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The Occlusal rims and
Do. Muaiyed. Maﬁmoud. Buzayau, BD8
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The occlusion Blocks (rims)
Occlusion blocks consist of wax rims attached to we| |—fitting trial
occlusion rims, definition:
Occluding surfaces fabricated on interim or final denture bases
for the purpose of making maxillomandibular relation records
and arranging teeth.
Denture base (base plate, record base):
- Is a we| |—adapted plate to which an occlusion rim is attached to.
- a rigid, relatively thin layer of wax, shellac, or thermoplastic (heat,
chemical, photo activated) polymer adapted over edentulous
surfaces of a definitive cast to form a base which, together with an
attached occlusion rim made of wax or similar material, serves as
the record base
A material or device representing the base of a_ removable_ dental
prosthesis. It IS used for making maxillomandibular relationship
records and for the arrangement of teeth
Trial denture base functions are:
i. To aid in transfer of accurate jaw relationships to an
2. Checks the accuracy of the final impression.
3. Attached to it the occlusion rims (used to record maxillo-
4. On which the artificial teeth will be arranged to help the try—in
5. Used to relate casts on an articulator
6. Record bases simulate the finished denture base.
Requirements of a trial denture base
1. It should be stable.
2. It should be biocompatible
3. It should be rigid.
4. Properly extended and accurately fitted & adapted to the cast.
5. Dimensionally stable.
6. Relieved from any undercuts.
7. Clean & smooth.
8. Proper thickness (around 2mm thickness not to be bulky).
9. Easily constructed
Types of record base
1 . Temporary record bases
2. Permanent record bases
1- Temporary record bases:
They are discarded and replaced by denture base material, once their role
in establishing jaw relation, teeth arrangement and try in is complete.
Types of temporary record bases materials:
1- Shellac base plate
2- Reinforced shellac base plate
3- Cold cure acrylic resin
4- Visible light cure acrylic resin
5- Vacuum formed vinyl and polystyrene
6- Base plate wax
7- Swaged tin
2- Permanent record bases:
They are not discarded and become part of the actual base
of the finished complete denture.
Types of permanent record bases materials:
1. Heat cure acrylic resin
3. Chromium—cobalt alloy
4. Chromium—nicke| alloy
Record base materials:
Shellac base plate
1 . They will adapt to intimate contact with the master cast. aA: fE§i: f"
2. Require short time for construction. /I
3. Inexpensive. T1 ‘X
4. Can be corrected easily by reheating and readapting to the master cast.
5. Uniform thickness.
Disadvantages: Although shellac record bases are easily and quickly
adapted, they are not considered satisfactory.
1. they warp, so do not fit accurately
2. distort easily
3. lack of rigidity
4. become brittle and break, and will not permit polishing of the borders
: Any undercuts are relieved, and separating medium is
applied to the cast.
- The forms are softened with an open flame and molded
to the cast with an instrument or the fingers.
- While the material is in a softened state, the excess is
removed with scissors.
- After hardening, the borders are smoothed but as a rule
will not take a polish.
° The manufactured form of shellac is softened with an open ﬂame.
° A ﬂattened wire is contoured and adapted across the shellac
Cold cure acrylic resin
1. Good strength no need for reinforcement
2. Good dimensional stability
3. Does not wrap during manipulation
4. Closely fit to the master cast
1. Require more time in fabrication
2. Difficult to control the thickness
3. Residual monomer can cause irritation to oral tissues
Methods of construction using cold cure acryle
1. Sprinkle on method (previously mentioned in
2. Finger adapted dough method (previously mentioned
in Impression chapter)
3. Flasking method
4. Wax-confined method
A wax pattern is constructed over the cast with a
thickness and contour desired for complete denture. The
cast and pattern are flasked, the wax is eliminated, and
acrylic resin is packed and allowed to set under the
pressure of clamps or press.
Vacuum formed vinyl and polystyrene
- Any undercuts are relieved, and separating medium is
applied to the cast.
- A sheet of base plate material placed over the cast and
inserted in the vacuum chamber. After proper heating, turn
on the vacuum. The sheet will adapt closely to the cast.
Base plate wax
1. Wet the cast
2. Soften the base plate wax over the flame and adapt it to
3. Remove the excess wax and make the borders round and
Heat processed acrylic resin
1. A wax pattern is constructed over the cast with a thickness and
contour desired for complete denture.
