Are Preparation Shades and Descriptions Needed for Posterior Teeth?
By Robert Winter on May 6, 2013 | 0 comments
The answer is: Yes!
Most technicians and dentists rely on all-ceramic restorations to achieve the desired esthetic and functional outcome. If a metal-ceramic restoration or another highly opacified core or substrate is used, it doesn't matter what the underlying tooth looks like because it has been taken "out of play." Esthetic problems can occur if the technician is not given appropriate information about the prepared tooth.
Ivoclar's e.max lithium disilicate is often the first material choice of dentists and technicians because of its strength and esthetic properties. The most common ingot or block used for a monolithic, surface characterized and glazed restoration at the Winter Laboratory is high translucency (HT). If the underlying tooth is normal color and value there will be no negative effect on the HT material. This assumes the tooth reduction was based on the manufacturer's recommendation for appropriate thickness to maximize strength.
If there are esthetic problems or challenges with the prepared tooth structure such as moderate to severe discoloration due to old restorations or secondary dentin formation which can be highly chromatic, those need to be masked out or it will negatively impact the value and/or color of the final restoration if it is made out of a translucent material.
If the technician receives information about the prepared tooth, the decision can be made to use a more opacified ingot like low translucency (LT) or possibly medium opacity (MO), to prevent the negative attributes of the tooth from impacting the final restoration.
Always keep in mind that the appearance of a LT or MO monolithic final restoration will appear to be more opacified than one that is layered or when compared to a restoration produced from the HT ingot. This may or may not be an acceptable choice for the final appearance. In extreme cases, using a porcelain-fused-to-metal crown may create the most ideal outcome, because any effect created by the underlying tooth is negated.