Complete Denture Try-In and Laboratory Processing

Prosthesis Try-In Appointment and First Assessment

During the first assessment of the prosthesis try-in, the primary objective is to check centric movements.

Clinical Evaluation Steps

• 1) Check casts in the articulator
• 2) Perform functional analysis
• 3) Evaluate aesthetics
• 4) Determine eccentric movements

Phonetic Assessment and Vertical Dimension

Phonetics are essential for determining the correct Vertical Dimension (VD):

• Labial (p, b, m): An increased VD makes it hard to close the mouth. A decreased VD leads to bad pronunciation and biting of the tongue (requires replacing or rearranging teeth).
• Labiodental (f, v): Pronunciation depends on the Incisal Edge (IE) of the Upper Central Incisors (UCI). An increased VD causes difficulty pronouncing, while a decreased VD results in tangled words.
• Linguodental (z, t, d): The tongue should be between the incisors when saying "z". A decreased VD causes the patient to bite themselves or mispronounce "t".
• Linguopalatal (s): Check the palate shape. An increased VD causes chattering.

Prosthesis Laboratory Finishing Procedures

This stage involves finishing and replacing the resin base with the final resin.

Wax-Up and Denture Modeling

The wax-up involves modeling the denture in wax with the desired shape. The resin is removed and replaced with wax. The process includes:

• Apply the 1st layer of wax from the anterior area to the posterior palatal seal (post dam).
• Fill the palate where the resin was removed.
• The 2nd layer obtains the final shape, imitating the rugae (preformed 2mm).
• On the buccal surface of the upper cast, extend to the deepest part of the frenum and ensure space is made for the muscles.

For the lower cast, the lingual surface should have a concavity providing space for the tongue (relieve the lingual frenum). The buccal surface should have a concavity for the muscular activity of the cheeks. It is important not to move the teeth, to cover all anatomical areas, and to maintain aesthetics.

Flasking and Polymerization Process

Flasking is the process of coating the cast and denture with wax in a flask to prepare for the future denture mould. The flask is a metal container where bottling and polymerization take place, and all wax is replaced with resin. Types include pressure, injection, and microwaves.

The Flasking Steps

1. Maintain a 1cm distance between the working cast and the flask.
2. Apply separating material for the plaster and the master cast.
3. Fill the drag with plaster and position the cast.
4. Remove irregularities and paint only the plaster with separator.
5. Place the cope.
6. Cover the whole model in plaster.
7. Close the flask and let the plaster set.
8. Put the flask in a pot for 15 minutes and separate the cope (containing teeth, resin, and wax) from the drag (containing plaster and the final cast).
9. Wash with boiling water and soap, removing all resin and wax.
10. Add separator to the cast and plaster.
11. Incorporate resin to the cope, adapt, and pack.
12. Close the drag and cope.

Final Polymerization

Place the assembly in a press and allow it to cool for 24 hours. Separate the drag and cope to obtain the working models with the resin adapted.