Composite Artistry Failure

From the composition of the composite material selected to the meticulousness of the dentist's technique, every element plays a pivotal role in determining the success or failure of the restoration. The three main factors that affect the outcome of any anterior resin restoration are the restoration's shape, shade, and characterization. When all three of these factors are correctly executed in a composite restoration, the results can mimic nature in a manner that rivals that of porcelain. Of the three, however, clinicians seem to struggle the most with selecting the right shades of their chosen resin and correctly locating where color characterization should be placed on the tooth.

When choosing colors, the enamel shades are often the most problematic. Enamel shades can be broken down into two primary categories: chromatic and achromatic. Although chromatic enamel shades, or enamel shades with chroma, are named using the VITA shade classifying system (eg, EA1 for enamel A1), it should be noted that there can be wide variability between the shades offered by different manufacturers. Chromatic enamel shades do not lower the value when placed over a dentin shade and can, on occasion, raise the value. Alternatively, achromatic enamel shades, or enamel shades without chroma, which typically have imprecise names such as "milky white," "incisal light," or "clear occlusal," will almost always lower the value of the tooth being treated. Beyond selecting the correct colors, correctly placing the various colors on a particular tooth to achieve the desired result can be challenging.

The following case report demonstrates how a substandard result was obtained in the restoration of fractured maxillary central incisors with composite resin, even when the shape and characterization were completed correctly, because placement of the final shade layer resulted in unacceptable esthetics.

A 26-year-old female patient presented for a cosmetic consultation to improve the esthetics of her maxillary central incisors (teeth Nos. 8 and 9). She explained that she had experienced trauma to these teeth while in college and that they had been restored with composite bonding, but "it didn't last" (Figure 1 and Figure 2). The pros and cons of retreatment with direct composite bonding versus porcelain were discussed, and the patient chose composite bonding. Photographs and scans were acquired and sent to the laboratory for the creation of a diagnostic wax-up. To communicate the precise amount of tooth structure to be replaced, lines were drawn on one of the photographs (Figure 3). Once the wax-up was received and approved, an appointment was scheduled to begin treatment.

When the patient returned, shade selection was completed at the start of the appointment to avoid the effects of dehydration, which can occur within the first 2 minutes of isolation. One enamel shade, one dentin shade, and one tint were chosen to complete the restorations. A color mock-up was not performed directly on the teeth. Instead, shade selection was completed using only VITA and custom shade tabs, which ultimately led to an unacceptable esthetic outcome.

Prior to isolation, a local anesthetic (Septocaine^®, Septodont USA) was administered to the patient. A split dam isolation technique was used with a heavy gauge rubber dam (Nic Tone, Nic Tone) and bite registration material (Futar^® Fast, Kettenbach) to block the palate (Figure 4). Teeth Nos. 8 and 9 were then each prepared with a deep bevel of 45° and a shallow bevel in a starburst shape. Both bevels varied in length and depth (Figure 5). After the preparations were sand blasted with 27-micron aluminum oxide (PrepStart^™, Zest Dental Solutions), they were etched with a 35% phosphoric acid etchant (Select HV^® Etch, BISCO, Inc.) for 15 seconds (Figure 6) and then rinsed with water for 30 seconds. Two coats of a universal adhesive (All Bond Universal^®, BISCO, Inc.) were applied to the preparations with a microbrush, each of which was scrubbed for 15 seconds, air-dried with hot air for 30 seconds (Figure 7), and then light cured for 15 seconds. Next, a lingual putty matrix, which was fabricated by the laboratory, was modified to seat correctly with the rubber dam in place (Figure 8) and then scored with an explorer (Figure 9) to permit visualization of the correct extension of the initial lingual shelf resin layer. An excessively thick resin layer would require significant adjustment at the end of treatment.

The initial lingual shelf layer was placed on both teeth simultaneously using the chosen achromatic enamel shade composite (Estelite Omega^® [Milky White], Tokuyama Dental America) (Figure 10). Because the sizes of the restorations were nearly identical, the sequence of their placement was unimportant, so the decision was made to restore tooth No. 8 first. Once PTFE tape was placed on the adjacent tooth to prevent any resin from bonding to it (Figure 11), the initial dentin layer was placed (Estelite Omega^® [DA1], Tokuyama Dental America), extending the resin over the fracture line and bevel (Figure 12). White tints (IPS Empress^® Direct Color [White], Ivoclar) were then placed to mimic the characterizations present in the in the natural dentition prior to applying the final layer of achromatic enamel (Figure 13).

After the same composite layering steps were completed on tooth No. 9, both restorations were ready for shaping, finishing, and polishing (Figure 14). A systematic approach to shaping the restorations was followed. First, a pencil was used to identify the transitional line angles, then discs and burs were used to adjust the line angles until they appeared identical on each tooth (Figure 15 and Figure 16). Following final shaping, finishing, and polishing, the occlusion was adjusted, and the patient was dismissed and instructed to return in 2 weeks for a follow-up appointment. When the patient returned, it was immediately clear that the final restorations did not blend properly. Although she stated that she was happy with the result, and the final shapes and characterizations were acceptable, the final layer of achromatic enamel caused the restorations to appear lower in value, and a clear delineation between the composite and the natural tooth structure was visible (Figure 17 and Figure 18).

In this case, an achromatic enamel shade with more warmth should have been chosen to more closely match the body of the tooth. The achromatic enamel shade selected was too neutral and slightly cool, so an ideal match was not achieved, and the final result was imperfect. The performance of excellent composite artistry requires dentists to overcome multiple challenges, including those involving occlusion, shape, color, and characterization. The selection of the correct color is crucial because it can greatly impact the final esthetic outcome of the restoration. Although both classic and custom shade tabs can be helpful in the shade selection process, creating a direct mock-up of the resin in the specific area that it will be placed on the tooth can lead to a more precise color match. Color perception can vary based on the thickness of the resin, which underscores the importance of trying the selected colors directly in the patient's mouth. By employing this technique, the author could have reduced the likelihood of choosing the wrong shade for the final layer of resin and produced a more esthetically successful final restoration.

Adamo E. Notarantonio, DDS
President
American Academy of Cosmetic Dentistry
Private Practice
Huntington, New York