Accurate shade evaluation is critical to the success of a case. When opaque restorations such as porcelain fused-to-metal crowns are fabricated, the shade can be evaluated critically on the stone cast and intra-orally, without any variability. The stone, underlying tooth and cement do not influence the outcome.
When the restoration fabricated is made of a translucent material, there are multiple variables that will affect the final shade. The relative opacity, translucency and thickness of the ceramic will have an influence, as will the color, opacity and thickness of the cement or bonding resin. In addition, the underlying substrate will influence the hue, chroma and value. The procedure used during try-in is critical, so in order to accurately evaluate the shade of the final all-ceramic restoration, the following steps should be taken:
- Remove the provisional and any residual cement from the tooth.
- Keep the tooth hydrated by working efficiently and by applying water to its surface. Dehydration of the tooth will affect its value and color.
- Try-in the restoration with a try-in paste that corresponds to the final cement or bonding resin which will be used. Do not try-in a restoration “dry” because an air space will be present between the ceramic and the tooth, creating an optically incorrect shade when compared to that achieved post cementation.
Unfortunately, many of the try-in pastes do not adequately represent the final set or cured materials. Always begin with a translucent and colorless material. If it is necessary to modify the color or there is a need to mask the underlying tooth substrate, choose the appropriate material to help you idealize the final shade. The two systems which I have used successfully over the years are 3M Relyx Veneer and Ivoclar-Vivadent Variolink Veneer or Variolink II.