Chapter 18 Visualising the end result – techniques to improve the predictability of aesthetic dentistry Dr Elaine Halley Principal of Cherrybank Dental Spa, Perth , elaine@jmiuk.com
When restoring teeth for anterior aesthetics, there are a variety of techniques available which increase the predictability of the treatment outcome. In many cases the treatment indicated to improve the aesthetics of a smile is elective in nature and so it is essential that informed consent is gained, and that the patient’s expectations are fully understood. Paying proper attention to the planning phase using specific techniques will in turn:
• Improve the predictability of the final result
• Enhance communication thereby reducing errors in communication between
dentist and patient and dentist and laboratory
• Ensure only specific removal of tooth structure as indicated by the treatment
plan, thus minimising unnecessary loss of healthy tooth tissue.
Failures in aesthetic dentistry may be classified in the following way:
• Psychological failures
• Technique failures
• Communication failures.
Psychological failures In other words, no matter how good the dentistry and the aesthetics, the patient will not be happy with the result. Sometimes this may be due to unrealistic expectations but occasionally there are other underlying psychological issues e.g. body dysmorphia, which manifest in a dissatisfaction with the dentistry. Careful time spent in the pre-planning stage, asking questions, listening to the patient and clarifying their expectations may help identify these potential patients. Technique failures These failures can be due to errors in the clinical situation or the laboratory procedures. There are obviously many possibilities for technique failures including failure to prepare the teeth adequately either for the clinical situation or for the material selected or a lack of understanding of the occlusal scheme. As clinicians,
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we need to do everything we can to minimise these failures, but also to accept that failures will occur to some degree. We should rectify them, critique ourselves and above all learn from our mistakes but we also need to be able to move on. Communication failures These can be failures in the communication between dentist and patient or between dentist and laboratory. The techniques described in this article can help reduce the errors in communication in both these situations. Digital imaging There are many programs available to the clinician to allow him or her to demonstrate to a patient how they may look with some changes in their smile. Imaging can also be outsourced by emailing a photograph with a prescription to a company which specialises in dental imaging, for example www.smilevision.net Imaging can serve as a diagnostic tool and also improve communication between patient and dentist. However, care must be taken that imaging does not set up false expectations with before and after imaging (Figures 1 and 2). In this case, due to the asymmetric lip, it would be very important to diagnose and explain the need for crown lengthening on the right hand-side in order to match the imaged result. An understanding of smile-design and clinical limitations is essential. Diagnostic wax-up Obtaining a good quality diagnostic wax-up on articulated models from a laboratory which understands smile design not only enhances diagnosis but allows a patient to visualise the end result. A template can be made from the wax-up which can be used to formulate a trial smile which is much more meaningful to a patient, and to formulate the provisionals after tooth preparation. In order for the laboratory to produce a good wax-up, they also need good quality photographs of the patient, especially full face, close-up smile and retracted smile, as well as a detailed description of the patient’s concerns and the dentist’s prescription. A stick-bite is a very simple and effective tool that can be used to transfer information to the laboratory about the horizontal plane in relation to the occlusal plane. A silicone bite registration material is syringed onto the lower anterior teeth. The patient is asked to bite together and a bend-a-brush or a wooden stick is twisted into the registration material in the horizontal plane. This is then levelled to the horizontal. It is very important that the patient is standing or sitting with their head in an upright position while the clinician levels the stick. It is often possible to imagine a horizontal line connecting the pupils and keep the stick level with that. However,
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in some patients, the level of the eyes is not horizontal and so it may be better to use an external frame of reference. A full face photograph of this bite in position is taken and sent to the laboratory so that they can be sure of the position of the incisal plane to the horizontal (Figure 3). In the same way, it is useful to send the laboratory a photograph of the face bow in position. Whilst every care is taken to line the face bow up correctly with the horizontal and vertical, a photograph can relay more information in that regard. Trial smile This is the technique which utilises a template made from a diagnostic wax-up. A temporary material (e.g. Luxatemp, DMG/Minerva) is flowed into the template and then seated over the teeth with no preparation. When it is removed, the material remains on the teeth. The excess flash can be removed with a hand instrument and the patient and clinician can view the results. A before and after photograph can be taken so the patient can review the results at a later date and discuss them with family members/ key decision makers as appropriate. Modifications can be made with flowable composite (e.g. Luxaflow, DMG/Minerva). The trial smile can then be removed with hand-instruments as no bonding has taken place. The trial smile works particularly well in cases of diastema closure or increasing the length of the anterior teeth (Figures 4 and 5). It can also be used to demonstrate the effects of using a lighter porcelain in the restorations if a lighter shade of temporary material is used. It is not as effective in cases where teeth are flared buccally as these teeth will stick forwards through the provisionals and may prevent the temporary stent from seating at all. Living splint For more complex cases involving full arch or full mouth reconstruction, where the occlusal scheme is being redesigned, the trial smile may be utilised as a definitive diagnostic. By etching and bonding the provisional material to the teeth, a template of the proposed restorations can be bonded in place, reviewed and adjusted as required over a period of weeks or months, in the same way as a splint may be utilised prior to tooth preparation. This can work very well in cases of extreme wear or tooth surface loss where the bite is being opened and restored into CR, and an allowance needs to be made for deprogramming of the muscles. Allowing a trial run of the occlusal scheme in composite that can be adjusted over a period of time as the condyle is able to fully seat prior to any tooth preparation is an advantage in obtaining a stable outcome for a complex case (Figures 6 and 7).
