proper mixing of the material. After the temporary cement has set, use the mirror and explorer to gently remove all excess cement from the crown and gingival area. Check the patient's occlusion again and allow you patient to rinse his/her mouth with water to remove any debris or loosened excess cement. At the end pf this appointment, make arrangements for future visits before dismissal of the patient. Be sure to annotate the DD Form 2322 with the date, time, and step of the next treatment planned. This information is essential to the dental laboratory for fabrication of the requested work.

INSERTION OF FIXED PROSTHETICS

The basic steps involved in inserting crowns and fixed FPDs are the same. Your instrument tray setup for insertion is the same as shown in figure 8-43. You will need to include assorted stones and burs for adjustment of the prosthesis. Usually, local anesthesia is not required since most patients can tolerate the minimal discomfort associated with the insertion of the prosthesis. The basic steps in delivery of the final prostesis include removal of the temporary, try-in and adjustment, stain and glaze, and permanent cementation.

Removal of the Temporary

The removal of the temporary is usually delegated to the dental assistant. Do this gently since your patient usually does not have anesthesia and may experience some slight sensitivity. Use the following steps when removing a temporary:

1. Use an instrument, such as a stellite, to loosen the temporary bond at the margin of the temporary.

2. Once removed, clean any debris or retained temporary cement on the tooth or teeth with a cotton pellet and cotton forceps.

Try-In

One of the first steps in the try-in of the prosthesis is the adjustment of the proximal contacts. Proximal contacts between adjacent teeth should exist, but be nonwedging. The proper amount of contact exists when there is a slight snap of dental floss as the dentist passes it through the contact areas. The dentist will check other aspects of the prosthesis as follows:

Ensures the prosthesis is fully seated.

Evaluates the pontic adaptation visually, and then passes dental floss between the pontic tip and the tissue ridge to ensure very little, if any, pressure is on the residual ridge mucosa.

Uses articulating paper to mark any areas of interference between the prosthesis and the opposing teeth, and then reduces them with dental stones and burs in a dental handpiece. If the prosthesis is completely metal, any surface roughness resulting in clinical adjustments is eliminated, and the metal is highly polished before cementation.

Stain and Glaze

If the prosthesis involves porcelain, the dentist will stain and glaze the porcelain to characterize the porcelain for maximum esthetics. Unstained and unglazed porcelain is referred to as being in a bisque bake state. Before the prosthesis can be cemented, it must be returned to the laboratory to fire the stain and glazed porcelain. After glazing, the laboratory will highly polish the exposed metal of the prosthesis. The prosthesis is now ready for cementation.

Cementing the Prosthesis

The final step in this appointment is the cementing of the prosthesis. The treatment site must be kept clean and dry throughout the procedure.

Zinc phosphate (ZnPO₄ ) and glass ionomer cement have been recognized as excellent permanent cementing agents for fixed prosthetics. ZnPO₄ , however, is highly acidic during the initial setting stage because of the presence of phosphoric acid. Therefore, ZnPO₄ can be quite irritating to the pulp tissues if the cementation process is not handled properly. Some dentist prefer to coat the preparation with copalite varnish before cementation with ZnPO₄ . Other permanent cements such as reinforced Zinc oxide and Eugenol (ZOE), ethoxybenzoic acid (EBA), and polycarboxylate (PCA) cements are less irritating to the pulp tissues, but have not proved to be clinically superior to glass ionomer as a permanent cement. You must follow the manufacturer's instructions for dispensing and mixing the particular cement selected.

To accomplish cementation of FPD, perform the following steps A through C shown in figure 8-45:

1. Isolate the treatment site with clean, dry cotton rolls, and gently dry the prepared tooth or teeth with a gentle blast of warm air or cotton pellet (step A). 8-32