The Translucency And Chroma Study Of Gingival Porcelain

The facial gingival tissue defect may negatively affect the esthetics of faciomaxillary region. The method that gingival defect is restored by using gingival porcelain are used frequently in clinic. Color is one of the important factors which affect the esthetics of metal-ceramic restorations. But the color of gingival tissue can't be imitated easily. Sometimes, the metal-ceramic restorations are modified many times in order to achieve proper color and form after finished. The initial color and translucency of gingival porcelain may be changed because of repeated-firing. Recent years, the study of chroma for porcelain material is payed more attention. In addition to this, translucency of prosthesis plays a very important role in the esthetics of prosthesis. But the research of gingival porcelain on the color and translucency seems really scarce.In this study, the color and translucency of gingival porcelain were measured by means of PR-650 spectra scan spectrocolorimeter, to find the rules that the translucency changed at different thickness and after repeated firing, and the rule that color changed after repeated firing. The results showed:1. The thickness is the important factor which affect the translucency of gingival porcelain. For the same gingival porcelain material, the thicker of the samples, the less of the transmittance, and the transmittance decreased slowly when the samples become thicker.2. The transmittance of gingival porcelain increased after repeated firing. The transmittance tend to increase when each of the four kinds of gingival porcelain are fired repeatedly.3. The L* values of gingival porcelain become more higher after repeated firing. But the changing rules is different because of the different kind of gingival porcelain. For Vita VMK95 G1, the L* values become higher when it is fired eight times. For Vita VMK95 G2, the L* values become higher when it is fired ten times. But for Ceramco3 pink tissue tint and Ceramco3 dark tissue tint, the L* values become higher when it is fired twice.4. The changes of a* values is different after repeated firing for different kind of gingival porcelain materials. For Ceramco3 pink tissue tint and Ceramco3 dark tissue tint, the a* values become higher when it is fired twice. For Vita VMK95 G1 and Vita VMK95 G2, the a* values have no changes when it is fired less than ten times. The gingival porcelain become more red.5. After repeated firing, the b* value of each group have a tendency to increase, but the rules are different.For Vita VMK95 G1 and Vita VMK95 G2, the b* values become higher when it is fired six times. For Ceramco3 pink tissue tint and Ceramco3 dark tissue tint, the b* values become higher when it is fired twice. The gingival porcelain become more yellow.6. The corlor of gingival porcelain is changed after repeated firing. For Vita VMK95 G1 and Vita VMK95 G2,â–³E is more than 1.5 when it is fired six times. But for Ceramco3 pink tissue tint and Ceramco3 dark tissue tint,â–³E is more than 1.5 when it is fired twice.The color difference is obvious.7. Repeated-firing negatively affects the color of gingival porcelain. The gingival porcelain restorations should be fired fewer times in clinic.