OMNICHROMA from Tokuyama Dental America uses spherical fillers to produce a red-yellow color spectrum that blends in with natural dentin.
Tooth whitening is one of the most frequently requested dental services. As part of my initial comprehensive examination, I ask my patients what changes, if any, they would like to see in their smiles. Invariably the answer is, “I’d like my smile to be whiter.” Since the concept of vital tooth nightguard bleaching was introduced in 1989,1 it has been a boon to dentistry and patients. It has also introduced interesting complications for restorative dentists.
The whitening of vital teeth with carbamide peroxide (which breaks down in the mouth to liberate hydrogen peroxide) in a custom-fitted nightguard has proven safe and effective. Alternative methods have been introduced, such as the popular in-office approach using very concentrated bleaching agents with or without lights, to expedite the treatment. Tooth bleaching has proven so safe that it has expanded beyond dentist supervision. Cruise ships, spas, and shopping mall kiosks (some in violation of state dental guidelines) began to offer tooth whitening, almost always without the supervision or guidance of a dentist. Self-administered OTC whitening products have become widely available in stores and on the internet. Although some of these may be of questionable value, those based on carbamide peroxide or hydrogen peroxide have mostly proven effective and can be used safely.2
Adverse effects, such as local gingival irritation from using whitening strips with a fit inferior to that of a custom-molded tray, do not seem to significantly affect sales of such products. Although the cost savings to patients may be a driving force, the lack of dental supervision can introduce issues. Patients are unlikely to realize that the shade of any restorative work done to teeth that are visible in the smile will remain unchanged by the bleaching process. A composite restoration or a ceramic crown fabricated to match teeth of a patient whose shade may once have been A4 on the VITA classical shade guide will look dark and out of place once that patient has whitened their natural teeth. If that issue is anticipated and discussed with a supervising dental professional, the patient will understand that replacement of the dark restorations may become necessary. If, however, the patient has used OTC bleaching products without supervision, this mismatch in shades can be disconcerting and the continued use of the whiteners compounds the problem. Recently, a product has been introduced that may provide a potential solution to such a dilemma.
Said to be the world’s first universal composite, OMNICHROMA is designed to match every patient from A1 to D4 with a single shade. Utilizing Smart Chromatic Technology, its uniformly sized supra-nano spherical fillers allow the material to match each of the 16 VITA classical shades.
Standard composite resins used in dentistry consist of a resin matrix and filler particles. The size, shape, and density of filler particles are responsible for the physical properties of the material. It is through the use of dyes and pigments that materials of various shades are created and designed to match the range of VITA classical shades. This necessitates that dentists stock a large inventory of composite shades, sometimes in varying translucencies, to match patients’ teeth. Some materials are better than others at replicating the desired shade, which can make it challenging to match a patient’s dentition. Of course, some patients’ teeth are not really a good match for any of the shades of the VITA shade guide, making it more difficult for a practitioner to create a restoration that blends with its surroundings. A newer approach to color in composite dentistry may unlock a remedy to this frustration.
“Structural color occurs when different wavelengths of light are amplified or weakened by the structure of a material itself, expressing colors other than what the material may actually be,” according to Tokuyama Dental America.3 OMNICHROMA (Tokuyama Dental America) represents the first use of structural color in composite dentistry. The composite’s 260-nm supra-nano spherical fillers are the exact size and shape needed to generate red-to-yellow color—the range found in human teeth. As light passes through the fillers, it produces this red-to-yellow spectrum and combines with the reflected color of surrounding dentition to create a perfectly seamless match.4 The material, when expressed, is an opaque milky white. When placed in a cavity preparation and light polymerized, the material blends with the adjacent tooth structure and resembles its surroundings.
A companion material, OMNICHROMA BLOCKER, can be used in large Class III or IV restorations where the absence of surrounding tooth structure can cause shade-matching interference. Uniquely, as the shade of the surroundings changes, so does the appearance of the restorative material. It is this characteristic that offers restorative dentists a new choice when dealing with patients who bleach their teeth without dental supervision.
Case History
Roughly 3 years ago, a 55-year-old patient presented after chipping the mesial incisal corner of tooth #9. The tooth was restored with a conventional composite resin, and an acceptable shade match was obtained. Recently, the patient presented again with some minor chipping of the tooth’s incisal edge. More important to the patient was the fact that the restoration previously placed was no longer a match to the surrounding tooth structure (Figure 1).
The patient had been using whitening strips regularly, without supervision. She had noticed, especially in photographs, that her filling looked darker than the tooth. When it was explained that her freelance bleaching had created the mismatch, she took ownership of the problem and requested that the restoration be replaced. She admitted, though, that she was likely to continue bleaching her teeth. Faced with the likelihood that we would be dealing with a similar scenario in the future, she was very receptive when I offered a possible solution.
I began by removing the existing restoration as completely as possible, creating a long bevel on the surrounding enamel. Using a piece of dead soft matrix material (Garrison Dental Solutions), I protected the adjacent teeth. I microetched the tooth with 50-µm aluminum oxide (Microetcher; Danville Engineering, Zest Dental Solutions) in case there was any remaining hard-to-detect composite material. I then etched the enamel (Figure 2) with 37% phosphoric acid (UltraEtch; Ultradent).
After copious rinsing, I placed my adhesive, CLEARFIL SE Protect (Kuraray America) and light cured (VALO curing light; Ultradent). I proceeded to build up a lingual shelf of the more opaque OMNICHROMA BLOCKER (Figure 3). I then layered the blocker with OMNICHROMA (Figure 4), curing after each increment. I shaped the restoration with a flame-shaped ultrafine diamond (Diatech) and multifluted carbide finishing burs (ET burs; Brasseler USA). I polished the restoration (Figures 5, 6) with Shofu Super-Snap polishing discs (Shofu).
Summary
In this era of esthetic dentistry, it is imperative that we can skillfully place restorations that match the surrounding teeth. In an extremely aware and discriminating patient with high expectations, even a beautifully placed and finished restoration may be deemed unacceptable if it is not a perfect shade match.
Typically, shade matching may require trial placement of a series of small increments of composite material on the tooth, followed by light curing, in a trial-and-error approach. Certain teeth that are poor matches to the VITA Classic shade guide may require mixing or layering of numerous shades of composite to accomplish an acceptable match. With OMNICHROMA we have a material that can simplify the process in many cases. As an added benefit, it may make it less necessary to house an expensive inventory of material in multiple shades to accomplish the task at hand.
References
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