34

www.dentistry.co.uk

Clinical

Creating predictable aesthetic results Dr Scott W Finlay explains the the application of the functional aesthetic matrix

restorative dentists, we need to be comprehensive in our evaluation of our success or failures. Our vision of failure is often narrowed to the fracture of the restoration, when in truth we need to also appreciate failure to represent all of the signs and symptoms of occlusal disease including tooth mobility or migration, gingival recession and sensitivity5.

As our understanding of the design of the stomatognathic system has evolved, we began to identify and address the two primary etiologies of dental deterioration: bacteria and force. By creating restorations that mimic natural tooth contours and with proper positioning, we can provide an environment that is cleansable and maintainable for our patients, and promote the best opportunity to obtain optimal biological health6. With the application of the functional matrix presented Dr Dawson, we can begin to manage the risk factors related to force. The functional matrix is a sophisticated system that is composed of three primary elements: teeth, muscles and a joint. A compromise in any one of these components will inescapably influence the other two. This matrix, when appropriately functioning, allows the muscles to respond in a non-antagonistic way, providing comfort and efficiency.

The design of this system allows the temporomandibular joints, when they are in their hinge axis position, to facilitate balanced simultaneous contacts on all teeth, with an anterior guidance that is in harmony with the envelope of function and a peaceful neuromusculature. This helps to insure an orthopedically stable position. The starting point of this functional matrix begins with a balance distribution of forces with muscles that are comfortable and coordinated due to the non-conflicting proprioceptive feedback from the sequentially loaded teeth (Figure 1). We begin with the assessment of the joint, because we are focused on predictability. Predictability that provides us with a reproducible, specific reference point we refer to as centric relation that is based upon our scientific understanding of the physiology in this orthopedically stable relationship7.

The baby boomers are coming of age. They are cumulatively beginning to experience the signs and symptoms of dental deterioration. They represent a significant demographic with very special dental needs. They enter our offices asking to improve their oral health and their smiles1. Many have done their online research and are requesting veneers, whitening and Invisalign. The restorative dentist’s challenge becomes the reconstruction of these smiles with plastic and glass, with predictability and durability. Adding pressure to this demand, the media and economy have influenced the mindset of the consumer, resulting in more educated shoppers who put great value on having it done right the first time2.

Although the ability to provide tooth-coloured restorative materials and techniques has been available for the past century, in the earliest form as silicate cements, the predictability and aesthetic results were disappointing3. Great progress was made in dental materials over the ensuing decades, but the missing link was the relationship of these aesthetic goals and the proper management of the engineering of the system within which these teeth functioned. These wonderful advancements in materials have allowed us to be even more conservative and effective in providing dental treatment4. However, relying on technology alone can be a double edge sword as it can also have the effect of getting us into to trouble faster. Dr Dawson tells us that 90% of failures are not attributed to the materials or techniques, but our failure to plan. As

Scott W. Finlay DDS, FAGD, FAACD graduated with honours from University of Maryland, Baltimore College of Dental Surgery and a GPR program at a Washington DC Area Trauma Hospital. He was accredited by the American Academy of Cosmetic Dentistry

in 2007 and received his fellowship in 2010. He currently serves as an examiner and was elected to a seat on the American Board of Cosmetic Dentistry for accreditation and is a contributing editor for the Journal of Cosmetic Dentistry presenting the examiner’s perspective. He is also the author of the recent revision of Contemporary Concepts in Smile Design, which is the criteria guide that serves as a basis for Accreditation in the AACD. Dr Finlay is a senior faculty member for the Dawson Academy. He teaches contemporary functional concepts related to aesthetics and restoring anterior teeth in a hands-on format. He has contributed articles that have appeared in professional journals such as the Journal of Cosmetic Dentistry, Dentistry Today, Dentistry (UK) and Vistas. He began his practice in Annapolis, Maryland in 1987 (www.AnnapolisSmiles.com) with a special emphasis on aesthetic and restorative dentistry. Dr Finlay is a fellow in the Academy of General Dentistry and has been awarded four gold metals in the AACD annual Smile Gallery. He has appeared on Baltimore Fox 45 Morning News and two other health television programmes as an expert in dental aesthetics.

Table 1 : Functional aesthetic analysis

Figure 1: The orthopaedic relationship of the articu-lator to the face

Figure 2: Dawson photographic series

35

www.dentistry.co.uk

Clinical

Our goal is to provide predictable solutions for our patients with the absolute best aesthetics possible. Our responsibility is to be our patient’s advocate in accomplishing this endeavour as conservatively as possible through the application of a timeless protocol. This protocol is a marriage of our understanding of how this system functions and our vision of universally accepted parameters of dental aesthetics, otherwise know as smile design. This protocol is comprehensive in nature and is evidence based.