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Provisional restorations In the his textbook Functional Occlusion, from TMJ to Smile Design, Pete Dawson states “Never proceed with the construction of final anterior restorations until the patient is happy with the anterior restorations�. As clinicians, if we really take the time to finesse our provisionals we can then transfer this information to the laboratory and reduce their need for guesswork. A simple check-list can be used to evaluate provisionals for function, aesthetics and phonetics. Any modifications can be made and an impression can be taken of the modified provisionals to accurately transfer the information to the laboratory. Pre-temporisation Galip Gurel in his textbook The Science and Art of Porcelain Laminate Veneers (Quintessence) advocates a technique whereby the provisional template is utilised to place the provisionals prior to tooth preparation, and then the depth cuts for material thickness removal are made through the provisional material. In this way, only the necessary enamel will be removed to provide enough thickness for the porcelain. This is an excellent technique to conserve as much tooth structure as possible. See Figure 8 for depth cuts in provisionals. Prep guides In the same way, utilising incisal and buccal prep guides made from the diagnostic wax-up can help the clinician to prepare the teeth predictably and conservatively. An understanding of the materials to be used and how much space is required by the technician is essential in delivering adequate yet conservative preparations (Figures 9-12). Case study A 67-year-old lady attended my practice stating that she had left her previous dentist because since he had replaced her upper anterior crowns, she had been unable to speak correctly. When I examined her, she had anterior porcelain bonded to metal crowns on the upper anteriors which looked to be of good quality and had good marginal integrity. However, her lower anteriors exhibited signs of wear. She had repeatedly attended her previous dentist who had told her it was all in her mind and that she needed to get used to the new crowns. They had now been in place for two years and she was miserable. Certainly, I was unable to hear any phonetic problem myself and alarm bells were ringing that this could be a potential psychological failure.
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I took face bow mounted study casts and discussed the situation with my technician. We felt that a possibility was that due to the wear on the lower incisors and loss of vertical dimension, these new crowns may have been altered in contour from her originals in order to re-establish guidance with the worn dentition. I was reluctant to remove what looked to me to be perfectly good crowns when our only indication was phonetics – and more so, the phonetic opinion of the patient rather than any clinical observation on my part. The f- and v-sounds appeared within normal limits but it was the s-sounds and ‘th’ that the patient felt she had to consciously concentrate on every time. A full mouth wax-up was indicated to restore the proper vertical dimensions and function. A CR bite registration was taken using a Lucia jig and face-bow recording allowed the models to be mounted. We spot-etched the porcelain with hydrofluoric acid, placed a trial smile over her existing crowns and left this in place for one week to evaluate the phonetics. At the review appointment, she was delighted. For the first time in years she felt she did not need to think about her speech. This technique gave me the confidence that if we could replicate the provisionals with the final restorations this lady would be comfortable with the phonetics. In reality, this transformed this case from what I felt may be a psychological disaster if I touched her otherwise healthy teeth, to a successful outcome. There are a multitude of factors that come into play when diagnosing, treatment planning and constructing restorations in aesthetic dentistry. Keeping abreast of the latest developments and techniques can help us to learn from our failures and improve our skills. Having a thorough understanding of smile design and best clinical practice can allow us to achieve predictable, functional and aesthetic results for our patients.
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Captions to figures Figures 1 and 2 Care must be taken that imaging does not set up false expectations Figure 3 Example of a stick-bite in situ Figures 4 and 5 The trial smile works particularly well in cases of diastema closure or increasing the length of the anterior teeth Figures 6 and 7 A trial run of the occlusal scheme in composit Figure 8 Depth cuts in provisionals. Figures 9-12 The use of Prep guides aids both clinician and technician
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