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Occlusion blocks
Definition; Occlusion blocks consist of
occlusion rims attached to well fitting
trial denture bases.
Uses of trial denture base :
› 1- Carries the occlusion rims on which jaw
relations are recorded.
› 2- Carries the teeth to help the try-in stage.
› 3- Checks the accuracy of the final
impression.
Requirements of a trial denture base;
It should be :
1-rigid.
2- Accurately adapted to the cast with proper
extensions.
3- Dimensionally stable with minimal warpage during its
use.
4- Relieved from any undercuts to avoid scrapping the
cast during insertion and removal.
5- Clean & smooth Pt. comfort.
6- Proper thickness 2mm .
7- Easy to construct.
Types of denture bases;
a. Temporary trial denture base.
b. Permanent denture base.
Materials used for temporary trial denture
base;
1. Hard base plate wax.
2.Shellac base-plate
3. Cold curing acrylic resin.
4. Swaged tin.
Shellac base plate
Advantages of Resin T.D.B over
Shellac bases :
1- Accurate fit to the cast.
2-High strength .
3-Dimensionally stable in the
mouth.
Materials used for permanent
trial denture base;
1. Heat cured acrylic resin.
2. Cast gold.
3. Chromium-nickel alloy.
4. Chromium-cobalt alloy.
The advantage of permanent trial
denture base. Is giving good idea
about extension, retention and
stability of the final denture.
The disadvantage is additional
shrinkage on second processing when
the teeth are added.
Heat cured A.R. :
Advantages :
1-Strong & rigid .
2- Control thickness ( during waxing up ).
3-Minimizes dimensional changes.
4-T.D.B.become part of the denture.
Disadvantages :
1-Time consuming.
2-Need to construct mounting casts.
3-Warpage second processing to attach teeth.
Metal Bases
Advantages :
1- No acrylic warpage.
2-More strength .
3-More accurate.
4-Less tissue change under the base.
5-More hygienic. Less porosity.
6-Good thermal conductivity.
7-Less deformation in function.
Disadvantages :
1-Cost 2-Difficulty in relining. 3-Time
consuming.
Stabilization of Recording Bases:
Additional stabilization is sometimes
required with temporary trial denture
bases through relining with Zn &
Eugenol impression material after
adaptation of tin foil to the master
cast.
Stabilization of temporary trial denture
base.
Occlusion rims:
Occlusion rims are generally made of pink
modeling wax.
Used to relate casts on an articulator
Record bases simulate the finished denture base
Wax occlusion rims simulate the position of the teeth
Occlusion rims
slightly bulkier
Provide additional
stability during
record making
Uses of occlusion rim:
1. Registration of jaw relationships.
2. Choice of the artificial teeth:
i. Midline is determined on it.
ii. High and low lip lines are determined on it to
indicate the length of the teeth.
iii. Canine lines width of the teeth.
Distance between the canine line & the posterior end of
the occlusion rim M-D width of posterior teeth.
3. Setting-up of teeth.
4-Support for lip & cheeks.
Special forms of occlusion rims:
1- Wax occlusion rims.( Most
commonly) .
2- Modeling compound occlusion
rims. Graphic tracing method.
3- Plaster and pumice rims.
Functional chew-in technique.
- The average height of the upper occlusion rim anteriorly is about 22mm for the lower the average distance from the lower sulcus to the incisal edge of the lower central incisor is about 16 mm.
- The posterior vertical height of the maxillary occlusion rim, is about 6-8mm when, while for the posterior lower region the height is equal to a point representing one-half the height of the retromolar pad.
- The labial surface of the maxillary occlusion
rim in the central area is approximately 8-10
mm anterior to the incisive papilla, and is
inclined labially, while the mandibular
occlusion rim from canine to canine area is
inclined slightly forward, but remains within
the border of the recording bases.
Adjust separately using
average dimensions:
Maxillary 20-22 mm
Mandibular – 14-16
mm
Use a Hot Scapel
Blade
Use a Hot Wax
Former
Maxillary rim
slightly facial to
compensate for
ridge resorption
Centered
over the
ridge to
maximize
stability
Posteriorly, the
occlusion rim
intersects 1/2 - 2/3
up the retromolar
pad
1-2 mm horizontal
overjet in anterior &
posterior in centric
position
Occlusion rims can be made from :
i- Modeling compound rims which are also
used for mounting different Types of
tracers when recording jaw relation by
the graphic method.
ii- Plaster and pumice rims they are sometimes used for the construction of occlusion rims when recording jaw relation by the functional chew-in technique.
Thank you
enumerate
1. Methods of releif
2. Functions of releif
3. Functions of boxing
4. Types of trays