Conservative Interdisciplinary Dentistry: A Digital Approach to an Analog Problem

INTRODUCTION
Restorative dentists now have the ability to prevent over-reduction of tooth structure, to preserve sound tooth structure, and to maintain teeth for longer periods of time. The well-known idiom WIDIOM (Would I Do It on Myself?) is more important now than ever, since augmentation rather than amputation is the preferred long-lasting approach to conservative treatment.

Because maintaining as much sound enamel and other tooth structure as possible is part of the ideal outcome, prerestorative orthodontics often enables the clinician to involve fewer teeth for the ultimate in conservative treatment. For years, fixed appliance orthodontics, an invaluable therapy for younger patients, has been traditionally advocated for children; however, it is an ideal treatment for both adolescents and adults. This fundamental shift in thinking translates to more conservative restorative dentistry for adults, because teeth can now be placed in the preferred position, extruded to manage bone and soft tissue, and positioned in anticipation of eventual implants and periodontal soft- and hard-tissue augmentation.¹

For example, a patient who presents with worn teeth could also display incisal edge and occlusal plane discrepancies. While these aesthetic and structure deficiencies could be corrected restoratively, doing so would require removal of significant tooth structure to accommodate strength, aesthetic, and space requirements. However, undergoing and completing orthodontic treatment would ultimately correct the occlusal discrepancies, providing a stable and balanced occlusion as the foundation for any additional conservative restorative treatment.^2,3

Fortunately, a number of digital dental technologies are available today to facilitate the collaboration and information sharing required for proper interdisciplinary treatment planning. These include (1) digitally based removable clear orthodontic aligners (such as Invisalign [Align Technology] or ClearCorrect), (2) 3-D intraoral impression scanners (such as iTero [Align Technology], 3Shape TRIOS Pod [BIOLASE], CEREC Omnicam [Dentsply Sirona], and PlanScan [Planmeca/E4D Technologies]), (3) CBCT, (4) CAD/CAM restoration design software and milling units, and (5) digital photography and other technologies that will assist in increasing efficiency and predictability, eliminating human errors, and reducing anxiety for clinicians and patients. Although no technology replaces risk assessment, knowledge, understanding of potential outcomes, or coordination among specialists,⁴ the most forward-thinking dentists are leveraging technology to speed processes, replicate with efficiency, and to provide consistent and predictable clinical results with a cost savings. When all members of the treatment team are fully aware of the patient’s specific concerns and desires, technology can empower them with access to the same risk assessment and diagnostic information, enabling them to ultimately achieve treatment outcomes that are satisfactory to the patient.⁵

CASE REPORT
Diagnosis and Treatment Planning
A 50-year-old male presented with anterior wear on his maxillary incisors, inquiring how to improve the overall appearance of his teeth and smile (Figure 1). He said his teeth originally had more length but had shortened throughout time. He did not recall grinding his teeth, but stated that it could have been a possibility given his stressful job in the financial profession.⁶

Figure 1. Pre-op view of a 50-year-old male patient in natural smile, revealing worn incisal edges and enamel erosion.	Figure 2. Pre-op retracted view of the patient’s teeth prior to initiating clear aligner therapy (eg, Invisalign [Align Technologies]).
Figure 3. Pre-op occlusal view showing extent of the incisal edge wear.	Figure 4. Lateral cephalometric radiograph revealing no wear on the posterior teeth.

Evaluating the maxillary anterior teeth and their relationship to the mandibular anterior teeth revealed a locked-in situation (Figure 2). Based on the incisal edge wear on the anterior teeth and the absence of wear on the posterior teeth (Figures 3 and 4), the patient was diagnosed with a constricted chewing pattern. He exhibited friction between the incisal edges of the mandibular teeth and lingual surfaces of the maxillary anterior teeth, with significant crowding and rotations, and there was no freedom of movement. Space limitation was also a concern.

