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Author: David M. Hern, D.M.D.

Guidelines for Fabricating Maxillary and Mandibular Visible Light Cure Record Bases and Wax Occlusal Rims

  1. Survey and outline the undercuts on the maxillary final cast. There will be left and right anterior undercuts and slight undercuts at the anterior aspects of the left and right tuberosites.
  2. Fill in the undercuts with pink bite rim wax. Use only enough wax to fill in the undercut as outlined (don’t overwax). No wax should ever extend into the peripheral roll.
  3. Survey and outline the undercuts on the mandibular cast. There will be a small undercut at the buccal aspect of the anterior portion of the residual ridge. There will also be large triangular-shaped undercuts in the left and right retromylohyoid areas.
  4. Coat the impression areas of both casts with a thin layer of petroleum jelly.
  5. Carefully remove the plastic sheets from the pink visible light cure (VLC) material (so as not to cause the material to pull and become too thin).
  6. With very lightly petroleum jelly coated fingers, apply the VLC material completely over the impression surface of the maxillary cast. Let the material slump into the palatal vault area. Gently adapt the VLC to the cast. If an air pocket is trapped at the depth of the palate, poke a vent hole in the VLC, letting the air escape through the vent hole and re-adapt the material. Then gently tap-tap the material in order to eliminate the hole and smooth the surface of the VLC.
  7. With a #7 wax spatula adapt the material into the entire peripheral roll. Cut the excess material off at the external aspect of the land area of the cast. Smooth the peripheral area of the VLC with your index finger, being sure that the peripheral roll of the cast is completely filled. Work the excess VLC off and make it flush with the land area.
  8. Be sure to have the posterior aspect of the maxillary record base extended 4mm. beyond the projected vibrating line. Thin the posterior aspect of the maxillary record base to one-half its original thickness with a forefinger coated in petroleum jelly. Excess thickness of material in this area will result in acrylic shrinkage and pulling away of the record base from the cast. Any space in excess of 2mm. between the record base and the cast indicates that a new record base will be required.
  9. For the mandibular record base, cut a trapezoidally shaped piece of VLC material and adapt the material to one side of the lower cast. Fill and fit the VLC material to the facial peripheral roll just as you did on the maxillary case. Fill and fit the material to the lingual roll just as you did on the external peripheral roll.
  10. Cut a second trapezoidally shaped piece of VLC material and adapt it to the other side of the mandibular cast. Fill, fit, and trim the facial and lingual peripheral rolls just as you did on the first side. Where the two pieces overlap each other at the midline, tap-tap the two pieces together and blend them into one seamless piece.
  11. Evaluate both baseplates and assure that the material is smooth, completely adapted to the other underlying casts and to the peripheral rolls. Other than the posterior aspect of maxillary, be sure there are no thin areas of VLC, which usually show as pink areas, are present. A uniform medium pink color indicates a consistent and proper thickness of the VLC record bases.
  12. Place the casts and record bases into a VLC curing machine with the carousel set at its lowest position and turn the machine on for two minutes. After this first exposure, remove the casts and bases. Gently tease the record basses off of the casts and replace the bases, upside down into the curing machine for six minutes. After this second cure wash the record bases with soap and water thoroughly inside and out.
  13. With a pineapple shaped acrylic bur, smooth and round all of the peripheries of both record bases. Fit them back onto their respective casts and selectively grin any internal aspects so that the bases fit snugly (they should not fall off nor should it require more than slight pressure to separate them.) Look at the posterior aspect of the seated maxillary record base. A new record base will be required if a space is greater than 2mm.
  14. Draw vertical lines at the area of the left and right second bicuspids on both record bases. Connect these lines with a line drawn parallel to and 2mm. above the anterior peripheral roll of each base plate. Draw a fourth line on the record bases, connecting the vertical lines, 4mm. lingual to the crest of the residual ridge of each cast.
  15. With your acrylic bur, thin the VLC material within this rectangular outline to paper thickness. (This window will make the setting of the anterior teeth easier.
