3rd class prosthodontics dr: reemahmed lec-2 diagnostic …

Tikrit University – collage of Dentistry 3rd class PROSTHODONTICS Dr: ReemAhmed

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Diagnostic cast Diagnostic casts are a supplement to the oral

examination, an accurate replication of the anatomic form

of the maxillary or mandibular dental arch showing the

relationships of the remaining teeth and the surrounding

.. tissues

Purposes from making diagnostic cast:

1- Diagnostic casts permit inspection from perspectives that are impossible to obtain when looking in the patient’s mouth

2-

Diagnostic casts permit extended observations and

comparasions far beyond the patient’s endurance for

holding his/her mouth open and are available for study

during the patient’s absence.

3- Diagnostic casts are used in educating the patient about his/her

dental needs and corresponding treatment plan.

Three steps of obtaining diagnostic casts:

• 1-An alginate impression is made directly in the patient’s mouth

producing a negative mold.


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• The impression is poured in dental stone, producing a positive cast.

• The cast is inspected for defects, repaired if possible, and trimmed to the proper size and shape on a model trimmer.

•

COMPONENT OF PARTIAL DENTURE (Cobalt –Chrome) REMOVABLE PARTIAL DENTURE Components of a Partial Denture a. Major Connector : The unit of a removable partial denture that connects the parts of one side of the dental arch to those of the other side. It's principal functions are to provide unification and rigidity to the denture.

b. Minor Connector A unit of a partial denture that connects other components ( i.e. direct retainer, indirect retainer, denture base, etc.) to the major connector. The principle functions of minor connectors are to provide unification and rigidity to the denture.

c. Direct Retainer : A unit of a partial denture that provides retention against dislodging forces. A direct retainer is commonly called a 'clasp' or 'clasp unit' and is composed of four elements, a rest , a retentive arm, a reciprocal arm and a minor connector .

d. Indirect Retainer : A unit of a Class I or II partial denture that prevents or resists movement or rotation of the base(s) away from the residual ridge. The indirect retainer is usually composed from(rest &minor connector) .

e. Denture Base : The unit of a partial denture that covers the residual ridges and supports the denture teeth.


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Some important terms

Height of contour:

A line encircling a tooth, designating its greatest

circumference at a selected position determined by a

dental surveyor

Under cut area


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A- Any areas cervical to height of contour used for

(under cut area) placement of retentive clasp components

b-Areas occlusal to the height of contour used for the

placement of non retentive, stabilizing, or reciprocating

components(non under cut area)

Types of undercuts(desirable &undesirable)

1-tooth undercut

2- soft tissue or bony undercut(on lingual side of the ridge).


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Angle of Cervical Convergence:

An angle viewed between a vertical rod contacting an

abutment tooth and the axial surface of the abutment

cervical to the height of contour

Path of insertion and removal

Path that the prosthesis is Placed/removed ,Usually a single

or path

The Direction in Which a Restoration/ Prosthesis Moves From

the Point of Initial Contact With the Supporting Teeth to

the Terminal Resting Position Where the Occlusal Rests Are

Seated and the Denture Base Is in Contact With the Tissue


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Path of Removal (P.R) Reverse of the Path of

Insertion

Advantages of a Single Path of Insertion

1-equalize retention

2-bracing and cross arch stabilization

3-minimize torque on abutment

4-allow removal without encountering interferences

5-direct forces along axes of tooth

3rd class prosthodontics dr: reemahmed lec-2 diagnostic …

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