November 2017
Volume 13, Issue 11

Peer-Reviewed

Digital Dentistry and Chairside CAD/CAM

Leveraging modern technology to provide more conservative dentistry

Clint Stevens, DDS, FAGD, FICOI

Dental practitioners still overwhelmingly choose conventional full coverage designs for indirect restorations. This is despite great advances in adhesive restorative materials, which can be used in ways that are significantly more conservative of tooth structure, even when compared to gold restorations.1,2 All-ceramic restorations now have a well-established track record for clinical success.3 Expectations for partial coverage all-ceramic restorations should be even higher. For example, a recent retrospective study looking at the clinical performance of over 34,000 all-ceramic restorations estimated that it might take 124 years to reach a 10% failure rate for IPS e.max inlays and 30 years for IPS e.max onlays.4

Digital impressions and chairside CAD/CAM can eliminate many of the barriers to conservative partial coverage treatment that are found in conventional workflows. Many of the concerns related to provisional retention and interappointment sensitivity are eliminated by single visit dentistry. This allows practitioners to make treatment decisions based on what is best for the patient without having to alter those decisions to accommodate patient/practitioner convenience, comfort, or workflow efficiency. Furthermore, digital systems may facilitate better dentistry. Digital models can help practitioners better visualize their preparations and anticipate how the future restoration will interface with the preparation and opposing dentition before it is ever fabricated (Figure 1). This immediate feedback allows for the optimization of the preparation and restoration in ways that are not possible with conventional dentistry, ensuring the best possible outcome for patients, regardless of what preparation style or restorative material is chosen.

Case Report

A patient presented with a chief complaint of a long-standing hole in his tooth that he wanted repaired. The patient thought that he might have had a filling in the tooth at one point in time, but was unsure. He reported no history of sensitivity or spontaneous pain. 

Clinical examination revealed that tooth No. 14 had a moderate-sized cavitation that included the mesial-occlusal surface and most of the lingual cusp (Figure 2). No overt pathology was noted radiographically, and the tooth had a positive, non-lingering response to cold;  all probing depths were 3 mm or less. As a result, tooth No. 14 was diagnosed as a fractured tooth with possible lost previous restoration and a normal periodontal, pulpal, and periapical status. After treatment options, risks, and benefits were discussed with the patient, he elected to restore the tooth with a partial coverage ceramic onlay.

Following delivery of local anesthesia, tooth No. 14 was prepared for an MOBL onlay (Figure 3). Digital impressions were then taken with the Planmeca Emerald digital scanner (Planmeca USA) (Figure 4). Following the design of the onlay restoration using Romexis PlanCAD software (Planmeca USA) (Figure 5), a high translucency IPS e.max restoration (Ivoclar Vivadent) was milled using the Planmeca Planmill 40 (Planmeca USA). The restoration was then de-sprued and tried in the patient’s mouth to check its fit (Figure 6). Next, the restoration was hand polished and fired in a Programat CS oven (Ivoclar Vivadent). The intaglio surface of the restoration was then treated with Monobond Etch & Prime (Ivoclar Vivadent) per the manufacturer’s instructions.

A selective etch protocol was chosen for the bonding of the restoration. After etching the enamel for 15 seconds with phosphoric acid, the tooth was rinsed and gently dried. Adhese Universal (Ivoclar Vivadent) was scrubbed on the preparation for 20 seconds, then it was air-dried and light-cured for 10 seconds with a Bluephase G2 curing light (Ivoclar Vivadent). Next, the restoration was bonded into place with neutral shade Variolink Esthetic DC (Ivoclar Vivadent). After occlusion was verified, the restoration was polished. A bitewing radiograph was taken to ensure complete cement cleanup (Figure 7). The final restoration was completed in one appointment with a total chair time of 90 minutes (Figure 8).

This case provides a perfect example of how digital dentistry and chairside CAD/CAM can facilitate better outcomes for patients. Because the restoration was completed in one visit, there were no concerns about retaining a provisional restoration or sensitivity between visits. By using a predictable, adhesively-retained restorative material, retention and resistance form were not needed and significantly more tooth structure was conserved when compared with a full coverage restoration. This would not be possible without the use of digital impressions and a chairside mill. Today’s digital dentistry workflows are better and faster than ever. The speed and accuracy of digital scanners such as the Planmeca Emerald allow for more conservative dentistry to be provided in a more efficient and patient-friendly manner than ever possible with conventional workflows.  

References

1. Edelhoff D, Sorensen JA. Tooth structure removal associated with various preparation designs for anterior teeth. J Prosthet Dent. 2002;87(5):503-509.

2. Edelhoff D, Sorensen JA. Tooth structure removal associated with various preparation designs for posterior teeth. Int J Periodontics Restorative Dent. 2002;
22(3):241-249.

3. Morimoto S, Rebello de Sampaio FB, Braga MM, Sesma N, Özcan M. Survival rate of resin and ceramic inlays, onlays and overlays: a systematic review and meta-analysis. J Dent Res. 2016;95(9):
985-994.

4. Belli R, Patschelt A, Hofner B, Hajtó J, Scherrer SS, LohbauerU. Fracture rates and lifetime estimations of CAD/CAM all-ceramic restorations. J Dent Res. 2016;95(1):67-73.

About the Author

Clint Stevens, DDS, FAGD, FICOI
Private Practice
Tulsa, Oklahoma

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