PREAT Precision Attachments

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Overdenture System

Male on the post-coping

The threaded base ring is either cast-to or soldered to the post and coping. The precision female is fixed in the acrylic resin either in the laboratory, or by the dentist.

Advantage:

Reduced chance of food impaction in the attachment

Fabrication of the post coping: Cast To Technique

Wax up the post-coping as low as possible (FIG 1). Use the (RE) P4 paralleling mandrel for the castable base ring. Thread the paralleling mandrel into the base ring (FIG 2). The occlusal surface must be at an angle of 90 degrees to the path of insertion (FIG 3).

Completely surround the base ring with wax (FIG 4). Make sure that the wax pattern ends only a few tenths of a mm below the upper metal ledge to prevent metal from flowing in (FIG 5). Paint liquid colloidal graphite (available from Preat Corporation), or anti flux, on the threads of the base ring to prevent any cast metal from adhering. Allow the graphite to totally dry before investing. A two stage investing process is recommended. Allow the initial investment to set for 30 minutes (FIG 6).

Tips:

Paint an anti-flux such as Colloidal Graphite on the threads to prevent flash from adhering to the threads. Let the Colloidal Graphite fully dry before casting.
Slowly flow investment into the threads of the base ring. Do NOT sandblast to remove investment.
Cut a small slot in the wax surrounding the base ring with a fine instrument to prevent metal from flowing into the base ring (FIG X).

The base ring may only be cast with precious or semi-precious alloys for the coping.

FIG X

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In cases of limited space, the post coping may also be waxed up in a concave form (FIG 7). The rounded shape of the coping provides for easy patient cleaning and hygiene maintenance (FIG 8).

The next step: Retaining the female in the prosthesis

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