Chapter 9 Anterior Direct Composites

Section A Direct Anterior Bonding: Minimally Invasive Dentistry at Its Best

Modern resin materials have opened a huge door of opportunity for both dentists and patients by offering an esthetic and minimally invasive alternative for restoring the dentition that can be accomplished in just one office visit. Direct composite restorations make it possible to restore defects, repair tooth structure invisibly (Figures 9-1 to 9-3), and change tooth shape and alignment (Figures 9-4 and 9-5) without the use of a dental laboratory. This chapter section explores the influence of composites on modern dentistry and guides dentists through the art and science of restoring the anterior dentition with composites.

FIGURE 9-1 A, Decalcification after orthodontic treatment. B, Tooth preparation. C, Invisible restorations created using Renamel Nanofill with Renamel Microfill overlay.

FIGURE 9-2 A, Hypoplasia (white spots). B, Defect eliminated invisibly by white spot removal and the use of Renamel Microhybrid overlaid with Renamel Microfill.

FIGURE 9-3 A, Worn incisal edges. B, Repaired incisal edges. Note the complete invisibility of the restorations.

FIGURE 9-4 A, Old composite veneers. B, Patient after color change with Renamel Nanofill and Renamel Microfill combination.

FIGURE 9-5 A, Dentition before realignment. B, Patient after realignment, along with tooth reshaping, gingival recontouring, and color change. Note the translucency achieved, with gray tint shining through the overlaying microfill.

For consistent esthetic results to be achieved, proper technique and the choice of materials are of paramount importance. Physical and handling properties, opacity, translucency, color stability, and polishability greatly affect the esthetic outcome of the restoration. Each material is unique and has its own place in achieving a beautiful result. When proper technique and the proper choice of materials are combined, the result will leave the dentist and patient more than satisfied. The author has chosen the specific materials in the cases discussed in this chapter to achieve these results.

For many years, anterior direct composites were believed to be inadequate restorations that were not strong enough to hold up in the mouth long term. The consensus was that composite procedures were inferior, time-consuming, and stressful, making it difficult for dentists to obtain predictable results.

In truth, however, composite procedures are actually less stressful for dentists because tooth preparation is kept to a minimum, no impressions are necessary, no temporization is required, the results are instantaneous, and there is no lag time because the laboratory is eliminated. Because the procedure is under the dentist’s complete control, he or she never has to worry about cementation or marginal integrity. If something must be corrected, it can be corrected chairside. If something must be repaired, it can be repaired in the office. Dentists can also use composite to quickly mock up the final results for their patients. Having patients see what their dentist can do for them is excellent advertising, showing creativity and the resultant beautiful work—a great practice builder!

Throughout the past 50 years, the materials and procedures for anterior direct composites have evolved immensely. Decades ago different types of plastic and composite materials were in use (such as Sevritron and Adaptic). In 1955, Dr Michael Buonocore revolutionized dentistry with his breakthrough research on acid etching of the enamel, which enabled plastic materials to adhere to tooth surfaces. He found that acid etching enamel before applying different materials greatly enhanced adhesion to tooth structure. As a result of these findings, composites were the breakthrough of the late 1960s as an anterior restorative. Ultraviolet-light curing in the 1970s and finally visible light curing in the early 1980s superseded earlier systems.

Over time, many different bonding agents have been developed with varying adhesive qualities. This is important because bonding agents allowed the dentist to have complete control in placing, shaping, and sculpting composite material. The new adhesive qualities permitted higher bond strengths to enamel and dentin and yielded a better bond to metal, porcelain, and other materials.

Great advancements have been made in composite materials over the years. Macrofill materials such as Nuva-Fil (DENTSPLY Research and Development Corporation, Los Angeles, California) were the first composites used in direct anterior dentistry. Macrofill composites were highly filled, large-particle-sized materials exhibiting great strength and low esthetic properties. In 1978 the first microfill material was developed and has since been the premier material for simulating the enamel surface.

Microfill composites are the best material for simulating the enamel surface both esthetically and biologically. Owing to their small-sized, uniform, spherical particles, microfills exhibit the greatest long-term polish and the best wear resistance; they are the most plaque resistant and exhibit a refractive and reflective index closest to that of the enamel surface. Microfills also most closely simulate the enamel surface in color density, polishability, light refraction, and reflection, in both the short and long terms, and give the natural vitality of a finished enamel surface. Microfills have a translucence that most closely resembles enamel, thus allowing tints to shine through. When microfill composites are used, fracture toughness must be addressed. The single contraindication for a microfill is use in high-stress areas because of its lowered fracture toughness.

Microhybrids were first developed to compete with microfill materials owing to their higher strength properties. Although microhybrids are not as polishable or as compatible with the tissues as microfill composites, their strength and opacity are extremely helpful in simulating the strength and support characteristics of the dentin. These composites work well for posterior restorations and, because of their increased opacity, for masking of dark or discolored areas. Their esthetic properties are not as good as those of a microfill or a nanofill composite; however, their physical properties include strength and fracture toughness. The mean particle size range of microhybrids is 0.4 to 0.7 micron. The larger particles are agglomerated up to 35 microns to give the material workability and strength. Because of their larger particle size, microhybrids are not as polishable, do not hold their polish long term, and are not as wear resistant as nanofills or microfills. The esthetic qualities of microhybrid composites do not compare with those of a microfill in any way.

