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by Dr. Ross W. Nash


When it comes to clinical durability in restorations, gold is the benchmark. However, many patients prefer the esthetics provided by tooth-colored alternatives. The following is a look at some alternative materials used for esthetic and cosmetic treatment, including direct composite resin, laboratory-processed composite, stacked porcelain, pressed ceramics and pressed/stacked porcelain.

Direct composite resin

Composite resin offers esthetics and conservative preparation, plus the results can be accomplished in a single appointment. In most cases, results can be expected to last 10 years or longer. Unlike previous chemically cured materials, light-cured composite resins do not experience amine discoloration. However, the resin matrix absorbs fluids; and pigments in coffee, tea, colas, fruit juices and wine can remain in the resin over time, affecting its color. Note, however, that the rate of discoloration varies among patients.

Figure 1 shows the anterior maxillary teeth of a teenage male who wanted a more esthetic smile. The right central incisor had been traumatized several years earlier. It was endodontically treated and it later ankylosed to the bone. Four direct composite veneers were placed to improve the esthetics and alignment of the central and lateral incisors. Figure 2 depicts composite resin added to the right central. The final result is shown in Fig. 3.

Laboratory-processed composite resin

An advantage of lab-processed composite resin is it can be highly polymerized through heat, vacuum or pressure treatments. It takes some preparation, however, to make room for the minimum 0.3 mm thickness needed for fabrication procedures. Because of the higher degree of polymerization, less fluid is absorbed in the resin matrix, in turn improving color stability. I’ve also found that processed composite resin lasts longer than direct resin. Patients can expect at least a 12-year life for restorations fabricated from this material.

Disadvantages of lab-processed composite include that it calls for slightly more tooth removal; working with this material requires two appointments; and the lab cost involved drives up fees.

The patient whose teeth are displayed in Fig. 4 had direct veneers placed 10 years earlier. She wanted them replaced with a more color-stable material. She presented with Class III restorations in the mesial of the maxillary lateral incisors and the mesial and distal areas of both central incisors.

In her case, processed composite was chosen for its increased color stability, conservative preparation and its lack of wear on opposing tooth structure during functional contact. Prepared teeth are shown in Fig. 5.Fig. 6). Figure 7 shows the final result.

Lab-processed restorations were bonded to place using a light-cured composite resin luting agent.

Stacked porcelain

In my experience, ceramic materials provide ultimate esthetics, durability, color stability and stain resistance. My early porcelain laminates were made with standard feldspathic porcelain. With these “stacked” porcelains, ceramists can develop beautiful, vital colors because the material is built-up incrementally and can be layered artistically. Conventional ceramics have a surface structure that can be quite abrasive to opposing natural tooth structure. The newer porcelains are much kinder to opposing structures, and can be polished intraorally. The lamination process fostered by bonding offers higher strength properties than cementation alone.

Some preparation usually is needed, because a thickness of 0.3 mm to 0.5 mm is desirable. Estimated longevity of these materials can be at least 15 years.

The patient whose teeth are shown in Fig. 8 wanted porcelain veneers to replace the original direct veneers on her maxillary central incisors that had discolored with time. She chose porcelain for its stain resistance and durability.

After removing the composite resin, it was discovered that very little enamel had been removed. To achieve a better result, she also chose to have veneers placed on the lateral incisors. The minimally prepared teeth are shown in Fig. 9. The four ultrathin porcelain laminate veneers are bonded to place in Fig. 10.

Pressed ceramics

Pressed ceramics result in ceramic restorations that have higher flexural strength than conventional feldspathic porcelain, but with the fit of gold restorations. The materials are made through a “lost-wax” technique. Molten glass is forced into a wax mold under pressure, causing the resulting material to have increased density compared to stacked alternatives. The result is monochromic; color variation must be established using surface stains or a cut-back technique to make room for adding-on surface porcelain for esthetics.

I prefer adding the surface porcelain. Although surface stains are easy to remove if needed, the depth of color that makes restorations look so vital sometimes can be compromised with surface staining. Note the preparation needed for pressed ceramics usually is greater than for stacked porcelains. Allow a full millimeter of room in the axial direction and 1.5 mm in the occlusal or incisal direction.

Pressed/stacked ceramics

This technique for anterior laminates and posterior facial veneers includes pressing a thin core and layering porcelain on the surface, resulting in the fit of a pressed material and the esthetics of a stacked material. Slightly more preparation is required than for stacked ceramics alone, but it is not as involved as previous pressed alternatives. Axial thickness of 0.7 mm and incisal reduction of 1.2 mm are desired. A definitive chamfer margin or moderate shoulder allows fabrication room.

Figure 11 presents anterior maxillary teeth of a male patient who wanted porcelain veneers to correct for color, shape and wear. Teeth were moderately prepared to allow for improved alignment and color change (Fig. 12). Figure 13 displays the pressed/stacked 360° laminates in place.

Esthetic yet selective

This article offers ways we can provide patients with functionally and esthetically superb restorations. No one solution is right for every clinical situation. I advocate the greatest conservation of natural tooth structure tempered by the desired end result.

Dr. Ross W. Nash is president of the Nash Institute for Learning in Charlotte, N.C., and an Accredited Fellow in the American Academy of Cosmetic Dentistry. His phone is 888-442-0242, e-mail is rosswnashdds@aol.com and Web site is nashinstitute.com.