Educational Supplement By Marshall White, DMD

Greetings from Howard

Welcome to the first of many informational supplements that we will bring to you through the pages of Dentaltown Magazine. We are proud to bring this important information to our community. Dentaltown.com has been in the business of dentists sharing information with other dentists since 1999, and our magazine is the natural extension of that exchange. It is only fitting that this inaugural insert feature the marriage of two unique technologies – Ceramco® Press and CAPTEK^TM.

The PFM crown has long been the bread and butter restoration for general dentists. While the restoration concept has stood the test of time, there is room for improvement. One of the key benefits to this new technology is the ability to wax, invest and press the porcelain anatomy rather than the laborious process of hand stacking porcelain. The laboratory industry is no different than your practice in their pursuit of faster, better and easier ways to deliver a finished product. Keller Laboratories fabricated the crowns you will see in this supplement, and they did an excellent job!

Ceramco Press to CAPTEK is an ideal marriage of materials. I have been very impressed with the esthetic warmth and pleasing tissue response provided by CAPTEK crowns. Additionally, the unique nature of the CAPTEK coping provides the perfect interface for a pressed ceramic. Like many dentists, I am skeptical of new materials, but I have very few worries as Ceramco Press and CAPTEK have solid track records.

Finally, our free community exists due to the support of our members and commitments form our advertisers. I would like to take this opportunity to thank the Dentsply Prosthetics Division for providing the funding to bring this information to our community. Remember, when you finish your first Ceramco Press to CAPTEK crown, post it in the message boards on Dentaltown.com.

Create a Great Day!

Howard Farran, DDS, MAGD, MBA
Founder/Publisher Dentaltown Magazine

Introduction:

When things go well (as is generally the case), treating our patients with indirect dental restorations, such as porcelain-fused-to- metal (PFM) crowns, is a team process that offers a very high degree of clinical predictability along with long-term functional reliability. It remains the most common material prescribed by doctors for their crown and bridge needs.

However, in looking at the process, we find areas of variable consistency, which occasionally can cause dissatisfaction to patients, dentists and laboratories. I have recently been using CAPTEK^TM substructures veneered with the Ceramco^® Press ceramics system (Fig.1). My experience to date with this combination of materials has been extremely positive. I’d like to discuss what I’ve discovered about why this unique combination helps overcome some of the PFM restoration’s limitations, but also how it does so without any compromise in that restoration’s performance. Importantly, it especially delivers great performance in three areas where we can all appreciate it – the lab process, in clinical esthetics and in ease of seating.

Limitations of the Current PFM Process:

Among the more challenging tasks for the dental laboratory technician, and especially to do really well, can be the stacking and firing of porcelain. Building a tooth in thin air, purely by the addition of ceramic material, requires patient attention and only poorly lends itself to a team approach. To boot, high temperatures are needed for manipulation of ceramics, the amorphous structure of which imposes limitations on the amount of handling and revision it will tolerate without losing its structural integrity. Using stacked feldspathic porcelain to create the cusps, fossae, cingula and other minutia of a crown is well within the capabilities of dental labs. However, consistently doing so with accurate anatomy, beauty, and efficiency has the potential to be very challenging. In short: this conventional process may be prone to variability with regard to anatomy, shade and strength.

Ceramco Press: An Innovative Veneering Process

By comparison, waxing, investing and casting an all-metal restoration is simply more efficient than stacking porcelain. Morphology is morphology, shape is shape, and there is very little variation in how that is attained with a malleable material like wax. There are no shrinkage issues to compensate for after casting, no worries about dealing with color and morphology simultaneously. But once cast, metals do not look like a tooth. Sure the shape may be right, even perfect, but it simply is not tooth-colored.

The Ceramco Press system, introduced in 2004, combines the aesthetic advantages of ceramics with a fundamental improvement in the processing of the PFM. By waxing a pattern to then invest and use in pressing a restoration (analogous to casting a metal restoration), Ceramco Press offers a number of ways to improve efficiency relative to stacking porcelain. Fabrication of restorations using pressed porcelain involves a process that in many ways is just like waxing, investing and casting to get a metal crown. Molten ceramic is injected, or “pressed,” into the void left in an investment after driving off an embedded wax pattern with heat. This lends itself well to a team approach and when the proper shading and translucency are chosen for the starting porcelain, the ingot of ceramic, the nuances of variations in color and texture can be managed with stains and glazes at finishing. This leads to greater consistency as well as greater uniformity from crown to crown: I love being able to count on a predictable shade appearance from crowns done at different times.

