Dr. Rella Christensen to Explore the Cutting Edge in Québec

Richard Gawel


This May, dental professionals from around the world will take part in the 47th Journées Dentaires Internationales du Québec. Presented by the Ordre des Dentistes du Quebec, the 3-day convention will provide a host of seminars and hands-on courses led by top dental experts at the Palais des Congrés de Montréal.

For example, TRAC Research’s Rella Christensen, RDH, PhD, will present “New Data—On Critical Dental Questions 2017” on Friday, May 26. Available for 6 continuing education credits, the day-long lecture will review the latest information from clinical testing about today’s cutting-edge technologies and techniques. Dr. Christensen recently gave us a preview of her presentation.

Q: What are the advantages of translucent zirconia?

A: The main advantage of translucent zirconia is its translucence. This allows a more lifelike appearance of zirconia in the aesthetic zone. A primary question today is if translucent zirconia can and should replace Ivoclar Vivadent’s e.max lithium disilicate. No one has the answer yet. Lithium disilicate has the advantage of historical perspective. Our clinical studies show that e.max can be durable when tooth preparations allow adequate thickness. Right now, our work has one year of clinical data on translucent zirconia.

Q: What are the disadvantages of translucent zirconia?

A: Two big disadvantages are its unknown clinical performance throughout time since it is so new, and its ability to match opposing and adjacent dentition reliably. It turns out that zirconia is difficult to color and it tends to have a bright white opacity that makes it stand out in the oral cavity, regardless of the improvement in translucence. In addition, zirconia finishing is an art rather than a science right now. When polished, the material can quite quickly take on an iridescent and gray cast, and it is difficult to impossible to go backwards and undo this problem once it has occurred during finishing. If the technician decides to glaze, we found that glazes begin to wear off within a few months and can leave a rough surface that patients can feel with their tongue and can wear opposing dentition. Right now there is a scramble to find ways to overcome these problems. 

Q: Are there other options to translucent zirconia that dentists should consider, and when would they be indicated? 

A: Dentists can also consider lithium disilicate and PFM for durability and aesthetics. Our studies show that the original full-strength full-contour zirconia (BruxZir) and PFM are still indicated in the following clinical situations:

  • Molar restorations;
  • Posterior multi-unit restorations;
  • Patients with abusive occlusion;
  • Patients with a high-risk lifestyle, such as athletes;
  • Where future endodontic needs are anticipated.

Q: What are current alternatives to “drill and fill”?

A: Today, the most discussed and controversial option to “drill and fill” is silver diamine fluoride (SDF) disinfection. The major objection to the procedure is it causes demineralized tooth structure to darken to a brown or black color. Although it does not discolor healthy tooth structure, the discoloration of demineralized tooth structure is permanent. However, SDF use throughout many years in Japan has been shown to delay, and possibly arrest, dental caries. At this point in time, dentistry does not have any methods or chemicals that stop dental caries and maintain health over the lifetime of the patient without the patient’s control of diet, oral hygiene, and saliva flow. SDF is under intensive study and gaining use by pediatric, geriatric, and humanitarian dentists.

Q: Can teeth be remineralized today using various techniques or products?

A: Although mineralization can be demonstrated in vitro in the laboratory, we have not been able to show a significant and sustained affect in vivo. “Remineralization” is an interesting word because it implies different things to different people. We find that patients think it means that their teeth will be returned to their former perfect condition if they use products dispensed by clinicians such as 5,000 ppm dentifrice, amorphous calcium phosphate, xylitol products, etc. But as clinicians know, this is not possible. At our lab, we use the term mineralization rather than remineralization to indicate that ions can be exchanged, but the tooth does not return to its original chemical and physical state. 

Q: How do you expect mineralization to evolve in the years ahead?

A: Based on history, progress will probably be slow and sustained. Everyone would like to be able to truly restore the tooth and/or prevent destruction in the first place. Some of the brightest minds in dentistry have tried to address this question for years, but we still appear to have a lot to learn.

Q: What are the advantages of laser use in general dentistry today?

A: Simple soft-tissue surgeries by general dentists have created a niche for lasers. These include troughing before impressions to control bleeding and gain access to margins, crown lengthening, implant access, operculum tissue removal, biopsies, etc. The ability of lasers to control bleeding during cutting has been a useful characteristic in all of these situations. 

Q: What are some of the latest treatments that lasers are being used to provide?

A: Probably the most exciting area for lasers is hard-tissue cutting. Lasers are being developed that are now more precise and more rapid in their ability to cut enamel and dentin. I am thinking of Convergent Dental’s Solea CO2 laser. Another area where progress has been made is the elimination of the CO2 laser articulated arm and very precise cutting tips and smaller handpiece. I am thinking here of the Light Scalpel CO2 laser. 

Q: Where do you see laser technology going next?

A: Many dentists would like to use a laser in periodontal treatment to kill microbes. We have not yet found a laser of any wavelength that does a credible job clinically in this area. The killing of certain microbes can be demonstrated in the laboratory, but our work shows clearly that the transition to clinical treatment does not give the same results microbiologically. However, this does not mean that methods will not be found in the future to accomplish this goal. 

Q: Are there other exciting treatments or technologies emerging?

A: Certainly the area of digital impressions is a technology on the cusp of bursting into general use. We are seeking imaging technology that will allow the clinician to see through the soft tissue and blood to image margins. New ultrasonic equipment for endodontic canal cleaning has also become available that could greatly improve this procedure. The area of dental implants is also moving forward rapidly with new products and more general dentists performing the surgical procedures as well as the restorative procedures. Control of the oral environment in an attempt to control dental caries is of high interest worldwide and has some interesting ideas under development. 

Dr. Christensen currently leads TRAC Research Laboratory, which is devoted to clinical research in oral microbiology and dental restorative concepts. TRAC Research is part of the non-profit educational Clinicians Report Foundation (formerly CRA) which she directed for 27 years. Throughout her career she has taught at the under- and post-graduate levels, authored many research abstracts and reports, and received numerous honors. She has performed research within the practices of hundreds of dentists and their teams seeking best patient treatments. She can be reached via email at rella@tracresearch.org.

Related Articles

Focus On: Caries Arrest

Focus On: Silver Diamine Fluoride

Focus On: Translucent Zirconia