Diagnostic Cast (also known as study model)
Before the teeth are prepared, impressions are made in alginate and stone casts are poured for the maxillary and mandibular arches. Why are they important? (ref. 5)
Allow for the study of the occlusal relationships of the teeth.
Provide critical information on the form, length and contour of the teeth.
Used as a tool by dentists to discuss treatment planning and expected results with patients.
Are most important for "complex" treatments (see Figure 1).

Figure 1. Mounted diagnostic casts.
What is a diagnostic wax-up?
After a diagnostic cast (see Figure 2a) has been made (usually from an alginate impression) wax is added to the cast by the dentist or dental technician. The final restoration will be made using the proposed anatomy, which is built in wax, on the diagnostic cast
(see Figure 2b)

Figure 2a. Close-up of diagnostic casts.

Figure 2b. Diagnostic wax-up.
When is a diagnostic wax-up helpful?
When several teeth are badly broken down or missing.
When changes in the shape of the teeth are required. The wax-up defines many aspects of the final restoration including tooth length, contour, occlusion, contacts and how the teeth relate to the face.
(see Figure 3)

Figure 3. Close-up of diagnostic wax-up.
Diagnostic wax-ups are highly recommended for "complex " treatments such as:
- Multiple units or full-mouth reconstruction's
- Treatments requiring alteration of occlusal contacts or occlusal function
Benefits of creating a diagnostic wax-up. (ref. 3)
The wax-up provides critical information to the laboratory which increases the probability of success for complex treatments.
The wax-up may be used as a template to create a custom provisional. This provisional acts as a preview for the final restoration (contour, color, and occlusion) (see Figure 4). If changes are necessary they can be communicated to the dental laboratory before the final restoration is made.

Figure 4. Provisionals made from diagnostic wax-up.

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