Prosthesis Coloring

PURPOSE: This study investigated the effect of amount of thickness reduction on color and translucency of dental monolithic zirconia ceramics. MATERIALS AND METHODS: One-hundred sixty-five monolithic zirconia specimens (16.3 mm x 16.3 mm x 2.0 mm) were divided into 5 groups (Group I to V) according to the number of A2-coloring liquid applications. Each group was then divided into 11 subgroups by reducing the thickness up to 1.0 mm in 0.1-mm increments (Subgroup 0 to 10, n=3). Colors and spectral distributions were measured according to CIELAB on a reflection spectrophotometer. All measurements were performed on five different areas of each specimen. Color difference (DeltaE*(ab)) and translucency parameter (TP) were calculated. Data were analyzed using one-way ANOVA and multiple comparison Scheffe test (alpha=.05). RESULTS: There were significant differences in CIE L* between Subgroup 0 and other subgroups in all groups. CIE a* increased (0.523.7) were obtained between Subgroup 0 and other subgroups. TP values generally increased as the thickness reduction increased in all groups (R2>0.89, P<.001). CONCLUSION: Increasing thickness reduction reduces lightness and increases a reddish, bluish appearance, and translucency of monolithic zirconia ceramics.
Ceramics* ; Prosthesis Coloring

Humans ; Prosthesis Coloring

Prosthesis Coloring ; Tooth

OBJECTIVETo compare the color character of VITA shade guide and the custom shade guide with metal substrate.

METHODSColor of 9 sites of 5 series of VITA shade guides and custom shade guides with metal substrate were measured by means of PR-650 spectrophotometer.

RESULTSThe color range of VITA shade guide were that L* was 56.86-73.86, a* was-1.29-3.69, b* was 7.09-21.94, and the transparence was 3.20-7.59. The color range of the custom shade guide was that L* was 60.59-78.54, a* was -1.09-4.99, b* was 7.60-22.35, and the transparence was 0.23-10.98. L*, a* and b* of the custom shade guide with metal substrate were higher than VITA shade guide, and the transparence was differet. The color difference of homonymy shade tab between custom shade guide and VITA shade guide was larger than 1.5 NBS.

CONCLUSIONThere is color difference between VITA shade guide and custom shade guide. Metal substrate has effects on the color of cero-metal prosthesis, and color selection in clinic should be carefully considered.

OBJECTIVETo evaluate the effectiveness on the application of mechanical toothguide training box (TTB) to chromatics teaching of prosthodontics.

METHODS12 preclinical undergraduate students were chosen to participate in the VITA 3D-Master shade-matching system simulant toothguide training process using Linearguide Training Box program of TTB. Toothguide Trainer program considered as a test was performed on the trained undergraduate students group, the postgraduate students group as well as the clinical prosthodontists group with under 5-year clinical experience. The test scores, elapsed time and the coincidence of chromatics single factor matching were recorded each time, the shade-matching efficiency was calculated. The data was analyzed with SPSS 13.0 software.

RESULTSThe shade-matching efficiency of undergraduate students trained by TTB (64.03 +/- 18.82) was significantly higher than before (P < 0.05), higher than the postgraduate students group and the clinical prosthodontists group (P < 0.05). The coincidence of chromatics single factor matching of trained undergraduate students were 64.64% (lightness), 88.57% (chroma), 87.70% (hue).

CONCLUSIONTTB is a effective tool for shade-mathing practice in chromatics teaching of prosthodontics. The trained undergraduate students are less sensitive in lightness-matching.

Dental Restoration, Permanent ; Humans ; Prosthesis Coloring

Dental Restoration, Permanent ; Humans ; Prosthesis Coloring

OBJECTIVETo evaluate the matching of the shade between beverage and modifying porcelain shade guide according to Munsell color order system, thus to provide the reference basis for selecting modifying porcelain to mimic the stain of natural tooth by technician.

METHODSThe shade of Vita Akzent, Vita Interno, Shofu Vintage & Unibond and Noritake Super Porcelain EX-3 shade tabs as well as 15 kinds of beverage were measured according to Munsell color order system on Color-Eye 7000A spectrophotometer. The difference of the frequency of approximate hue, value, and chroma between shade tabs and beverage were compared by calculating the Fisher exact probabilities.

RESULTSThe frequency of approximate hue between 4 kinds of shade tabs and 15 kinds of bev-erage was significant different (P<0.05), while the frequency of approximate value, and chroma was not significant different (P>0.05).

CONCLUSIONExcept the hue, the color distribution of 4 kinds of shade tabs was similar to that of 15 kinds of beverage. But the color of beverage also can be approximately matched by any kind of modifying porcelain by mixing porcelain powder of appropriate hue, value, and chroma.

OBJECTIVETo analyze the final color of Solidex in six thickness interacting with three different backgrounds.

METHODSFive specimens of Solidex in each shade A1, A3, and C2 were fabricated at thickness of 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mm. The CIE L(*)a(*)b(*) values of specimens were measured using a colorimeter (ShadeEye NCC) to determine the colorimetric difference, when the specimens overlaid on different backgrounds.

RESULTSWhen the thickness was more than 1.8 mm, the color difference (DeltaE(*)ab < 1) was not perceived by human observers. When the thickness was 1.4 mm or less than 1.4 mm, the color difference (DeltaE(*)ab > 2.72) was considered clinically unacceptable between alloy background and two types of composite resin background.

CONCLUSIONSAlloy background had more evident influence on the final color of Solidex than composite resin background. When making metal-free crown restoration using Solidex, it was advisable to make the composite resin more than 1.8 mm thick.