January 2013, Volume 9, Issue 1
Published by AEGIS Communications
Incorporating CAD/CAM into the Operatory
When it makes financial sense, this technology can transform dental practices.
Dentists tend to develop a comfort zone within a number of procedures they perform routinely. These may be the procedures they learned in school or post-graduation continuing education classes. For some creatures of habit, the “routine” procedures of drill-and-fill and an occasional crown satisfy their desired goals. For others, the mundane routine of a dental practice is not enough; they yearn to learn new procedures and engage in new techniques that keep dentistry exciting. New procedures and methods can be intimidating at first, recalling the feelings experienced in dental school when removing a tooth or cutting a crown preparation for the first time. As with so many other endeavors, proper training and repetition can create proficiency.
In terms of technology, incorporating CAD/CAM dentistry (eg, CEREC®, Sirona Dental Systems LLC, www.sirona.com; E4D, D4D Technologies, www.e4dsky.com) probably has the most significant impact on a dental practice. Not only does it affect the way restorative dentistry is performed, but it also has an impact on patients, practice marketing, and the practice’s financial bottom line.
In the world of CAD/CAM dentistry, inexperienced dentists may feel overwhelmed just thinking of all the changes that must be made in the practice when considering adopting CAD/CAM. It is human nature to feel reluctant to change, especially when the change has a high price tag. CAD/CAM dentistry is a significant investment and the thought of this expensive piece of technology becoming a dormant, dust-collecting object can be frightening (and it does happen for some). However, the thought of delivering complete dentistry in one visit that can transform the patient’s experience and mindset from a negative one to an extremely positive one is very exciting. Patients are not often excited about having an impression taken and wearing a temporary for 2 weeks, and then having to return. Once a patient has experienced one-visit dentistry, they are hooked and will only seek out offices equipped to satisfy their need for that type of dentistry in the future.
A Systematic Approach
As with any new endeavor, a systematic approach can ease some of the tension experienced when finally committing to CAD/CAM dentistry. The first step is deciding on the system that seems best for the individual practice—such as either the CEREC system or the E4D system. It would be prudent to have each system brought into the office and “test-drive” the equipment on a willing patient or staff member. (The representative will provide needed assistance.) This may require several restorations until a decision can be made. Both systems can produce the same end-result; their differences lie in the manner in which it is accomplished.
CAD/CAM systems are composed of the acquisition unit and the milling unit. The acquisition unit can move room to room, whereas the milling unit should be located in an area in the office where it can be put on display. It is exciting for patients to watch their own crown being milled. Other patients in the office will also be interested in watching the milling process. Exposing the patient base to this high-tech equipment creates a perception that the office is on the “the leading edge.” Patients have a tendency to brag when their dentists offer new procedures; and certainly telling friends that they had a new crown made in one visit is a highly effective marketing tool.
External marketing can also pay large dividends. Advertising in the local newspaper with before-and-after photographs emphasizing that the dental work is completed in a single visit will create major interest in the marketplace.
Scheduling is the next area to consider, because as with any new procedure, the learning curve can be steep and the time allotted for it in the schedule can become problematic. Simply doubling the normal time allowed for a single-crown appointment may serve as a guide for the first few restorations. As the clinician and assistant perform more procedures, the scheduling time can be adjusted. Keep in mind that the normal second insertion appointment is no longer scheduled so that time now becomes available.
Clinical Procedural Changes
Unlike in the dental laboratory, where the technician can “fudge” inconsistencies with a preparation, the computer software doesn’t have as much flexibility. One of the most common complaints from dental technicians is insufficient occlusal reduction, especially toward the lingual aspect of the second molar preparations. In the case of a ceramo-metal crown, the technician can either create a reduction coping that the clinician would use to modify the preparation at the insertion appointment or fabricate the crown with a metal occlusal island. The clinician does not have that ability to compensate for an under-reduction problem when fabricating CAD/CAM restorations.
The preparation must be corrected and re-scanned with new images. Otherwise, the restoration will have an insufficient ceramic thickness and be doomed for failure. Therefore, the preparations need to be adapted to what the computer is designed to see and mill. There are certain parameters that are put into the design program that the clinician selects. One of the parameters includes the minimal thickness of the crown. When the computer knows that the final restoration lacks this thickness, it will notify the dentist before moving into the milling phase. Flat margins with a 90° exit angle are easier to scan then a reverse or trough margin. Feather-edge margins are not only difficult to read, but they are also difficult to mill. Sharp line angles, undercuts, unclear margins, or insufficient interproximal reduction can all be potential problems in the scanning, design, and milling process. Once these concerns are recognized during the preparation phase, the whole process is streamlined. Taking a cookbook approach to preparation design will facilitate the fabrication process.
