Written by Kevin L. Winters, DDS Friday, 31 August 2007 19:00
Posterior composite dentistry has become a well-accepted treatment that many practitioners provide. Proper bonding techniques combined with the superior materials that are now available allow beautifully aesthetic posterior restorations to be placed. In addition, the materials now can provide wear similar to enamel, so long-term success is quite high.
Replacing amalgams with composite is an everyday occurrence in many offices. Still, dentists are often hesitant to do so for fear of postoperative sensitivity. It is amazing how an entire segment of the dental materials market is devoted to reducing or stopping sensitivity. This article presents a technique that is extremely reliable for replacing amalgam restorations with composite. When this technique is followed closely, you can expect little, if any, postoperative sensitivity. It is very important that the steps of this technique are strictly followed.
|Figure 1. Amalgam restorations preoperatively.||Figure 2. Rubber dam in place.|
|Figure 3. Amalgam restorations removed; decay present.||Figure 4. Decay removed; preparations complete.|
|Figure 5. Enamel margins with etchant.||
Figure 6. Entire preparation with etchant.
In this case presentation, Figure 1 shows a typical quadrant of amalgam restorations that have been in place more than 10 years. Note the multiple areas of marginal breakdown as well as the obvious aesthetic problems of having so many “black” fillings in these teeth. The patient agreed that she would like to have them removed and replaced with more aesthetic composite fillings.
The material selected for restoring these teeth was Amelogen Plus (Ultradent Products), which is a microhybrid that is 76% filled with an average particle size of 0.4 to 0.7 µm. The material exhibits excellent chameleon ability to blend in with tooth structure. Fifteen shades are available.
After anesthetizing the patient, a rubber dam was placed. This is important for several reasons. It helps with the ease of doing the procedure, it is more comfortable for the patient, and it helps isolate the teeth from unwanted moisture and saliva contamination (Figure 2).
The next step was to remove the amalgam restorations; this revealed areas of decay (Figure 3). This is very common when removing old amalgams, and based on my clinical observations I expect to see decay in these situations. Utilizing both high-speed instrumentation and low-speed with a round carbide bur, the decay was excavated, and the surface was ready for bonding (Figure 4).
I like to use a chlorhexidine scrub (Consepsis [Ultradent Products]) before etching. This step is to remove any tooth debris and to provide a cleaner surface for etching. After rinsing, a 35% phosphoric acid etchant was applied (Ultra-Etch [Ultradent Products]) by first rimming the enamel margins and then filling in the remainder (Figures 5 and 6). This was allowed to sit for 10 seconds on the dentin. After rinsing thoroughly for 10 seconds, the surface was lightly dried, being careful not to desiccate it.
Figure 7. Moist dentin.
Figure 8. Applying PQ1.
Figure 9. Layer of flowable composite.
Figure 10. Incremental layering of dentin shade.
I have found it very important to keep the dentin surface moist before bonding. Overdrying can be one of the leading causes of sensitivity. There are several choices for moistening the dentin surface. I like UltraCid F (Ultradent Products). It is a benzalkonium chloride product with fluoride. This wetting agent has antibacterial properties and helps to disinfect the surface. After application of the UltraCid F, high-speed suction was used to remove any excess. By simply holding the tip over each tooth just for a second, you get a nice, moist surface (Figure 7).
It was now time to apply the bonding agent. I used PQ1 (Ultradent Products) for these restorations. PQ1 has a unique chemistry and consistently provides some of the highest bond strength scores. It is a filled agent, and I only use it on direct restorations due to the film thickness (Figure 8).
The first layer of composite was then applied. I always use a flowable composite for this. Flowable composites adapt to the dentin surface more intimately and can help act as a shock absorber for the polymerization shrinkage that occurs when the rest of the layers of composite are added (Figure 9).
The next few layers of composite act as the dentin replacement. As such, the majority of the time either a shade A3.5 or A3 is chosen. Using shade A3 Amelogen Plus, I began to rebuild the tooth incrementally (Figure 10). Each cusp was made individually to minimize polymerization shrinkage effects. Sometimes sensitivity due to cuspal flexure is attributed to the polymerization of quantities of composite that are too large.
Figure 11. Enamel layer.
Figure 12. Polishing with brush.
Figure 13. Beautiful composite restorations.
As the occlusal table was approached, enamel layers were placed next. This shade should mimic the color of the enamel of the tooth. Many times you can use a translucent enamel shade and let the chameleon effect of the composite draw in the color. In this case, I chose a B1 shade because the value of this tooth was pretty high. Again, cusp by cusp, the tooth was built to its anatomical form (Figure 11).
Once this final enamel layer was completed, the occlusion was checked. Verifying and adjusting the occlusion usually does not take long if you have followed the anatomical contours of the tooth. Polishing was accomplished with Jiffy (Ultradent Products) cups and polishing brushes (Figure 12).
As can be seen in Figure 13, the final results are amazing. You can see how the incremental buildup technique allows for a very natural color distribution within the tooth. In the grooves you pick up the color of the darker dentin composite, while on the incline planes and ridges you can see the B1 composite providing higher value.
This technique of replacing a quadrant of amalgams and incrementally rebuilding the teeth with composite takes only around 20 to 30 minutes. By charging the appropriate fees for these high-quality restorations that will last for years, this can be a very profitable procedure that is easily and predictably accomplished every day in your office.
Disclosure: Dr. Winters conducts product evaluations for several companies, including Ultradent Products, from which he receives financial remuneration as a consultant.
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