Aesthetics and Removable Prosthetics

Design, implementation, realization: These 3 words represent the theme of American Academy of Cosmetic Dentistry (AACD) 2016 International Conference in Toronto. Well-thought in title choice, these words are the essence of the artistic mindset, with maybe the addition of the word vision. Vision is the predecessor to the reality of the others. Vision…design…implementation…realization. Seeing the end result, in advance of treatment, is visionary. Observing the final product of our efforts at completion is realization. These become the bookends, with the technical and clinical expertise in the middle, described as design and implementation.

Much has to be considered in the rehabilitation of a patient who has been debilitated from tooth destruction and tooth loss. This debilitation refers not only to the inherent functional and aesthetic compromise that may exist intraorally but, equally as important, to the impact on extraoral features of facial aesthetics. It is the outline of vision, design, implementation, and realization that guides us through our treatment process to the optimal dento-facial aesthetic and functional outcome.

VISION
Preoperative Condition at Initial Visit
Any attempt to design a functionally aesthetic dentition without first considering what surrounds it is akin to furnishing a multimillion-dollar condominium overlooking Central Park with a folding chair and a card table and having the expectation of acceptability. It does not work. One would not complement the other. There is no synergy, balance, or proportion, and there must be.

Figure 1. Frontal view showing unsupported lips.	Figure 2. Right view showing lack of upper lip support and concave profile.

Figure 3. Left view showing lack of upper lip support and unsupported facial volume.

To not look first extraorally (the facial perspective) likely would lead to an inferior aesthetic result within the dentition. How so? The deficiencies in the lower third of the face are very often impacted by the deficiencies within the design of the dentition. Observation of the face tells us a lot about what we can do to enhance it via aesthetic dental design. Lip support: lack of it yields a compromised facial profile. Cheek support: lack of it gives a “sunken-in” look. Tooth display: lack of it signals an aged face/individual. Shade: incorrect choice reeks of unnaturalness. All can (and do) dramatically affect the aesthetics of the face. Our challenge is to select methods of treatment that answer the above and to do so in a way compliant with functional guidelines that provide long-term stability.

DESIGN
Extraoral (Facial) Evaluation
In the patient presented, there is the obvious lack of support in the lower one third of the face (Figures 1 to 3). Compromise of the facial profile, ie, lack of upper lip support and collapse of the cheek area, pronounced nasolabial fold, along with thinness of the upper lip were evident. Lack of underlying dental support was a significant part of the etiology of the compromised facial aesthetics. Tooth loss and implant failure with consequential alveolar destruction both horizontally and vertically were significant factors contributing to the concave and unaesthetic profile exhibited here. An organized and systematic approach is required to evaluate, diagnose, and resolve aesthetic problems predictably.¹ This is accomplished through evaluation of the relationship between intraoral and extraoral facial references.

Figure 4. Frontal pre-op view showing defective dentition/implants.	Figure 5. Right lateral view showing defective dentition/implants.
Figure 6. Left lateral view showing defective dentition/implants.	Figure 7. Occlusal view showing the screw-retained provisional prosthesis.
Figure 8. Primary bar on model.	Figure 9. Secondary bar (internal) and latch mechanisms within wax-up.

Intraoral Evaluation
This patient presented with a history of extensive defective restorative treatment, and had been previously treated with implants in the maxillary arch, which had then been restored with metal ceramic crowns/bridgework. The anterior implants had failed and had been removed. The patient was wearing a partial denture, which was being retained by the remaining posterior implant bridges. The alveolar ridge had been significantly compromised by the implant failures in this area and their subsequent removal. The anterior alveolar ridge was dimensionally deficient, resulting in significant collapse of anterior lip support that could only be maintained by the removable prosthesis. Both implant bridges were defective and the implants on the upper left posterior quadrant were failing. The occlusal scheme showed a staggered (stepped) interarch relationship, which had contributed to the overall failure of this previous rehabilitation. The lower arch too was compromised with defective restorations that would require correction (Figures 4 to 6). Rehabilitation of this patient would require extensive restoration of the entire lower and upper arch, each requiring different treatment measures to address functional and aesthetic conditions of the dentition and the face.

