The Science of
Communicating
the Art of Dentistry

Laboratory work authorization forms are mainly developed in the form of written instructions,two-dimensional drawings or photographs. These can be supplemented with other forms ofcommunications, which will give three-dimensional information and take into account thelips, which are considered the frame of the teeth. This article will describe a systematicapproach to communication with a patient and laboratory technician using three-dimensional aids such as a smile replica, lip reproductions, provisional restoration casts and soft tissue casts.

Article copyright 1998 Journal of the California Dental Association.
Photographs copyright of the authors.

One of the least emphasized but most important aspects of restorative dentistry is communication. ¹ This communication must include the patient so his or her desires and expectations can be understood. The clinician must understand what a patient desires, but the patient must also understand restorative and anatomic limitations. The communication of esthetic parameters must then be made to the laboratory technician who will fabricate the restorations.

The ideal situation exists when the laboratory technician can meet the patient and the clinician personally during the diagnostic phases of the treatment. ² Such a meeting will allow the laboratory technician to evaluate and gather information that is unavailable from mounted casts or a written work authorization form, such as the personality of the patient and the activity of his or her lips. Most clinical settings do not allow this interaction, since the dental laboratory and the dental office are often in separate locations. Thus, proper communication with the dental technician becomes a critical challenge for the success of treatment, especially in esthetically critical situations. ^3-5

Understanding the Patient's Requirements

The most important aspect of the patient's treatment is diagnosis. ^6,7 Once the diagnosis is determined, it will dictate the treatment. ^8,9 In an esthetically driven treatment plan, the diagnosis includes understanding the patient's desires and expectations. Will the patient accept natural-looking teeth, or does he or she want what is commonly referred to as a "Hollywood" smile, with white monochromatic teeth and artificial esthetic parameters? Does the patient understand the limitations that he or she presents with, or does he or she have unrealistic expectations? If the patient's desires are not realistic, the patient should be informed of the limitations at this time and further educated, otherwise, any future explanations will only be seen as excuses.

In Figures 1 and 2, each of the patients has his or her own cultural esthetic parameters, which can be very different from that of the restorative dentist.

One of the best decisions a clinician can make is to decide against treating a patient with unrealistic expectations. It is also important to educate the patient about esthetics but at the same time to keep in mind that ultimately the patient is almost always right when it comes to esthetics. The axiom "Beauty is in the eye of the beholder" is very true when it applies to dental esthetics.

Just as important is that the"esthetic zone is where the patient thinks it is." ¹⁰ This is well-demonstrated in some cultures where anterior gold restorations are very fashionable, thus in the eyes of these patients, very esthetic (Figure 1), while for some other cultures, exaggerated canines are esthetic (Figure 2).

Figure 3 - In a complete denture, the restorative dentist has maximum artistic freedom.

We should inform and educate patients about esthetics, but we should never impose our esthetic parameters on them, otherwise the consequences can be disastrous both emotionally and financially. Also, we need to keep in mind that as the patient's degree of edentulism decreases, the esthetic freedom that we enjoy as restorative dentists, decreases. When the type of restoration changes from a complete denture to a removable partial denture to a fixed partial denture and to a single unit restoration, our esthetic freedom gets more and more restricted. Restoring a single central incisor is by far more challenging than restoring several adjacent teeth. Similarly, creating an esthetic denture is far easier than a three-unit fixed partial denture, since we have a lot of freedom in selecting the shade, contour and position of the teeth, as well as in creating the gingival matrix around them to compensate for bone resorption and recession (Figure 3). ¹¹

As shown in Figures 4 through 7, the smile replica is an easy way to give information about the existing restorations, smile line, gingival architecture and buccal corridors. An irreversible hydrocolloid impression is made of the teeth and lips, and then reproduced by pouring tooth-colored and tissue-colored acrylic resin in the appropriate areas.

Figure 12 - A completed diagnostic wax pattern.

Visual Communication Tools

The challenge is to communicate all the gathered information to the laboratory technician who will create the final restorations. Evaluating the patient for esthetics begins with a survey of the patient's facial features. Items to note are facial symmetry, midline deviations, the parallelism between the occlusal plane and the interpupillary line, etc. ¹² The smile and lips are then evaluated, noting the smile line, amount of tooth display, buccal corridors, gingival display, gingival architecture and symmetry, and gingival type which can be thin or thick and scalloped or flat. ¹³

As shown in Figures 8 through 11, the lip reproduction can be a very helpful three dimensional tool to aid in the placement and correction of the incisal edge and to develop the smile line.

As shown in Figures 16 through 19, an abraded shade tab can be characterized using surface colors to match the tooth. Figure 13. Acrylic overlay fabricated on existing casts. Figure 14. Intraoral evaluation of the acrylic resin overlay. Figure 15. Intraoral evaluation of provisional restorations that will serve as a matrix for the definitive restorations.

Next, focus on the teeth and evaluate their form, the presence and shape of mamelons, their texture and other internal characteristics. ^14,15 The initial information that needs to be transferred to the laboratory technician includes diagnostic casts mounted in centric relation using either an average axis or transverse horizontal axis record, with the correct articulator settings. Complete face photographs, both facial and profile, as well as closeups of the smile and teeth, can also be beneficial. ¹⁶ The limitations of photographs, however, are that they are two-dimensional. Therefore, three-dimensional representations of the patient's smile and the lips can be valuable information both during the diagnostic (provisional) phase, as well as during the fabrication of the definitive restorations.

