LAB NOTES: Based on what you now know about Lava, where do you see its use in restorative dentistry?

Dr. Sorensen: Based on our in vitro research, clinical research and my clinical experience with LAVA, I see a huge potential for Lava in restorative dentistry. The whole class of zirconia ceramics has revolutionized fixed prosthodontics. The high strength and high fracture toughness of zirconia finally provides dentistry with an all-ceramic material that rivals metal ceramics.

I believe that the LAVA system offers dentists a predictable and reliable fixed prosthdontic material for routine use in posterior restorations. This will expand the number of clinicians using all-ceramic restorations.

The high-strength zirconia ceramic substructure facilitates conventional cementation. A large number of dentists in the country are averse to the more time consuming and technique sensitive adhesive cementation.

Our research on marginal fidelity of all-ceramic systems has shown systematic and predictable achievement of excellent marginal fits of both crowns and bridges.

Couple all of these features with consistent esthetics that are superior to metal ceramics and you have a winning formula for clinicians’ acceptance of LAVA for private practice.

LAB NOTES: How does a dentist choose between using Lava versus a PFM? Are there instances where using Lava makes sense over other all ceramic crowns such as In-Ceram or Empress?

In my practice I have developed a hierarchy that differentiates the selection of a ceramic system based on:

1. Tooth position in terms of anterior and posterior location
2. The amount of remaining tooth structure.

For anterior tooth restorations I typically utilize a minimally invasive approach using veneer type restorations. My material of choice for 13 years has been adhesively cemented Empress ceramic restorations. You just can’t beat the exceptional esthetics of the highly translucent Empress ceramics. If I have a dark tooth substrate, then I use a more opaque ceramic substructure material like Lava zirconia, In-Ceram Alumina or Procera alumina to block out discolored tooth structure.

For posterior single crowns or 3- and 4-unit bridges I nearly always use Lava zirconia. The zirconia ceramic provides the strength and fracture toughness to resist the higher occlusal stresses in the posterior region. The high strength ceramic also allows conventional cementation.

Another significant advantage of the shaded Lava substructure becomes evident if I have not sufficiently reduced the occlusal aspect of my tooth preparation. During the occlusal adjustment as one grinds down to expose the substructure ceramic, it is not a problem with the shaded Lava substructure:

1. First, the shade of the substructure is dentin colored allowing maintenance of excellent esthetics.
2. Second, because of the fine grain size of the polycrystalline zirconia the substructure can be polished to an extremely smooth surface that is kind to the antagonist tooth structure.

Caveat: On the other hand, upon exposure of the opaque porcelain on a pfm restoration, a very rough and abrasive surface is created which also highly anesthetic.

LAB NOTES: We have seen numerous promotions lately about another all-ceramic product, Wolceram. How is Wolceram different from LAVA?

First, let’s be clear on what this intensely advertised system is. Wolceram is not a new ceramic; it is merely a CAD/CAM method of fabricating In-Ceram Alumina substructures. Because of the slip-cast fabrication technology In-Ceram remains the most accurately fitting all-ceramic restoration available in dentistry. The system also has the advantage of accurately reproducing all types of margin configurations including beveled margins.

The disadvantage of the Wolceram In-Ceram Alumina system is that alumina suffers significant degradation in strength in the presence of moisture, which of course is a big problem in the mouth. We found in an in vitro study evaluating flexural strength that In-Ceram alumina went from 535 MPa when stored in air and after one week of water storage dropped to 370 Mpa While this may be acceptable strength for single units, it may be insufficient strength for bridgework. In-Ceram Zirconia stayed at essentially the same at about 665 MPa and Lava zirconia remained unchanged at 1050 MPa.

LAB NOTES: If a dentist has had problems with all ceramic crowns in the past (such as breakage or sensitivity), what is it about Lava that should give him or her confidence in prescribing it?

We have already discussed how zirconia is a major advancement in high-strength all-ceramic systems that approach metal ceramics. Clinical studies evaluating zirconia substructures for 3 and 4-unit posterior bridges have found very high success rates at five-years. I think dentists can feel very comfortable using the Lava system for crowns or bridges anywhere in the mouth. Being able to use conventional cementation should significantly reduce the incidence of sensitivity for practitioners.

LAB NOTES: I understand you have started your own teaching institute, the Pacific Dental Institute. Can you tell us about the institute and the curriculums offered?

In my many years of teaching dental students, graduate specialty students and dentists in continuing education courses, I came to realize that dentists learn best by taking the didactic concepts and then applying them in hands-on courses. We all learn best by doing. That is why the curriculums we have developed at PDI primarily involve hands-on courses and live patient treatment courses.

By experimenting and working with the materials on typodonts in a relaxed environment the doctors in our courses can gain the confidence to go back to their practices on Monday morning and feel comfortable using these techniques on their patients.

Treatment planning after learning the materials and techniques is a critical part of the education process and probably the most important aspect of what the doctors take home with them. At the same time, I have also observed that dental schools are not graduating dentists that have clinical competency in posterior direct composites, porcelain veneers, adhesive ceramic onlays, various all-ceramic fixed prosthodontic systems, esthetic analysis and smile design. This has created a great demand by both recent dental school graduates AND experienced clinicians.

We also conduct one-year implant continuums in conjunction with implant surgeons. Dentists bring their patients in for group treatment planning and then our surgeons perform the grafting surgeries and implant placement. We then guide the doctors through soft-tissue site development with provisional restorations, impression procedures, prosthesis design and delivery.

There is a tremendous amount of cross learning that goes on between the doctors in the course because everyone has different types of patients needing single tooth replacement; partially edentulous patients on up to completely edentulous patients. Again, treatment planning is so critical in implant therapy and probably the most important aspect of what the doctors learn in our courses.

1. We also have courses on
2. Digital intraoral photography and imaging
3. Conventional and digital shade selection and communication
4. Team courses with doctors and ceramists matching single tooth restorations
5. Converting a dental practice to a digital dental office

John A. Sorensen, D.M.D., Ph.D., FACP
Director
Pacific Dental Institute
drjohn@pacdent.com

Bio
As Founder and Director of Pacific Dental Institute in Portland, Oregon, Dr. Sorensen is engaged in a practice limited to prosthodontics, currently conducting five clinical trials on all-ceramic fixed prosthodontic systems as well as in vitro materials testing, and providing hands-on continuing education programs in fixed prosthodontics and implant dentistry.  Previously he was The Oregon Dental Association Centennial Professor of Restorative Dentistry and Director of the Dental Clinical Research Center at Oregon Health Sciences University.  Prior to that he was Associate Professor and Director of the Advanced Prosthodontics Specialty Program at the University of California, Los Angeles.  Sorensen is a diplomate of the American Board of Prosthodontics.  Dr. Sorensen has published over 65 research articles and chapters, and over 110 research abstracts.   He has given over 100 invited lectures in 26 countries.

Additional info
After a 19-year career in academics Dr. Sorensen established the Pacific Dental Institute in 2003.  The goal of Pacific Dental Institute is to help dentistry achieve clinical excellence.  From his many years in dental education Dr. Sorensen understands that dentists learn best when they actually perform the procedures rather than passively watch a lecture.  The institute offers an extensive array of small group hands-on courses and live patient treatment courses the help dentists master advanced prosthodontic, operative and esthetic procedures.  Another objective of the institute is to help dentists to understand materials, technique rationale and above all, master treatment planning.

PDI has extensive research facilities including the Applied Material Testing Lab and a Clinical Trials Division which is currently conducting clinical studies on a number of all-ceramic bridge systems and ceramic implant abutments.