IMPLEMENTATION
Treatment Phase
Complete radiographic, periodontal, photographic, and clinical examinations were implemented along with mounted diagnostic models. Evaluation revealed failing implants in the maxillary left area. The implants in the maxillary right area were deemed salvageable. The anterior segment of the maxillary arch provided enough bone to propose placement of implants in this area. It was decided to place implants (Straumann) in the Nos. 8, 10, 12, and 14 areas to supplement the existing and salvageable implants in the Nos. 2, 4, 5, and 6 positions. The implants placed were Straumann Regular Neck Tissue Level in the Nos. 8, 9, and 14 positions and Narrow Connection Bone Level in the No. 12 position.

Figure 10. DuraLay (Reliance Dental) verification index on model.	Figure 11. DuraLay verification index.
Figure 12. Primary bar try-in.	Figure 13. T-Scan (Tekscan) evaluation of the occlusion.
Figure 14. Retracted view of final prosthesis.	Figure 15. Lateral profile view showing prosthesis in place and facial support.
Figure 16. Final prosthesis showing latch mechanisms.	Figure 17. Extraoral view of prosthesis.

Prosthetic Design
The choices in design are removable, fixed-removable, and fixed. Because of the compromised alveolar ridge and lack of vertical height, and requests by the patient, consideration of a removable prosthesis (den­ture) was eliminated.

A fixed implant-retained bridge design presented a challenge to effectively attain excellent dental aesthetics. The incisal to cervical length (to the ridge) would be unaesthetic (proportionally compromised). Creation of an aesthetic (extraoral) soft-tissue profile (upper lip and buccal corridors) would not be optimally attainable with a fixed design with this patient’s hard-tissue deficiencies.

Due to the need to provide significant facial support extraorally, and to provide excellent dental aesthetics and function, it was decided to utilize a fixed-removable design prosthesis. Choices in this were varied. The patient and doctor desired the most retentive design that allowed her to access all implant areas for optimal hygiene while providing optimal aesthetics. Again, the issue of stability and security of the prosthesis was of paramount importance to the patient. A screw-retained overdenture presented one option but negated the ease of cleansability on a daily basis. A LOCATOR attachment (ZEST Anchors) consideration could have been a viable and more economic choice providing a fixed/removability option. However, due to the extreme length between the alveolar ridge height and the ideal location of the incisal edge (occlusal plane) position, concerns about lateral force stability were in question.

Given the above issues, the doctor, patient, and laboratory team (Dental Arts Laboratories [DAL; Peoria, Ill]) made the decision to utilize the “Spark Erosion Bar” design.

Preprosthetic design required the removal of all failing implants and the strategic placement of new implants. The retained/usable implants in the Nos. 12, 13, and 14 positions along with the (ultimately to be extracted) implant in the No. 15 position provided retention and reference for the existing removable transitional prosthesis until integration of recently placed implants occurred. Once integration was attained, a new, more aesthetic, and accurately functional transitional (screw-retained) prosthesis was fabricated, following the functional and aesthetic guidelines of the diagnostic wax-up. In conjunction with this, the lower arch was restored using lithium disilicate (IPS e.max [Ivoclar Vivadent]) restorations. The upper transitional prosthesis (Figure 7) was equilibrated to a stable centric relation with the newly placed lower arch restorations. This provided a more accurate record of the ultimately desired aesthetic and functional design of the final prosthesis. Once the patient was in a comfortable and aesthetic position, the spark erosion technique would have a predictable outcome.

Spark erosion technology is a highly advanced system for producing the ultimate in combination fixed/removable precision partial dentures and implant prosthetics. Using precise electro-machine milling and electro-machined attachment applications, spark erosion is ideal for implant reconstruction and is indicated for the maxillary/mandibular full-arch and partial trauma case reconstruction, especially where significant loss of facial support has occurred.²

This implant-supported restoration featured a double-bar design consisting of a fixed/detachable primary bar with a removable secondary bridge. This combination of fixed primary bar and removable secondary bridge would provide the patient with a rigid fixed restoration with the following unique advantages:

• Maximum aesthetic (tissue adaptation) and phonetic (ridge lap) design
• Maximum strength and overall stability, ideal for the Class II and III jaw relationship and bruxism
• Precision double-bar design allows for correction of compromised abutment location
• Removable secondary bridge for hygiene access
• Versatile, patient-friendly at­tachment design
• Absolute parallelism
• Compatible with all implant systems (Figures 8 and 9).

