Digital Design: Predictability, Profitability, and Efficiency

INTRODUCTION
How do we, as clinicians, meet the challenge to continually maintain competence in a constantly changing technological environment? How do we leverage new technologies to simultaneously improve the predictability of successful patient outcomes and increase profitability? When do we recognize that a technology-driven protocol offers enough improvement to justify the initial increased cost and learning curve necessary to adopt that procedure into a practice?

Digital Smile Design (DSD) is a technological breakthrough that can improve patient and laboratory communication, increase case acceptance, and provide a more predictable protocol for a successful cosmetic outcome. However, DSD is not simple and requires collaboration with a master ceramist for the vision to be brought to life. The ceramist also must have digital fabrication workflows in place.

This author admits to not being technologically savvy, yet has successfully incorporated these techniques into daily practice. This case report will serve to explain state-of-the-art real-time digital design, linking 3-D prosthetic planning with fundamental principles. In addition, this article will present proven communication techniques and outline the specific procedural steps, from diagnosis to wax-up to the final fabrication and delivery of the completed ceramics.

CASE REPORT
Diagnosis and Treatment Planning

A 34-year-old female patient presented for a functional and aesthetic assessment of her dental condition. She received a comprehensive exam, full-mouth series of radiographs, and a periodontal evaluation and diagnostic photos. Her medical history indicated that she had esophageal reflux, which was controlled with an over-the-counter medication. A clinical evaluation revealed a canted and gummy smile, with her right vermillion border being more apical than that on her left with a full smile. Her teeth were yellow, rotated, eroded, and chipped (Figure 1). Many teeth exhibited cupping (Figure 2), indicating that the erosive component was outpacing the frictional damage. She presented with a deep bite, a hypermobile lip, and a vertical maxillary excess.

Figure 1. Canted, gummy smile with vertical maxillary excess; yellow, worn, and rotated teeth. Figure 2. The cupping observed demonstrated that the chemical component was outpacing frictional damage.

A treatment plan that included orthodontics and orthognathic surgery was presented. This was refused by the patient as she was seeking a simpler, quick solution to her situation. Since the gingival levels needed to be equalized in order to attain harmony, she was referred to the periodontist, and crown lengthening was planned. A digital design for a surgical template was fabricated from polymethyl methacrylate (PMMA) to guide this surgery, and a wax-up for the provisional composite prototypes was created. Records, including a face-bow and bite sticks, were taken for communication to the ceramist.

Digital Smile Design
The ceramist uses a natural smile photo and identifies landmarks on the photo and correlates this with the same landmarks on the digital design. It is critical that the photo is taken with the patient looking straight into the camera lens with a big smile, allowing the best evaluation of facial landmarks (Figure 3). Custom templates of tooth libraries that have various shapes and styles are then evaluated. Using Keynote software, they are placed over the preoperative smile. Adjustment and fine-tuning by the user (ie, the ceramist) occurs until initial design for treatment communication in 2 dimensions is completed. This has been considered state of the art for many years (Figure 4). With the integration of full 3-D digital designs, using software programs (such as the 3Shape Dental System), these 2-D images can be entered as overlays into the actual 3-D design. The translucency of the design can be turned up or turned off (Figure 5). This allows analysis of the relationship between the design proposal and the original preoperative condition.

Figure 3. A straight, big smile allowed for facial landmark identification for Digital Smile Design. Figure 4. In Keynote, templates were chosen and modified for initial design in 2-D.
Figure 5. Design overlay was placed in 3Shape Dental System. Translucency can be turned off, allowing analysis of pre-op and digital design proposal. Figure 6. Design proposal showing where crown lengthening needed to occur.

This case clearly showed the areas that needed to be crown lengthened during the periodontal surgery (Figure 6). Moving these digital prototypes into the full-face photo using the same landmarks executes a virtual try-in (Figure 7). The ceramist and the dentist can communicate via email or TeamViewer in real time. Once agreement has been reached, the PMMA overlays are milled and fit to the model. Contours and surface morphology can be refined by hand at this point. It is also possible to mill the same file out of a white wax and glue it to a second model as a diagnostic wax-up. The milled PMMAs can be used as an aesthetic preview to help visualize what would be possible with complete treatment. They can also be used as a template to guide the periodontist in the crown lengthening procedure. It is important to note that this design is done prior to surgery, so after the gingival remodeling of periodontal surgery has been completed, the milled wax-up would need to be fit to a new model exhibiting the final gingival position (Figure 8). This can be done by hand, with milled wax from the previous design, or a new diagnostic wax-up can be completed post-surgery.

