TOWNIE CLINICAL: Match the Translucency of Enamel, Not the Color By: Tony Soileau, DDS

The traditional way of choosing the shade for composite restorations is to choose a shaded enamel color based on the total color profile of a tooth. The dentin and enamel “shades” are taken into account as one unit such as B1, A2, C4, etc. While this method has served dentistry well for several years it can be very confusing and misleading. Factors such as actual dentin color, enamel thickness, and enamel opacity are usually not considered. A shade tab which matches the “color” the closest is chosen and that shade of composite is then layered onto the surface of the tooth to be restored. This method can force the dentist to perform additional steps to restore the tooth to a natural look. Ceramists have long since looked at replicating the color of natural teeth differently. They look at teeth in terms of the “color” of the dentin and the “opacity or value” of the enamel. This is how teeth exist in nature. All of the “color” of teeth comes from the dentin. Enamel does not have color of its own. Enamel is like a pane of glass. It is either clear or frosted (opaque) or some degree of opacity in between. It is this opacity of the enamel which creates the “value” of a tooth. Two teeth with the same color of dentin but different opacities of their enamel will have different shade numbers depending on how much of the dentin shines through the enamel.

Karen wanted her central teeth to be the same length and have the space between them closed as much as possible. She already had braces and did not want them again. She also wanted something more conservative to her natural teeth than porcelain veneers, but still wanted a restorative outcome that looked very natural.

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Karen’s case was not a question of color but of opacity. She has very white teeth but also has a degree of translucency to her enamel. This is why she has a halo along her incisal edge and many subtle nuances to her teeth that must be reproduced in order for her restorations to be lifelike and undetectable. The key to restoring her smile with composite will be to match the translucency of her enamel, not the color. This will allow the true color of her dentin to continue to shine through creating subtle shade changes (Fig. 1).

The case is isolated with a split rubber dam and a flexible black tab. I chose to create the length and shape of number 9 first and then match number 8 to it. Both centrals were rotated mesially. The initial preparation included flattening the distal line angles and simply roughening the mesial and facial surfaces. I used mosquito-shaped fine grit diamonds from Axis Dental for this step. I then placed a Mylar strip bent 90 degrees between the contacts. By bending the strip as opposed to wrapping it around the teeth, I am able to create ample interproximal contact. I then etched the entire facial surface of tooth number 9, and placed several coats of Exite primer and bond from Ivoclar Vivadent and lightly aired them. The primer was then cured for ten seconds. I used a PAC light to cure my bonded restorations (Fig. 2).

My first layer was Enamel Medium Value. This matches the translucency of her natural enamel. I start by condensing the layer between the mesial contact with the Ivoclar Composite Instrument (Fig. 3).

I feathered the layer with a brush dipped in primer across the facial surface. I initially place all my layers with a metal instrument and may use it for some spreading. But, I sculpt each layer with a wet brush. This gives me greater control of the composite. Sculpting with a brush the way a ceramist works with porcelain is much easier for me than working with a metal instrument. There is no “pull back” with a wet brush and air bubbles are practically eliminated (Fig. 4).

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After curing this layer I create the dentin lobes with Enamel Effect Blue. The blue lobes do not replace the dentin but the space where the dentin is not found. This is what creates a halo in nature. The light passes through the incisal edge where it is not reflected by the dentin and only partially reflected by the enamel (Fig. 5).

This layer is lightly smoothed with a wet brush. Using a brush creates slightly diffused lobes and allows for better adaptation of the next layer.

A thin layer of Enamel Value High is then placed along the incisal edge. By using a higher value this will create the white line of the halo found at the incisal edge. In nature this is the part of the tooth where the enamel rods are perpendicular to the light so the light is reflected back resulting in a white line along the edge of the tooth. This is then smoothed with a brush and both the Enamel Value High and Enamel Effect Blue lobes are cured (Fig. 6).

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A layer of Enamel Value Medium is then applied to the remaining facial surface, smoothed, and cured (Fig. 7).

Next, the facial surface is contoured with a fine grit mosquito shaped diamond (Fig. 8).

The facial surface of number 8 is then etched and primed (Fig. 9).

Because I am lengthening the tooth, I start by creating the lingual surface with a layer of Enamel Value Medium. This layer is then brushed smooth and cured (Figs. 10, 11 and 12).

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I next place a thin layer of Enamel Value High along the incisal edge. This is followed by Enamel Effect Blue to create the space between the dentin lobes. These two layers are then smoothed and cured.

A final layer of Enamel Value Medium is applied to the remaining facial surface, smoothed, and cured. The restorations are contoured and refined with a fine grit diamond. Anatomy and characterization are created with a superfine grit diamond (Fig. 13).

Polishing is the final step. Rubber cups or points are not needed to polish 4 Seasons composite. They have the tendency to remove all texture and anatomy from the restoration. Natural teeth are not usually as smooth and shiny as rubber polishers can make restorations. This can cause an unnatural looking result. I use a Robinson bristle cup from Patterson with Shammy Bright Diamond Porcelain polishing paste. I use light pressure and only polish them for a few seconds. This polishes the restoration without removing the anatomy (Fig. 14).

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Ivoclar’s 4 Seasons composite makes it very simple to create lifelike restorations without the need to cover up one layer with the next. You simply replace the parts of the teeth that are missing with the appropriate layers and polish. It takes all the guesswork as to the correct shade and replaces it with a system as simple as the color of dentin followed by the opacity of the enamel. Truly lifelike restorations, once thought to be complex and required numerous types of composite layers, can now be done with just the two or three layers found in natural teeth (Figs. 15, 16 and 17).

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Tony is a general dentist from Lafayette, Louisiana. He was born and raised in south Louisiana, making him a true Cajun. This means he loves life and meeting new people. His practice focuses on restorative rehabilitation and cosmetic enhancements. He lectures nationally and internationally on the use of digital photography and computer assistance for diagnosing, treatment planning, and performing comprehensive dental procedures. He is among the most sought after lecturers today. Tony can be contacted at (337)234-3551 or tony@smilesbysoileau.com.