Question:
What is the role of color in contemporary esthetic dentistry related to…
Color Education and Training
Dr. Paravina
Numerous resources for education and training are currently available. The most recent one is the second edition of Fundamentals of Color, edited by Chu et al and released in February 2011. A Contemporary Guide to Color & Shade Selection for Prosthodontics is a webinar and DVD published by the American College of Prosthodontists. This is richly illustrated didactic resource complemented with 12 instructional videos.
The Society for Color and Appearance in Dentistry (SCAD) is a significant professional source associated with education in this area. Its Journal of Color and Appearance in Dentistry (JCAD, a permanent supplement to the Journal of Dentistry) has a very high impact factor. The conferences include evidence-based education, demonstrations, hands-on courses, and lunch-and-learn sessions covering a variety of topics such as resin composites, ceramics (with dentist-, ceramist-, and team perspectives), CAD/CAM and related areas of “digital” dentistry, research on translucency, tooth whitening, dental photography, implant esthetics, education and training on visual and instrumental shade matching, and other topics.
Dental Color Matcher, a free online color education and training program for esthetic dentistry, is another valuable resource. Hosted through the SCAD website (www.scadent.org), this program is, in essence, a computer game, consisting of interactive color-matching exercises using the VITA Linearguide 3D-Master shade guide (closest match and exact match exercises, and match the pairs exercises), a didactic video, and quiz. Upon program completion, all users can print a diploma issued by the SCAD, and can obtain 2 continuing education hours (also free of charge).
Resources are available—it is up to us to use and implement them to enhance the esthetic outcome of our dentistry. As the American author James Michener's observed, “an age is called dark not because the light fails to shine but because people refuse to see it.”
Tooth Whitening
Dr. Kugel
As both a researcher and a clinician I have noted that esthetic aspects of tooth color are difficult to quantify. Desired tooth whitening occurs by two means: either acting upon extrinsic or intrinsic tooth stains. To remove intrinsic stains that accumulate below the enamel surface, bleaching is an appropriate option. It is generally believed that tooth whitening is the result of oxidation of unsaturated (colored) extrinsically or intrinsically derived stains.
While numerous measurement techniques have been used to assess tooth color, some are subjective and non-linear, making the evaluation of whitening efficacy difficult. The most common method of measuring tooth color uses shade guides, such as the Vita Shade Guide, in which the tooth and the guide are observed simultaneously. The results of using this guide depend on several factors, including the observer's experience and physical condition, external light, and the shade guide that is selected for use.
At Tufts, we recently tested the Bleach edguide Vita 3D-Master with good results. This guide was developed for visual evaluation of tooth whitening and it has a wide color range and a more consistent color distribution than other guides. There are also a number of technology-based systems on the market which in theory should allow for a more objective measure of color when used properly by both the dentist and laboratory. These devices employ RGB, colorimeters, and spectrophotometers. The major limitation to the use of these systems has been cost and documented effectiveness.
In dentistry, color matching of natural teeth to restored teeth has been and still is one of our biggest challenges. The widespread use of OTC and dentist-delivered whitening has made our job even tougher. Knowledge along with experience is the key to success in esthetic dentistry.
Dental Ceramics
Dr. Chu
Color matching of dental restorations is one of the most critical elements of a successful esthetic outcome. Feldspar-based (feldspathic) ceramics has been the standard in dental ceramics for decades and still remains the primary material used for the veneering of alloy-based and zirconia-based substructures for single and multi-unit restorations.
The shift from metal-ceramic restorations to all-ceramic high strength ceramics has been a slow and constant evolution. Its inception began in the 1960s with the introduction of the metal oxide reinforced all-ceramic crown (ie, platinum foil crown).
The early 1980s witnessed the birth of a shrink-free alumina core crown as well as a castable glass ceramic. In the early 1990s, leucite-reinforced glass ceramics were invented that employed leucite crystals in an amorphous glass matrix.
The evolution continued in 2000 with the development of lithium-disilicate glass ceramic materials to improve the strength of single and multiple-unit restorations. In the continued effort for metal-free FDPs, zirconium dioxide ceramics were developed. Zirconia is an extremely strong and durable material for FDP frameworks. Colored cores are available and recent understanding and improvements in the bond interface and firing cycles has minimized the reported rates of “chipping” of the veneering ceramic. Monolithic CAD/CAM designed and milled solid zirconia restorations can be colorized in the pre-sintered state for both pink and white esthetics. In addition, developments of new monolithic lithium-disilicate ceramic restorations mostly for single-tooth restorations—whether CAD or pressed—have shown impressive in vitro strength results with a large choice of colored ingots and CAD blocks with various translucencies.
Color and dental ceramics has always been an important marriage to achieve the desired esthetic outcomes. Significant strides in research and development of such products and technologies from both the strength and color/translucency aspects have continued to make dental ceramics an exciting part of esthetic restorative dentistry.
About the Authors
Rade D. Paravina, DDS, MS, PhD | Dr. Paravina is the acting director of the Houston Center for Biomaterials and Biomimetics, and associate professor, Department of Restorative Dentistry and Biomaterials at the University of Texas School of Dentistry at Houston.
Gerard Kugel, DMD, MS, PhD | Dr. Kugel is the associate dean for research at Tufts University School of Dental Medicine.
Stephen J. Chu, DMD, MSD, CDT | Dr. Chu is an associate professor and the director of esthetic education at Columbia University College of Dental Medicine.