Preoperative Try-In
The accuracy of the digital design technique was evaluated and verified by placing the templates over the facial of teeth Nos. 4 to 13. When the template was positioned correctly, it was noted that tooth No. 11 extended apically beyond the template. Crown lengthening on tooth No. 6 was the treatment selected to correct this height discrepancy. To communicate the desired position to the surgeon, a black marker was used as a reminder that no gingival tissue was to be removed in this area (Figure 9). This also aids in verifying the height of tooth No. 6 when equalizing the right and left canine height.

Figure 7. Digital prototypes placed in full-face photo for virtual try-in and communication between ceramist and dentist. Figure 8. In order to create provisional prototypes at the preparation appointment, milled wax from the previous design must be fit to a new model that exhibits the final post-op gingival position.
Figure 9. Verifying polymethyl methacrylate surgical template accuracy. (Note canine height discrepancy.) Figure 10. First surgery: template height guided the surgical incisions.

Surgical Protocol
The surgical template was positioned intraorally to guide the crown lengthening surgery. The template provided the surgeon with the specific tissue heights that would be necessary for a successful outcome. Incisions were made with a No. 15c Bard-Parker blade to match the length created in the digital design phase and communicated through the surgical template (Figure 10). Once the tissue was removed from teeth Nos. 6 to 11, the bone level, relative to the new gingival tissue height, was assessed. Osseous reduction was accomplished in that segment with a flapless approach using a piezoelectric bone surgery unit (Piezosurgery Touch [Piezosurgery Incorporated]).1

Tactile sensation combined with visual feedback facilitated removing the amount of bone necessary to provide a 3.0 mm distance from the newly created gingival margin to the osseous crest.2 The bone was thin, allowing for easy removal with very little heat generation. Using this technique, no sutures were necessary in the anterior, providing an aesthetic benefit to the patient postoperatively. In the posterior segments, the bone was deemed too thick to utilize a flapless approach. Thick bone is a relative contraindication to the technique described above, as it is easy to leave a lip of bone resulting in a crater. Further, heat generation can more readily become an issue in a flapless environment when there is thick bone present. Resorbable sutures were used in the posterior to replace the flap.

Porcelain Preparation
At the post-op evaluation appointment, gingival harmony and symmetry were confirmed (Figure 11). Of course, the previously noted hypermobile assymetrical lip display on a full smile was still present. The preparation appointment was then scheduled.

The patient presented with rotated laterals and an enamel deficiency on both the facial and lingual surfaces of the teeth due to erosion. This necessitated a choice for full-coverage restorations to augment this biostructually compromised dentition.

Figure 11. Surgery final: verification that contra-lateral gingival harmony was attained. Figure 12. Circumferential loss of enamel dictated full-coverage prep design. Note the stump shade differences.

Local anesthetic was administered. The provisional addition silicone (Siltech [Ivoclar Vivadent]) stint, fabricated from the digital design, was filled with a bis-acryl temporary material in a bleach shade (Luxatemp Automix Plus Bleach [DMG America]) and placed in the mouth. The patient previewed and then approved this direct prototype. Depth cuts were placed using diamond depth-cut burs (Brasseler USA RWMIN.3/.5/.7) across the gingival and middle third to establish the amount of facial reduction. Then incisal edge depth cuts were placed to ensure 2.0 mm removal of enamel from the desired postoperative incisal edge.3,4 A modified shoulder (Brasseler USA BR8847KR.016) preparation was done with the margins placed at the free gingival margin. After completing the preparations, a face-bow (Panadent), MIP bites (Megabite [DenMat]), bite sticks, and vinyl polysiloxane (VPS) impressions (Take 1 Advanced [Kerr]) were done. Stump shade (shade of the prepared tooth structure) documentation (Figure 12) was also done as another important part of the communication with the ceramist. The bis-acryl provisional restorations were then fabricated and documented with photographs.

The patient returned 2 days later for an aesthetic re-evaluation and an occlusal analysis. The right side prototypes were noted to be slightly different than the left in outline form, length of the lateral, and the shape of the incisal embrasures. She was unsure of which side she preferred, so a second re-evaluation was scheduled for one week later. At that time, a detailed laboratory prescription with shape, form, incisal translucency, and surface texture was created. Photos and impressions/models were taken of the approved provisionals along with new face-bow records and bite. These were then delivered to the ceramist for digital design of the definitive porcelain restorations.

