Removable Prosthodontic Calibration

1. Removable Prosthodontic Calibration Dr. William G. Golden Clinical Associate Professor and Prosthodontist Director of Removable Prosthodontics

2. Increased Vertical Dimension I think everyone here would recognize these two examples as an open bite (increased vertical dimension).

3. Increased Vertical Dimension But how about these?

4. Increased Vertical Dimension How do you correct the dentures without starting over? • Refine the fit of the denture bases to the mouth with PIP. • Verify the correctness of the vertical position of the upper anterior teeth. • If the vertical position of these front teeth are too long, adjust the maxillary anterior teeth by selective grinding until the fricative sounds are clear and distinct.

5. Increased Vertical Dimension How do you correct the dentures without starting over? • Remount the casts by using a new facebow record and centric relation record. • Intraorally, reduce the maxillary anterior teeth until the wet/dry line of the lower lip contacts their incisal edges. • Replace the maxillary back on the articulator and raise the guide pin. • Reduce the occlusion of the maxillary posterior teeth until the maxillary incisors meet with the mandibular incisors in protrusive. • Evaluate the VDO of the dentures in the mouth and make another CR record.

6. Increased Vertical Dimension How do you correct the dentures without starting over? • Remount the mandibular remount cast. • Remove all maxillary teeth from the denture base. • Replace the denture base on the maxillary remount cast. • Set a new set of teeth on the maxillary denture base. • Perform a wax try-in of teeth. • Intraorally, evaluate the VDO of the dentures and the function of the teeth.

7. Increased Vertical Dimension How do you correct the dentures without starting over? • Box and pour the denture as if it were a final impression. • Trim the cast with the denture in place and send it to the lab for processing, clearly stating in the lab prescription the denture base is to be retained as the denture base of the final denture. • Have the lab finish and polish the denture and return it ready to insert in the patient’s mouth. • Evaluate and treat it as you would the original denture.

8. Vita shades • Only two of the Bioform shades correspond with the Vita shades - shades 59 & 69, therefore, please do not request them. • We do not provide teeth for complete dentures made in the predoctoral clinic that are the brands made for these shades.

9. 10 & 20 Degree Teeth • These are not available for use in complete dentures in the predoctoral clinics. • Students are not trained to use them and it just adds more confusion to their limited understanding of complete dentures. • Often, when students complete an occlusal equilibration, the anatomical teeth resemble 10 & 20-degree teeth anyway.

10. Porcelain Teeth We do not encourage the use of porcelain teeth in the predoctoral clinics because they are very hard to equilibrate to establish bilaterally balanced occlusion.

11. Anatomic teeth for Class II & Class III patients? • These don’t allow the freedom of movement needed for a Class II patient. • There are very difficult to set in a crossbite situation as is often the case with a Class III patient. • Unstable dentures cause sore spots.

12. Zero-degree teeth set with a compensating curve? • We set zero-degree teeth in a monoplane occlusion. If there is no vertical overlap of the anterior teeth, what is the need for a compensating curve? • “Balancing ramps”?

13. Anterior guidance with zero-degree teeth? There should be no anterior guidance/interference in any complete denture. This causes instability of the denture, leading to discomfort and broken/dislodged teeth.

14. Patients expecting a reline at six month mark? • Option of reline presented up front. • Patient insisting on reline instead of new denture. • Interim prosthesis. • Erroneous billing. • Patient dissatisfaction with the ‘fit’. • Patients not wanting to pay for the tissue conditioner relines. If these interim dentures are determined to be suitable for relining, they are then reclassified as immediate complete dentures and relined. The code for the denture must be changed at that time and the patient’s account will be changed to reflect the adjustment and the patient will be charged the difference in cost between the interim complete denture and the immediate complete denture. The patient will also be billed for a reline. The student will get credit for a reline.

15. Mandibular posterior teeth not set over the ridge. Mandibular posterior teeth must be set over the ridge. • Anatomical mandibular posterior teeth must be set with the buccal cusps over the middle of the mandibular ridge. • Zero-degree mandibular posterior teeth are set with the central fossae over the middle of the mandibular ridge. • Lines must be drawn on the casts to indicate the middle of the ridge. • Lines must be drawn on the casts to indicate the depth of the anterior vestibule.