Without moving both the maxillary and mandibular teeth, sufficient space for treatment planning conservative restorations to enhance the patient’s smile and restore the worn tooth structure could not be established.^2,7 Additionally, restorations placed in the patient’s current alignment would be at risk for cracking and failure.^3-5 Although initially apprehensive about orthodontic intervention, the patient agreed to an immediate conversation with an orthodontist in the adjacent office to discuss possible treatments and potential outcomes, after which a formal consultation was scheduled. Options presented to the patient were traditional fixed ortho­dontic appliances and clear removable aligner therapy.^8-10

After considering his options, the patient elected to proceed with clear aligner treatment (Invisalign). However, he did inquire about whether aesthetic restorative treatment could be rendered without aligner therapy. The implications and long-term risks of undergoing restorative treatment without first properly addressing alignment and space issues were then thoroughly discussed. The patient was also advised that should he elect to forgo orthodontic treatment, the restorative dentist would not proceed, since the risk assessment and prognosis indicated that treatment would be compromised with premature restorative failure being the ultimate outcome.⁶

Digitally Planning Aligner and Restorative Treatment
Digital technologies were essential tools for visualizing and treatment planning the anticipated outcome of restorative treatment, which would be predicated on the specific tooth movement accomplished through the aligner therapy.¹⁰ Digital photographs, a short video consultation with the patient, and accurate preoperative impressions (COUNTER-FIT [CLINICIAN’S CHOICE Dental Products], an alginate substitute impression material) were among the diagnostic records gathered for use in constructing a digital smile design in Keynote presentation software. This enabled the patient and orthodontist to preview the required changes in tooth form and space (Figure 5).

When the patient presented to the orthodontist for planning the clear aligner case, digital impressions were taken of his entire dentition using an iTero Chairside Scanner. These scans were digitally transferred to Invisalign for generating a ClinCheck movie, allowing the patient and orthodontist to preview the anticipated tooth movements and final tooth positions (Figure 6).¹⁰ After review and acceptance of the proposed aligner treatment, the aligners were ordered and delivered to the patient. Properly aligning the teeth and creating the space for restorative treatment required the use of 12 trays during the course of 6 months (Figure 7).^9,10 Following aligner treatment, a lingual retaining wire was bonded from teeth Nos. 22 to 27 to prevent relapse, after which the patient was released to begin restorative treatment.

Figure 5. A digital smile design was constructed as a preview of the required changes to tooth form and space and as a guide for both orthodontic and restorative treatment.	Figure 6. The Invisalign ClinCheck enabled the patient and orthodontist to preview the anticipated tooth movements and final tooth positions.
Figure 7. View of the patient’s teeth following Invisalign treatment. Note the retraction of the mandibular incisors.	Figure 8. Teeth Nos. 7 to 10 were conservatively prepared in enamel only.

Restorative Diagnostic Mockup
To create an intraoral diagnostic mockup, an additive approach was taken to build up teeth Nos. 7 to 10. The enamel on these teeth was left unprepared, and they were isolated using NeoDrys (Microcopy) and cotton rolls. A universal adhesive (Adhese Universal [Ivoclar Vivadent]) was applied to the enamel and light-cured (Bluephase Style [Ivoclar Vivadent]). A flowable composite resin (Tetric EvoFlow [Ivoclar Vivadent]) was then slowly and gradually placed to build up the line angles, incisal edges, and facial contours. After light-curing, the final contours and shape were established using a polishing disc system (Diacomp Composite Polishing Kit [Brasseler USA]). Final adjustments were made to determine tooth length and then polishing was accomplished utilizing a combination of gross anatomy polishers and fine final polishers (DEFine [CLINICIAN’S CHOICE Dental Products]). At this point, aesthetics and phonetics were verified with the patient sitting upright and having a brief conversation.

Impressions and Preparation
An impression of the intraoral mockup was captured (Template Clear [CLINICIAN’S CHOICE Dental Products]) and the patient was then anesthetized. Using specifically designed porcelain veneer preparation depth cutters (Ritter & Ramsey Indirect Restorative System [Brasseler USA]), the minimal amount of tooth reduction required (0.5 mm to 0.7 mm) was achieved according to Gürel’s aesthetic pre-evaluative temporary protocol.^7,11 This allowed the preparations to remain in enamel, which has been shown to contribute to restoration longevity due to the quality of the supporting tooth structure substrate (Figure 8).^7,12

The mockup was removed, the final preparations smoothed and polished, and 0.08 dental packing cord (Siltrex) was placed to slightly deflect the gingival tissue. Care was taken not to disturb the attachment complex or to violate the biologic width. Next, the preparations were then rinsed with copious amounts of water. Preparation photographs and intraoral digital impression scans (iTero Chairside Scanner) were also taken, and the opposing arch and bite were recorded. These records were sent to the laboratory for margin marking.