Digital Design of Porcelain Restorations
Photo orientation is critical to aesthetic digital design. The patient must be looking straight at the camera while displaying a full smile. This photo is imported into the design software and a level horizon is defined using the interpupillary line. The software then levels the image, and additional parallel lines are added to evaluate gingival symmetry and incisal plane. These lines greatly help in the evaluation of the orientation of the composite prototypes and diagnose any desired changes to be made in the definitive porcelain restorations. In this case, the ceramist noticed that the provisionals canted slightly to the patient’s left and the gingival levels were more canted and apical on the patient’s left as well. The incisal plane appeared higher on the left and lower on the right (Figure 13). The patient’s facial image was then synched to the digital scan by distinguishing landmarks common to the photographs and the digital scan. The restorative design was superimposed on the facial image. The design was then modified and developed to optimize integration of facially generated aesthetics and function for the definitive lithium disilicate (IPS e.max [Ivoclar Vivadent]) restorations (Figure 14).

Figure 13. Image was leveled to interpupillary line followed by addition of parallel lines to evaluate gingival symmetry, incisal plane, and vertical midline. Figure 14. Landmarks synched patient’s image to digital scan, followed by previewing of porcelain design superimposed into the facial image.
Figure 15. Adjustable virtual articulator was used to evaluate the design in functional movements prior to milling. Figure 16. Final design translucent and provisional design in blue, showing intentional design changes.

Anterior palatal anatomy dictates form and function. By using an adjustable virtual articulator, mimicked from the real world, we were able to evaluate and optimize the functional envelope prior to milling (Figure 15). An image showing the provisional in blue and the final design as a translucent overlay aided in analysis of how closely the provisional adhered to the position of the final restorations (Figure 16). Small corrections could be made to midlines, incisal edges, and contralateral symmetry. These discrepancies were noted by the patient, and she asked for the appropriate corrections in the final restorations. The dentist, prior to milling of the restorations, approved the final digital design.

A Multi Ingot BL2 (Ivoclar Vivadent) was chosen by the ceramist in order to obtain the final color of 010-020, chosen by the patient. The digital design can be either milled in ceramic or it can be milled in wax to allow pressing of the restorations. Milled wax requires a traditional lost-wax casting process, which is more labor intensive than milled ceramic, but it has a few advantages. Wax can be milled and pressed much thinner than ceramic can be milled, which was not a factor with this patient. However, the Multi Ingot BL2, which had the ideal optical properties for this patient’s needs, is only available in pressable ingots and not in millable ceramic blocks, so the case was milled in wax and pressed.

After the wax was milled, it was checked for fit and contour on the model and any hand finishing needed could be completed at this time prior to pressing. After pressing, the restorations were fit back to the model where minor contour adjustments and final surface morphology were created. The restorations were selectively cut back for any desired effects that needed ceramic layering. Although the Multi Ingots have some incisal translucency, cutting back just the facial-incisal area and creating some additional effects with a traditional “ceramist with a porcelain brush” technique created additional natural translucency (Figure 17). The Multi Ingot family is good at covering moderately discolored restorations due to its increased opacity in the gingival one third. And yet, this ingot requires little, if any, layering with its more translucent incisal third. The overall result of less layering is a stronger all-ceramic restoration. This is because a much higher percentage is composed of the 400 MPa LiS2 pressed lithium disilicate material and a very low percentage is made up of the weaker (100 MPa) layering ceramic. Internal effects were layered into the incisal area with powdered ceramics. The basic color of the ingot while seated on a composite die to replicate the effect of the underlying tooth color was evaluated and modified via staining. Final contour, glaze, and polish were accomplished and the restorations were delivered to the dentist (Figure 18).

Delivery Appointment
The 10 maxillary lithium disilicate (e.max) full-coverage crowns (teeth Nos. 4 to 13) and 4 mandibular (teeth Nos. 23 to 26) lithium disilicate (e.max) veneer restorations were placed intraorally for aesthetic evaluation using try-in gels (Variolink Esthetic [Ivoclar Vivadent]). Once approved, the restorations were removed and cleaned by applying a universal cleaning paste (Ivoclean [Ivoclar Vivadent]) to the internal surfaces, then rinsed with water. The intaglio surfaces were then treated using a universal primer (Monobond Plus [Ivoclar Vivadent]), the (mandibular) teeth were etched (SELECTIVE HV ETCH [BISCO Dental Products]), and a bonding adhesive (ALL-BOND UNIVERSAL [BISCO Dental Products]) was applied. Next, the maxillary crowns were bonded into place with using Variolink Esthetic (dual-cured) and the lower veneers were cemented in using Variolink Esthetic (light-cured).

