As a nation of educated people, we usually choose quality healthcare and often seek out the best. Although many factors play a part in the type of care delivered, Americans still retain the freedom of choice. The high quality of healthcare delivery has helped bring the average life span of Americans to around 80 years of age.
For an aging population, nutrition plays an important role in the quality of life. The ability to masticate food, the confidence to smile, and the lack of worry about a failing dentition all play their roles. Hippocrates stated, “Let your medicine be your food and let your food be your medicine.” This fundamental truth becomes most obvious to the hospital patient recovering from illness or surgery when diet plays a significant role in the speed of recovery.
When we look to restore a dentition that has worn fillings, treatment planning should include options that provide patients with as long-term a restorative material as possible. Today, we have one of the best healthcare delivery systems in the world. Through patient education in the operatory, patients have become better informed about their restorative options. All-porcelain onlays (versus a full-crown preparation) have become an excellent choice for replacing worn amalgams and composites. Unquestionably, a full crown has a great track record for strength, but the indirect onlay restoration using adhesive dentistry has really come into its own as one of the best treatments of choice. This option allows the doctor to save as much healthy tooth structure as possible.
Maintaining sufficient tooth structure with an onlay should result in the restoration outlasting a full-crown restoration and reduce the procedures needed for each tooth over the course of a person’s life. Additionally, root surface decay along crown margins should be significantly reduced with an accurately fitting ceramic onlay, reducing the need for re-treatment with a new crown and reducing the risk of future endodontic needs. Since the average American is living in excess of 79 years,1 this is a choice that should always be considered when restoring teeth with faulty and fatigued restorations. Once the majority of patients are out of their cavity-prone years and appearing in the office with fatigued restorative material, the onlay is an ideal choice to achieve excellent function, minimal tooth reduction, and expected long-term restorative results.2
The following case report involves using a machinable ceramic possessing outstanding tooth-like characteristics while utilizing the CEREC 3D CAD/CAM system (Sirona Dental Systems) as the delivery unit (Figure 1). With an increasing number of dentists retiring and fewer dentists graduating, patient demand in the dental operatory is changing. Additionally, with the reduction in the number of laboratory technicians, the opportunity to have an in-house laboratory is an excellent benefit for the dentist. The technique described affords this opportunity in one convenient appointment.
CASE REPORT
A 48-year-old patient presented to the office complaining of sensitivity involving several of his teeth. The patient suspected that his fillings were worn and wanted them replaced but desired to avoid amalgam. Clinical examination showed 3 fatigued amalgam restorations in the patient’s lower left quadrant that needed replacing (Figure 2).
 |
 |
| Figure 1. CEREC 3D display (Sirona Dental Systems). | Figure 2. Teeth 18, 19 & 20 preop worn amalgams. |
Preoperative digital pictures were made using a Canon G3 digital camera with a macro prismatic diffuser attachment. Digital x-rays were taken using a Schick No. 2 sensor and reviewed. The patient was educated regarding gold, amalgam, and composite materials using the CAESY comparative materials program. He was also shown the CAD/CAM program in CAESY that shows how a one-appointment porcelain restoration is made. The patient elected to have the machinable ceramic onlays done in one appointment.
The patient presented for treatment and was anesthetized using 4% Citanest plain (prilocaine HCl) without epinephrine (DENTSPLY Pharmaceuticals). After preliminary anesthesia, a second carpule of lidocaine 2% with epinephrine was administered, and we waited until profound anesthesia was established. A nonlatex rubber dam was placed (Figure 3) using a No. 12 ivory rubber dam clamp on tooth No. 18, and orange wedgets dental dam stabilizing cord (Hygienic) were used to hold the dam in place between teeth Nos. 22 and 23. The patient requested that we isolate the teeth so that when we removed the amalgam, none of it would go down his throat. The use of a rubber dam is beneficial in all aspects of routine restorative dentistry. Once in place, it provides easy access to the entire quadrant for both the dentist and assistant. It also provides security for the patient during the procedure.
 |
| Figure 3. Nonlatex rubber dam isolation. |
A 245 carbide bur was used to remove the old amalgam fillings (Figure 4). This allows the preservation of as much healthy tooth structure as possible. The flutes of the 245 bur provide a depth gauge. A minimum of 1.5 mm of thickness (occlusal pulpal thickness) is needed at the fissure line of the inlay/onlay restoration (Figure 5). This is important, since it allows the establishment of the inclines of the occlusal table and reduces the need for a lot of occlusal adjustment once the restoration is seated.
