucency (fully anatomic pressed combined with the staining technique) were inserted clinically (mean observation time 10.4 months). The preparation of the teeth was defect-oriented and cusp/dentin supported to utilize the ceramics’ chameleon—effect. All restorations were luted adhesively by means of Variolink II (36 cases) or Multilink automix (17 cases). 25 of the restorations were inlays and 28 were partial crowns. 18 restorations were luted on premolars (34%) and 35 restorations were luted on molars (66%). One week after luting (baseline recall) two calibrated dentists evaluate all the restorations concerning their aesthetic properties and translucency using the clinical

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evaluation criteria as described by Hickel et al. [J Adhes Dent 2007;9:121–47] (table). The statistical analysis was performed using SPSS 16.00. Aesthetic properties Translucency

A1 clinically excellent/very good 3.1 no difference in shade and translucency

A2 clinically good 3.2 minor deviations

Results: In 39 (73.6%) cases [23 inlays (59%), 16 partial crowns (41%)], the aesthetic properties of the restoration was rated as clinically excellent/very good (A1). 14 (26.4%) restorations [2 inlays (14%) and 12 partial crowns (86%)], were rated as clinically good (A2) for their aesthetic properties. None of the ceramic restorations were evaluated as A3, A4 or A5. Nearly all restorations (37 cases = 94.9%) rated as clinically excellent/very good (A1) showed no difference in shade and translucency (rate 3.1). Just two restorations (5.1%) appeared clinically with minor deviations in translucency (rate 3.2). The group of restorations rated as clinically good (A2) contained 10 (71.4%) restorations with no difference in shade and translucency (rate 3.1) and 4 (28.6%) restorations with minor deviations in translucency (rate 3.2). None of the ceramic restorations appeared with a translucency rate 3.3, 3.4 or 3.5. Conclusions: The e.max press ceramic with the new hightranslucency has the potential to create inlays and partial crowns of defect—oriented tooth preparations with high aesthetic properties and a naturally appearing translucency. doi:10.1016/j.dental.2009.01.086 Spectral transmittance and color of base dentine ceramics for all-ceramic restorations D.J. Wood 1,∗ , T. Shiraishi 2 , R. Van Noort 1 1 2

The University of Sheffield, Sheffield, United Kingdom Nagasaki University, Nagasaki, Japan

Objectives: The aim of the research was to observe spectral transmittance in the visible spectrum and compare the total (Tt), diffuse (Td) and direct (Tdir) transmittance of fired VM7® (VITA, Germany) base dentine ceramics for all-ceramic restorations in the 3D-master shade system. Methods: Three disc samples 13 mm in diameter and 1.0 mm in thickness from each shade were produced following the manufacturer’s instructions. Both faces of the fired discs were ground to a P600 SiC grit finish. Spectral transmittance data for Tt and Td in the visible spectrum were collected at 1 nm intervals using a computer-controlled spectrophotometer. Tdir was calculated. One shade (3M2) specimen was reduced in thickness to 0.4 mm at 0.1 mm intervals and the transmittance measured at each thickness. Results: Principal results are summarized as follows: (1) The light transmittance through base dentine can follow Beer–Lamberts law between the clinically relevant thicknesses of 0.4–1.0 mm. (2) With increasing value from group 5 through group 1, Tt increases systematically across the visible spectrum in

each of the chroma groups M1, M2, and M3, with the exception of two shade specimens, 3M2 and 4M3.

A3 clinically sufficient/satisfactory 3.3 clear deviations but acceptable

A4 clinically unsatisfactory 3.4 (localized) clinically unsatisfactory

A5 clinically poor 3.5 unacceptable

(3) With increasing chroma Tt decreases significantly in the short wavelength range in groups 1 and 2. In groups 4 and 5, an increase in transmittance is observed at longer wavelengths above 500 nm. The maximum slope of the Tt curve increases and moves slightly towards the longer wavelengths.

Conclusion: When comparing value, a decrease in long and short wavelengths is observed with an increase in the differential coefficient, therefore suggesting a possible 2nd phase of 620 nm grain size is related to value as reported for Dentine Ceramics. When comparing chroma, a decrease in light transmittance at short wavelengths (