صناعة اسنان

Complete Denture Impression

Lecture 4/ Dr. Rana Rabee

A complete denture impression : is a negative registration of the entire denture bearing, stabilizing, and border seal areas present in the edentulous mouth.
A preliminary impression : is an impression made for the purpose of diagnosis or for the construction of a tray.
A final impression : is an impression for making the master casts. The master casts are used in constructing the dentures.

Objectives of impression making

PRESS
P - Preservation of the alveolar ridges.
R - Retention
E - Esthetics.
S - Stability.
S - Support.


Preservation of the alveolar ridges: Covering as much of the supporting areas as possible - minimize the possibility of soft tissue abuse and bone resorption.


Retention of a denture is that quality inherent in the dental prosthesis acting to resist the forces of dislodgment along the path of placement

Stability

means resisting displacement by functional horizontal or rotational stresses
Relationship of the denture base to the underlying bone
Attained by more intimate contact of labial and buccal flanges with the labial and buccal slopes and of the lingual flanges with the lingual slopes of the ridge.

To be stable a denture requires :

Good retention
No interfering occlusion
Proper tooth arrangement
Proper form and contour of the polished surfaces
Proper orientation of the occlusal plane
Good control and coordination of the patient's musculature.

Support

The resistance to vertical forces of mastication and to occlusal or other forces applied in a direction toward the basal seat.

Esthetics

Thickness of the denture flanges


Thicker denture flanges are preferred in long-term edentulous patients - labial fullness.

Impression should perfectly reproduce the width and height of the entire sulcus for the proper fabrication of the flanges.

Areas of support are divided into

Areas of support

Primary

Maxillary: Posterior ridges and flat areas of the palate
Mandibular: Buccal shelf, posterior ridges
Reason: These are the areas that are at right angles to the occlusal forces and usually do not resorb easily

Secondary

Maxillary: Anterior ridge and all ridge slopes.
Mandibular: Anterior ridge and all ridge slopes.
Reason: These are the areas that are greater than at right angles to occlusal forces or are parallel to them; also the areas of edentulous ridge that are at right angles to occlusal forces but tend to resorb under load.
Slight
All vestibular areas that provide very little support but are needed for the very important peripheral seal