Dental materials chapter 5

The acid used most commonly to etch tooth structure for bonding procedures is?

• Citric

• Hydrochloric

• Hydrofluoric

• Phosphoric

Which one of the following statements about bonding to enamel is true?

• Bonding is achieved by micro mechanical retention

• Bonding is achieved by chemical bonds

• Bonding is achieved by resin tags penetrating the collagen matrix

• Bonding to enamel is less reliable than bonding to dentin

Bonding to dentin by the total etch technique

• Is best on dentin that has been etched with 37% phosphoric acid for 30 seconds

• Is stronger when the dentin is well dried after etching

• Is inhibited by formation of the hybrid layer

• Is best accomplished when the dentin is kept moist after etching

One of the following statements about total etch resin bonding agents is true?

• Water is the most common solvent used with these bonding agents

• They form a hybrid layer the best with dry dentin

• They chemically bond to the composite resin

• They chemically bond to the dentin

Self- etching bonding systems

• Use 37% phosphoric acid as the etchant

• Use acidic primers to etch the tooth structure

• Require rinsing after etching

• Generally etch enamel equally as well as dentin

Total- etch bonding systems

• May result in tooth sensitivity caused by overdrying or over etching

• Do not require a separate etching and rinsing step

• Do not require drying of the primer

• Do not provide a good etch of uncut enamel

With the total etch system when bonding to dentin, one of the following statements is true. Which one?

• The dentin surface should be thoroughly dried after etching and rinsing

• The surface of the etched, rinsed, and lightly dried dentin should be "glistening"

• The surface of prepared dentin should have visible water droplets

• Once you have dried the etched surface, it cannot be rewetted

Dentin sensitivity can be caused by

• Pressure changes in the column of fluid within the dentin tubules

• Stimulation of odontoblastic processes within the dentinal tubules

• Open (unsealed) dentinal tubules

• Overetching or overdrying of the dentin

• All of the above

The smear layer

• Is a tenacious layer of cut tooth debris on the surface of enamel and dentin

• Is easily removed by rinsing with water

• Is necessary for good bonding

• Is not removed when bonding by the total etch technique

All of the following statements about bonding to repair fractured porcelain on a crown are true except one.

• The surface is cleaned and roughened

• 10% phosphoric acid is used to etch the porcelain

• Silane is applied after etching to enhance the bond of adhesive resins to the porecelain

• Composite resin is usually used to restore the fractured portion