Standard Operating Procedures: Trimming Dental Models

Objective:

• Removal of excess plaster
• Provide accurate replica of dental dentition
• Presentation: clean, symmetrical, without voids
• Trim excess and plaster extensions (distal of mandibular molars ) which interfere with proper occlusion in wax bite
• Soak models in water to facilitate trimming
• Set table at 90˚ to wheel - Drop table angle when atomic features are wider than the base
• Trim Maxillary Cast

  • Grind the base of maxillary cast parallel with occlusal plane

  • Grind the heel of maxillary cast perpendicular with mid-palatal raphé

    • Mark the mid-palatal suture, and trim the posterior surface perpendicular to this, to a point just posterior to the hamular notch.

    

  • Using the 30˚ jig, cut the sides of the maxillary cast 60˚ to the base—do not overcut!! The center of the cut should be to depth of the vestibule

  • Using the large 60˚ jig, cut the anterior of the maxillary cast at 30˚ to the base. These cuts should start at the canine and end at the midline and should be equal in length.

  • Using the small 60˚ jig, cut the posterior angles of the maxillary cast at 120˚ to the base. These cuts should start to be equal in length.

• Trimming the mandibular cast
  • Using the wax bite, place the casts together in occlusion With the base of the maxillary case on the table, grind the heel of the mandibular cast parallel with that of the maxillary cast MAND. MAX. place the mandibular heel on the table and grind the base of the cast parallel with the maxillary base MAX. MAND.
  • with the models articulated, trim the sides of the mandibular cast at 60 heel with the jig, as described above ˚ to keeping the models articulated in the wax bite, trim the heels flush and then trim the sides (at 60˚) flush
  • round the anterior portion of the mandibular cast smoothly from canine to canine 60° 120°
  • Lastly, articulate the 120˚ e models and trim upper and lower distal corners flush at 5. 6. Check Bases
  • The maxillary and mandibular models should sit in occlusion when placed on the heels, distal corners and sides Lightly freshen up all parallel sides with casts in occlusion as Bases should be symmetric and 1/2” to 5/8” thick Finishing
  • Smooth scratched bases with wet/dry sandpaper Fi l any voids with a 50/50 mix of plaster & stone, re Remove fins of plaster on vestibules or bases Label models with last name, date the records were taken, and chart # needed first name, age in years sand smooth months (e.g. 30 Allow to completely dry and soak in model gloss, if available8),