Protocols in the fabrication of the spark erosion bar are as follows.

Appointment 1 (Primary Impression)

• Record primary impression with stock tray. A preliminary impression is recorded over the healing abutments or the temporary abutments, providing the laboratory with a preliminary working cast. This preliminary cast will provide the restorative dentist and the laboratory with the initial criteria for final prosthetic abutment selection and allow for construction of a custom tray for the final impression.
• Allow 3 working days in laboratory for fabrication of custom tray.
• The existing temporary bridgework or denture will need to be relieved in the areas of the healing abutments and incision sites, and soft-lined with a conventional liner.

Appointment 2 (Master Impression)

• Place final abutments or inserts and check for proper fit and tightness.
• Place transfer components.
• Make sure the base of the abutment is flush with the surface of the implant. This relationship can be verified radiographically to ensure complete seating.
• Record final impression. The impression material used was a vinyl polysiloxane (Flexitime [Heraeus Kul­zer]).
• Once the impression has been recorded, remove the transfer coping from the implant and attach to the appropriate analog (abutment or implant analog). The coping/analog assembly is inserted into the impression in proper position.
• The impression was sent with coping/analog assemblies in position to DAL for fabrication of the master stone or soft-tissue cast along with fabrication of the verification index and the occlusal record bases, allowing for 4 working days in the laboratory.

Appointment 3 (Centric Jaw Relationship/Verification Index)

• A verification index is fabricated to aid in the evaluation of the master cast, and to help ensure that each implant bar or bridge framework will be cast and delivered with a passive, accurate fit.
• Waxing sleeves or gold cylinders are secured to the master cast and are luted together with a light-cure resin. The index is then delivered for try-in.
• Try-in verification index without fixation screws to verify a passive fit.
• Visibly check to see if the index sits passively on the abutments; then use gentle finger pressure to determine if there is a discrepancy in fit (rocking, fulcrum, or gap). If there is a discrepancy, simply cut the framework and reassemble to the corrected position.
• Once the individual sections are firmly secured to the abutments with the fixation screws, lute the reassembled framework together with a light-cure resin, such as GC PATTERN RESIN (GC America) or DuraLay (Reliance Dental)—although this was not necessary due to proper initial fit.
• Remove the assembly from the mouth and secure it to the proper analogs, using the fixation screws. Place the assembly into a stone paddy and send to the laboratory. The lab would then retrofit the master cast to the position of the corrected verification index (Figures 10 and 11).
• The framework can now be waxed and cast with the assurance of an accurate master cast. Secure the occlusal record base with the fixation screws, and record the vertical and centric jaw relationship. Contour the rim and relate any conventional landmarks, then re­cord mould and shade selection.
• Send verification index and centric jaw relationship to the lab—allow 5 working days in laboratory for wax setup for try-in.

Appointment 4 (Wax Setup for Try-In)

• Evaluate wax setup for proper aesthetic display and vertical and centric relationship.
• Return to the laboratory for fabrication of the plaster matrix and the Spark Erosion primary bar—allow 8 to 10 working days in laboratory.

Appointment 5 (Spark Erosion Primary Bar Try-In)

• Prior to constructing the secondary framework with the swivel-latch and friction pin attachments, the primary bar is delivered for try-in (Figure 12).
• Try in bar without fixation screws and evaluate for a passive fit to the prosthetic abutments. If there is any rocking, or if a gap exists between the bar and the abutment, section the bar in the area where the discrepancy exists.
• Secure the individual sections to the abutments with the fixation screws and reassemble with GC PATTERN RESIN or DuraLay (this was not necessary due to proper fit).
• Remove the assembly from the mouth, and secure it to the proper analogs using the fixation screws.
• Place the assembly into a stone paddy and send to the laboratory for soldering. The lab would wax, cast, and mill in the secondary framework and then electro-machine the swivel-latch and friction pin attachments. Allow 10 to 12 working days in laboratory.

Appointment 6 (Spark Erosion Precision Implant Restoration Try-In)

• Evaluate the fit of the primary bar and secure with fixation screws.
• Place and evaluate the secondary framework with the swivel-latch attachments engaged.
• Evaluate the wax-up for proper aesthetics, function, and phonetics.
• Return both primary bar and secondary framework with the wax-up for final processing and finishing—allow 4 working days in laboratory.

