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Versatile CAD/CAM Digital Impression Technology

  • March 1, 2010
  • 16 minutes read
  • 15 years ago

We must accept the fact that the world around us is literally changing daily. Our profession is no different than the rest of the world; change is rapid and inevitable (like death and taxes) in dentistry! For long-term survival it is important that we learn to adapt to new technologies and maximize what they have to offer.

It is becoming increasingly evident that digital technologies are here to stay in dentistry. Specifically, digital CAD/CAM technologies are proven to be beneficial for patients and dentists, bringing the possibility of making chairside and laboratory assisted restorations to every dental practice. 
Being fascinated with technology and efficiencies, the prospect of utilizing digital impression technologies to speed up restoration fabrication and to improve overall communication with dental laboratories was very appealing to me. About a year ago, I upgraded to CEREC Bluecam (Sirona Dental Systems) to achieve both chairside and laboratory digital restorations. The following case presentations will demonstrate the excellent results that I found to be typical of CEREC with Bluecam technology, and the clinical processes involved.

 

CASE REPORT 1
Diagnosis and Treatment Plan
David, a mid-30s male, presented to our office as an emergency patient for a limited exam. His chief complaint was cold sensitivity with lingering throbbing, and a “broken piece of tooth” in the upper right area. He was interested in saving the teeth and wanted to get back on a regular dental schedule. However, due to his hectic work schedule, time was a major consideration.

Figure 1. Preoperative bitewing radiograph showing extensive decay in the distal aspects of tooth No. 3.

 Figure 2. Preoperative photo demonstrating the failing amalgam restorations.

Limited radiographic (Figure 1) and clinical examination revealed decay into/near the pulp on tooth No. 3 extending subgingivally, and failing amalgam restorations in teeth Nos. 2 and 4 with poor broken down margins (Figure 2).

The limited treatment plan focused on addressing the chief complaint: pain in the upper right area. The patient opted for complete endodontic therapy, a full-coverage restoration on tooth No. 3, and direct composite resin restorations for teeth Nos. 2 and 4. This would be accomplished in a single visit due to his hectic work schedule. The patient was given a prescription for PenVK antibiotic and provided a small deposit to reserve his 2.5-hour appointment a few days later.
When completing multiple teeth in a single visit, whether direct or indirect, it is important to create a “plan of attack” to maximize efficiency. In order to give complete access to finish and polish the interproximal contacts, it was determined to complete the direct restorations first. The crown would then be prepared and fabricated chairside utilizing the CEREC Bluecam, and during the milling process, endodontic treatment would be completed. The final glazed (in-office) restoration would then be delivered.

 

CLINICAL TREATMENT PROCEDURES
The patient was given anesthetic infiltration (Septocaine [Septodont]) to achieve profound anesthesia, and the upper right quadrant was isolated using the Isolite system (Isolite Systems) (Figure 3). The failing amalgam restorations and recurrent caries were removed and the preparations were finalized for Class II direct composite resin restorations. To assist in forming interproximal contacts and proper contours, V-Rings (Triodent) and wedges were placed on both teeth simultaneously (Figure 4). The direct composite resin restorations (Gradia Direct [GC America]) were finalized using an incremental placement technique (Figure 5). Full attention could now be given to tooth No. 3.

Figure 3. Isolation, excellent retraction of tongue/cheek, along with simultaneous suction and light was achieved using Isolite (Isolite Systems).

Figure 4. V-Ring (Triodont) matrix system was used to provide proper contour and form for the Class II composite resin restorations.

Figure 5. Completed Class II direct composite resin restorations (Gradia Direct [GC America]) in teeth Nos. 2 and 4.

Figure 6. 2.0-mm depth cuts were created with a depth reduction bur (Occlusal Router [Meisenger]) to ensure adequate reduction for the final all-ceramic restoration.

Figure 7. A polishing disc (Super-Snap Disc [Shofu]) was utilized to shape and polish interproximal contours.

Figure 8. Caries detecting dye (Seek [Ultradent Products]) was placed on tooth to confirm removal of decay.

Figure 9. Final crown preparation, tooth No. 3. Note the decay extending into palatal aspect of pulp as expected from radiograph.

Figure 10. Using magnification provided by a dental microscope (Global G6 [Global Surgical]), 4 canals were located and access was achieved.

Figure 11. The canals were shaped with rotary nickel titanium instrumentation and obturation was completed. Tooth was made ready for a bonded restoration.

Figure 12. Access was filled with resin cement/buildup material (Anchor [Apex Dental]).

