Material Selection for All-Ceramic Restorations
Monolithic digital technology has a growing presence in the dental laboratory.
Gregg A. Helvey, DDS
Imagine that a dentist, who is also a client, attends a continuing education seminar and hears the speaker make a pitch for a manufacturer’s new ceramic system, detailing all of its associated benefits. The speaker encourages attendees to demand that their laboratory acquire the system or find a laboratory that offers it.
Many dentists are not aware that the average dental laboratory does not inventory all of the ceramic systems on the market. They can be quite costly and there just is not enough discretionary profit in today’s economy to buy every new ceramic system available. Therefore, it is crucial that dental laboratories make informed decisions when it comes to choosing the all-ceramic systems they will stock in their businesses.
Making a Selection
Laboratory technicians must consider several important factors when selecting a ceramic system. First, they must take into account what the dentist is thinking. The author began his career as a dentist many years ago, and at that time, his main concerns were price, esthetics, and strength—likely in that order. He did not care how the restoration was made or how long it took the technician to complete it; he just wanted a restoration that was cheap, looked good, and did not break.
Later, the author became a dental technician and his outlook changed. He started to understand the complex considerations laboratories must take into account to satisfy and maintain their client base. As his interest and knowledge in ceramics grew over the years, he reprioritized his concerns—with esthetics and strength climbing to the top and price plummeting to the bottom. As a dentist fabricating all of his own ceramics, the author needed a system that was versatile, easy to use, and less time-consuming.
Versatility is key to a successful ceramic system. The track record for Concept (Ivoclar Vivadent, www.ivoclarvivadent.com.) proves that. As one of the first heat-cured composite systems, it was a very good product—the downside was it could only be used for inlays.
The market for Concept slowed when belleGlass™ (Kerr Dental, www.kerrdental.com) and Sculpture/FibreKor (Pentron Laboratory Technologies, www.pentron.com) were introduced as products that could also be used for crowns, bridges, and veneers. Laboratories then began to realize they could fulfill their client needs by investing in one system that could provide inlays, crowns, and veneers instead of having to buy multiple pieces of equipment.
Numerous studies in the literature have documented the surprisingly low bond strength of layered or pressed ceramics to various substrates such as different metal alloys, alumina, and zirconia. Esthetic demands have led to a greater use of non-metallic, high-strength core materials in today’s technology. These esthetic core materials include alumina, zirconia, zirconia-toughened alumina, magnesium aluminate spinel, and monolithic ceramic materials.
And although the studies of monolithic ceramic restorations have been short-term, many show tremendous promise. When comparing the labor intensity and required equipment differences involved with the fabrication of ceramo-metal, zirconia, or alumina-based restorations versus monolithic ceramic restorations, the latter requires the least.
Dental technology is headed in a monolithic digital direction. The industry is moving toward the development of one system that will provide inlays, onlays, single crowns, short- and long-span bridges and implant crowns and will never require a substructure. With an increase in the use of digital impressions such as CEREC Bluecam (Sirona, www.sirona.com), E4D Dentist™ (D4D Technologies, www.e4dsky.com), Lava™ Chairside Oral Scanner C.O.S. (3M ESPE, www.3mespe.com), and Cadent iTero™ (Cadent Inc, www.cadentinc.com) and improved ease of data transfer to the laboratory, the frequency of traditional impressions by clinicians and of typical model and die construction in the laboratory continues to decrease. A ceramic system that fits the needs of the patient, the dentist, the laboratory, and the latest technology is paramount.
Currently, the IPS e.max from Ivoclar Vivadent is the only monolithic all-ceramic system on the market that is formulated to meet a majority of the needs and provisions outlined above. However, as materials research and development move forward, the market will see new monolithic ceramic materials in the near future.
About the Author
Gregg A. Helvey, DDS
Adjunct Associate Professor
Virginia Commonwealth University School of Dentistry