2. The cast and pattern are flasked, the wax is eliminated, acrylic resin
is packed and heat processed.
3. The processed base is removed from the cast, smoothed, and
polished at the borders.
Advantages: they are rigid, accurate, stab/ e, not subject to distortion,
and suitable for arrangement of teeth.
Disadvantages: require considerable time, more expensive.
Definition: occlusion rims are occluding surfaces
constructed on record bases or permanent denture bases to
be used in recording jaw relations and for arranging teeth.
1. The position should be in the anticipated position of the
2. It must be securely attached to the base.
3. The occlusal surface must be smooth and flat.
4. It should be contoured to support the lip and cheeks
5. All the surfaces should be smooth.
The occlusion rims are used to:
a. The level of the occlusal plane.
b. The arch form.
c. Proper lips support.
2. Record the maxi| |o—mandibu| ar relations.
3. For arrangement and setting of the teeth.
4. Selection of the teeth size, ( canine lines, midline,
high and low lip lines)
Wax Rim characteristics:
1. Wax rims are smooth and have a flat
occlusal surface. They are about as
wide buccolingually as denture teeth -
wider in the posterior, narrower in the
2. The occlusal rim must be centered
buccolingually over and parallel to the
residual ridge crest.
3. Except for the anterior portion of the
maxillary occlusal rim is labially
A- Maxillary arch
1. The anterior wax rim height is 20-22mm
2. The posterior wax rim height is 16-18mm (from the center of
the ridge the height would be 8mm).
3. The width of the anterior rim is approximately 3—5mm.
4. The width of the occlusal rim in the posterior region is
5. The occlusal rim is properly sealed to the baseplate without any
6. The posteriors of the occlusion rims are cut at a 30° angle to
B- Mandibular arch
l. The anterior wax rim height is 15-18mm
2. The posterior wax rim height covers 2/3 of the retromolar pad.
3. The width of the anterior rim is approximately 3- 5mm.
4. The width of the occlusal rim in the posterior region is approximately 8-
5. The occlusal rim is properly sealed to the baseplate without any VOldS.
Materials & methods
A- Wax ready-made occlusion rim
1. It is supplied as a horse shoe shaped rim, adapt it in the proper position
on the record base.
2. Softened it slightly, sealed it with the record base by the aid of a wax
3. Smooth all the surfaces
B— Hand—made occlusion rim
1Uniform| y soften a sheet of hard pink baseplate wax. Flame
the wax in a Bunsen burner flame slowly by passing the wax
quickly through the flame many times. When the wax is
thoroughly softened, fold the wax in half.
Continue to flame the wax to soften it. Repeat the folding and
warming until the entire sheet of wax is used.
2. The other way, the wax is simply rolled into a tight cylinder,
then shaped to arch form.
3. Form the wax into a horseshoe shape and adapt the wax to
the record base over the ridge crest area.
4. Begin at the right tuberosity area and continue to the anterior
and opposite tuberosity area. Seal it to the record base with
molten wax using a hot
5. Use a pancake turner or a heated wax spatula to develop a
flat occlusal plane.
6. The width and height of the occlusion rim then adjusted
according to the measurements mentioned before.
Maxillary Occlusion Rim Adjustment
1- Maxillary rim slightly should be facial to
compensate for ridge resorption.
2- (lncisal display) Anterior height 1-2 mm below the
lip at rest/ when the patient slightly smiles
3- Horizental extension;
1- The upper occlusal record anterior edge should
touches wet line of lower lip (the Vermilion border)
when ‘F’ or ‘V’ sounds (Count ‘50—60’).
2- The labial surface of the wax anterior to incisive
papilla 8 - 10 mm
3- Lips should be unstrained
4- To confirm correct wax block dimensions:
- Naso—| abia| angle z 90°
- Philtrum depressed (not full)
- Vermilion border showing (not inverted)
Maxillary Occlusion Rim planes Adjustment
1- Frontal (Mediolaterally) the occlusal plane parallels the pupils (Fox plane
can be used
2- Anterio—posteriorly, The Maxillary denture occlusal plane should be
parallel to the camper’s line
Mandibular Occlusion Rim Adjustment
1- Posteriorly, the occlusion rim intersects 1/2 — 2/3 up the
2- Anterior height even with the corners of the mouth when
the lip is relaxed (Buccal corridor
3- 1-2 mm horizontal overjet
4- Unstrained lips, Vermilion border showing