Describe the different structures of the oral cavity that the dental laboratory technician requires from a final impression for a removable prosthodontic appliance, and compare these with the requirements for a fixed- prosthesis case.

Both the methods used in making conventional impressions and digital impressions are shown in this presentation. The various impression materials are described and their suitability for fixed prosthodontic impressions is discussed. Materials described include irreversible hydrocolloid, reversible hydrocolloid, polysulfide, condensation reaction silicone, addition reaction silicone, polyether, and alginate substitutes. The design principles and methods for making custom impression trays are described. Impression methods are demonstrated in detail and are supplemented with a video demonstration.

Explanation:

answer:

i don't believe the ocean is purple, but it might once have been:

as for the sky, according to nasa:

"sunlight reaches earth's atmosphere and is scattered in all directions by all the gases and particles in the air. blue light is scattered more than the other colors because it travels as shorter, smaller waves. this is why we see a blue sky most of the time."