Restoring the Tetracycline Stained Dentition
Blocking out discolored dentin while mimicking the natural tooth structure
Tyler Wynne, DDS
Restoration of the optical properties of the natural dentition is key to achieving esthetic success. Our perception of tooth color is an intricate phenomenon with numerous factors, such as lighting conditions, translucency, opacity, light scattering, gloss, and the human brain and eye, influencing the overall observation of tooth color.1 If irregular tooth form and position is present with abnormal tooth color, the esthetic deficiencies are amplified.
The patient in this case presented with an extremely low value of her teeth (Figure 1). In the past she had composite bonding in an attempt to lighten the color of her tetracycline-stained teeth and several years ago the bonding was removed, exposing the dark dentin shade and irregular translucency. To complicate the matter, when the composite was removed, the facial aspect of the teeth were left flat and abnormally textured from bur markings, resulting in unusual light reflection, which made the teeth look square and boxy (Figure 1 through Figure 3). The facioversion and rotation of teeth Nos. 26 and 27 resulted in asymmetrical mandibular incisal embrasures and distracting negative space (Figure 3). The patient desired a brighter and more youthful smile.
Diagnosis and Treatment Planning
In 1948, tetracyclines were introduced as broad-spectrum antibiotics used in the treatment of many common infections in children and adults.2 A side effect of tetracyclines is the ability to chelate calcium ions and to be incorporated into teeth, cartilage, and bone, resulting in yellow or gray to brown discoloration of both the primary and permanent dentitions with a prevalence of 3% to 6%.2 The intensity of the staining depends on the time and duration of administration, as well as the dosage and type of tetracycline.3 The severity of the staining, age of the patient, and esthetic goals dictate which treatment option—bleaching, direct resin, or ceramic restoration—is indicated.
The patient’s tetracycline staining posed a challenge for the ceramist to ensure an effective masking of the underlying discoloration and simultaneously create the illusion of a natural intensity in tooth shade.4
In order to address the patient’s esthetic concerns, 14 all-ceramic maxillary restorations (three full-coverage crowns, four veneers, seven onlay veneers) and 14 all-ceramic mandibular restorations (three full-coverage crowns, nine veneers, two onlay veneers) were treatment planned. The Authentic® Pressable All-Ceramic system (Jensen Dental, www.jensendental.com) was selected due to its strength, optical properties, conservative preparation design, and its ++ ingot was ideal for blocking out discolored teeth. The patient desired a very bright, youthful smile and selected a bleach shade between Ivoclar Vivadent’s (www.ivoclarvivadent.com) BL2 and BL3 shades, with internal coloring to be added to create a more life-like effect.
A comprehensive temporomandibular joint (TMJ) examination is always completed during the diagnostic phase. A stable Piper Stage I TMJ diagnosis was confirmed for both right and left TMJs after negative muscle palpation, negative history of clicking and symptomatic joints, TMJ Doppler auscultation, centric relation (CR) load testing, and normal range of motion testing was completed.5,6 Six structural elements including disc alignment, disk shape, ligament anatomy, masticatory musculature, joint space, and condylar bone anatomy were assessed as normal.5,6
With anteroposterior overlap of teeth Nos. 26 and 27 with the mandibular arch, the decision was made to first re-contour the portions of teeth Nos. 26 and 27 outside the preparation zone to achieve alignment and a more uniform arch form. A 0.8-mm facial and 1.5-mm incisal reduction was desired in this case, so a 0.5-mm depth-cutting diamond and 0.3-mm depth cutting diamond were sequentially used. The author used an indelible marker to mark the depth cuts to ensure that all tooth structure was cleared to the depth of the depth cuts. Contacts are cleared for several advantages: the technician is provided with control over placing and correcting misaligned midlines; alterations in color can be made in this area to mimic natural teeth; the lingual margin is placed in a free cleansing area; and it increases retention form.7 Because the target incisal reduction is 1.5 mm and the author uses a round-ended diamond with a diameter of 0.75 mm at the tip, the author sank the diamond bur twice its diameter to ensure a 1.5-mm reduction. In order to help block out the discolored dentin, Renamel® Microhybrid composite shade B1 (Cosmedent, www.cosemedent.com) was bonded on the interproximal and facial surfaces of teeth Nos. 22 through 27. The author placed mechanical retention grooves with a quarter round bur on the facial surfaces of teeth Nos. 22 through 27 and a much higher value of the stump form was achieved (Figure 5). This created a much lighter stump form on which to build the porcelain.