NewsletterBy James F. Simon, DDS, Med | Mojdeh Dehghan, DDS
Today’s dental students are extremely technologically literate given that they have grown up using computers for communication, education, research, and games. They are extremely interested in new technology and are eager to learn how to use it now and in the future in their dental practices. Because this technology has been proven to be accurate and effective, it is imperative that the dental schools teach it to students to keep them current with what is developing outside of the academic environment. Dental students are capable of delivering demanding clinical tasks after appropriate training. To achieve a clinically adequate performance, it is necessary to consider the basic rules and technology associated with ceramic restorations.1 Basic principles are something that can be and should be taught in the dental school environment so that the future practitioner, hopefully, does not need to learn it by trial and error in their practice.
CEREC® (Sirona Dental Systems, www.sirona.com) is an acronym for “Ceramic Reconstruction” and is one of the CAD/CAM systems available for the practicing dentist to use as part of his/her practice.2 As one of the two available chairside units, it has been in use since 1987. When it was first introduced, there were many questions about the fit, anatomy, and difficulty of design for the restoration. Those issues have been addressed in each improvement of the hardware and the software. There should now be little criticism of the fit or longevity of this type of restoration if the basic principles of proper preparation and design are followed.3-7
The University of Tennessee College of Dentistry was one of the first dental schools in the United States to embrace this technology and make it part of the undergraduate curriculum. The dental school was given five CEREC® 2 units in 2000, and purchased a CEREC 3 unit in 2001. This technology has been part of the undergraduate curriculum since that time. In 2011, because of a Gifting Program established by Sirona Dental Systems and the support of the Dean, the dental school was able to acquire another ten CEREC® 3 units. This has allowed the more complete integration of this technology into the curriculum starting with the first year and continuing until graduation.
CEREC technology is here to stay. Presently, PubMed lists 432 research papers that have been published on this one technological advancement. Presently, there are over 12,000 CEREC units in the United States and over 34,000 units in use worldwide; this does not take into account the units that the chairside competitor E4D® (D4D Technologies, www.e4dsky.com) has sold.
Thirty-seven dental schools have one or more units in use, and eight dental assisting schools are teaching imaging and design to their students. Veterans’ Administration Hospital Clinics, US military bases, and the Indian Health Clinics are also using this technology to deliver one-appointment, quality care for their patients. For them, the ability to deliver an intra- or extra-coronal restoration in one appointment—something that normally takes two appointments—is extremely important because of special time constraints of their patient population, as many travel for miles or may be shipped out before the restoration can return from the laboratory.
With its purchase in 2001, the CEREC technology has been integrated into the curriculum at different stages of the student’s education. Since 2008 (the first time laptops were required for all the students), all of the first-year students have had the CEREC software loaded on their laptops and have been introduced to its manipulation as part of the Dental Morphology Course. They can easily change the contours of the teeth to see what happens and can learn what this means for the occlusion and the anatomy. It is an enlightening experience for them to shift from working with wax to working with a 3D computer image.
Some of the clinical faculty had commented that the students did not know the steps necessary to deliver a crown when they got to the clinic because it had been cost-prohibitive to have the laboratory fabricate a crown for every student in pre-clinic to use for practice. Sirona loaned the dental school a second CEREC unit for the pre-clinical laboratory. This allowed for the milling of an anterior and posterior tooth from a previously prepared typodont tooth at a much-reduced cost—the cost of the block. Each second-year student was then able in the preclinical lab to go through the steps to deliver and stain and glaze two crowns on the typodont prior to going into the clinic. This year, with four additional units in the pre-clinical laboratory for student use, every second year student has prepared, powdered, imaged, designed, and milled an all-ceramic crown for a bicuspid and has prepared an MOD onlay for a molar that they will image, design, mill, and bond as part of their third-year Aesthetic Dentistry Course (Figure 1).
In the past, the senior dental students were offered a Senior CEREC Elective that they could sign up for and learn more about CEREC technology. This year, with the additional three units in the clinic, the students were able to have more hands-on experience with the machines and approximately a dozen crowns have been constructed, stained and glazed, and delivered to their patients in the clinic by these students. This has been a cost savings to the University because there is no lab bill for the construction of these restorations, and the quality of the crowns has been assured because of the complete control of the faculty and the student.
