Treatment Planning for Restorations: Available Options

Dentistry Today


Last month, I examined a set of criteria for the diagnosis of recurrent decay and when to change an old restoration. In this article, I will examine the treatment options available once the diagnosis has been made and discuss their pros and cons. I also will present a treatment planning paradigm that is becoming the standard in dentistry today.

Our current restorative paradigm in dentistry is to consider the longevity of the restoration as our prime consideration. In so doing, we have ignored a more important goal, which is that the tooth be in function until the end of the patient’s life. These 2 goals are not one and the same, because in considering only the longevity of the restoration, we overlook what comes next. With each successive cycle of decay, repair, breakdown, and repair, less and less tooth remains to be restored. We must no longer examine a tooth from a short-term point of view. The lifetime of the tooth and the cycle of breakdown and repair must be examined.

We now realize that everything we place will break down in time and will need to be replaced. Therefore, the new paradigm must include not only the maximum longevity of the restoration but also the absolute retention of healthy tooth structures. This ensures that the cycle of breakdown and repair is extended and that when the time comes to replace the restoration, there is sufficient remaining tooth structure left to rebuild. 
Not only do we as dentists need to be aware of this new paradigm, but the patient must also be made aware. Patients make different choices for themselves when it is explained to them in this manner. 


Nonbonded Restorations
(1) Amalgam is a short form for mercury silver amalgam. It is comprised of 60% to 70% mercury and 30% silver with 5% to 10% other assorted metals. On the plus side, amalgams are easy to place, relatively inexpensive, technique insensitive, and can be expected to last at least 10 years and frequently double that. In the short term, it appears to be an easy choice since it is fully covered by most dental plans.

Amalgam has become unpopular with many patients due to its mercury content and its black, unaesthetic appearance. Its main downside is the way the tooth must be overprepared. The fact that the material is not bonded requires that we must remove the enamel as wide as the decay has undermined it. Frequently, whole cusps must be shoed, necessitating vast destruction of healthy enamel and the placement of retentive pins. Large amalgams leave the tooth weakened by the new restoration and significantly overprepared compared to other restorative materials. The lack of bonding between the restoration and tooth weakens the tooth and may lead to premature loss of one or more cusps, hastening the arrival of full coverage. 
Many teeth restored initially with amalgam will not survive a lifetime due to the amount of enamel destroyed at first and subsequent placements. These restorations fit the new paradigm for longevity but fail miserably at conserving tooth structure. 

(2) Gold has almost been forgotten by mainstream dentistry but remains one of the best restorative materials for class I and small class II restorations. On the plus side, wear resistance is excellent, it is highly biocompatible, and there is no mercury. Gold is more aesthetic than amalgam, but this is still an issue for many of today’s aesthetic- conscious patients. Its main advantage is longevity. Well done class I and II gold restorations may be unrivaled for longevity ince they frequently will attain 20- to 30-year life spans. It is the only restorative material that has such a proven track record

On the downside, like amalgam, gold preparations involve the removal of significant amounts of healthy enamel and the shoeing of thin cusps, since cusps may not be undermined and draw is required for placement. Retention of larger, multicusp class II restorations is also a problem. Cost is high in the short term, and these restorations are frequently not covered by insurance companies. 
Gold restorations fit the paradigm for longevity, but due to retention issues, they are best suited to class I and small class II restorations. If properly placed, from the first cycle, gold should only have to be placed 2 times in a lifetime before a full-coverage crown is required. In terms of longevity alone, gold should allow for lifetime retention of the tooth. If only patients didn’t mind the color… 

Bonded Tooth-Colored Materials
(1) Composite Resin is basically glass particles embedded in a Bis-GMA resin. Its main advantage over amalgam is that it is a bonded material and as such may be placed under undermined enamel. The preparation design for a bonded restoration is much more conservative than that for an amalgam because laterally spread decay can be scooped out with a round bur, and the enamel cusps can be completely undermined and conserved without the need for shoeing. This material fits the criteria for minimal preparation and maximum retention of tooth structures. It is tooth-colored, highly aesthetic, and usually fully covered by dental plans. It has become the filling material of choice, knocking amalgam into disfavor.

