Oral Health Group
Feature

The Challenge of Treating Dark Teeth

April 1, 2006
by Stephen D. Poss, DDS and Ray Foster, CDT


With all the challenges of the clinician today, handing of dark teeth is one that can be a concern. Some clinicians avoid treatment on these types of patients or cover the tooth with porcelain fused to metal crown in an attempt to mask out the dark substructure of the tooth. This author will attempt to cover some of the challenges that the clinician will face everyday in their practice.

There are several different indications that can concern the clinician. First, the dark root syndrome. This is caused by previous endodontic treatment that has slowly darkened over time. Trauma can also cause a tooth to slowly discolor as well (Figs. 1 & 2). Dentistry such as porcelain fused to metal crown can create a dark root syndrome. As light travels down the long axis of the crown, the metal will project a darker looking root.

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There are also many baby boomers that were unfortunately given the antibiotic tetracycline as a child. This resulted in various degrees of brownish-gray hue to the teeth.

In the 1980s tetracycline teeth were addressed with direct bonded veneers in an attempt to mask the gray. This resulted in only moderate success because of the grey hues “bleeding” through and the eventually staining of the composite.

As bleaching became more popular in the early to mid-90s the unfortunate results from bleaching did not give a lot of encouragement for naturally whiter teeth to the tetracycline case. This included both in-office and home bleaching products.

This author will address the single dark tooth as well as the complex tetracycline case.

One technique that has been performed for years is to hide the dark tooth and root by placing a subgingival margin. The results were sometimes mixed because of the tissue response. Porcelain fused to metal crowns could still give off a dark margin even though they may be placed several millimeters below the gingival surface. Some clinicians rely too heavily on the dental laboratory to mask or block out the dark color. This can lead to a monochromatic restoration and give a very artificial appearance (Fig. 3).

This dark root syndrome is the first hurdle this clinician wanted to address. All ceramic restorations are becoming the norm for almost all anterior restorations. If the gingival area is the only aspect of the tooth that is dark, then a traditional .5mm facial reduction is adequate for the entire facial preparation. Once that is obtained, a thin diamond bur can be placed at the gingival margin. With the high-speed hand piece, the clinician can slowly make a ditch or trough (Fig. 4). This ditch should extend from the mesial facial to the distal facial line angles. The ditch should extend at least a millimeter below the gingival crest. The clinician will need to be careful not to extend the ditch to break through the exterior facial wall or not leave the facial wall of the ditched area too thick. The ditched area can then be prepared for a layer of opaque composite. The ditched area should be cleaned with chlorhexidine, rinsed, then etched with phosphoric acid for 15 seconds and rinsed as well. A thin coat of adhesive can be placed and light cured (Fig. 5).

This clinician does not recommend a white opaque to block out the ditched area. This could result in a margin that is too white. A flowable composite like the Universal Revolution Opaque (Kerr Dental Orange, CA), which is more like a low value A-1 composite, is recommended. Once this is bonded to place the clinician can smooth the composite as well as the tooth. If the ditch is done correctly the ceramic restoration should still have a thin margin of tooth to bond to at the cervical margin.

When the clinician has multiple teeth such as a tetracycline case that has to be veneered the dentist has a considerable task to make this case not look to monochromatic. Each case has its unique challenge. There are varying degrees of tetracycline staining. Also the “dark band” can run anywhere across the facial surface. Usually it is mid-facial (Figs. 6 & 7). The clinician also has to realize that the deeper the preparation the darker the tooth can become. Preparation for most tetracycline cases requires the clinician to break both mesial and distal contacts so that there is not any interproximal bleed through at the gingival crest. If the patient has a dark band through the facial aspect of the tooth then a trough should be made and again some type of blending opaque composite applied (Fig. 8).

Additionally the clinician may decide to make the facial reduction slightly deeper from .5mm to .8-1mm. This may also require a trough anywhere across the facial surface if there is a darker band of tetracycline staining. Good preoperative photographs can go along way assisting the laboratory technician. Also photographs of stump shades of each tooth are critical to make sure that the underlying tooth structure does no influence the final outcome.

CLINICIAN CASE

This patient presented with a darker tetracycline case (Figs. 10 & 11). He had attempted to bleach his teeth several times with no success. After determining the patients wishes a diagnostic wax-up was ordered as well as a provisional matrix of his new desired shape (Fig. 9). Eight upper teeth and eight lower teeth were prepared due to the possible contrast if only the upper was prepared. The upper right central incisor was extremely dark at the gingival so a trough was made and opaque composite was placed to prevent the gingival bleed through when the veneer was placed. The stump shade was picked and adequate photographs of the preparations were made to assist the dental laboratory.

The prepared teeth were cleaned with chlorhexidine and air-dried. A coat of Glumma (Heraeus Kulzer Amonk, NY) was placed and also air-dried. A bis-acrylic provisional material was injected into the matrix and placed on the prepared teeth and allowed to dry. The provisionals were trimmed and polished. After approval of the shape and contours of the provisionals an aliginate impression was taken for the dental laboratory to follow as they fabricate the porcelain veneers.

The photographs of the stump shade and the approved wax-up were sent to the laboratory as well.

Ray Foster of the Las Vegas Esthetics contributed from a dental technician standpoint of how the porcelain veneers were fabricated to create a natural looking smile.

This tetracycline case presented the problem of having to block out the underlying tetracycline stained teeth while providing vital, lifelike restorations. We achieved this by working with the Empress Esthetic kit, utilizing the E02 ingot. This ingot is the most opaque in the kit, which was able to block out the dark color underneath.

All units were waxed to full contour and pressed. Because of the opacity of the ingot, additional layering techniques are needed to stay away from a bright, opaque, fake looking restoration. All of these crowns were cut back at the incisal third. We then used small amounts of the wash paste to highlight the internal aspects of the restorations.

After this firing, we overlaid using the medium translucency porcelain that is provided in the Empress Esthetic kit. Cutting back the pressed, opaque restoration and then overlaying with translucent porcelain provided a nice look, blending naturally from gingival to incisal edge. The addition of the internal wash paste helped to give depth to each restoration.

A final external stain bake using the Empress Universal Stains enabled us to match the desired shade of 030/020/010 from Ivoclar’s bleach shade guide. After applying Empress Universal Glaze the units were hand polished with a diamond paste and then delivered to the doctor for insertion.

Because of the materials provided with the Esthetic kit, we were able to provide a product that fit the needs of this case and that met the expectations of both the doctor and the patient.

The patient returned in two weeks and the provisionals were removed and the veneers were tried on with a translucent try-in past
e. With patient approval the upper and lower arch were bonded to place. With the proper preparation and a knowledgeable dental technician the tetracycline case can be given a very natural looking brighter smile (Figs. 12 & 13).

This will give the clinician the confidence to treat a variety of teeth no mater the degree of discoloration.

Dr. Poss is the past Clinical Director of both the Advanced Anterior and Posterior Continuums at the Las Vegas Institute. He maintains a private practice in Brentwood, TN.

Ray Foster, CDT, is the owner of the dental lab Las Vegas Esthetics. He is involved in all levels of dental lab work for the continuums at the Las Vegas Institute.

Oral Health welcomes this original article.


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