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After studying this chapter, the student will be able to do the following:
1. Give reasons why correct dispensing, timing, and mixing of materials are important.
2. Discuss the difference in setting times of dental materials in the oral cavity and on the instrument tray.
3. Summarize the recommended guidelines for light-activated dental materials.
A dental hygienist must understand the composition, use, physical properties, and manipulation techniques for commonly used dental materials. This will promote office efficiency, economy of materials, and quality care for the patient. Based on this understanding, a few general rules should be followed to ensure success in the manipulation and application of these dental materials.
I. Follow the Manufacturer’s Directions
A. It is very important to read, understand, and follow the directions that accompany dental materials. One should not only read the directions but also understand why each step is performed in the manner directed by the instructions.
B. Office personnel should save copies of directions for the materials used in that office. It is recommended that these copies be kept in a file, hard copy, or digital. Thus, if the directions for a kit are lost, a copy will be readily available. Most manufacturers have directions available online.
C. When a new material is purchased, practice using the new material at least once before using that material clinically. Check the “feel” of the new product; how does it compare to other products?
D. Store materials in a cool dry place. The shelf life of many materials is lengthened by refrigeration. On the other hand, some materials will gel or mixtures will separate if they are refrigerated. See manufacturers’ directions for proper storage.
II. Mixing and Setting Times
A. Use a clock that has a second hand or displays seconds to time etching, mixing, setting, and other important time spans. This applies to the clinic and to the laboratory.
B. The mouth is a warm environment. Therefore, materials set faster when in the mouth than on the instrument tray or countertop. If a material is set on the instrument tray, it is set in the mouth. Exceptions to this rule are materials that set by cooling, such as impression compound, and light-activated materials.
C. The setting of some materials is also accelerated by the humidity of the mouth.