1. Properties of Dental Materials DA 122 Dental Materials

2. Council on Dental Materials, Instruments, and Equipment  Subgroup of the American Dental Association  Sets standards and specifications that all dental materials must meet

3. Acidity  1. affect oral tissues: Changing acidity levels determines use of products in oral cavity  2. acidity of materials may cause irritation to gingival tissue or damage to pulp  Ex. Mountain Dew!!

4. Adhesion  Chemical or physical force or attraction that holds unlike substances together

5. Biting Forces  Stress  Strain  Tensile  Ductility  Compressive  Malleability  Shearing  Bruxism

6. Stress and Strain  Stress: reaction of an object to resist external force  Strain: Enough stress placed on an object to cause change or deformation

7. Tensile  Pulls and stretches a material  Tensile stress and strain causes structure to be elongated  Ex. Tug-of-war

8. Tensile Strength  Resistance to a pulling force  Important quality of dental materials

9. Ductility  Ability of material to withstand forces of tensile stress without failing

10. Malleability  Ability of a material to withstand compressive stresses without fracturing  Capable of being reshaped or flattened

11. Shearing  Slides one part of material parallel to another, in back and forth motion  Ex. Cutting with scissors

12. Biting Forces

13. Bruxism  Grinding of teeth  Example of shearing

14. Corrosion  Tarnish: reactions of saliva and metal to cause dullness and discoloration

15. Dimensional Change  Shrinkage or expansion of dental material or other substance  Distortion  Disfigurement  Deformation (remember the 3 D’s!)

16. Distortion  Mis-shaped, twisted out of proper or normal shape

17. Deformation  Distortion or disfigurement

18. Prevention of dimensional changes  Distortion, disfigurement and deformation are all undesirable changes  Occur when dental materials are mishandled

19. Elasticity  Capable of maintaining or returning to normal size and shape after having been stretched  EX. Rubber bands

20. Flow  To move in a manner similar to a liquid stream  To creep or slump  Ex. Compare water and honey

21. Galvanism  Electrical shock resulting when two dissimilar metals contact one another in the mouth  Oral fluids act as a carrier between the two metals  Ex. Biting on a piece of tin foil with an amalgam restored tooth

22. Hardness  Resistance of material to scratch or indent  “hard as a rock”

23. Microleakage

24. Retention  Means by which materials and surfaces are held in place 1.mechanical retention 2.chemical retention

25. Mechanical Retention surfaces are prepared to hold materials in place

26. Chemical Retention  Chemical reaction between tooth surface and material

27. Bonding Process  Process by which materials adhere firmly or hold together  Dentistry uses bonding agents to bond dentin and enamel with restorative materials

28. Solubility  www.twinkiesproject.com/solubility.html www.twinkiesproject.com/solubility.html  Ability/rate of material to dissolve in fluid  Important if material is going to be exposed to the saliva and might dissolve and expose tooth structure

29. Thermal Properties  Relate to temperature (i.e. heat)  1. thermal conductivity/sensitivity  2. thermal expansion

30. Thermal Conductivity  Ability of a material to feel, transmit, or react to heat

31. Thermal Expansion  Reaction of material with heat to cause expanding or contracting

32. Exothermic Properties  When a dental material releases heat when it sets Example: pour dental models in gypsum- heats as it sets

33. Viscosity  Ability of a liquid to flow  Thicker material: Less flow More viscous  Olive oil  Thinner material: More flow Less viscous  Vinegar

34. Wettability

35. Key Terms Activity Using index cards make key terms for the properties of dental materials Copyright 2012 Porter and Chester Institute, Inc. All rights reserved