For the novice, scanning the preparation for the different digital views required might take the same amount of time that is needed for a fast-setting triple-tray impression. Where the procedure can become time-consuming is the actual step-by-step crown design created on the computer. Like anything new, the more this step is practiced, the more proficient the clinician will become. Usually a basic instructional course is included with the purchase of a CAD/CAM unit. Once the practitioner has had time to digest the basics, there are many avenues of advanced techniques to pursue in seminars, study groups, or online forums.
The time to fabricate the restoration will also depend on the type of restorative material that is used. For completing a non-stained, non-oven–glazed, leucite-reinforced ceramic restoration, the patient’s time can remain in the same scheduling column. It becomes a drill, scan, design, mill, and insert procedure. If the clinician desires to add external staining and possibly glazing, then “oven time”—an additional 10 to 15 minutes—must be incorporated into the schedule, either in the same schedule column or in a separate column. This step can also be delegated to the trained chairside assistant. If lithium disilicate (IPS® e.max, Ivoclar Vivadent, www.ivoclarvivadent.com) is the restorative material of choice, then 20 minutes of oven time and 5 minutes of cooling time must be factored into the schedule.
It is not uncommon for new CAD/CAM owners to decide against incorporating a porcelain oven into the office, saying they do not want to become a laboratory technician. If the practice is planning to restrict the restorative materials to either the all-resin Paradigm™ MZ100 (3M ESPE, www.3mespe.com) or combined nanoceramic particle in a cured resin matrix (Lava™ Ultimate Restorative, 3M ESPE), a porcelain oven will not be necessary.
On the other hand, if the clinician wants to offer IPS e.max ceramic restorations, a porcelain oven is necessary. A porcelain oven will also allow the practitioner to bring ceramic restorations to a higher level of esthetics by using chairside staining techniques. There are continuing education classes that teach advanced staining techniques, or the clinician can spend time with a local laboratory technician and watch how to revitalize restorations by incorporating staining.
Another advantage of having a porcelain oven in the office is economic. If, for example, a single all-ceramic crown for a maxillary central incisor is needed and the shade is off, it must be returned to the laboratory and the patient must return for a second appointment. Each additional patient visit and laboratory correction further erodes the profit margin—possibly to the point that it goes negative; it also increases the patient’s disappointment and inconvenience. However, with a porcelain-staining oven, the clinician can correct the shade during the first appointment, thus preserving the profit margin and delighting the patient. A porcelain oven is a practice asset that clinicians should learn to use.
There are other pieces of equipment that will aid the clinician in isolation, preparation, and cementation. The success of the restoration comes down to the ability of the acquisition unit to capture the preparation detail and offer a clear view of the margin. Using a diode laser unit easily exposes the margin and is less time-consuming than packing retraction cord. There are also LED light retraction devices that help keep the tongue and cheek clear during the preparation and scanning steps. Flat-end diamond burs are also necessary for the correct margin design. These are just a few extra items that can be added to the clinician’s armamentarium to help simplify the process.
The Other Side of the Coin
Before jumping on the CAD/CAM wagon and thinking that eliminating the laboratory bill will make this a high-tech profit center, it is important to take a step back and assess all the costs. Once the unit is purchased, a service contract is highly recommended and that is at an additional cost. Also to consider is the cost of the supplies necessary to mill the ceramic blocks, including diamond burs, milling liquid, polishing wheels, and the blocks themselves. Some of these expenses are fixed and some are variable. The fixed expenses—ie, the monthly service plan and lease payment—remain the same no matter how many units are produced in a month. The variable expenses parallel the number of restorations made, so the cost of the fixed expenses decreases as the number of restorations increases. It is not enough to justify the expense based on a desire to eliminate the laboratory bill; care should be taken to calculate the cost differential between the monthly laboratory bill and the fixed and variable expenses of using a CAD/CAM unit to determine whether the purchase makes financial sense.
CAD/CAM dentistry is exciting and is the future of dentistry. Clinicians should learn about it, engage it, and see for themselves the transformation not only of their office but also the patients, which happens in a short period of time.
About the Author
Gregg A. Helvey, DDS
Adjunct Associate Professor
Virginia Commonwealth University School of Dentistry