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Written by K. William “Buddy” Mopper, DDS, MS Wednesday, 01 October 2008 00:00
Today, in an attempt to replicate lifelike tooth structure aesthetically, clinicians can choose from a multitude of anterior and posterior composite resin materials. As a result, dentists face a dilemma in deciding what product to use and when. This article will explain the protocol that I follow and will help readers identify and select the ideal product for a specific use.
In my experience, no other dental material is as versatile and useful as this category of restorative products. Understanding direct composite resins and using them regularly in your practice has many advantages (Table 1). When one truly understands how to utilize these materials properly, long-lasting, truly aesthetic results are easily achievable. Composite resin can help you produce invisible aesthetic restorations of all types.
Table 1. Advantages of Direct Composite Restorations.
I know this from my personal, long-time clinical experiences with this class of dental materials and their associated techniques. I have been using light-activated direct composite resin restoratively for more than 35 years. For the past 20 years, my practice has been limited to producing aesthetic changes using only composite resin. Although my practice is all-encompassing, with my partners doing indirect restorations of all kinds, I have limited my practice to direct placement restorative techniques. Procedures where I use direct composite resins in my practice include the following: class I, II, III, IV, and V restorations, tooth reshaping and realignment, diastema closure, repair of intraoral defects, veneering for color change, veneering mutilated dentitions, tooth lengthening, incisal edge reinforcement, and composite and/or porcelain repairs.
COMPOSITION OF COMPOSITE RESINS
What categories of composite resin materials are available to us for use in our clinical armamentarium? Let’s examine them by discussing their properties and seeing where they fit into our clinical techniques.
Microfills are an important addition to your armamentarium if you want to create truly aesthetic, lifelike restorations. This class of composite resins offers the highest level of aesthetics because it most closely simulates the actual enamel surface of a tooth. Since microfills have the smallest average particle size (0.04 µm) of direct composite resins, they polish to a high luster better than any other material on the market. They also hold their polish over time and exhibit better wear characteristics than other types of composite resins. Microfills are also more stain and plaque resistant, making them more biologically compatible with the gingival tissue. In addition, they have the highest refractive and reflective indices of any composite resin category, producing the most realistic translucency.
However, microfills are less filled than other composite resins. As a result, they will not exhibit the same strength properties as a microhybrid or nanofill composite. Because of this, I utilize a layering technique placing an enamel layer of microfill composite resin (Renamel Microfill [Cosmedent]) over a stronger, dentin layer composite. For the dentin layer(s) I use either a microhybrid or nanofill composite (Renamel MicroHybrid or Renamel NANO [Cosmedent].) Restorations built in this way exhibit optimal aesthetics and wear resistance due to their outer microfill enamel layer.
Microhybrids are able to most closely simulate the dentin of natural tooth structure. Because of their higher strength and greater opacity, microhybrids are perfect for supporting the microfill enamel layer. Microhybrids have a larger particle size than the nanofill and the microfill composites, resulting in higher strength properties. Since microhybrids are the most opaque of the 3 composite types, they are also great for masking out unwanted color and achieving extreme color changes.
Microhybrids are also less polishable, more difficult to marginate, and will wear faster than microfill resins. As microhybrids most closely simulate the dentin of tooth structure, they will not obtain the same aesthetic results for an enamel layer as a microfill resin. In my practice, I use microhybrids as the substructure under microfills in areas that require high strength and maximum opacity.
The incorporation of nanofill technology into composite resins is an important advancement in the field of aesthetic dentistry. Nanofill composites combine conventional filler technology with nanoparticles to achieve both strength and aesthetics in one material. Currently, two distinct types of nanofill composites are in the marketplace: completely nanofilled resins and nanohybrids (ie, Renamel NANO). Completely nanofilled resins contain nanometer-sized particles throughout the resin matrix. Nanohybrids, on the other hand, consist of larger particles surrounded by nanometer-sized particles. Although these nanofill materials vary in composition, the goal is the same—creating a “universal” dental composite.
As previously mentioned, nano-hybrids contain nanometer particles combined with more conventional filler technology. These large particles provide similar strength properties to hybrid materials while exhibiting higher polishability, as seen with the microfill resins. Unlike microhybrids, nano-fill composites have a lifelike opacious translucency that is very natural in appearance. It is important to note that these materials will not hold their polish as long as microfill resins, and, as a result, may be more susceptible to plaque and staining over time. However, when compared with conventional microhybrids, nanofill composite resins will maintain better surface smoothness and polish and are thus great for the single-product user.
