Question

A diagnostic cast (also called study model) made from an alginate impression is found to have numerous small blebs (leads) of stone on the occlusal surfaces of the teeth. The best way to prevent this from happening is to:

A) apply a layer of petroleum jelly on the occlusal surfaces before taking the impression
B) spray a water-based separator on the occlusal surfaces before taking the impression
C) wipe some alginate onto the occlusal surfaces of the patient's teeth before seating the tray
D) heat the stone mix before pouring it into the impression

Answer 1

To prevent small blebs on a diagnostic cast from an alginate impression, option c)wiping some alginate onto the occlusal surfaces before seating the tray is the best approach.

Step-by-step explanation:

When creating a diagnostic cast, the presence of small blebs or beads on the occlusal surfaces can be problematic. The best way to prevent this kind of error when creating a cast from an alginate impression is to thoroughly wipe some alginate onto the occlusal surfaces of the patient's teeth before seating the tray. This method ensures that there are no air pockets between the tooth surface and the alginate material, which can lead to the formation of blebs during the casting process.

Therefore, the correct answer is option C) wipe some alginate onto the occlusal surfaces of the patient's teeth before seating the tray.