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.

OBJECTIVEThe purpose of this study was to evaluate the color changes of gingival porcelain through varying thickness and shade of porcelain of ceramometal restorations.

METHODSIn this study a spectrophotometer (PR-650) was used for color analysis. The color changes of dentin porcelain and gingival porcelain with three varied thickness (0.3 mm, 0.6 mm and 0.9 mm) were investigated. In addition, the color variances of Shofu vintage porcelain shade A2, A3 and B2 were tested.

RESULTSThe results showed that decreased L * value of ceramometal restorations and increased a * value were due to the increase of the gingival porcelain thickness, color measurements showed the same trend as the increased dentin porcelain thickness and the opaque and dentin porcelain with different color affected the appearance of gingival porcelain.

CONCLUSIONThe color of gingival porcelain would be changed with the differences of thickness and shade of porcelain of ceramometal restorations.

OBJECTIVETo study the fitness of color dimension between Vitapan 3D-Master shade guides and nature teeth.

METHODS2,159 nature teeth from Nanjing population and Vitapan 3D-Master shade guides were analyzed by dental chromameter ShadeEye NCC on CIE L*a*b* color system.

RESULTS1) The color dimension of natural teeth displayed a broader range than those from Vitapan 3D-Master shade guides. Comparing with incisor group, canine-premolar group had better fitness with Vitapan 3D-Master shade guides. 2) In color space, incisor values a* shifted toward green (-a*), while the shade guide values a* located toward red (+a*). The shade guide lacked tabs of values L* 71-78 and a* -1.5-(-)0.2 for natural incisor. 3) According to the perceptibility threshold AE*ab<1.4, the match rates with Vitapan 3D-Master shade guides was 33% in incisor group and 50% in canine-premolar group.

CONCLUSIONVitapan 3D-Master shade guides had inferior match with nature teeth from Nanjing population, especially in incisor.

Dental Restoration, Permanent ; Humans ; Prosthesis Coloring

Dental Restoration, Permanent ; Humans ; Prosthesis Coloring