Where should you use nanofill composites? Although you can really use nanofill materials to create cosmetic dental restorations of all kinds, I have identified a few key areas where nanofill composites fit into my dental practice: posterior restorations, veneering lower anteriors, building up incisal edges, the classic class IV restoration, and finally, when restoring or increasing cuspid rise. They can also be utilized when the doctor wants to use only one material, instead of layering a microfill over a microhybrid; as a support material for class IV restorations; any tooth lengthening; adding cusps to worn molars or bicuspids; and for veneering mandibular anterior teeth (when strength is a concern) and posterior restorations.
OPAQUERS AND TINTS
Opaquers and tints are key ingredients to creating beautiful invisible restorations. During the restorative procedure, opaquers allow you to block out unwanted color, while tints help you bring the desired color back into the tooth. The use of both opaquers and tints is where your creativity as a dentist can really shine. However, opaquers and tints should always be used sparingly. Also, be careful when choosing tints and opaquers, as some manufacturers make these materials too opaque. Let’s examine the difference between these 2 materials.
Opaquers. The main advantage of opaquers is that they produce opacity and block light transmission. Use opaquers anywhere you would like to produce opacity in your final restoration. Since opaquers increase the value of a restoration, they are great for masking out metals and dark stains.
Tints. Tints are used to help increase the hue and chroma of your restoration. Since tints transmit light, they are great for adding translucency back into your restoration. Unlike opaquers, tints decrease value. I use tints to help develop a realistic-looking enamel surface from within.
Table 2. Questions When Selecting a Composite Resin System.
To excel in direct composite resin techniques, you should find a system that gives reliable and long-lasting results, then stick with it! Ask yourself the following question: How many composite materials have you shelved because some guru says another product is better, only to be disappointed once you have used it? When you are looking for a system, you should consider certain criteria (Table 2).
One should understand that no material in itself will deliver the ideal restoration. This is because material selection is only one part of direct resin bonding. Equally important is the dentist’s technical ability. Proper technique involves many components, including the following:
- Proper preparation technique for each procedure.
- Method of material placement—this involves complete understanding of tooth morphology and the sculpting techniques necessary to achieve it.
- Knowledge of layering and how to use various materials in combination—this will enhance the overall physical, aesthetic, and biologic results of each procedure (ie, when to use microhybrid, nano-fill, microfill, tints, and opaquers).
- Utilizing the proper finishing and polishing techniques—this will achieve the most lustrous, plaque- resistant, stain-resistant, and wear-resistant finished result. One must understand when and how to use finishing burs, discs, rubber impregnated points, and polishing paste to obtain the desired result.
Note that knowledge and technical abilities in all the above-mentioned areas can be greatly enhanced by an excellent hands-on workshop experience. I would recommend that you consider this if you have not already done so.
CASE REPORT: DIRECT COMPOSITE RESIN TECHNIQUE
|Figure 1. Maxillary anterior composite restorations at 22.5 years postoperatively. Only minimal chipping can be seen. Note the highly polished surface of the microfill composite resin material. (Small area of extrinsic stain, tooth No. 11).||
Figure 2. Renamel Microfill is exceptionally color stable and wear resistant. Note the excellent color match of the restoration to the shade tab (VITA Classical [Vident]) after 22.5 years.
Many years ago, I placed direct composite resin veneers on my son’s maxillary anterior teeth (Nos. 6 to 11) to close spaces utilizing only a microfill (Renamel Microfill). Over considerable time, Robert had some chipping due to aggressive eating habits. These defects were easily repaired. Photos, taken at 22.5 years postoperatively, show minimal chipping of the composite material and excellent color stability (Figure 1). As mentioned previously, microfills hold their polish long-term better than any other type of composite resin material, especially when the right dentifrice and toothbrush are used (Figure 2).
I made the decision to redo Robert’s case in the fall of 2007. The treatment goals were to achieve great aesthetics while establishing proper disclusion by improving his canine rise. Therefore, the new aesthetic restorations were done by utilizing both nanofill and microfill composites.
Let me take you through the reasoning involved in the proper material selection thought process:
I could have done the entire case using a nanofill and achieved excellent results, but I wanted the best of both worlds: strength and aesthetics. I wanted a microfill surface because of its long-term polishability and optimal, lifelike aesthetics. I used a nanofill to complete the functional portion involving the right and left cuspids. This would give me the strength required on a support tooth, along with great aesthetics and an excellent color match to the laterals and centrals. The technique is shown in detail in Figures 3 to 15b. Now, many would ask, why not porcelain veneers? And, I would ask, why porcelain veneers? What did we achieve with my son Robert after 23 years? We achieved long-lasting results with minimal preparation. We observed only minimal (nonpathologic) recession due to material biocompatibility (and good oral hygiene habits), total color stability with excellent aesthetics, complete and intimate bond of the composite-to-tooth surface (no cementation), and easy-to-repair restorations (Figure 16). Oh, by the way, Robert still eats ribs!