Create the shape in wax, press that identical shape with the porcelain, cut the sprue and initiate finalization, deal with occlusion, then fine tune the color according to the doctor’s prescription. Each step can be perfected by a different person, or a different team of people, and the efficiency gains are substantial. Done right, this can also be accomplished while sacrificing nothing in the way of quality. In fact, in terms of certain criteria such as minimizing the presence of porosities, there can actually be improvement in quality over traditional methods.

Now, despite the advantages afforded by use of a pressable format, these materials are still porcelain-glass ceramics that, as a class, are quite intolerant of cyclic deformationi. A way to strengthen or reinforce the ceramic dental materials would be a welcome addition to their use. That is precisely why, decades ago, traditional porcelains began being fired, or “fused” to metal copings – the metal imparts strength and resistance to long-term cyclic deformation during function. By natural progression the time-tested porcelain-to-metal concept has been applied to the pressable ceramics. A wax-up is made directly on a metal coping. This wax-on-metal pattern is invested, etc., and ultimately a pressed porcelain-to-metal crown is divested and finished.

Enter CAPTEK: a unique composite metal

My preference for metal copings is a material called CAPTEK. Its uncommon structure, as well as its singularly unique physical and biological properties, makes it an attractive option for both the lab and the doctor. While heat is used to adapt the CAPTEK to a die, there is no actual casting involved, so there is no need to separately wax-up, invest and burn-out in order to make a framework/coping in addition to the waxing, etc., necessary for the pressing of the porcelain. CAPTEK’s deep yellow gold color generates a background for porcelain that adds what has been described as “warmth” or even “vitality”ii to the appearance of the finished crown. So, with CAPTEK we can have the beauty of porcelain, and a metal beneath that both strengthens the ceramic and enhances its innate beauty.

I think of a CAPTEK PFM as the further-refined, modern version of an old standard. It has a unique, patented composite metal substructure that imparts very attractive physical and biological properties to the crown. CAPTEK is classified as a composite metal because, as opposed to the homogenous structure of alloys, it contains a strong internal skeleton of very hard, interconnecting particles of high fusing platinum and palladium. This internally supports and strengthens the 97.3% pure gold matrix that surrounds and permeates that skeleton. This internal skeleton also bestows a degree of thermal stability. It is hypothesized that, in effect, it neutralizes the forces that lead to distortion of cast copings, while the gold creates a beautiful background for ceramic materials. Ceramco Press + CAPTEK crowns are as versatile and easy to use as a traditional PFM, they can be cemented conventionally, and will accommodate any margin designiii. By virtually eliminating thermal distortion CAPTEK can achieve margin gaps of 15 microns, but there are still more reasons why CAPTEK is a better choice over cast alloys.

With pressable ceramic to a conventional metal coping, the coping must be waxed, invested, burned-out and cast, then in a separate protocol the pressable ceramic must be waxed and pressed to that metal framework. A coping of CAPTEK isn’t waxed-up or invested or cast. Its creation is much shorter and less-involved, so getting to the ceramic part is accomplished more quickly and in fewer steps (Fig. 2). Again, the lab sees efficiency gains and, due to the fabricating technique, there is much less uncertainty or variability in the thickness of the coping.

While prior to Ceramco Press + CAPTEK, this technique met with success, there remained substantial room for improvement. Simply pressing ceramic against a metal substructure did not predictably lead de facto to fusion of the two substrates. As had been discovered when fusing conventional porcelains to metals, the bond of pressable ceramics to metals is affected by any number of factors related to the metal or alloy and to the ceramic being used. However, unlike the traditional methods, current experience in enhancing that bond between pressables and metals is still growing quickly.

By improving the quality and the durability of the fusion of this pressable material to a CAPTEK substructure, Ceramco has been able to accomplish those goals. The Ceramco Press opaquers are applied to the CAPTEK coping prior to waxing and pressing (Fig. 3), and these materials adsorb to CAPTEK’s intricate surface providing an intimate contact that will ultimately lead to a strong micro-mechanical bond of Ceramco Press to the CAPTEK coping (Fig. 4). For measurements in vitro, there is no significant difference between the compressive strength of a conventional PFG crown and the compressive strength of a crown of Ceramco Press-to-CAPTEK. A respectable palette of opaquers, ceramic ingot shades, ingot translucencies, and external characterization stains permit a very high degree of control over aesthetics – including the post-pressing enamel porcelains, the system boasts in excess of 50 means for managing color and characterization.