Figure 13. Retraction cord is removed and facilitates easy cement cleanup.

Figure 14. Occlusal view of finished all-ceramic restoration (IPS Empress CAD block [Ivoclar Vivadent]). Note the excellent aesthetics and contours that were achieved in single visit using the CEREC Bluecam (Sirona Dental Systems).

To ensure a uniform and proper occlusal reduction, a 2.0 mm depth reduction bur (Occlusal Router [Meisenger]) was utilized for all-ceramic crown preps (Figure 6). After interproximal reduction was completed (856-016 Coarse [Microcopy Disposable]), a diamond-polishing disc (Super-Snap Disc [Shofu]) was used to smooth any imperfections in the adjacent restorations (Figure 7). At this point, the rough crown preparation was completed with a 856-016 Coarse, and the tooth was inspected for residual decay with caries detecting dye (Seek [Ultradent Products]) (Figure 8). Removal of dye-stained dentin led to pulpal exposure as was predicted based upon evidence found in the radiographic examination. The preparation was finalized with a fine grit diamond bur (856-021 Fine [Microcopy Disposable]) and tissue retraction was accomplished using dental cord (Ultrapak [Ultradent Products]) to allow full visualization of margins.

Once the preparation was completed (Figure 9), the digital impression images were captured quickly and efficiently intraorally with CEREC Bluecam. The restoration was designed chairside and the IPS Empress CAD block (Ivoclar Vivadent) was sent to the in-office CEREC MCXL milling unit for fabrication.
During the milling process, the upper right was isolated with a rubber dam and straight line access was created. Using magnification provided by a dental microscope (Global G6 [Global Surgical]), 4 canals were located and shaped with rotary nickel titanium instrumentation (GT Series X [DENTSPLY Tulsa Dental]) (Figure 10). At this time the milled restoration was retrieved and tried in the mouth to verify marginal integrity. To maximize efficiency, the milled restoration (Empress) was stained and glazed; while all 4 canals were soaked, cleansed, and obturation completed (Figure 11). The buildup and final restoration delivery were completed in a single step utilizing resin buildup/cement (Anchor [Apex Dental]) (Figures 12 and 13).
The technique, as described above, resulted in a single, efficient appointment that provided the patient with an excellent and highly aesthetic outcome (Figure 14). This addressed his chief complaint and built confidence in our practice.

 

CASE REPORT No. 2
Diagnosis and Treatment Plan
Gerald, a mid-40s male, came into our office for his hygiene recare appointment. This occurred about 12 months after completing endodontic treatment on his mandibular right first molar (tooth No. 30) at the specialist’s office. Typical of this scenario, the temporary restoration was now well beyond the intended lifespan and the tooth had recurrent caries (Figure 15). Luckily, the tooth was asymptomatic. Having recently accepted a new job with dental benefits, he was now ready to proceed with the final full-coverage restoration that was recommended to be done immediately after finishing the endodontic treatment.

Figure 15. Preoperative view tooth No. 30 showing the failing temporary restoration as it appeared many months after endodontic treatment.

The treatment plan was straightforward in this situation. We decided to place a lithium disilicate (all-ceramic) crown (e.max [Ivoclar Vivadent]). For those not familiar, lithium disilicate is an extremely strong and durable full-contour monolithic ceramic restoration. For comparison purposes, traditional ceramics have a strength around 100 to 120 mPA, compared to 360 to 400 mPA for e.max. This strength allows lithium disilicate restorations to be either resin bonded or traditionally cemented. It also has the aesthetics and vitality you would expect from an all-ceramic. In my hands, e.max has been shown to be a successful posterior alternative to traditional PFM or zirconia-based all-ceramic restorations when indicated.

This case also provided a great opportunity to utilize a newly available and completely digital workflow system called CEREC Connect (Sirona Dental) for fabrication of the restoration via collaboration between the dental office and dental laboratory.

 

Technological Implications

Leslie Silverman, DDS
For many patients, taking a tooth impression often feels messy, claustrophobic, and quite literally leaves a bad taste in their mouth. The CEREC AC digital technology creates an optical image that avoids the usual messiness of the conventional process and results in a far more consistently accurate replication of a patient’s dentin. With little more effort than the wave of a wand, you are able to capture images that will greatly improve the marginal integrity, occlusion and contacts of the restoration by virtue of the fact that you are fabricating the restoration directly from an exact digital image of the tooth rather than from a less precise manual impression. Truly a win-win for both dentist and patient!

