CAD/CAM Restorations for the Digitally Integrated Dental Practice
CBCT provides the foundation for diagnosis and treatment
Anthony Ramirez, DDS, MAGD, DICOI
For a decade, in-office 3D imaging with a cone-beam computed tomography (CBCT) scanner (Galileos®, Dentsply Sirona) has been the foundation of my complete dental examination. I scan, diagnose, treatment plan, and present cases in a single visit.1,2 There are numerous benefits to this workflow, including conducting an enhanced 3D virtual analysis, fabricating CAD/CAM surgical guides, milling restorations in-office, and performing guided implantology.
A new patient presented for a consultation with the chief complaint of two fractured maxillary central incisors and mild discomfort in the upper right quadrant. Initial diagnostic information was gathered by clinical examination, periodontal evaluation, intraoral photography, and a full mouth series of radiographs (Schick 33, Dentsply Sirona) (Figure 1 and Figure 2). An enhanced 3D evaluation was recommended to obtain a complete understanding of the pathologies that were discovered to be associated with teeth Nos. 3 and 15. This analysis indicated that tooth No. 3 could be rehabilitated by dismantling the crown and re-treating the root canal system, followed by restoration with a new post, core, and in-office milled lithium disilicate crown (IPS e.max®, Ivoclar Vivadent). The porcelain-fused-to-metal (PFM) crown on tooth No. 3 was sectioned, the existing post was removed, and endodontic re-treatment was performed using rotary instrumentation. After the root canal system was instrumented and shaped, it was obturated with gutta-percha and provisionalized.
When the patient returned for the definitive restoration, the tooth was asymptomatic. A post (Flexi-Post red #1, Essential Dental Systems) was inserted into the palatal canal and a resin core buildup was completed. After the full coverage preparation was imaged and designed, the restoration was milled from a block (IPS e.max® LT, Ivoclar Vivadent) using an in-office milling machine (CEREC MC XL, Dentsply Sirona). This material was selected because its properties would help to block out the core shade and it could be stained and characterized to blend in well with her adjacent PFM crowns. Following milling, the CAD/CAM restoration was stained, glazed, and fired in a ceramic furnace. The well-fitting and natural looking crown achieved a nice result (Figure 3 and Figure 4). The process of inserting this crown was effortless because no adjustments were necessary due to the accuracy of the digital impression and the control involved in the design of the restoration.3,4
The maxillary central incisors exhibited worn, fractured incisal edges that created an unesthetic smile. The decision was made to restore these teeth with CAD/CAM veneers in a single visit using lithium disilicate, which can be highly esthetic and is frequently used in the esthetic zone. First, a resin mock-up was bonded to provide a blueprint for the definitive restorations. Next, the patient was informed that, without orthodontic treatment, it would be necessary to maintain a sizable diastema between the veneers to produce an esthetically acceptable result. She elected to decline the orthodontic option. The CEREC software's "biocopy feature" was used to catalog mock-ups of these teeth, which were later referenced to design the final restorations. At the incisal edge, the preparations left 1.5 mm of surface to support two veneers with sufficient thickness (Figure 5). Digital impressions were obtained, and the restorations were designed based upon the biocopy and the resin mock-up. The grid feature within the CEREC software aided in determining what incisal length would look best (Figure 6). The two restorations were subsequently milled, glazed, crystalized, and bonded, producing an esthetically pleasing result (Figure 7).
The treatment of tooth No. 15 was approached quite differently. The probing depth at the distal aspect was 12 mm and CBCT imaging revealed a non-restorable, interradicular periodontal-endodontic lesion (Figure 8). Tooth No. 15 was extracted and bone grafting was performed to prepare for its replacement. A mineralized cancellous allograft was placed, covered, and contained with a resorbable collagen membrane. The bone was allowed to mature for 4 months. After a new CBCT scan was obtained to evaluate the newly established bone volume, the decision was made to place a bone level implant (Straumann® Bone Level Implant, 4.8 x 8 mm; Straumann).5-8 A surgical guide (OPTIGUIDE, SICAT) was fabricated and utilized to place the implant during a flapless, guided surgical procedure (Figure 9). By utilizing a "crown down" approach, the placement of a well-positioned, easy-to-restore implant was achieved while avoiding the maxillary sinus in an uneventful implant surgery. After 12 weeks of osseointegration, the implant was restored in a single visit with a CAD/CAM-produced, screw-retained implant crown.9 The patient was happy with the final result (Figure 10).
The 3D visual communication of the patient's undistorted oral and maxillofacial anatomy provides the basis for enhanced diagnostic judgments that lead to improved treatment planning and an increase in case acceptance. The use of CBCT imaging and CAD/CAM restorations has increased predictability, efficiency, and productivity while creating strong, esthetic, and cost-effective restorations.
About the Author
Anthony Ramirez, DDS, MAGD, DICOI
Brooklyn, New York
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