Transforming Aesthetics Using CAD/CAM Dentistry

Dr. Perry E. Jones

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INTRODUCTION
When a patient presents with a dental injury, or a request for improved aesthetics in the anterior, there are well-established treatment planning guidelines, restorative techniques, and biologic principles we can follow to ensure an optimal outcome. One of the great advantages of modern dentistry is the availability of digital tools and versatile restorative materials that clinicians can use to fine-tune and confirm prosthetic design in advance of the final restoration. We can test out a proposed design with custom, prefabricated provisionals; make chairside adjustments; and communicate those changes to our dental laboratory team with a high degree of accuracy, thanks to the precision of dental CAD/CAM technology. This treatment approach can help achieve beautiful results that align perfectly with the patient’s expectations, even in the most challenging cases.

Digitally produced custom temporaries (such as BioTemps Provisionals [Glidewell Laboratories]) offer a close approximation of the desired restoration, and the provisional(s) can be adjusted via additive and subtractive processes to refine the prosthetic design(s). This allows the clinician to evaluate several considerations, including fit, contacts, crown contours, soft-tissue margins, and interdental papillae—all of which are of paramount importance when doing restorative work in the aesthetic zone. Then the adjusted provisionals are used to update the digital design for the final restoration, which replicates the fit, contours, and aesthetics approved by the dentist and patient.

Figure 1. Retracted anterior view of the patient’s initial condition. It shows the mesial angular fracture of tooth No. 8 that was a part of a 3-unit maxillary fixed partial denture (bridge) spanning teeth Nos. 6 to 8. Note that the damaged lithium disilicate bridge was accompanied by another existing bridge spanning teeth Nos. 9 to 11, which also had a fracture on the lingual surface of tooth No. 9 (not visible in this image). The 2 bridges were originally provided to restore congenitally missing lateral incisors. Figure 2. Close-up of the patient’s dental injury and presence of a significant black triangle between teeth Nos. 8 and 9. The lack of interdental papillae was likely due to the design of the existing bridges, which did not adhere to Tarnow’s Principle. By correcting this issue with the new restorations, the open gingival embrasure could be improved or even eliminated, especially with the use of custom, pre-made provisionals to refine the prosthetic design and shape the soft tissue.

Cases in which patients present with open gingival embrasures, or black triangles, pose particular challenges in the aesthetic zone. However, by following the Tarnow Principle, which states that the interdental papilla will be present when the measurement from the contact point of the teeth to the crest of ridge is 5.0 mm or less, clinicians have a straightforward path to success.1 The use of custom provisionals allows clinicians to both test this principle and to contour the soft tissue in preparation for the final restoration(s).

In this clinical case report article, it will be demonstrated how success was achieved in an aesthetically demanding situation. In addition, it will outline how the urgent needs of a patient with a fractured tooth in the aesthetic zone were addressed by adhering to biologic principles using custom provisionals and taking full advantage of CAD/CAM dental technology.

CASE REPORT
Diagnosis and Treatment Planning

A longtime patient presented with a broken lithium disilicate restoration on her maxillary right central incisor (Figure 1). The fractured crown was part of a 3-unit, layered all-ceramic bridge with a zirconia substructure. The injury occurred after the patient tripped and fell during a social gathering (Figure 2). In addition to wanting to take care of this urgent need, she also stated her desire for a smile makeover to address some pre-existing aesthetic issues. The patient was unhappy with the appearance of her teeth in the anterior segment, including a large black triangle between teeth Nos. 8 and 9. Therefore, the broken restoration represented an opportunity to correct these issues.

Figure 3. Right (a) and left (b) buccal views show existing lithium disilicate 3-unit bridges spanning teeth Nos. 6 to 8 and 9 to 11. Replacing the patient’s fractured maxillary right central incisor afforded the opportunity to replace both bridges with a high-strength material and improve the aesthetics of her smile, which was desired by the patient prior to her dental injury.
Figure 4. Impressions were taken and sent to the lab team along with instructions for correcting the interproximal contacts, closing the black triangle, and enhancing the gingival margins. Based upon this information, BioTemps Provisionals (Glidewell Laboratories) were digitally fabricated so that the patient could “test drive” the proposed restorations. This would allow the clinician to fine-tune the prosthetic design before the final 3-unit bridges were produced. The PMMA material from which the BioTemps Provisionals were fabricated is easily adjusted, making it ideal for the challenging aesthetics of this case. Note how the BioTemps shown on the diagnostic wax-up were designed to bring the contact points between the 2 bridges closer to the gingiva and the crest of the ridge.
Figure 5. At the next appointment, the patient’s existing bridges were sectioned to aid in their removal. The vertical cuts were made using a high-speed coarse diamond bur. After making the cuts, a towel clamp was used to remove the bridges.

She presented with 2 anterior fixed partial dentures (bridges) spanning teeth Nos. 6 to 9 and Nos. 9 to 11. These restorations were delivered several years previously to restore her congenitally missing lateral incisors (Figure 3). The patient agreed to replace both bridges as part of the treatment plan.

While the patient’s needs were long-term in nature, she also wanted a temporary solution for her broken tooth, which was a source of social embarrassment. Custom prefabricated provisionals were suggested because they afforded the opportunity to fine-tune the prosthetic design, close the black triangle to the maximum degree possible, and begin shaping the interdental papilla for the final restoration. The patient liked the idea of provisionalization and agreed to the treatment plan.

Impressions were taken at the initial appointment to serve as the basis for the BioTemps provisional restorations.