The application of this advanced level of treatment planning is not about elitism, or dentistry for the rich and famous. Whether the solutions involve plastic or ceramic, implants or partials, the decision process remains the same. We must not be overly focused about selling products off the shelf like veneers, bonding or implants, but a treatment solution that endorses and promotes health, providing balance in a maintainable environment. This consistency in treatment planning presents a unique value in challenging economic times, when treatment may involve transitional stages that allows for upgrades in the future when resources permit8.

The process begins with a complete exam and an understanding of the patient’s desires. Our responsibility

is to study this forensic data and make recommendations for treatment based upon the signs and symptoms of dental disease that exist. Educating the patient about their dental needs and relating them to their desires, provides a platform to make decisions that are well supported and in the patient’s best interest. The protocol involves four stages:• �2D�treatment�planning – an assessment of the

biological, structural, functional and aesthetic components of the smile creating a vision with the end in mind

• 3D�treatment�planning – the in vitro creation of a dental blue print through the use of diagnostic mounted models with the anticipated surface changes to the teeth modelled in wax

• Prototype�restorations – the in vivo testing of the design of the contours and positions of the teeth in the patient’s smile

• Definitive�restorations – the delivery of the final restorations.In 2D treatment planning we begin with the first of our

checklists to help insure our result. In our 2D functional aesthetic checklist we assess the stability of the joints and complete a tooth-by-tooth evaluation (Table 1). We begin to create a vision of potential solutions for the aesthetic and functional needs of the patient. Smile design are those

Figures 6a-e: Photos of incisal guide table and incisal matrix

Figure 3: Smile design architecturei

Figure 5: Matrices from wax-up

Figures 4a and b: The dental blue print – the occlusal analysis and diagnostic wax up

Figure 6a

Figure 6c

Figure 6e

Figure 6b

Figure 6d

Figure 7: The four step protocol to predictable aesthetics: pre-op, diagnostic wax up, prototypes, final restorations

Figure 6d

parameters of dental aesthetics that have been recognised and vetted over the past several decades (Figure 2). Our analysis of smile design is divided into three sections to conceptually assist our evaluation (Figure 3). We begin with the broadest strokes of smile design and progressively narrow our focus to critique the individual characteristics in our attempt to emulate nature. The concepts of global aesthetics focuses on those criteria that are observed in un-retracted smiles and how the smile orients to the face and the lips that encircle them.

As we continue to narrow our study, our attention aims toward the elements of macro aesthetics. Macro aesthetics identifies the shapes and contours of teeth and their relationship to each other. Our final frame of reference converges on micro aesthetics, which are those criteria related to the subtle intricacies of shade, textures, translucencies and surfaces effects that make teeth look like teeth. These are the criteria that aid us in fooling the eye and allowing restorations to blend invisibly into the smile. Although aesthetics in the purest sense is a subjective experience that is open to artistic interpretation, it is first important to establish a universal set of objective, systematic criteria that will allow us to measure and guide our evaluation process. It is important to keep in mind however, that every smile is not the same. The true art in creation of a beautiful smile is modulated by the specific idiosyncrasies of the individual patient and their underlying functional requirements. The core principle is that if we don’t first share a common set of parameters for dental aesthetics and smile design, then deviations from these criteria can only be met with inconsistent success and uncertain value. Effective artistic interpretation can only come after mastering the proper founding principles of smile design9.

In 3D treatment planning we have the opportunity to begin to test out our best guess of how we envision the smile to be. This is accomplished with the use of accurately mounted diagnostic models in duplicate. While one set of models provides our original reference point, the second set is manipulated with the use of reductive re-contouring or additive waxing to begin to simulate the anticipated results. This anticipated design can then be virtually tested on the articulator to see if it meets the functional parameters for stability and predictability. Once the contours of the teeth have been defined by this modulation process it becomes our dental blueprint (Figure 4). A specific set of matrices can then be fabricated from this blueprint, to be utilised chairside to allow our preparations to be efficient and conservative. These matrices will also aid in the fabrication of prototype provisional restorations (Figure 5)10.

The prototype restorations play a far more important role than simply a transitional phase as the lab fabricates the definitive restorations (Figure 6). These prototypes are a reflection of the anticipated shapes and contours of these final restorations and allow us to verify two important criteria related to function and aesthetics. The

36

www.dentistry.co.uk

Clinical

errors due to ineptness and insure a functionally, beautiful result (Figure 8).i Picture courtesy of Bay View Dental Lab

