5.2. complete denture
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Bases with Occlusal Rims (Record Blocks) Used to:Restore the esthetics with denture by:
- establishing lips & cheeks support.- deciding tooth show & tooth positions.- Deciding the level and inclination of occlusal plane.- selecting shape, mould, shade & material for CD teeth.
Register the mid-line & inter-canine width.Establish Jaw Relation (MMRs):
- Vertical Relations.- Horizontal (Centric & Lateral Relations).- Orientation relations.
Establish CD occlusal relations compatible with jaw movements.
Materials Used for Making Occlusal Rims:Pink Modeling Sheet Wax.Compound Impression material.Mix of Plaster of Paris & Pumice (1:1).Auto-polymerizing PMMA Resin.
Adding Wax Occlusal Rims to Record Bases:Confusion exist on how to make the upper rim (ACB). Customize occlusal rims so that they do not require:
- too much addition or removal at chair-side. Useful guides include:- Pre-extraction records (Biometric guides, Extracted
Teeth, Dentate jaw casts, RPDs, IDs, CDs (Copy dentures).Measurements, Alma gauge, Alameter & Papilla-meter.Similar guidelines also apply to lower rim but:
- The 'Manchester rim' for use in the central-bearing apparatus CR method reduces the potential for confusion over dimensional parameters. - Height of lower rim not higher than retro-molar pads.
Divide inter-muco-buccal folds distance (38 mm) as:- 22 mm from upper MB fold to incisal surface of rim.- 16 mm from lower MB fold to incisal surface of rim.
Warm the mid-section (width-wise) of a wax sheet.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. Uniformly soften this wax sheet by repeated passing it: -
thru the flame of an adjusted Bunsen Burner. Fold the wax in half lengthwise and then widthwise.Pass thru the flame again & fold in half length-wise. One side of wax block should be rounded & smooth.The other side should have all of the free wax sheet
ends laminated together. Flame soften & bend wax-block into “U” shape
lengthwise.
Push the laminated end firmly down onto the residual ridge area of the maxillary record base.
With fingers, mold the labial surface of the soft wax down as far as to the land area of the cast.
Center the body of wax over crest of upper ridge. Mold the lingual surface of the wax smoothly
toward the palatal surface of the record base. Visualize the wax & ensure 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 cast land area to the occlusal surface.
The incisal edge of the maxillary wax rim should be 22mm from the land area as measured in the lateral incisor area.
Enough bulk of wax available to accommodate the above mentioned 22mm height anteriorly.
Posteriorly, occlus. surf. parallel to crest of upper RR. Create proper BL width of the occlusal plane:
- 3mm in area of anterior teeth.- 5mm. In bicuspid area & 7mm. in molar area.
Projected center of occlusal plane over crest of RR. Heat Hyde scraper to smoking.Take the wax rim base off the upper cast.Run the flat surface of the hot blade up and down the
facial surface of wax. Feather wax right to the edge of the record base.
Facial surface wax is smooth and has no voids. If voids are present, add wax to the defect with a hot
wax spatula. Wax in the anterio-facial region has a slight anterior
inclination.Wax in facial aspect of bicuspid & molar areas is more
upright. Heat wax spatula to smoking & shape lingual wax to a
smooth, void-free inclined surface. Wax should feather right onto the palatial surface of
the Base. Occlusal portion of rim centered over RR. Have correct widths of occlusal surface of the rim.
Flatten occlusal plane with a smoking Hyde scraper. Maintain rim height as 22mm. Plane of rim parallel to the mean foundation plane of RROcclusal surf is flat bucco-lingually & uniform void-free. Cut distal aspect of rim at mid-point of 2nd molar area. Have the posterior surfaces angled slightly toward the:
- anterior from the base interface to the occl. plane.
No wax, other than a slight film on the palatal and tuberosity aspects of the record base.
Smooth any wax flashing at the peripheral roll edges.
Smooth the wax using a paper towel with cold water or:- a piece of nylon mesh.
LOWER RIM:
Repeat the same procedures for lower rim, except for the following variations:
- anteriorly, height of rim is16mm above land area.
- lingual surface of rim fitted down to lingual peripheral roll in the same manner as the facial aspect of rim is finished down to LB peripheral roll.
- occl. Surf. of rim on a flat plane from its anterior point of reference to its posterior left and right points of reference,
- Rim height up to the level of ½ of the retro-molar pads.
- width of lower rim is same as the upper rim.
