89 - impressions and models for complete denture technology

appointments for complete denture

1. history taking, examination and recording information

2. primary impression

3. try in

4. denture delivery

5. final impression

6. first follow up

7. jaw relationship

8. adjustments

what ahppens on 1st appointment for complete denture

• main complaints

• reason for loss of teeth

• history of main complaint

• social history

• dental history

• medical history

• habits

• radiographic examination

• extraoral and intraoral examiantion

• treatment plan

what occurs in 2nd appointment (primary impression)?

Step #1: selection of trays (metal - better support, or hard plastic - undergoes plastic deformation)

Step #2: modification of the trays

Step #3: impression taking

Step #4: evaluation of the impression

Step #5: disinfection

what is objective of impression making?

• PRESS

• Preservation of alveolar ridge

• Retention

• Esthetic

• Stability

• Support

technology to craft complete denture

1. Mix the gypsum in proper water/powder ratio.

2. The lower part of the flask is filled first. Put the model in it (max. 1cm over the edge of the flask - without the shaft).

3. Soap water, isodent and other for isolation after hardening.

4. Put the upper part and fill it with plaster (gypsum).

5. After hardening - put the flask in boiling water for 5 minutes.

6. After that open it up and remove the plasticized base plate and the wax.

7. Isolation.

8. Mix the acrylic resin (polymer/powder + monomer/liquid).

9. Stages of polymerization:

• Wet sand phase

• Sticky ("threads") phase

• Plastic ("working") phase

• Elastic ("gummy") phase

10. Put the acrylic resin in the empty space, close the flask and press it.

11. High temperature polymerization cycle:

• Long: put the flask in room temperature water, heat it for 30 minutes while the temperature rises to 60 degrees Celsius. On 60 degrees, leave it for an hour. Then heat it for another 30 minutes while it rises to 100 degrees. On 100 degrees, leave it for 30 more minutes then slow cooling for 2 and a half hours.

Short: for 30 minutes after the water starts to boil. (No more than 100 degrees Celsius, because the monomer/liquid evaporates at 100.3 degrees Celsius!!)

12. After cooling - removing the denture from the gypsum. 13. Cleaning and polishing.

preliminary impressions are taken with?

factory made impression trays (special strays)

In most cases, made from metal alloys, factory-made impression trays are for edentulous alveolar ridges.