References1. Brown, M.; Orsborn, Ph.D., C.; (2006) Boom: Marketing to the Ultimate Power Consumer – the Baby-Boomer Woman. Amacom, New York.2. Furlong, Mary S.; (2007). Turning Silver into Gold. Financial Times Press, New Jersey3. Terry, Leinfelder, Geller et al. (2009). Aesthetic & Restorative Dentistry. Composite Resins (3): 82-85.4. LeSage, B. (2010); Revisiting the design of minimal and no-preparation veneers: a step-by-step technique. 38(8):561-9.5. Dawson PE, Cranham JC; (2007) Dent. Today. Aesthetics and function: conflict or complement? 26(10):80, 82-3.6. Dawson, PE. (2007) Functional Occlusion: From TMJ to Smile Design. Chapter 1, Mosby. 7. Dawson, PE. (1999) Position paper reguarding diagnosis, management and treatment of temporomandibular disorders. J Prosthet Dent 81:174-178.8. Calamia JR, Levine JB, Lipp M, Cisneros G, Wolff MS; (2011) Smile Design and treatment planning with the help of a comprehensive esthetic evaluation form. Dent Clin North Am. 55(2):187-209.9. Blitz N, Steel C, Willhite C. (2000) Diagnosis and Treatment Evaluation in Cosmetic Dentistry. Amer Acad of Cosmetic Dent., Madison, WI.10. Hussain K., (2011) Challenging nature: wax-up techniques in aesethics and functional occlusion. Br Dent J 9;11(11):575-611. Regish KM, Sharma D, Prithviraj DR. (2011) Techniques of fabrication of provisional restoration: an overview. Int J Dent 2011:134659.12. Strassler HE, Lowe RA. (2011) Chairside resin-based provisional restorative materials for fixed prosthodontics. Compend Cintin Educ Dent 32(9):10, 12 14.13. Clements WG. (1983) Predictable anterior determinants. J Prothet Dent. 49(1):40-5.14. Kaiser DA. (1981) Fabricating a custom incisal guide table. J Prothet Dent 45(5):568-9.

evaluation of the prototype restorations is accomplished 48 hours post-op. Functionally we want to customise the anterior guidance and harmonise it with the envelope of function. Phonetically, we need to test the length and position of the incisors to the patient’s tolerance in speaking. In our 2D treatment planning, our goal was to maximise the display of the anterior teeth.

Through a series of phonetic exercises with the prototype restorations, we can confirm the need for any further adjustment. One guideline in verifying incisal edge position is the use of the ‘F’ sound. The ‘F’ sounds, when softly spoken will help to determine if the teeth are too long. It should be noted however, that forcefully pronounced ‘F’ sounds would allow the muscles to accommodate and not necessarily give a proper indication of proper tooth length. These phonetic exercises will only provide clues to teeth that are too long, not too short. The second component that is evaluated with the prototypes is the criteria related to global and macro aesthetics. The orientation and alignment of the teeth to the face is a critical communication reference for the laboratory. Once the final adjustments to the prototypes are completed, and approved by the patient and the doctor, a copy of these approved provisionals are sent to the lab11,12.

In the creation of the definitive restorations, the lab now has the information to produce predictable, beautiful restorations. The laboratory technician will use the approved provisional model to create two key indices that will assist in this predictability. The first is an incisal edge matrix. With a mounted approved provisional restoration, a putty matrix can capture the exact horizontal and vertical position of the incisal edges of the anterior teeth. This will facilitate the reproduction of this incisal edge position in space with the final restorations13. The second index that the technician will create is a custom incisal guide table. With the mounted approved provisional model in place, the incisal pin is raised off the incisal table of the articulator. A dollop of resin or composite is placed on the incisal table with a lubricated surface. The approved provisional model is then moved through all excursive movements defined by the guidance that has been carefully refined and captured on the lingual guiding surfaces of the provisionals. The movement of the incisal pin through the resin material on the incisal table will record these contours, enabling the technician to reproduce these surfaces in the definitive restorations13.

When the restorative dentist receives the restorations from the lab in anticipation of delivery, he should also receive back the two key indices (described above) for verification. The restorations can then be presented to the patient with a level of confidence that requires very little modification. There should be no surprises at this point, and the final focus prior to delivery should simply be the refinements related to micro aesthetics.

Predictable, durable and aesthetic dental restoration can only come from the implementation of a reproducible protocol. This protocol must honour the functional and aesthetic parameters that are found in nature. In the end, each case is treated four times (Figure 7): • Visually through the tools of 2D Tx planning and

smile design• Virtually through the use of mounted models and a

Dx wax-up• Through the use of prototype restorations as a trial

test in the patient’s mouth• Definitive restorations.

The commitment to a successful protocol will eliminate

LONDON 201225th - 26th MAY 2012DENTISTRYLIVE.CO.UKBOOK NOWScott Finlay will be speaking at Dentistry Live on 25-26th May 2012. Book your place now on 0800 371 652

Figure 8: A successfully treated case(before/after)

“The orientation and alignment of the teeth to the face is a critical communication reference for the laboratory”