 |
 |
| Figure 4. Using 245 carbide bur for depth cut and amalgam removal. | Figure 5. An illustration of minimum ceramic thickness for porcelain onlay. |
Once the old fillings were removed, Snoop caries detection dye (Pulpdent, Figure 6) was placed on all the preparations to help find any residual areas of decay. The preparations were then finalized, ensuring that the walls of the proximal boxes were flared enough (Figure 7) so that the corner of each box at the junction of the gingival margin and the wall margin of the facial and lingual walls of all the boxes were visible (Figure 8). To acquire a successful optical impression for a machinable ceramic restoration, all wall segments of a proximal box or a buccal or lingual wall must be flared enough so that all corners of the cervical margins in the optical impression are on the screen.
 |
 |
| Figure 6. Caries detection dye applied to preps. | Figure 7. Preps finalized. |
 |
|
| Figure 8. Red dots illustrate what you must see in the optical image for the restoration to draw. | |
The preparations were then powdered with Vita powder (Figure 9). Prior to using the powder, it was filtered by my assistant to remove some large clumps in the bottle. This ensures that a fine-textured coat of powder is applied to the tooth. Multiple optical images were taken of all the preparations and stored in the preparation library. Then the green arrow of the CEREC 3D program was pushed and the entire quadrant of preparations was displayed on the computer screen (Figure 10).
 |
 |
| Figure 9. All preps powdered. | Figure 10. CEREC 3D quadrant of preps. |
The dies were trimmed virtually, the automatic cavosurface margin finder was activated, and the margin was placed. The entire virtual die was enlarged to its highest magnification, and the margin placement was checked and corrected (if necessary). The corners of each wall and cervical margin were checked to make sure the red dot was in its proper location. The restoration was then proposed from the dental database library (Figure 11).
Tooth No. 19 was designed first (Figure 12), and the milling process was started. While the first restoration was being milled, another program was opened in the CEREC 3D software, and the restoration for tooth No. 19 was virtually seated (Figure 13) so that the contacts, marginal ridges, and occlusal, buccal, and lingual embrasures could be designed for tooth No. 20. An example of the contact for tooth No. 20 is shown in Figure 14.
 |
 |
| Figure 11. Automatic margin finder. | Figure 12. Number 19 being designed in 3D. |
 |
 |
| Figure 13. Number 19 design completed. | Figure 14. Contact designed in 3D. |
Once the design was finished for tooth No. 20, it was saved and virtually seated (Figure 15), then tooth No. 18 was designed like tooth No. 20 (Figure 16).
 |
 |
| Figure 15. Both Nos. 20 and 19 virtually seated and beginning tooth No. 18. | Figure 16. Tooth No. 18 restoration being designed against No. 19, which was virtually seated. |
Once the restoration for tooth No. 19 was milled, it was tried in and polished using the Ceraglaze polishing system (Axis) and cemented using RelyX Unicem cement (3M ESPE). Occlusion was checked and adjusted using a high-speed handpiece and water spray. Then the restorations for teeth Nos. 20 and 18 were seated and cemented using the same technique. The bite was adjusted and polished in the mouth using the Ceraglaze intraoral set (Axis) to remove scratches and achieve a natural “wet look” shine on the porcelain.
CONCLUSION
Three worn amalgams were removed and high-strength tooth-colored material was placed in one visit utilizing machinable ceramics and the CEREC 3D delivery unit (Figure 17). In today’s fast-paced society, efficient quality service is what patients demand. The dentist and staff want high levels of production with superior profitability and the ability to service the patient with excellent materials. The technique described in this article makes quadrant dentistry more efficient than ever.
 |
| Figure 17. Restorations for teeth Nos. 18, 19, and 20 seated, bonded, and polished. |
References
1. American Association of Retired Persons. A profile of older Americans. Washington DC: American Association of Retired Persons; 1993.
2. al-Hiyasat AS, Saunders WP, Sharkey SW, et al. Investigation of human enamel wear against four dental ceramics and gold. J Dent. 1998;26:487-495.
Dr. Benk is a graduate of Emory University School of Dentistry, where he served on its restorative faculty before the school closed. He has a fellowship with the International College of Oral Implantologists. In private practice in Atlanta, he can be reached at (404) 872-7755 or jrbenkdds@earthlink.net.
Disclosure: Dr. Benk is on the faculty of the CEREC Success Center of the Southeast, where he provides training to both dentists and their staffs on CEREC 3D basic, intermediate, and advanced courses. He is a certified Patterson Basic Trainer for CEREC 3D and lectures on practice integration of CEREC 3D and the advantages of machinable ceramics.