Appointment 7 (Delivery)

• Secure the primary bar with fixation screws and seat the secondary restoration, demonstrating to the patient how to engage and disengage the swivel-latch attachments.
• Evaluate aesthetics, fit, and occlusion.
• Instruct patient on proper home care and oral hygiene considerations.

REALIZATION
The overdenture prosthesis was constructed in acrylic and with Mondial i and Premium denture teeth (Heraeus Kulzer). Challenges sometimes exist when attempting to match prosthetic teeth to ceramics and natural dentition. The Mondial system (Heraeus Kulzer) of denture teeth is unique in that it has a nanostructure design previously only known in the field of composites. This results in a significant resistance to wear and consequently, a longer lifespan. Unlike most common denture teeth, the Mondial line is much more naturally aesthetic due to the blending of multiple layers of dentin and enamel shades of composite to create a natural, lifelike effect.³

The prosthesis and lower restored dentition were equilibrated utilizing T-Scan (Tekscan). T-Scan provides dynamic occlusal measurements revealing the level and timing of force on individual teeth and the occlusal stability of the overall bite (Figures 13 to 17).⁴

The benefit of choosing a removable/fixed design with the spark erosion bar technique enabled us to effectively address intra- and extraoral aesthetic concerns and overall functional stability of the prosthesis. Analysis of the soft-tissue profile by measurement of the nasolabial angle, lip protrusion, and interlabial distance clearly reveals the dramatic aesthetic impact of enhanced facial support and volume through dental design (Before and After Images).⁵

CLOSING COMMENTS
Between the vision we have for the outcome of a case and the realization of it in the end, there exists the design and implementation of it. Design and implementation are grounded in the understanding of craft and art. Craft being the mechanics of its construction and art being the quality of its construction, both of which are contained within and impact the frame of the oral-facial complex. What is to be gained here is that optimal realization can only be attained through understanding that there is a synergistic relationship between what we design intraorally and what surrounds it extraorally; and that one should always be addressed in consideration of the other.

Acknowledgements
The author would like to acknowledge Dental Arts Laboratories (DAL) (Peoria, Ill). and the quality people in their employ and for their expertise and support; Dr. Jay Beagle, DDS, (periodontist and implantologist, Indianapolis, Ind); and the AACD for their everlasting mission to continue to implement change through the highest standard of education and support to its members.

References

1. Chiche G, Pinault A. Artistic and scientific principles applied to esthetic dentistry. In: Chiche G, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago, IL: Quintessence Publishing; 1993:13-23.
2. Heraeus Kulzer, LLC. Mondial i and Mondial with NanoPearls. heraeus-kulzer-us.com/media/webmedia_local/north_america/pdf_files/brochures/Mon­dial_Brochure_2012_pages.pdf. Accessed March 14, 2016.
3. Salinas TJ, Finger IM, Thaler JJ II, et al. Spark erosion implant-supported overdentures: clinical and laboratory techniques. Implant Dent. 1992;1:246-251.
4. Kerstein RB, Wilkerson DW. Locating the centric relation prematurity with a computerized occlusal analysis system. Compend Contin Educ Dent. 2001;22:525-536.
5. Ferguson DJ. Growth of the face and dental arches. In: McDonald RE, Avery DR, Dean JA. Dentistry for the Child and Adolescent. 8th ed. St. Louis, MO: Mosby Elsevier; 2004:534W-549W.

Dr. Kirtley has been involved in the field of cosmetic dentistry since 1985 and has positioned himself as an international leader in dentistry through teaching, lecturing, writing, and providing aesthetic smiles seen on patients throughout the United States and Europe. He completed his DDS at Indiana University and is an accredited member of the American Academy of Cosmetic Dentistry and the British Academy of Cosmetic Dentistry, presently one of a very few dentists worldwide to be accredited in both the United States and the United Kingdom. He is a part of the leading cosmetic teaching institution, The Aesthetic Advantage, located at the Rosenthal Institute in New York City. Additionally, he serves as a visiting lecturer at New York University College of Dentistry. He can be reached by phone at (317) 841-1111 or via email at the address george@smilesbygeorge.com.

Disclosure: Dr. Kirtley reports no disclosures.