Methods of attaching artificial teeth to denture bases

A. Using Acrylic Resin.
B. Using Cement.
C. Processed directly to metal.
D. Cast with the framework.
E. Chemical Bonding.

A. With Acrylic Resin:

Used for porcelain or acrylic resin artificial teeth.

PORCELAIN TEETH :

Are mechanically retained.
Anterior porcelain teeth are retained by acrylic resin surrounding their lingually placed retention pins.
Posterior teeth are retained by acrylic resin in their diatoric holes.

RESIN TEETH:
With resin bases these are retained by means of chemical union.
With metal bases retention is accomplished by means of :
Nail head retention,
Retention loops
Diagonal sprues placed at random
any junction of acrylic resin with metal should be an undercut finishing line or should be associated with some retentive undercut.

B. With Cement :

Used for porcelain or resin tube teeth and facings.
Means of mechanical retention.
Disadvantages:
1. difficulty to obtain satisfactory occlusion.
2. lack of adequate contours for functional tongue and cheek contact
3. unaesthetic display of metal at gingival margins.

MODIFICATION:

attachment of ready-made acrylic resin teeth to metal base with acrylic resin of the same shade.
Called as PRESSING –ON a resin tooth not the same as using acrylic resin for cementation. Applicable to anterior replacements

METHOD of both above : refer Mc Cracken 10th ed. Pg 162.

C. Processed directly onto metal bases :

Used with resin teeth chiefly .
Comprise of laboratory fabricated cross – linked polymer teeth .
Recesses are carved in denture pattern either by hand or around manufactured teeth , occlusal relation established in mouth and transferred to articulator and processed in acrylic resin , better attachment to metal bases than by cementation.

Can be used with porcelains but difficult to prepare recesses in porcelain

D. Cast with framework

Comprise of metal teeth
Done when the space is too limited for the addition of a tooth but yet this is desirable to prevent extrusion of opposing tooth especially in cases of second molars.

CONSIDERATIONS:

Chrome – alloys are abrasion resistant so occlusal contact should be held to a minimum to prevent periodontal damage to the opposing tooth and associated discomfort..
Occlusal adjustments on gold alloy are easily accomplished whereas chrome alloys are difficult to adjust therefore chrome should be used only to fill space and prevent extrusion .

E. Chemical bonding:

Used for acrylic resins on metal frameworks.

TWO METHODS

1. Sections of metal frameworks that are to support the teeth are roughened with abrasives and then treated with a vaporized silica coating.
Acrylic bonding agent is applied on this followed by a thin film of acrylic resin to act as a substrate. Later attachment of acrylic resin teeth r processing of resin.

2. TRIBOCHEMICAL COATING: Involves sandblasting the metal framework with special silica particle material Rocatec-plus.