Figure 17. Multi Ingot BL2 (IPS e.max [Ivoclar Vivadent]) was cut back on the incisal facial to allow room for layered ceramic and produce internal effects. Figure 18. On composite die for verification of color, surface texture, and translucency.
Figure 19. Post-op note: crooked smile, contralateral gingival harmony, and lifelike emergence profiles, tooth contours, and color. Figure 20. Exceptional dentofacial results using 3-D prosthetic planning.

The occlusion was evaluated by having the patient close into maximal intercuspation to verify that all posterior teeth displayed bilateral and simultaneous forces. Movement in all excursive directions was also evaluated. The software had identified areas where occlusal clearance was minimal and the maxillary lingual porcelain was fabricated thin. Adjustment occurred by recontouring the opposing mandibular porcelain.

With the patient sitting up, thick blue articulating paper (Bausch) was placed and the chewing cycle was mimicked. Lateral streaks on the canines were maintained and all lateral streaks on the posterior teeth were removed. All streaks on the lingual of the central incisors in the chewing envelope were carefully adjusted along with the facials of the lower incisors with evaluation from a frontal perspective so the aesthetics and length were preserved. Sibilant sounds were verified and no lisp was present. Finishing and polishing of all surfaces of ceramic (Dialite [Brasseler USA]) was completed, then post-op photos (Figures 19 and 20) and records for Essix retainers and a maxillary flat plane occlusal splint were taken. (Note: The patient had reported intermittent, nocturnal bruxism and still wants to ensure longevity of her restorations.)

CLOSING COMMENTS
This case displays a state-of-the-art technology that can alter the way a dentist performs even a familiar and otherwise successful procedure. An evaluation of clinical parameters will prevent problems before their occurrence. The technology allows corrections to be made during the procedure and before cementation, because errors will become visible in the provisional design. The final outcome is more aesthetic, functionally sound, and shows improved longevity and predictability.

Acknowledgment
The concepts demonstrated were learned at the Kois Center and through many courses presented by the American Academy of Cosmetic Dentistry. The author would like to thank Matthew Roberts, CDT, from CMR Dental Lab (Idaho Falls, Idaho) for the digital design detail and ceramic artistry; Dr. Ralph Wilson of Phoenix, Ariz, for the periodontal surgery; and Jean Martin, DDS, for editing.


References

  1. Wilson RF. Innovations in periodontics session 2. Presented at: 94th Annual American Academy of Periodontology Meeting; September 2008; Seattle, WA.
  2. Kois JC. The restorative-periodontal interface: biological parameters. Periodontol 2000. 1996;11:29-38.
  3. Magne P, Belser UC. Novel porcelain laminate preparation approach driven by a diagnostic mock-up. J Esthet Restor Dent. 2004;16:7-18.
  4. Gürel G. The Science and Art of Porcelain Laminate Veneers. Hanover Park, IL: Quintessence Publishing; 2003:241-251,261-276.

Dr. Bassett, a graduate of The Ohio State University College of Dentistry, practices comprehensive restorative and aesthetic dentistry in Scottsdale, Ariz. She is president of the American Academy of Cosmetic Dentistry (AACD) and is an Accredited Fellow, which is the highest level of achievement recognized by the AACD. She is an associate member of the American Academy of Esthetic Dentistry, a member in the Academy of Fixed Prosthodontics, and a Fellow in the AGD. She also serves as a Kois mentor and is adjunct faculty at the Arizona School of Dentistry, where she has taught the aesthetic continuum. She is a national lecturer (also a Catapult speaker), a published author, and a member of the editorial board of several peer-reviewed publications. Recognized in Dentistry Today’s Leaders in Continuing Education, she can be reached via email at This email address is being protected from spambots. You need JavaScript enabled to view it..

Disclosure: Dr. Bassett reports no disclosures.

Mr. Roberts started making gold restorations for his father’s dental practice as a teenager. He opened CMR Dental Lab in 1978. As a member of both the America Academy of Esthetic Dentistry and one of 35 accredited dental technicians in the American Academy of Cosmetic Dentistry, he has kept in the forefront of his field. He is currently a member of the faculty at the L. D. Pankey institute, helping to teach the aesthetic solutions program for dentists and technicians. With a keen interest in continuing education programs, he founded the Team Aesthetic Education program to provide hands on training for dentists and technicians to work with manufacturers to develop or improve products, and he is now providing Internet-based video education as well. He is on the editorial team for many of the prominent journals in dentistry and lectures internationally. He can be contacted via the website teamaesthetic.com.

Disclosure: Mr. Roberts reports no disclosures.



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