Since 2001, a separate area in the student clinic was designated for Aesthetic Dentistry. This clinical area allows for closer supervision of the students by the faculty when performing more complicated esthetic treatments. At the present time, this is the area where all CEREC restorations have been prepared, fabricated, and delivered. Since its beginning, this clinic has been averaging 75 to 85 CEREC restorations in addition to veneer cases, complex anterior esthetic issues, and nightguard construction. Most of these esthetic clinic restorations have been inlay and onlay restoration, as this technology lends itself perfectly to the school’s goal of conservation of tooth structure whenever possible without the constraints dictated by some outside influences.
Because many dental students are not capable of completing a restoration in one appointment, the protocol has been for the student to do the preparation (Figure 2), make an impression, and temporize the tooth during the clinic session. The restoration is then constructed off the model when the student or the instructor has more time to design and fabricate the restoration without the pressure of time (Figure 3 and Figure 4). The patient then returns for the delivery appointment where the restoration is bonded to place (Figure 5).
With the extra units in the clinic and the additional training of the students and faculty, more restorations should be fabricated in-house. This will help reduce the turnaround time from the laboratory, reduce the cost to the University, and will be a learning experience for the students as they can see their preparations magnified. This will give them a better understanding of the preparation criteria and help them to determine how they will need to make the preparations better in the future. This close evaluation should lead to better preparations in all areas of the clinic. An instructor will approve the design before the restoration is milled which will give additional time to point out the areas of adequate and inadequate preparation and design improvements.
CEREC units have also been installed in the AEGD clinic and in the Graduate Prosthodontic Clinic. All residents and faculty in these two areas have been trained to use the machine. This allows for both patient care and the potential for some research projects for these graduate students.
Dental students do not have the same expertise and speed as a dentist who has been in practice for years. That is the reason that the restorations will be constructed off models rather than doing it directly on the patient, as is recommended. Not every dental student who graduates will go into an office that has CAD/CAM dentistry available; however, it should be the responsibility of dental schools to introduce the student to proven, developing technology. The University of Tennessee College of Dentistry has been one of the leaders in dental education in incorporating technology into the curriculum because of the support and encouragement of the past and present administrations.
Dr. Simon is a consultant for Sirona Dental Systems.
1. Wrbas KT, Hein N, Schirrmeister JF, et al. Two-year clinical evaluation of Cerec 3D ceramic inlays inserted by undergraduate dental students. Quintessence Int. 2007;38(7):575-581.
2. Mormann WH, ed. State of the Art of CAD/CAM Restorations: 20 Years of CEREC. Chicago, IL: Quintessence Publishing; 2006.
3. Fasbinder D. Clinical performance of chairside CAD/CAM restorations. J Am Dent Assoc. 2006;137:22S-31S.
4. Simon JF, Schmidt B. New CAD/CAM system combines simplicity with sophistication. Contemporary Esthetics and Restorative Practice. 2003;7(9 suppl):15-22.
5. Ural C, Burgaz Y, Sarac D. In vitro evaluation of marginal adaptation in five ceramic restoration fabricating techniques. Quintessence Int. 2010;41(7):585-590.
6. Rekow ED. Dental CAD/CAM systems. A 20 year success story. J Am Dent Assoc. 2006;137(suppl 1):5S-6S.
7. Bernhart J, Brauning A, Altenburger MJ, Wrbas KT. Cerec3D endocrowns—two-year clinical examination of CAD/CAM crowns for restoring endodontically treated molars. Int J Comput Dent. 2010;13(2):141-154.
James F. Simon, DDS, MEd
Director of Division of Esthetic Dentistry
Department of Restorative Dentistry
University of Tennessee College of Dentistry
Memphis, Tennessee
Mojdeh Dehghan, DDS
Associate Professor
Department of Restorative Dentistry
University of Tennessee College of Dentistry
Memphis, Tennessee