The digital Surface Tesselation Language (STL) records file was transferred to iTero for milling a model from wax and then forwarded to the laboratory team for use in the fabrication of pressed lithium disilicate restorations (IPS e.max Press [Ivoclar Vivadent]). Although zirconia is an all-ceramic option in certain restorative cases, the final aesthetic restorations being done here would be partial-coverage bonded restorations, and zirconia is not a good choice in this clinical situation. However, the physical, optical, and excellent strength (400+ MPa flexural strength; fracture toughness [SEVNB] 2.5-3.0 MPa•m^½) properties of IPS e.max Press lithium disilicate would serve to maintain the incisal edge strength, while the ability to cut back the facial surface would contribute to both highly aesthetic outcomes and fracture resistance.

Provisionalization
The preparations were scrubbed with a 2.0% chlorhexidine gluconate paste (Consepsis Scrub [Ultradent Products]), then rinsed and dried. A self-etching adhesive primer (OptiBond Primer Bottle 1 [Kerr]) was then scrubbed on the preparations.

An A1 shade of provisional material (Luxatemp Automix Plus [DMG America]) was placed in a clear impression made from the mockup, then placed over the prepared teeth. After 3 minutes, the provisional impression was removed. The provisionals were then carefully trimmed using ET burs (Brasseler USA), and the occlusion was verified using foil (TrollFoil [TrollDental USA]).

An at-home protocol was reviewed with the patient, including instructions not to bite into or chew any hard/tough food items. When he returned one week later for a tissue and engineering check, any interferences were adjusted, and the shades were chosen for the final restorations in collaborations with the patient.

Impressions and photographs of the provisionals were taken during this appointment (Figure 9). Additional information for the dental lab team included taking a stick bite (relating the incisal edge to a flat surface), along with a Kois Dentofacial Analyzer so that the case could be mounted on an articulator (Panadent).

Restoration Fabrication
Based on the STL file and the milled wax model, the laboratory team used CAD software (3Shape) to design and then press the restorations from high translucency lithium disilicate ingots (IPS e.max Press; HL BL1). They were tried on the model to confirm fit, then cut back facially to enable porcelain layering for depth and characterization, done without interfering with the incisal edge. (A layered porcelain incisal edge would have been weaker than the entirely pressed edge.) The finished restorations were then sent to the dental office for delivery to the patient.

Figure 9. The provisional restorations would help guide the aesthetic, shape, and length requirements for the final restorations.	Figure 10. A universal cleaning paste (Ivoclean [Ivoclar Vivadent]) was applied for 20 seconds then rinsed off with water to remove surface debris and phospholipids from the internal restoration surfaces.
Figure 11. A hydrofluoric and silane coupling agent (Monobond Etch & Prime [Ivoclar Vivadent]) was applied to the internal restoration surfaces.	Figure 12. With Teflon tape applied to the canines to protect them from the surface conditioning, phosphoric acid gel was applied to the enamel preparations for 10 seconds.
Figure 13. A universal adhesive (Adhese Universal [Ivoclar Vivadent]) was applied to the preparations for 15 seconds per tooth using a VivaPen (Ivoclar Vivadent).	Figure 14. A Warm Air Drier (A-dec) was used to evaporate the ethanol solvent in the universal adhesive.

Delivery of the Final Restorations
During the delivery appointment, the patient was anesthetized, the provisionals removed, and any remnants of bis-acryl cleaned away. A microetcher was used to quickly abrade the tooth preparation surfaces, and the restorations were tried in dry to verify fit. After removal, the internal aspects of the restorations were cleaned using a universal cleaning paste (Ivoclean [Ivoclar Vivadent]) (Figure 10), then thoroughly rinsed and dried. Next, the restorations were simultaneously etched and silanated using Monobond Etch & Prime (Ivoclar Vivadent) (Figure 11). Per manufacturer instructions, the etch and prime solution was applied to the internal surfaces, agitated for 20 seconds, and then allowed to stand for an additional 40 seconds. Next, the restorations were then rinsed thoroughly and dried with water- and oil-free air for 10 seconds.¹³

The teeth were isolated with a nonlatex rubber dam, and Teflon tape was applied to the canines to prevent involvement of those surfaces. Phosphoric acid gel was applied for 10 seconds to the enamel preparations (Figure 12), and then thoroughly rinsed off, leaving the surface moist. An 8th generation universal adhesive (Adhesive Universal) was scrubbed onto each tooth for 15 seconds (Figure 13),^14,15 and a Warm Air Drier (A-dec) was used to evaporate the solvent carrier (Figure 14).¹⁶ The adhesive was light-cured for 10 seconds per tooth (Bluephase Style) (Figure 15).

