National Dental Assisting Examining Board (NDAEB) Practice Exam

What is the best method to prevent small blebs of stone on the occlusal surfaces of teeth in a diagnostic cast?

1. Wipe some alginate onto the occlusal surfaces of the patient's teeth before seating the tray

2. Use a more viscous solution for impressions

3. Ensure the tray is seated rapidly

4. Cool the alginate before making the impression

The correct answer is: Wipe some alginate onto the occlusal surfaces of the patient's teeth before seating the tray

Wiping some alginate onto the occlusal surfaces of the patient's teeth before seating the impression tray is effective in preventing small blebs of stone on the occlusal surfaces of diagnostic casts. This method helps to create a thin layer of material that can enhance the homogeneity of the impression and reduce the likelihood of air entrapment between the occlusal surfaces and the impression material. By applying alginate directly to the teeth, it allows for better detail capture and minimizes the risk of material pooling or forming irregularities during the impression process. While other methods, such as using a more viscous solution or ensuring the tray is seated rapidly, might influence the overall quality of the impression, they do not specifically address the occurrence of blebs on the occlusal surfaces in the same targeted manner. Cooling the alginate may affect its setting time, but this adjustment does not directly relate to preventing the formation of blebs. Therefore, the correct choice of wiping alginate on the teeth before seating provides a proactive and direct solution to achieving a smooth and accurate impression without imperfections.