16. Clinical remount is not necessary? Clinical remounts are always necessary for complete dentures. • Increased stability • Increased retention • Increased function • Increased patient satisfaction

17. Erroneous Patient Remounts • Casts not mounted in CR. • Poor centric relation record – not at the first point of occlusal contact, not one piece. • Poor quality facebow transfer/remount index • Inaccurate or no protrusive record. • Horizontal condylar guidance is not set properly.

18. Erroneous Patient Remounts • Maxillary dentures are not flat-surfaced (if a monoplane occlusion is used.) • Monoplane teeth - guidance setting not established parallel to the occlusal plane. • Mandibular occlusal plane not flat and in intimate contact with the maxillary occlusal plane. • Poor quality remount casts. • Instructor did not thoroughly evaluate the remount.

19. Safety & Infection Control Regulations • Faculty not enforcing them. • Faculty not following them. • Students not properly attired. • Patient not wearing safety glasses. • Student not wearing safety glasses. • Children in the area. • Student blowing on dentures with the mouth. • Student not wearing protective mask properly.

20. Safety & Infection Control Regulations • Flames too near to hand disinfectant dispensers. • Students not keeping area clean, especially the sink area. • Students not disinfecting the impressions. • Patient not wearing a patient napkin. • Student using a non-sterile instrument to mark the midline on the wax rim. • Students using improper knife or using it improperly.

21. Guide pin is not set at zero. • Initial mounting - not set on zero. • Remounting - not set on zero. • Cannot assume the setting is correct. • Student used articulator for another case. • Guide table was not set so the pin was contacting the axis of rotation mark and the incisal guide angle was changed.

22. The condylar guidance is set wrong for the teeth. • Student used the articulator for another case and forgot to change the setting. • Student didn’t know what the correct setting was. • The condylar lock nut is loose.

23. Master casts/final impressions have no hamular notches. • Cast finished down too close in the distal. • Hamular notch was not captured in the impression. • Student did not box the impression properly and leave adequate room for the land area.

24. Master casts/final impressions have no retromolar pads. • Cast finished down too close in the distal. • Retromolar pad was not captured in the impression. • Student did not box the impression properly and leave adequate room for the land area. • Retromolar pad area was reduced because it interfered with protrusive or lateral movements. (Occlusal plane must be at least 2/3 of the way up the highest retromolar pad.) • Cast would not fit in the processing flask.

25. Master casts/final impressions with excessive width in the vestibular areas. • Compound was not scraped/trimmed adequately. • The tray was not reduced enough initially. • Excessive blockout of undercuts. • Mandibular trays without finger rests. • Inadequate border molding. • Student chilled the compound before placing the tray in the mouth.

26. Trays with improper handles Trays must fit the mouth have handles that will not interfere with the border molding process and still allow for easy placement and removal. • Handle did not come off crest of ridge. • Handle was too short to grasp. • Handle was made at right angle or drooping down (prevents lip from being raised or lowered completely in that area). • Mandibular tray without finger rests.

27. Trays that are under-reduced for the impression. • Overextended impressions in the vestibular area. • Complete dentures (particularly the lower) with excessive flange length. • Frenular notches are not present.

28. Casts with insufficient or no land area • Cast finished down too close in the distal. • Student did not box the impression properly and leave adequate room for the land area.

29. Master casts that are too thick or too thin. • Impression was not properly boxed & poured. • Thickness of the cast base was over-reduced or under-reduced. • Student tried to make up for thin cast by pouring a second pour on the base. • Student did not box and pour the cast but used the double-pour method.

30. Final impressions made of materials other than polysulfide impression material. • We use a low viscosity (light-body, injection type) wash of polysulfide impression material to make our final impression for a complete denture. • Easier to remove from a cast without breaking or otherwise marring the cast.

31. Improper baseplates/improper blockout destroyed casts. • Insufficient blockout. • Wrong separating medium was used. • Trays were under-reduced. • Casts were not soaked in hot water before removing the tray/impression. • Students focused on a tight fit/lots of suction with baseplates rather than on protecting the casts.

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