Predictable Restorative Excellence -- Part 3 By John C. Cranham, DDS

In the third part of this series we will be discussing the specifics of restoration selection for posterior teeth. Since the explosion of the aesthetic revolution, there has been increased pressure to provide dentistry that looks, feels and functions like the natural dentition. Longevity expectations are also high. Patients expect an outstanding aesthetic restoration that will serve them for many years.

While many wonderful restorative materials exist, sometimes so many choices can lead to confusion. Still other times, a dental practice can get so excited about doing one type of restoration, that they use it for every situation. The old adage “once you have a hammer, everything looks like a nail” sets in.

The key is to set up an office protocol. To develop a process that will help the dental team choose a restorative material that will meet the patient’s aesthetic objectives, and also address the factors that could cause a restoration to fail. The concept is to slightly over-engineer the restoration so whatever the limiting factors, the chosen material will address it.

It would be nice if one material existed that would satisfy every situation. A material that conserves maximum tooth structure. A material that would bond to the tooth structure no matter what the environment in which the bonding occurred. And finally a material that could withstand whatever occlusal forces were placed upon it. Since one restorative material like this does not exist, it is important for the dental team to develop a series of restorative options to fit the needs of a variety of clinical situations. This is far better than trying to get the patient to fit the restorative material!

Evaluating the Occlusion
One of the most important factors to consider when choosing a restoration is to evaluate the forces generated by the patient. If signs of instability exist in the gnathostomatic system (tooth wear, tooth mobility, tooth migration, sore musculature or TMD), then we should focus on not only fixing the occlusion, but also choosing a more durable restorative option. In other words, in a patient with bruxing or clenching habits, you might choose a bonded inlay, where many times you would be comfortable doing a direct resin restoration. Go with a more durable restorative material when the forces dictate it.

Evaluating the ability to achieve 100% isolation
One important factor to evaluate prior to restoration selection is the ability to achieve 100% isolation. While this is not a problem in many instances, sometimes the position of a subginvial box or a crown margin back on a lower 1st or 2nd molar is not the most predictable place to bond. Remember the goal is to choose a restoration that will predictably work for the patient.

There is, therefore, a need for a non-bonded alternative. In these situations we can either alter the periodontal architecture (crown lengthening surgery), to accomplish isolation, or choose a traditionally cemented aesthetic restoration, like a contemporary metal ceramic crown.

The Restorative Options
While many good aesthetic posterior options exist, for the purpose of this article we discuss only three. These three, however, when utilized correctly can work 95% of the time. The key is to evaluate the patient from the aforementioned perspectives, and choose the restoration that will create the optimum result from an aesthetic and longevity point of view.

The Direct Resin Restoration Utilizing Point 4
The success of posterior direct restorations have become so successful that many dental schools are teaching their students that this is the first restoration that should be placed in a tooth! Why? Because it allows us to remove only the part of the tooth that is damaged, and then replace it with a material that bonds to the tooth. This is very different than how most of us were trained on amalgams.

Figures 1 and 2 exhibit a standard prep and post op of a direct resin utilizing Kerr’s Point 4. This is a size that works extremely well with direct resin. It is predictable because the tooth can be easily isolated, and the resin has multiple walls to adhere to. The wear rates of these modern materials are excellent, so we can build them into occlusal function and they hold up fine. If however, the patient has obvious signs of occlusal problems related to parafuction, I may choose to over-engineer this restoration and do a bonded onlay such as a belleGlass restoration. The enhanced physical properties of materials cured outside the mouth in the presence of heat and pressure will function even better in these situations.

Fig. 1

Fig. 2

Class II restorations also can be done quite well. Figures 3 and 4 are a pre-op and 6-year post-op of direct resin restorations on teeth 19 and 20. When, doing a Class II in direct resin, it is important to closely evaluate the buccal-lingual dimension of the box. The larger the area, the less predictable restoring with direct resin becomes. Switching to an indirect material in these situations, will not only add strength, but add tremendous control when restoring ideal contact form.

Fig. 3

Fig. 4

The Indirect Inlay–The belleGlass Onlay Restoration
The indirect inlay onlay restoration should be thought of the “intermediate restoration.” It is used when the restoration size is too large for direct materials, but not large enough to warrant a full coverage restoration. Another example is the patient who has signs and symptoms of clenching or bruxism. In this case you may choose to do smaller indirect inlay restorations, to maximize the strength of the material.

