Re: Versatile CAD/CAM Digital Impression Technology

[Drsumitra]

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.

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.

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.

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).