The heating element is housed inside a metal assembly at the very top portion of the unit. This section will become extremely hot when in use. Use caution. Before use, inspect the vacuum holes in the platform to make sure they are not obstructed. Inspect the rubber sealing gasket for cracks and deterioration. Clean the exterior of the unit and inspect the electrical cord and plug before each use.
The vibrator (fig. 8-21) is used to move dental plaster or dental stone mixes when pouring a cast. The vibrator also increases the density of the mix by eliminating air bubbles. A rheostat control is used to adjust the intensity of the vibration from a gentle agitation to a vigorous shaking.
To maintain the vibrator, cover the rubber platform and body of the unit with a plastic cover. As a safety precaution, check the power cord and plug for defects before use.
Some of the common prosthodontic instruments you and the dentist will use during patient treatment and in the fabrication of dental prostheses are explained in the following paragraphs.
To remove a crown from a tooth, the dentist uses a crown remover instrument (fig. 8-22). The handle on the crown remover is encircled with a heavy-steel weight that slides from one end of the handle to the other. Two interchangeable points make up the working end. One of these points is contra-angled and the other is straight. Both points have a right-angle
Figure 8-21 .- Vibrator.
Figure 8-22. - Crown remover.
projection at the top. When the crown remover is used properly, the tip is placed over the margin or junction of the crown and tooth first. Then the sliding weight on the handle is tapped against the bottom part of the handle.
The roach carver (fig. 8-23) is a double-ended instrument used to cut, smooth, and carve dental waxes. At first glance, it appears to look like a wax spatula. A closer look reveals a spear-shaped blade at one end, with a deep-welled, very small spoon at the other end. Both ends have very sharp edges. The deep-welled end may al so be used to carry melted wax.
Usually, two kinds of knives are used in the prosthodontic treatment room: the compound knife and plaster knife. As the names imply, one is used with compound, and the other with plaster.
The compound knife (fig. 8-24) has a fairly large, red plastic handle and detachable blade. Routinely the #25 blade is used to trim impression compound, wax, and other materials that require an extremely sharp cutting edge. The blade is almost identical to a larger version of the #11 surgical blade. Your primary concern with the compound knife is to replace broken or dull blades.
Figure 8-23. - Roach carver.Continue Reading