A light-cure only aesthetic resin cement (Variolink Esthetic, Shade 0 [Ivoclar Vivadent]) was placed in each veneer, and the centrals followed by the laterals were seated with the operatory light turned off (Figure 16). The restorations were spot tack-cured into place and then, using the wave technique, the curing light was applied for 3 seconds per tooth (Figure 17). This enabled easy removal of excess cement from the teeth using a brush (Benda Brush) and/or interproximally with floss. Final light-curing was then performed from the facial, lingual, and incisal aspects, and additional excess cement tags were removed using a scaler (Figure 18).

To ensure there was no interference to the envelope of function, the canine incisal edges were additively sculpted to recreate cusp tips. These teeth were first etched, then a universal adhesive (Adhesive Universal) applied and cured. Shade A1 of an aesthetic direct composite (IPS Empress Direct [Ivoclar Vivadent]) was then placed, light-cured, and finished.

When the rubber dam was removed, a 200-μm horseshoe articulating paper (Bausch) was placed with the patient sitting upright, and the patient spoke to capture the envelope of function. Any aberrant lines on the lingual of the maxillary incisors were removed with a football diamond (8379 .018-fine football diamond [Brasseler USA]); this process was repeated until all stray lines were removed. A 0.008 shim stock was placed to ensure that no friction between the incisal edges of the mandibular teeth was in contact with the lingual surfaces of maxillary tooth structure.

The patient returned one week later for a final tissue and engineering check, as well as to verify that the envelope of function had not been altered, thus protecting the new restorations. Final polishing of the composite resin was also accomplished using fine polishers (Figures 19 to 21).

Figure 15. The adhesive was then cured for 10 seconds per tooth (Bluephase Style [Ivoclar Vivadent]).	Figure 16. A light-cure only aesthetic cement (Variolink Esthetic, Shade 0 [Ivoclar Vivadent]) was placed in each veneer.
Figure 17. Spot tacking each veneer for one second secured them in place, enabling easy cleanup of any excess cement.	Figure 18. A scaler was then used to remove any excess cured veneer cement.
Figure 19. Post-op retracted view of the final tooth display.	Figure 20. Post-op view of the patient’s natural smile.

Figure 21. Close-up retracted postoperative view of the final pressed lithium disilicate (IPS e.max Press [Ivoclar Vivadent]) restorations. Note the aesthetics, healthy tooth-to-gingival tissue interface, and increased length of the cuspids achieved using direct composite.

CLOSING COMMENTS
Working according to an interdisciplinary team concept in which everyone involved (orthodontists, periodontists, and the laboratory team) gathers and shares appropriate data minimizes potential risks and helps achieve long-lasting treatment success for the patient. The ultimate goal of conservative aesthetic restorative dentistry includes: ideally preparing less tooth structure and maintaining as much healthy enamel as possible, making the final restorations as structurally strong as possible, and following the patient’s established envelope of function. Violating any one of these principles could result in treatment failure. Therefore, evaluating each patient’s unique biological makeup and discussing his or her restorative desires in the context of findings from analyzing the risk assessment for restorative treatment are essential to success. In this patient’s case, the incisal edge wear was caused by malpositioned lower anterior teeth. Involving more teeth (or tooth structure) was not desirable because it would put even more teeth in the system at risk. As demonstrated in this case, moving the teeth into the ideal positions, as a prerestorative step, is of paramount importance.

Acknowledgment
The author would like to thank the following individuals for contributing their professional expertise and talents to the successful outcome of this case: Scott Meier, DMD, for performing the ortho­dontic treatment, and Dwight Rickert, CDT, from Preferred Dental Ceramics (Indianapolis, Ind) for fabricating the beautiful all-ceramic restorations.

References

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Dr. Ritter has a private practice focusing on adhesive and aesthetic dentistry. He graduated from the Medical University of South Carolina College of Dental Medicine in 1994. He is also a Kois Center and Spear Education graduate. He is adjunct assistant clinical professor of prostho­dontics and operative dentistry at Tufts School of Dental Medicine and also an adjunct faculty clinical professor prosthodontics at Nova Southeastern College of Dental Medicine. In addition, he is a member of the American Academy of Restorative Dentistry and a member of the American Academy of Esthetic Dentistry. He is one of Dentistry Today’s Leaders in Continuing Education. He lectures internationally on cosmetic dentistry, implant dentistry, new materials, joint-based dentistry, digital technologies in and for the modern dental office, and social media. He can be reached at (561) 626-6667 or via email at drritter@ritterandramsey.com.

Disclosure: Dr. Ritter reports no disclosures.

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