The process is simple: The dentist lightly applies an optical aerosol spray to the teeth and then activates the Bluecam camera in live capture mode. The dentist then scans the camera over the patient’s teeth while it automatically snaps digital images (there’s no longer the need to simultaneously manipulate a foot pedal). The camera’s LED technology produces highly detailed digital impressions, operates twice as fast as with older infrared technology, enables shorter acquisition times (less than 2 minutes for a full arch), and includes a built-in shake control which helps to stabilize the camera to ensure consistently clear and accurate results. Resulting digital impressions have numerous advantages over conventional impressions:

• The dentist can review images in real time, from angles and perspectives that were largely inaccessible prior to digital imagery
• The laboratory can receive your case immediately (through the internet) and can provide feedback while the patient is still in the office
• Improved patient experience may lead to increased patient referrals.
Once the digital impression is complete, the dentist has 2 options:

 

SINGLE-VISIT DESIGN
Mill and place the restoration in one visit. Some advantages of the single visit option include reduction of chair time, elimination of the need for a temporary and an additional injection, and added control over the final restoration. With sufficient practice and training, the design phase can be as short as 2 to 3 minutes and with the upgraded MC XL milling unit the mill speed can be as quick as 4 to 6 minutes (depending on partial or full coverage).

MULTIVISIT DESIGN
Upload the image, using CEREC Connect, to a dental laboratory equipped with an inLab milling unit to create and complete the restoration. (This can be done in most any material, including gold.)

As with any new process or technology introduction, CAD/CAM and digital impression systems have a learning curve and will likely take some time to master. Much of your success in using these systems will depend on the level of preparation and competency associated with the handling of the software and other equipment involved.

 

Clinical and Laboratory Procedures
Treatment began with the removal of the remaining temporary restoration and any recurrent caries (Figure 16), and confirming long-term restorability. Once I was confident that the tooth could be restored, I placed a bonded buildup, finalized the preparation according to material requirements, and completed the tissue retraction with a combination of diode laser (Picasso [AMD Lasers]) and cord (Figure 17) to allow complete visualization of the margin.

Where things change from traditional techniques is with the integration of CEREC digital impressions. Instead of taking a vinyl polysiloxane impression and mailing it to the dental laboratory, a few quick digital images are acquired with the CEREC Bluecam. Then, the data, along with a digital prescription, is immediately sent digitally to the laboratory through the secure CONNECT portal.

 

Figure 16. Temporary restoration and recurrent caries were removed.

Figure 17. A buildup was completed, and final preparation for an all-ceramic crown was done. Tissue retraction was placed prior to taking the digital impressions.

Figure 18. Digitally produced models, in articulation.

Figure 19. Close-up view of the digital restoration on the digital model. This restoration was created in the dental laboratory using the CEREC inLab milling unit, then finished (stain/glazed) by the dental technician.

Figure 20. The completed lithium disilicate (all-ceramic) restoration (e.max [Ivoclar Vivadent]) on tooth No. 30. Note the excellent margins and aesthetics of this digitally lab-fabricated restoration.

From a dental practice perspective, this digital workflow allows several advantages over traditional restoration fabrication techniques. The dental laboratory technicians receive the case within minutes and begin making the restoration. In fact, there have been times where I have received a restoration back from our dental technicians on the same day. All photographs are integrated into the laboratory prescription and sent with the digital impressions to aid the dental ceramist in matching the restorations. Optionally, the dentist has the ability to mark the margins prior to sending the case for situations where the margin may be unclear.

Once the dental technicians receive the digital impressions, they can decide to order digitally-printed models or to make the restoration directly without models. In this case, we jointly decided to opt for the use of a digitally-printed model. The laboratory receives the models ready for fabrication—pinned, sectioned, margins ditched, and articulated (Figure 18). Having a digital model allows the laboratory complete freedom in technique of making the restoration. In this case, the e.max restoration was created using the CEREC inLab milling unit. The margins and contacts were subsequently refined by the dental technician on the printed model (Figure 19).
The final restoration was returned to our office about 5 days after sending it to the laboratory. The patient returned to the office and the restoration was bonded using a self-etching dual cure resin cement (Multilink [Ivoclar Vivadent]). The final result is a strong and aesthetic digitally-fabricated restoration (Figure 20).

 

Practice Management Ramifications
Amy Morgan
Every new piece of technology and advancement in clinical processes affects how you manage your practice. In this article the author worked with the CEREC Bluecam—a dental restoration product that allows a practitioner to produce an indirect ceramic restoration using a variety of computer-assisted technologies. If your vision is to provide dental alternatives that are high-quality, state-of the-art restorations, then technology like this could be a wonderful addition to the traditional crown and bridge practice.

