ABSTRACT
Objective; To evaluate the effects of gingival shade guide in visual shade-matching in vitro models. Methods; 42 tabs of Shofu NCC shade guide were adopted for color measuring. Each tab was fixed in the middle of Gingiva-Indicator, Guray(1,2,3,4) respectively and located in a black box. The measurements were made using the Shadepilot instrument. The color parameters ( CIE1976L * a * b * ) of cervical, body, incisal area of each tab were recorded. The color difference A E value in the same position of each tab was calculated between non-gingival shade guide group and Gumyl ,2,3,4 groups with Shadepilot software. Results; The AE value in the same position of 42 tabs between non-gingival shade guide group and 4 gingival shade guide groups were; cervical (2.93±0.79)NBS,body(0.51±0.27)NBS and incisal(0.61 ±0.29)NBS. In the cervical, body and incisal area, there was no statistically difference among Gumyl ,2,3,4 groups on affecting shade of tabs(P >0. 05). Conclusion; The gingival color has an effect on the cervical shade of tabs, and it can be recognized by human eyes, while gingival color has little effect on the shade of body and incisal area.
ABSTRACT
Objective:To evaluate the masking ability of the Rely XTM Veneer try-in pastes. Methods: 100 discolored teeth, including 50 nonvital ones and 50 vital ones, has been collected and restored respectively with all-ceramic crowns and veneers. Five try-in pastes including A1, A3, Translucent (Trt), White opaque(WOT) and B0.5 Opaque(B0.5),which were different in shade, were used to try in before adhesion. The color was measured by a digital colorimeter, and expressed in terms of 3 coordinate values(L*、a*、b*) of the CIE1976- L*a*b* system.Then the color differences of crowns and veneers ?E=[(?L*)2+(?a*)2+(?b*)2]1/2 as well as the value of Light (L= L*)、Chroma[C=〔(a*)2+(b*)2〕1/2] and Hue [H=arctan(b*/a*)] were calculated. The thickness of the measurement point was also measured and recorded. A one-way ANOVA was used to analyze ?E as well as L, C and H. Results:The chromatism of the veneers after try-in was higher than that of the crowns(P
ABSTRACT
Objective:To observe the consistence of the color and optical parameters of metal-ceramic, all-ceramic and composite resin with Vita Classical shade guides. Methods:Specimens of VITA VMK95 metal-ceramic, In-Ceram all-ceramic and Artglass composite resin according to the same area with Vita Classical shade guide were made respectively. ?E_ ab ,L,a,b between specimens and shade guide were calculated. Results:The mean ?E between shade guide and all-ceramic or composite resin was less than 3 NBS. The mean ?E between shade guide and metal-ceramic material was 13.78 NBS, the significant difference could be identified by visual determination (P