  16. Warm the mid-section, width-wise, of a piece of pink bite rim wax and break it into two halves. Warm an end of this half piece and an end of a full piece of pink wax. Slightly overlap and fuse the two ends together to form one elongated piece of wax. Pass this wax through the flame of a properly adjusted Bunsen burner. Several passes in all directions will render this wax uniformly soft.
  17. Fold the wax in half lengthwise and then widthwise. Pass through the flame again and fold in half lengthwise. One side of the block of wax should be rounded and smooth and the other side should have all of the free wax sheet ends laminated together. Pass this laminate end through the Bunsen burner flame, and after it has softened slightly, bend the block into a “U” shape lengthwise.
  18. Push the laminated end firmly down onto the residual ridge area of the maxillary record base. Using your fingers, mold the facial surface of the soft wax down as far as to the land area of the cast. Center the body of wax over the crest of the maxillary ridge. Mold the lingual surface of the wax smoothly toward the palatal surface of the record base.
  19. Visualize the wax and be sure that it is placed on the base such that the anterior section of the denture will be oriented with a slight anterior sloping of the labial surface from the cast land area to the occlusal surface.
  20. The incisal edge of the maxillary wax rim should be 22mm. from the land area as measured in the lateral incisor area.
  21. Be sure that you have enough bulk of wax to accommodate the above mentioned 22mm. height anteriorly and that you will be able to maintain the occlusal portion of the wax posteriorly parallel to the crest of the maxillary residual ridge. You will need sufficient wax to create the proper facio-palatal ridge of the occlusal plane, 3mm in the area of the anterior teeth, 5mm. in the bicuspid area, and 7mm. in the molar area. Also be sure that the projected center of the wax occlusal plane will be centered over the crest of the residual ridge.
  22. Heat your Hyde scraper to smoking, take the wax rim and the baseplate off of the maxillary cast, and run the flat surface of the hot blade up and down the facial surface of the wax. Feather the wax right to the edge of the record base.
  23. Be sure that the facial surface wax is smooth and has no voids. If voids are present, add wax to the defect with a hot #7 wax spatula. Be sure the wax in the anterio-facial region has a slight anterior inclination and that the wax in the facial aspect of the bicuspid and molar areas is more uptight.
  24. Heat a #7 wax spatula to smoking and smooth the lingual wax to a smooth, void-free inclined surface. The wax should feather right onto the palatial surface of the VLC.
  25. As you adjust the lingual surface be sure that you have the occlusal portion of the rim centered over the residual ridge and that you have the correct widths of the occlusal surface of the rim.
  26. Once all the above points are properly completed, flatten the occlusal plane with a smoking Hyde scraper. Be sure that the height is 22mm. from the lateral incisor land area anteriorly and it is parallel to the mean foundation plane of the residual ridge as you go posteriorly. Be sure that the occlusal surface is flat bucco-lingually, uniform and void-free.
  27. Cut the distal aspect of the maxillary rim, posteriorly, at the midpoint of the second molar area. Have this posterior surface angled slightly toward the anterior from the VLC interface to the occlusal plane.
  28. Finally, smooth the wax using a paper towel with cold water. A piece of nylon mesh will also smooth the wax very nicely.
  29. There is no wax, other than a slight film on the palatal and tuberosity aspects of the maxillary record base. Smooth any flashing of wax at the peripheral roll edges.
  30. Repeat the same procedures that you completed on the maxillary wax rim on the mandibular rim, except or the following variations. Build up the wax rim, anteriorly, to a height if 18mm. above the land area at the location of the lateral incisor. The lingual surface of the mandibular wax rim is fitted down to the lingual peripheral roll in the same manner as the facial aspect of the wax rim is finished town to the labio-buccal peripheral roll. The occlusal surface of the mandibular wax rim is on a flat plane from its anterior point of reference, 18mm above the land area, to its posterior left and right points of reference, one-half the height of the retromolar pads. The width of the mandibular wax rim is the same as the maxillary rim.