Creating CAD/CAM indirect restorations

Restorations created with dental CAD/CAM devices, specifically CEREC by Sirona, have directly and profoundly changed the process of creating indirect restorations. The technology developed during the past 25 years is revolutionary and represents a major shift in technique, materials, speed, comfort and convenience. Today’s machinable materials are up to 300% stronger than conventional all-porcelain restorations, and can be milled into highly durable crowns, inlays, onlays and veneers.

For the CEREC inLab laboratory, there are several distinct advantages to digital impressions. They are totally clean (obviously), never contain voids or distortions, and the design of the restorations can begin immediately with no wax-ups, copings or guesswork. These are all important factors for ultra-accurate fit and same-day turnaround. The CEREC inLab concept can breathe new life into American dental laboratories, especially smaller, individually owned labs. This technology provides the opportunity for them to successfully compete with the large, corporate labs as well as offshore labs.

The big winner is the patient, who can receive highly esthetic, lifelike restorations in a single day, if desired.

Case Presentation by Dr. McLaren

In this maxillary first bicuspid-to-first bicuspid veneer case, the patient was a bruxer with a traumatic bite and severely worn incisal edges. Orthodontia improved the edge-to-edge bite and corrected mesial rotation of tooth No. 9 prior to restorative treatment (Figs. A and B). Tooth form was restored first with an injection-molded, direct-bonded composite technique to establish acceptable esthetics and a stable occlusal relationship with minimal overbite relationships. This was copied in the final restorations.

The case required minimal enamel preparation, as the incisal thirds had been worn away. Maxillary anterior teeth were reduced slightly (0.5 mm) on the facial surfaces from incisal edges to gingival margins. The lower incisal edges were restored with light-cured composite material.

The nearly completed lower incisal edges and composite mockups determine appearance and desired anterior occlusion of the final restorations (Fig. C).

01 Photos were sent to the CEREC inLab laboratory at UCLA to aid in the design of the veneers. The bicuspid-to-bicuspid tooth preparations and try-in of a CEREC veneer prior to porcelain customization and glazing by the ceramist is shown (Fig. D). Note the preparation of the margins.

02 The CEREC AC Bluecam digital scanner was used to take a digital impression of the prepared teeth, and the data was uploaded via CEREC Connect to the inLab laboratory.

03 The Digital Dental Designer (DDD) involved in this case is a CDT who is fully trained on the CEREC inLab system, and very experienced in digital tooth designing used the CEREC (Fig. E). He designed all 8 veneers and then sent the data to the lab’s CEREC inLab milling unit. A VITABLOC RealLife milling block is shown at the beginning of its transformation (Fig. F).

04 After milling at the lab, the veneers were sent to the office for a try-in later that same morning (Fig. G). I had the DDD design the gingival margin areas slightly thicker so I could shape them without risk of chipping the material. Fine diamond instruments were used for trimming and ­shaping (Fig. H).

05 After try-in, the CEREC patient may leave and return later that afternoon for bonding. The doctor is free to treat other patients.

Customization

06 After shaping the gingival margin areas, the veneers were returned to the lab for customization. The ceramist cut back the facial incisal third in preparation for minimal porcelain layering, coloring, contouring and glazing.

07 The ceramist used a diamond wheel instrument to cut back the facial incisal thirds of each veneer in preparation for customization (Fig. I).

08 Minimal porcelain layering was done to add translucency, color and contour to the facial and incisal edges (Fig. J). The technique effectively mimics enamel; in fact, I refer to the ceramist who does this as the “Enamelizer.” The veneer will be baked and then contoured with a fine diamond instrument prior to glazing. The newly layered and glazed CEREC veneers shown on a cast (Fig. K). Note the translucency and realistic color and depth achieved by this minimal layering and finishing technique.

Post-op results

09 The patient returned to the office that afternoon for bonding of the CEREC customized veneers. A filled, light-cured composite was used to bond the veneers to the teeth. Minimal layering and finishing is the key to these lifelike veneers. The DDD and “Enamelizer” at inLab do all the tooth design work and customization.