If a practice is not computer and digital savvy, then the initial costs of implementing a system like this may feel overwhelming. The return on investment (ROI) does come in decreased chair time, and increased patient commitment. Implementing CAD/CAM restorations may also directly relate to cost savings. The percentage reduction in laboratory fees saved can be as much as 5 to 7%, with many doctors reporting only a 1 to 2 % increase in dental supplies, once fully integrated. There is no question that a one-appointment restoration does significantly in­crease efficiency and is extremely attractive to a busy patient who is not interested in multiple visits.
When implementing these new procedures, the most impacted team members are the dentists and their chairside assistants. The transferable abilities that create excellent crown preparations, temporaries, and crown seats are not the only skill sets needed to master the CAD/CAM restorations. To be successful, there needs to be comfort with computers and digital imaging/images, involving a whole new set of skills and a significant learning curve. There’s no doubt that if the doctor and the clinical team is motivated and focused, proficiency is absolutely possible. To realize a ROI, the training plan has to go beyond just training for competence, to ensuring confidence and speed when utilizing these new technologies.
The whole team must be involved in the training and implementation plan, as the systems directly impacted by this new service include: scheduling, financial arrangements, and collections. Ideal day templates that had once focused on production blocks based on a traditional crown preparation, and specific times set aside for the crown seat, will need to be altered. When initially integrating this technology, scheduling doctor time and assistant time will be very different and must be planned for appropriately. The biggest problem that we see is that dentists do not give themselves and the team adequate time to truly integrate new technologies, thus creating frustration and sometimes abandonment. Once proper training has been completed, there is no question that the schedule becomes more efficient with CAD/CAM technologies because restorations can be completed in one visit. This in turn impacts how the team sets financial arrangements for the restoration, and how they ultimately collect any balance due. Also it is vital to set clear guidelines on fees, and how to handle any initial remakes so the team feels unified in handling any patient service issues.
If your patients are inspired by innovative new processes that are efficient and effective—they will be excited about these new in-office and related in-lab technologies. Marketing in newsletters, website, etc, needs to be upgraded to educate new patients and patients of record on the benefits of CAD/CAM restorations. This is not a quick fix, but a long-term cultural change that can provide lasting benefits to your patients, and to you and your team. So, plan well, train thoroughly, and then enjoy the results.

CLOSING COMMENTS
I hope the previous case reports have demonstrated the positive clinical realities of digital impressions.

Overall, I have found the digital impression workflow to significantly enhance my overall practice. Patients have been “wowed” and the final results have been able to meet my expectations in terms of integrity margins, interproximal contacts, and occlusal contacts and aesthetics. The new addition of laboratory-assisted restorations has opened the lines of communication necessary between dentist and laboratory to consistently produce excellent results in a quicker timeframe. The end result is the technology has helped me grow as a clinician. 
I would highly recommend this technology to any dentist looking to further enhance his/her practice.

 

Dr. Agarwal, a 1999 graduate of University of Missouri-Kansas City, maintains a full-time private practice emphasizing aesthetic, restorative, and implant dentistry in Raleigh, NC. His work and practice has been featured in numerous consumer and dental publications. He has completed extensive continuing education with many dental leaders. Dr. Agarwal regularly presents entertaining and informative programs to study clubs and dental organizations nationally. Through his real-world approach to dentistry, practice enhancement, and balancing life, Dr. Agarwal has motivated dentists and energized team members to increase productivity, profitability, and start enjoying dentistry again. He can be reached at dra@raleighdentalarts.com or at tbonespeaks.com. 

Disclosures: Dr. Agarwal is a certified CEREC trainer for Patterson Dental and Sirona Dental Systems. He, nor any family members, has financial interest in the products or companies mentioned in this article and has not received any compensation for mentioning or using products in this article.

Dr. Silverman serves as a senior consultant at Pride Institute. Drawing on her years in private practice, Dr Silverman has helped hundreds of dental practices nationwide achieve their clinical, organizational, and business objectives. She lectures frequently on topics that include reducing practice stress, optimizing financial results, and maintaining work/life balance. She can be reached via e-mail at leslies@prideinstitute.com.

Disclosure: Dr. Silverman reports no conflicts of interest.

Ms. Morgan serves as the CEO of Pride Institute. She is a dental consultant and international lecturer. Over the years, Ms. Morgan has facilitated the successful revitalization of thousands of dental practices using Pride Management Systems. She can be reached at amym@prideinstitute.com.

Disclosure: Ms. Morgan reports no conflicts of interest.