Figures 3a and 3b. A shallow labial prep is placed ranging from 0.8 mm at the incisal to 0.4 mm at the gingival. The gingival margin is placed 0.3 mm below the free margin for aesthetics and long-term gingival health. After a total-etch technique, Complete bonding adhesive (Cosmedent) was applied.
|Figures 4a and 4b. The lingual surface of No. 6 is reduced about 0.5 mm across the entire incisal one third, allowing a complete labial-lingual wrap of the incisal edge, creating better fracture resistance/ retention form. The first application of Renamel NANO A2 is placed lingually to establish canine rise. (Note: This material’s no-slump, no-stick properties allows easy sculpting/shaping of the incisal tip.)|
|Figures 5a and 5b. After polymerization of the incisal tip, Renamel NANO was used on the mesial proximal to add to the width of the cuspid to match the other side of the mouth. Note: Space between cuspid and laterals is not fully closed because it would have delivered a disharmony in size. Proper morphology of each tooth is completed, making finishing and polishing much easier.||Figures 6a and 6b. Addition of facial Renamel NANO A2 and the use of gloved finger (no powder, and clean and dry) to manipulate material into place. Apply light pressure with a tapping motion to allow for rapid and easy placement and precontouring.|
|Figures 7a and 7b. Use of titanium-coated instruments ensures easy placement of nanofills without sticking. Similar to buttering bread, the composite is spread and thinned simultaneously. A G3 instrument (Cosmedent) allows for easy placement on facial surfaces. An IPC Carver (Cosmedent) cleaves excess material interproximally and at gingival margins. Morphology and contours are achieved, but the material has not yet been polymerized.||Figures 8a and 8b. Prior to polymerization of the facial surface, the incisal areas are presculpted with the multipurpose instrument (Cosmedent). After polymerization the G3 instrument is used along with finger pressure to aggressively compress the incisal composite into presculpted areas.|
|Figures 9a and 9b. Incisal material in place and polymerized (note translucency difference between the incisal edge and the body material). To ensure the proper seal of gingival margins, apply a small amount of Renamel Nano material and sculpt with the IPC instrument.||Figures 10a and 10b. The G3 is used to sculpt and smooth subgingivally to completely seal margin. Material application and morphology is complete. (Note how much attention is given to properly sculpted tooth form.) Then the material is light-cured for 60 seconds.|
|Figure 11. Final composite resin veneer (No.6) after polishing. Note multichromatic nature (gingival to incisal), natural canine morphology, and canine disclusion.||Figure 12a. Upper left cuspid (No 11). Composite application complete and polyermized prior to finish. Figure 12b. Use of discs to contour the labial surfaces, to properly contour line angles, and to develop embrasure surfaces.|
|Figure 13a. Note retraction with an 8A instrument (HuFriedy) to protect gingival tissue and an 8392-016 diamond (Brasseler USA) while trimming and defining the gingival tissue. Figure 13b. Further define tooth and prepolish with a fluted ET6 bur (Brasseler USA).||Figure 14a. A diamond-impregnated point (Diamond Polisher Medium [Cosmedent]) is used to form/polish mesial and distal grooves and further develop the central lobe on the cuspid. Figure 14b. Fine and superfine discs (FlexiDiscs [Cosmedent]) are used to achieve a high luster while maintaining facial anatomy.|
|Figure 15a. The tooth is buffed (FlexiBuff) [Cosmedent] and polished (Enamelize polishing paste [Cosmedent]) in order to achieve an exceptionally smooth surface. A Felt FlexiPoint (Cosmedent) with Enamelize polishing paste is used to enhance the mesial and distal grooves. Figure 15b. Final polish. Note excellent color match to Vita shade tab.||Figure 16. Completed case: Tooth Nos. 6 and 11 were done with Renamel NANO A2 Body and Medium Incisal. Tooth Nos. 7, 8, and 10 were done with Renamel NANO and overlaid with Renamel Microfill A2 Body and Medium Incisal. Tooth No. 9 was not veneered, but the mesial and distal diastema closures were done using only Renamel Microfill.|
Disclosure: Dr. Mopper is co-founder and chairman of Cosmedent, where he is responsible for its educational programs and product development.
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