On the downside, however, there are concerns about the longevity of this material. Wear resistance has become quite acceptable, but the process of layering the composite due to polymerization shrinkage can lead to internal tensions, microgaps on the pulpal floor that cause biting sensitivity, microleakage at the margins, and a host of technique issues that lessen the ultimate longevity of these restorations. These are the most technique-sensitive restorations available today, and longevity varies from dentist to dentist depending on skill, experience, and training. These restorations bite back if you rush. They demand attention to detail and time spent finishing and polishing. 
If everything goes well and the dentist allows adequate time for proper placement, these restorations can be expected to last from 7 to 12 years and possibly longer.
Clearly, these restorations meet the paradigm for conservation of tooth structure, but for now they fall short in the longevity criterion. This will most likely change in the near future as tremendous research efforts are being made with these materials in the hopes of overcoming these issues. 

(2) Porcelain and composite resin indirect inlays and onlays. These materials are the state of the art in dentistry today because they meet the demands of both dentists and patients. They are tooth-colored and highly aesthetic. They are preserving of tooth structure as decayed cusps can be undermined and back-filled with composite or glass ionomer, and then the onlay can be prepared without the need to shoe the cusp and remove healthy enamel. All of the polymerization and shrinkage issues of layered composite resin restorations are overcome since the restoration is bonded in one piece. Its major advantages over gold are beautiful aesthetics, and because of high bond strengths to enamel and dentin, they can be used for all restorative needs, from class I to completely unretentive large class II restorations. Bonded composite resin and porcelain inlays and onlays have none of the disadvantages and all of the advantages of gold except one—a long track record to back them up. The technology simply hasn’t been around long enough, but so far, 15-year data make these restorations look like a very good choice.
(3) Full coverage crowns. For many dentists uncomfortable with the technique sensitivity of bonding, the short lifespan of composite, and patients who don’ t want black or gold teeth, porcelain crowns have become the fashion of choice these days. Long-lasting and aesthetic, these restorations seem to meet the criterion of a long-lasting restoration. In the hands of most dentists, these crowns will probably last anywhere from 15 to 20 years, a good value for the patient. Once the dentist has placed enough of them, they can be quite lucrative since an experienced dentist can prepare a crown in around 40 minutes to an hour and place it in about 10 minutes. Some speed demons even prepare and temporize in as little as 10 minutes. Now that is lucrative. However, I think that the rush to place what is likely to be the tooth’s last restoration as a first choice, and cutting down significant amounts of healthy tooth structure to prevent cusp breakage, is gross overtreatment in light of the treatment options previously outlined. Of all restorations, the full-coverage crown is the least conservative restoration, even if it may be one of the longest lasting. If your crown lasts 20 years (and statistically speaking 15 seems to be the average) and your patient is 40 years old, how will you restore that tooth when it inevitably decays subgingivally?

This restoration should be used as a last resort or in cases where the tooth has or will have root canal treatment and significant tooth structure is already missing. 
I know that this point of view will stir some deep-seated feelings among many dentists who are routinely placing crowns as their treatment of first choice. However, the evidence that bonded onlays will last as long as a crown while conserving tooth structure is mounting. Few “gurus” out there today don’t routinely place bonded onlays as first-choice restorations. Every continuing education continuum that I know of is teaching techniques on posterior bonded indirect restorations. CAD/CAM milling machines like the Cerec machine (Sirona) now allow for reliable, 1-appointment delivery of precise-fitting inlays and onlays backed by the most comprehensive research in the industry. New techniques, technologies, and materials are quickly making the old restorative paradigm obsolete. 

If you are not routinely placing inlays and onlays, now may be the time to rethink your restorative paradigm. Remember: it’s not how long the restoration lasts that counts—it’s how long the tooth will last.

Dr. Arvanitis maintains a full-time dental practice in Waterloo, Canada, and has taken more than 1,100 hours of continuing education from some of the most renowned masters of cosmetic and implant dentistry. He is a fellow of the Academy of General Dentistry, a fellow of the International Congress of Oral Implantologists, a member of the American Academy of Cosmetic Dentistry, and a member of the American Association of Implant Dentists. He can be reached at (519) 748-2282.