Clinical and Laboratory Protocols: The Provisionals
One week later, the patient returned for delivery of the temporary restorations. Modern provisionals that are made prior to preparation of any teeth afford many advantages. In addition to offering durability and favorable aesthetics, temporary materials like PMMA can be adjusted with ease to create a precise fit and ideal occlusion, contours, and aesthetics. The BioTemps Provisionals used in this case were fabricated by the dental laboratory team (Glidewell Laboratories) based upon the initial impressions and instructions for correcting the gingival margins and interproximal contacts (Figure 4). These specifications included ovate contours to help develop the soft tissue and interdental papillae. Furthermore, the provisionals were designed in a way that would situate the base of the contact area between the maxillary central incisors less than 5.0 mm from the crest of the ridge, per the Tarnow Principle.

Figure 6. After removing both bridges, a light preparation was performed on the abutment teeth for the new bridges, including teeth Nos. 6, 8, 9, and 11. Figure 7. The BioTemps bridges were tried in, and then reline material (Jet Acrylic [Lang Dental]) was used to fill the voids between the intaglio surface of the provisional restorations and the tooth preparations. The reline material was also used to make slight adjustments to the gingival margin of tooth No. 11. Note the immediate aesthetic improvement and reduction of the open gingival embrasure between teeth Nos. 8 and 9. By designing the temporary bridges in adherence with the Tarnow Principle, the soft tissue would fill in even more during the provisionalization phase of treatment.
Figure 8. Impressions were taken of the touched-up tooth preparations and the slightly modified BioTemps for incorporation into the design of the final restorations. Since the patient had fractures to her teeth and restorations on several occasions, the final 3-unit bridges were fabricated from BruxZir Full-Strength Solid Zirconia (Glidewell Laboratories) to ensure the maximum strength of the restorations. After a month of having the patient in provisionals, the final BruxZir restorations were delivered. As virtual replicas of the approved temporaries, the new bridges fit with precision and immediately established optimal aesthetics. Note the elimination of the black triangle, which was the patient’s primary area of concern besides her initial dental injury.
Figure 9. Lateral views of the restorations illustrate how well the soft tissue adapted to the solid zirconia bridges. The patient was pleased with the final restorations, the design of which she had grown accustomed to during the provisional phase of treatment. She now feels more confident in social situations and likes to show off her new smile.

At the next appointment, the patient’s existing 3-unit restorations were removed, and vertical cuts were made to aid in their removal (Figure 5). Then the tooth preparations were touched up with a coarse diamond bur (Figure 6). The provisional, 3-unit bridges were tried in, and a reline material (Jet Acrylic [Lang Dental]) was used to fill the voids between the tooth preparations and the internal concave surfaces of the bridges present on teeth Nos. 6, 8, 9, and 11 (Figure 7). Note that a reline material, composite resin, or light-cure acrylic can be used as an additive material for provisional restorations.

Prefabricated provisionals are adaptable to the soft tissue and to chairside adjustments needed to hone prosthetic designs. It was noted that the dental lab team was able to establish gingival margins that were quite close to the desired outcome. Material was added to the temporaries at the chair to make slight alterations to the crown margin of tooth No. 11. After adjusting and delivering the temporary restorations, the patient was thrilled. She remarked that the provisional restorations were already far better than what she had before. She was especially pleased to see the dramatic improvement of the open gingival embrasure between teeth Nos. 8 and 9.

When patients are this happy with their provisional restorations, they often show them off to their friends, which can give the reputation of your practice a boost.

Restorative Phase
Next, an impression (iTero Digital Scanner [Align Technology]) was taken of the provisional restorations so that any chairside adjustments could be replicated in the final restorations. While the final restorations were fabricated, the provisionals provided immediate relief from the aesthetic issues and the social anxiety that the fractured tooth had caused the patient to feel.

The laboratory team used the impressions of the modified temporaries to update the designs for the definitive 3-unit bridges. Then the high-strength monolithic zirconia (BruxZir Full-Strength Solid Zirconia [Glidewell Laboratories]) restorations (including 3-unit bridges for teeth Nos. 6 to 8 and Nos. 9 to 11) were milled. This material was selected because the patient had fractured her teeth on several occasions, calling for a maximum-strength solution.

Delivery of the Final Restorations
The monolithic zirconia bridges were delivered and exhibited the same fit, contours, occlusion, and aesthetics as the BioTemps Provisionals (Figure 8). Because the gingiva had been contoured by the provisional crowns, there was virtually no soft-tissue inflammation upon seating of the restorations (Figure 9). The black triangle present at the time of initial consultation was completely closed as a result of following the Tarnow principles and fine-tuning the prosthetic designs with custom temporaries. The patient was extremely happy with the outcome and remarked, “I can’t wait to show off my new front teeth.”

CLOSING COMMENTS
In this case, we were able to not only replace the fractured bridge, for which the patient required urgent treatment, but we were also able to dramatically improve the aesthetics of her smile by eliminating the large open gingival midline embrasure. This is an advantageous approach in clinical situations that demand a high level of aesthetics because the clinician can test the prosthetic design in the patient’s mouth before the restoration is milled from a high-strength material. Furthermore, because the patient grows accustomed to wearing the provisional, the final restoration has a near 100% chance of aligning perfectly with the patient’s expectations.


References

  1. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol. 1992;63:995-996.

Dr. Jones received his DDS degree from the Virginia Commonwealth University School of Dentistry, where he has held adjunct faculty positions since 1976. He maintains a private practice in Richmond, Va. He has been a member of Align Technology’s speaker team since 2002, published numerous articles on digital dentistry, and recently founded Mobile Imaging Solutions (scans4you.com). Dr. Jones belongs to several dental associations and is an MAGD in the AGD. He can be reached via email at perry@drperryjones.com.

Disclosure: Dr. Jones reports no disclosures.

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