The most recently developed composite materials are nanofills. Nanofills are considered today’s universal material, exhibiting qualities of immediate polishability and great surface smoothness. In addition, nanofill materials are strong, demonstrate low shrinkage, and offer good opaquing qualities. They are recommended for use on their own or underneath a microfill, except in areas where extreme color changes are needed. Their translucent quality allows the vitality of the tooth to be apparent when the light reflects through them. When used as a universal anterior material, nanofills exhibit excellent surface smoothness and ease of handling and good color. However, when compared with microfills, they will not maintain their polish long term and do not have the same translucent qualities of enamel. Although not yet proven clinically, nanofill composites are unlikely to be as biologically compatible with the gingival tissues over time as their microfill counterparts.

To summarize, microhybrids exhibit great strength and opacity; therefore they are great for dentin replacement. Nanohybrids exhibit good strength and better esthetics then microhybrids and thus are more suited for a universal material. Microfill composites are the most esthetic of the three composite types and are the only materials that closely simulate the enamel surface. (Microhybrids and nanofills simulate dentin in strength and opacity, whereas microfill simulates enamel.) When there is enamel involvement, especially in anterior sites, microfill is still the most appropriate choice. If the dentin’s physical properties are an issue, either nanofill or microhybrids are more appropriate.

Opaquers help dentists achieve complete invisibility of the restoration with composite by blocking unwanted color and raising the value of the final restoration. Unfortunately opaquers are underused in the profession because of a lack of knowledge of their importance and insufficient training in their application. For consistently reliable restorative results with complete invisibility to be achieved, opaquers are a necessary adjunct to the practitioner’s armamentarium. Opaquers are primarily used to block out the unwanted shine-though from a dark under-color, to block metal, to cover a tetracycline stain, or to eliminate unesthetic translucent shine-through. Truly invisible restorations require the use of a sophisticated opaquer that works in relationship with the composite system that is used.

The best example for the value of a reliable opaquing system is when repairing a fractured incisor. Often clinicians try to replicate the dentin color and then overlay this layer with a compensating shade of enamel to achieve the right surface color. This involves considerable guesswork and offers inconsistent results. An alternate approach is to consider only the surface color. For example, if a fractured tooth is A1, then an A1 hybrid or nanofill can be added to recreate the incisal dentin portion of the tooth to help achieve opacity and strength. To eliminate translucent shine-through, an A1 opaquer can be placed over the top of the nanofill or microhybrid (Figure 9-6) to block and blend. Once the shine-through has been eliminated, there should be no difference between the tooth surface and the restoration. The addition of A1 microfill will create a perfect match of material to tooth structure and completely simulate the entire enamel surface once finished and polished. In this type of system, the colors of the opaquers, microhybrids, nanofills, and microfills should match one another and the corresponding shade guide exactly; only their values are different. (The Renamel Restorative System by Cosmedent [Chicago, Illinois] is the best example of this.)

FIGURE 9-6 A, Fractured central incisors before repair. B, Left central with Renamel Microhybrid (shade A1) added for strength. Opaquing necessary because of translucency. C, Addition of Cosmedent’s Creative Color opaquer A1 to block translucency and to blend color. D, Opaquing completed. E, Addition and sculpting of Renamel Microfill #A1. F, Restoration contoured, finished, and polished. Note the complete blend of composite into tooth structure with no apparent demarcation.

Tints are yet another underutilized material that if used properly can greatly enhance the esthetics of anterior composite restorations. As with opaquers, lack of knowledge and lack of training in the application of tints is common. Tints are used to enhance incisal translucency as well as gingival hue and chroma. A good tint must be transparent to allow the light to shine through and carry the color into the overlying composite layer. Because of its translucency, microfill is the only composite material that truly allows this phenomenon of color shine-through to take place, creating the color realism from within (Figure 9-7). This is yet another reason for using microfill as the prime enamel layer.

FIGURE 9-7 A, Tint application using Cosmedent’s Creative Color gray tint with a Cosmedent #1 brush at the incisal. Note that the tip of the brush aids in placement control. B, Tinted area complete and outlined. A thin incisal edge is left devoid of tint in an attempt to develop a halo. C, Renamel B1 Microfill placed over hybrid and tinted layer. D, Completed veneer. Note incisal translucency, incisal halo, and characterization. E, Completed case 1 year postoperatively. Note the exceptional polish retention.

Composite materials are indicated for almost all types of anterior restorations, from surface and incisal defects to routine restorations such as class III (Figure 9-8), class IV (Figure 9-9), and class V (Figure 9-10). They are ideally suited for other situations such as diastema closures, anterior veneering for color change, tooth reshaping, and tooth realignment to obtain a desired smile design (Figure 9-11). In addition, composites can be used for any type of treatment; such as full-bonded crowns (Figure 9-12), short-span anterior bridges, and porcelain repairs (Figure 9-13) which can all be constructed with direct composite resin. The indications for the use of anterior composite materials depend on how skilled the operator is, how comfortable the procedure feels, and how well the operator can develop the desired restoration. Although these restorations have the undeserved reputation of not holding up, when done properly they generally last at least 20 years (Figure 9-14).