When to Complete a Diagnostic Wax-Up

This article is the second in a series discussing diagnostic wax-ups (DWU). The first article addressed the question of why you should do a DWU. A DWU is an outcome-based diagnostic tool that should accurately represent the desired result of treatment. This article will outline when the clinician should prescribe the DWU.  

When to complete a diagnostic wax-up

The timing of DWU fabrication depends on its purpose. The DWU should be completed after the final treatment plan is established, unless it is needed for diagnostic purposes. While I know many clinicians use the DWU as a tool to educate patients before treatment is accepted, there are other options that are less costly and equally or more effective to accomplish this objective.

Relying on wax-ups for diagnostic purposes

The diagnostic wax-up can be used as a diagnostic aid to establish the desired esthetic changes (e.g. tooth position, alignment, inclination, proportion and morphology) and develop or confirm the occlusal scheme and function. If other team members (e.g. specialists) will be involved in the case, their input (along with that of the patient) should be solicited before the DWU prescription is sent to the lab. 

As the DWU is being produced, the clinician should work closely with their laboratory to verify whether the planned treatment is viable from a functional and/or esthetic standpoint. For example, a clinician’s treatment plan may include upper anterior veneers, but as the wax-up is being completed, the technician may notice that appropriate functional contact is not able to be established.

In this case, full-coverage restorations will be needed to accomplish the treatment goal, necessitating a change in the treatment plan. If the wax-up is fabricated before all input is given, significant changes may be needed at a later point, necessitating a remake and additional lab costs.   

Using wax-ups for patient communication purposes

Some clinicians use the DWU as a visual aid to show the proposed outcome to the patient before they accept treatment. If you take this approach, the clinician must establish the value of this step before the patient accepts treatment. Establish the value of the DWU by explaining to the patient that it:

• is a diagnostic aid
• establishes a clear visual representation of the proposed outcome
• establishes the desired esthetic changes and confirms the occlusal scheme and function
• confirms the treatment plan is achievable
• is used during treatment to fabricate treatment aids. 

Some patients may have trouble relating the changes you will create in the size and/or arrangement of their “new teeth” to the wax representation on a stone model. Take care to explain that the purpose of a DWU is to assist the patient in understanding esthetic changes made in arrangement, alignment, morphology, and function of the proposed teeth, and is not representative of the final color. 

While the white wax used by some laboratories may be more visually appealing to the patient, DWUs are often done using gray or another color so technicians can better visualize changes in morphology and avoid eye fatigue caused by the highly reflective white. 

Alternative methods to the DWU for communication

I suggest you consider the following alternatives to the DWU for communicating the proposed treatment outcome to your patients:

1. Photographs
   • Possibly the most effective means of communication is before and after photos of your own patients. This communicates the level of clinical and laboratory services that you offer. During patient consultation, showing case photographs of similar patient treatments can be invaluable. Be sure to get a release form from past patients for any full-face photos that you use.
2. Facially Generated Treatment Planning (FGTP) Template: Spear’s FGTP template can be used on pre-treatment photographs to quickly and simply provide a visual simulation of the potential treatment outcome. 
   • Computer drawings are used to give patients a visual representation of the esthetic changes proposed in tooth length, proportion, alignment and gingival level. Using the overlay template on the patient's pre-treatment photographs is a great adjunct to showing before and after photos of previously treated patients. The FGTP overlay templates are line drawings that are positioned and sized to represent the proposed outcome of treatment. Because they are viewing their own teeth, patients will understand how the changes will affect their smile. This visual tool gives the clinician the opportunity to explain different treatment options (such as orthodontic vs. periodontal treatment to change gingival levels), by altering images during the consultation and involving the patient in the decision-making process. This is a more effective communication tool than attempting to describe the changes using a stone cast. 
3. Intra-oral Mock-up
   • Made from the DWU after the final treatment plan has been established, this can be a highly effective way to communicate the proposed outcome in the patient's mouth, if minor changes are proposed. A stent made from a stone cast of the DWU is used to form provisional material (Luxatemp) directly over the patient's natural teeth. After the material sets, the copyplast stent or silicon index is removed from the mouth. Any flash of composite material that may extend onto the soft tissue is removed. The patient can now see the mock-up of the proposed outcome over their teeth and view the positive effect on their smile and facial appearance. Unfortunately, if significant changes are planned in tooth position (alignment, inclination, or rotation), the visual representation of the proposed outcome is often significantly distorted. This occurs because the pre-existing malpositioned teeth displace the stent or index, distorting the new tooth position. This may result in the mocked-up teeth being displaced labially with excessively thick incisal edges. The maxillary lip drape over the teeth can be negatively affected, as will the feeling of the mocked-up teeth on the lower lip and patient phonetics. If a mock-up is used in this instance, clear communication with the patient about the limitations of the visual pre-treatment must be communicated before starting the procedure.

How to set up fee structures for diagnostic wax-ups

Because of the costs involved, a fee structure should be implemented in your practice to accommodate the use of DWUs. Common options I have seen include:

• the cost of the DWU is absorbed by the clinician
• the cost is paid by the patient
• the cost is credited to the patient if they consent to have the treatment performed

My recommendation is to have a diagnostic charge as a component of your clinical fee structure on cases with multiple functional and esthetic changes. A rate can be established that varies according to the complexity of the case. For example:

            Full mouth diagnostic fee: $xx

            Full arch diagnostic fee: $xx

            Partial arch diagnostic fee: $xx

The DWU is an excellent tool for evaluating and confirming that a treatment plan is viable based on patients’ esthetic and functional needs or expectations. Using the DWU appropriately will help minimize changes or compromises in the plan of care once the patient has accepted treatment. The next article will discuss when to complete the DWU for a variety of clinical scenarios.