But there are other advantages to the use of CAPTEK as a metal substructure. As a result of its high gold content, CAPTEK’s rich color can be used to further enhance the beauty of the pressable ceramic. Also, there is some very interesting in vivo science, funded by the Forsythe Institute, showing that this material actually reduces bacterial plaque accumulation by at least 71% when compared to non-restored teeth in the same mouthiv. Tissue response to CAPTEK margins is ideal and it promotes exceptional ongoing tissue health (Figs. 10 through 13).

Clinical Cases

Case One. An adult patient requires restoration of two teeth, #s 18 & 19 due to a failed direct composite and the fracture of both lingual cusps, respectively (Fig. 5). The patient is firm in a desire for an esthetic alternative to all-metal, and a porcelain-fused-to-gold crown is prescribed for each tooth. Following initial occlusal reduction, all restorative is removed, then all carious dentin is removed with #2 and #4 round burs. The excavated tooth is cleaned, rinsed and lightly dried, then a composite core is bonded in place.

Following core placement, careful occlusal reduction is accomplished so as to give the lab ~2.0 mm clearance and taking into account the cross bite occlusion of #18. Initial axial reduction of ~0.5 - 1.5 mm is performed, then using a ferric sulfate solution hemostasis is achieved where the distal aspect of the interdental papilla was chronically inflamed adjacent to the fractured box portion of the failed composite in #18. Retraction cord was packed in the sulci, the final chamfer margins refined, line and point angles were smoothed and rounded (Fig. 5). Temporary crowns were fabricated and both teeth were hybridized to seal their surfaces. An impression was taken and provisional crowns cemented.

At the next appointment, the temporary crowns were removed without need for local analgesia and the final Ceramco Press + CAPTEK crowns tried in. Needed minor adjustment to lighten contact between the units was made and the intaglio of both were lightly particle-abraded with 50µ Al2O3. Then Interface and Simplicity-2 were applied and light-activated per manufacturer’s protocol to those interior surfaces and the crowns bonded to the teeth with a dual-cured resin-based cement (Fig. 6). Tissue response was excellent at three weeks following placement (Figs. 7 & 8).

Case Two. An adult male pt. presents with recurrent caries on teeth #s 2 and 3. They will be restored with gold 7/8 crown #2 and Ceramco Press + CAPTEK for #3. The first molar is prepared for full coverage in a manner similar to the teeth in Case One, but with a circumferential modified shoulder of ~0.5 mm. There is 2 mm of occlusal reduction and 0.5 – 1.5 mm axially. Margins are placed ~0.5 mm sub-gingivally on the buccal for aesthetics, and interproximally by necessity (Fig. 10). The lingual margin is placed supra-gingivally. At cementation, fit was superb, and only very minor adjustments were necessary (Figs. 11 & 12).

Conclusion

I always appreciate the insights my lab colleagues (in this case, Keller Laboratories) share with me. It has helped me learn techniques to make my crown and bridge practice more rewarding and profitable. Ceramco Press provides us with incredible predictability in esthetics, fit, form and function. The increased density of Ceramco Press provides for greater strength than in the past. When combined with CAPTEK, the esthetics become predictably more natural, strength is enhanced, and tissue health is incomparable. In these cases, the combination eliminates the guesswork in contouring and shade fidelity.

New developments have given labs and dentists new ceramics and new metals for use in the classic PFM crown. This unique combination of materials provides strength and beauty like the long-familiar PFM, but refines the concept to bring even more benefits to that old stand-by. The Ceramco Press + CAPTEK crown truly goes beyond being “just a PFM.”

References
i Chitmongkolsuk S, Heydecke G, Stappert C, Strub JR, Fracture strength of all-ceramic lithium disilicate and porcelain-fused-to-metal bridges for molar replacement after dynamic loading, Eur J Prosthodont Restor Dent. 2002 Mar;10(1):15-22.
ii Shoher I: Vital tooth esthetics in Captek restorations. Dent Clin N Amer. 1998 Oct;42(4):713-8, x.
iii Zappala C, Shoher I, Battaini P, Microstructural aspects of the Captek alloy for porcelain-fused-to-metal restorations, J Esthet Dent. 1996;8(4):151-6.
iv Goodson JM et al: Reduced dental plaque accumulation on composite gold alloy margins. J Periodontal Res. 2001 Aug;36(4):252-9.

Marshall White, DMD is a general dentist in private practice. A 1985 graduate of the University of Pittsburgh School of Dental Medicine, Dr. White is a tireless advocate of scientifically-based decision-making in dental treatment. As an author and teacher, he has written and spoken nationally and internationally on endodontics, operative dentistry and minimally invasive dentistry. Dr. White practices in rural Licking County, Ohio, where he resides with his wife and their three sons. He can be reached by e-mail: m@mwdmd.com.