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