One of the great trends in dentistry is a shift towards maximum conservation of tooth structure. Through adhesive dentistry it is possible to strengthen teeth without having to completely cut them down. Figure 5, exhibits a pre-operative state of teeth 14 and 15. Tooth 14 has a fractured MF cusp that is sensitive to biting and cold (cracked tooth syndrome). Tooth 15 has an occlusal amalgam that has secondary caries around it. The patient has no signs of parafunctional activity. This is a perfect place to shoe the MF cusp and restore with an indirect onlay restoration. Figure 6 reveals the post-operative photo. Tooth 14 was restored with a belleGlass onlay, fabricated by Dental Arts Laboratory in Peoria, Illinois. Tooth 15 was restored with Point 4 Direct Resin. Notice the chameleon affect of this material. How well it blends with the surrounding tissue. Photographs were used in this case to communicate the color of the occlusal stain.

Fig. 5

Fig. 6

Figure 7 shows a classic pre-operative state. A 65-year-old woman who wants to have her smile back, and also wants all the “black metal” out of her mouth. She, again, has no parafunctional habits, and likes the idea of being as conservative as possible. These teeth are too large to predictably and easily restore with direct resin, and yet may be too small to require traditional crown and bridge. A quadrant of belleGlass onlays were used to restore this case (Fig. 8). They were also fabricated at Dental Arts Laboratory.

Fig. 7

Fig. 8

Contemporary Metal Ceramic Crown-Captek
Previously, a full coverage porcelain-fused to-metal crown was a pretty aggressive restoration; especially if you wanted an esthetic result. One-and-a-half millimeters and 360 degree shoulder preparations were utilized to allow for porcelain butt margins. While these were aesthetic, they removed a lot of the healthy underlying tooth structure and could predispose it for fracture.

Additionally, a lot of facial, lingual and occlusal reduction was required to allow for the metal, the opaque porcelain layer (to block out the dark oxide layer on the metal surface), and the body porcelains. Under reducing lead to an opacious looking crown lacking translucency.

Today several companies have emerged to try and develop a metal ceramic crown, that would require less reduction, but still have a beautiful finished product. One of the hottest companies in that arena is Captek.

Figure 9 exhibits the pre-operative state of tooth 30. It is has had endodontic therapy and been built up with a direct resin core. The 26-year-old patient has a history of clenching and parafunctional activity. Because of this the tooth was treatment planned for maximum protection with a contempory metal ceramic crown (Captek).

Fig. 9

The tooth was prepared to the ideal specifications (Fig. 10), as was outlined in Part One of this series. The final impression was made (outlined in Part Two), and all model and die procedures were completed. What makes Captek such an interesting product is how it is fabricated. It is not, in fact, an alloy. It is a composite metal. The coping is fabricated in a two step process. The first involves a layer of Captek P (Fig. 11) that is primarily platinum and palladium. It is the center of the coping and provides the strength, and the core. The next layer added is the Captek G (Fig. 12-97.5% gold and 2.5% silver). Upon firing the Captek G is pulled into the Captek P through capillary attraction. The result is a composite metal, with platinum and palladium at the center and gold on the external internal surfaces. The result is a very strong, extremely thin, gold coping.

Fig. 10

Fig. 11

Fig. 12

Because of the warm gold color, far less opacious porcelain is required (Fig. 13). In fact, it is desireable to let the gold color shine through the porcelain. The benefit for the patient is only 1-1.2mm of facial and lingual reduction is required with a light chamfer margin. With this amount of room, a beautiful end result can be obtained (Figs. 14 and 15). The laboratory work in the case was fabricated by Alvin Filastre at Ceram-O-Arts in Lakeland, Florida.

Fig. 13

Fig. 14

Fig. 15

Conclusion:
We are practicing dentistry in an unbelievable time. More information exists on the subject of esthetics, function and adhesion than any other time in history. At the same time, we are seeing vast improvements in restorative options for our patients. In a contemporary restorative practice it is incumbent that we develop a restorative protocol to choose the best restorative material for the patient, rather than making the patient fit the restorative material. By doing this, we will predictably serve the long term esthetic and restorative goals of our patients. DT

Want to know more? You can find out more about Captek on the message boards at www.dentaltown.com in the Anesthesiologists General Discussion, Search Words (typed exactly)–Crowns or onlays

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Dr. John C. Cranham has a cosmetic oriented restorative practice in Chesapeake, VA, where he resides with his wife and three children. An honors graduate of the Medical College of Virginia in 1988, he maintains a strong relationship with his alma mater, as an Associate Clinical Professor, teaching Graduate Prosthodontics and AEGD programs.

John is an internationally recognized speaker on the Esthetic Principles of Smile Design, Contemporary Occlusal Concepts, Laboratory Communication and finding Happiness and Fulfillment in dentistry. Most recently, John has founded PRE (Predictable Restorative Excellence) Seminars which provide a combination of lecture, mobile hands-on programs, and intensive 2-3 day hands-on experiences at his office in Chesapeake, VA. John can be reached at 757-465-8900 or at smiledoc@aol.com

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