The smile replica is a simple procedure whereby an irreversible hydrocolloid impression is made of the patient's lips and teeth while the patient is smiling. This impression is then poured with autopolymerizing tooth-colored acrylic resin in the teeth areas and tissue color in the remaining areas. The result is a three-dimensional reproduction of the patient's teeth and lips (Figures 4 through 7). Another valuable communication tool is the lip reproduction. ¹⁷ This procedure has been previously described and can provide crucial information about incisal edge placement, especially if existing restorations or incisal wear have altered the teeth (Figures 8 through 12).

Transferring information about color and shade is probably one of the most difficult aspects of communicating with the laboratory technician. Many articles and textbooks have been devoted to this topic, and the readers is referred to them for further information. ^18-27 An important point to make is the environment in which the shade is determined and the restorations fabricated. ²⁸ Neutral surroundings both in the laboratory and the dental operatory are crucial, as well as a light source with a color rendering index greater than 90 and a color temperature of 5,000 degrees Kelvin. ^29,30

Research has shown the inadequacy of most shade guide systems. ^31-34 Therefore, when it is not possible to find a perfect match, a shade higher in value and lower in chroma should be selected. ⁵ An abraded tab of the selected shade can be modified with surface colors to match the tooth (Figures 16 through 19). ²⁹ This method is especially useful to communicate unique characterizations that some teeth exhibit. Another method of communicating the shade of the teeth is providing a detailed drawing to the laboratory technician. ^35,36 This color map of the tooth can be very detailed, but it is somewhat more difficult to master (Figure 20).

Figure 20 - A detailed drawing can be used to communicate shade and texture with the laboratory technician.

These tools, in addition to a thorough laboratory work authorization form, are necessary for the laboratory technician to develop the diagnostic wax patterns. Once the patterns are completed, they need to be evaluated by the patient. Several methods are available to evaluate diagnostic wax patterns, including evaluating on the articulator and making tooth-colored acrylic resin overlays, which can be trial placed and modified intraorally (Figures 12 through 14). But by far the best method and the method that is recommended for any extensive restorative treatment is the provisional restoration (Figure 15). ^37-40

The Provisional Restoration as a Matrix

As shown in Figures 21 through 24, the provisional restoration is the best method to evaluate patient acceptance. Once the provisional restorations are accepted by the patient, they can be used in duplicating and creating the definitive restorations. This figure shows provisional restorations evaluated intraorally. The soft tissue cast reproduces the gingival tissues that are lost on the working cast. It will help the laboratory technician in visualizing the sot tissues when contouring the gingival embrasures and is made by making a pick-up impression of the frameworks. Care must be used in selecting compatible materials for the impression and soft tissue materials. Figures 23 and 24 show the definitive restorations.

Provisional restorations can be used to develop and modify the diagnostic wax patterns according to the patient's desires and wishes, as well as functional requirements. Once the patient is satisfied with the esthetic, phonetic and functional aspects of the provisional restorations, they will be used in communicating the patient's esthetic demands to the laboratory technician (Figures 21 through 23). ⁴¹

Complete arch impressions are made of the provisional restorations intraorally. A silicone putty impression is made of these casts to be used to create full-contour wax patterns. This same index is also used as a guide to cut back the wax to provide a uniform layer of porcelain. Complete arch impressions of the prepared teeth are made and cross-mounted with casts of the provisional restorations. Depending on the extent of the treatment and circumstances, a new lip replica may be made at this time. Most often this is not necessary since the provisional restorations will be duplicated to create the final prosthesis. The laboratory technician now has enough information to fabricate the metal frameworks. When these are ready, they will be trial placed intraorally and their fit checked and adjusted. Since most of the information about the soft tissue is lost when trimming the dies for the framework wax patterns, a pick-up impression is made at this time to create a soft-tissue cast. It is important to select the impression material as well as the soft tissue material carefully so that they are compatible. ⁴² With this cast, the laboratory technician has enough information about the gingival architecture and margin location to create the gingival embrasure forms to maximize esthetics. The final restorations are returned in the bisque bake stage for another esthetic evaluation. Since these are very close duplications of the provisional restorations, patient acceptance is almost certain. When the patient and dentist are satisfied, the restorations are returned to the laboratory for glazing and polishing.

Summary

Written laboratory work authorization forms are not adequate to communicate both the science and art of dentistry. Several techniques and three-dimensional visual tools (smile replica, lip reproduction, provisional restoration casts and soft tissue casts) are available to better communicate these artistic and esthetic parameters with the patient and laboratory technician. Using a systematic approach, it is possible to evaluate and communicate the patient's esthetic and functional needs to the laboratory technician in a precise fashion.

Author

Krikor Derbabian, DDS, is an associate clinical professor in the Restorative Department of the University of Southern California School of Dentistry.

Riccardo Marzola, DDS, is an associate clinical professor at the USC School of Dentistry.
Alessandro Arcidiacono is a dental technician and clinical instructor at the USC School of Dentistry.

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To request a printed copy of this article, please contact Krikor Derbabian, DDS, USC School of Dentistry, 925 W. 34th St., Room 4366, Los Angeles, CA 90089-0641.