Chapter 5 Flashcards
The most commonly used etchant/ conditioner for tooth bonding is
Phosphoric acid
ranges from 10-38%
Etched surface of a permanent tooth should have a ____ appearance when dried
frosty
Smear layer
when a cavity prep is cut, Layer of debris from cutting forms on the surface of the cut dentin and enamel
3 things about smear layer
- Composed of mostly tooth structure (hydroxyapatite and collagen) may also contain plaque, bacteria, saliva, and even blood.
- sticks tenaciously to the dentin surface and plug the opening of dental tubules and can’t be washed off with an air and water syringe
- interfere with the formation of the bond to dentin
What is etching
on enamel, removes a small portion of the surface
- reduces the ends of the enamel rods, and created microscopic pored between adjacent rods
- creates a highly roughed surface with many tiny pores where resin can lock
Acid that creates the best etching pattern
Phosphoric acid
How does Etchant Come and how is it dispensed
Liquid - brush, small cotton pellet, small sponge
Gel- dispensed from a syringe, needle tip, or brush
Benefits of gel- they contain silica and they stay in place
How long to etch enamel on permanent teeth
20-30 sec
How long to etch enamel on highly mineralized
up to 60 due to being more resistant
How long to etch enamel on primary teeth
60+ sec, due to enamel having a prism pattern that is not as well structured and is more resistant to deep resin tag formation
When etching both enamel and dentin as in a coronal cavity preparation, what is the best way
Apply the acid to the enamel first for 10 seconds, and then to the dentin for 10 seconds. That way enamel will be etched for a total of 20 seconds and dentin only 10 seconds.
Which etch or tooth conditioner is used when seating or repairing ceramic restorations?
Hydrofluoric acid
When are posts placed within the roots of endodontically treated teeth to retain dental materials used to build up the teeth
When coronal tooth structure is inadequate for restorations with a crown
Etch gel is typically a ___% of phosphoric acid
37
What is it called when teeth have been over dried after etching
desiccation
Desiccation Why can this contribute to postoperative sensitivity?
Traps air in the dentinal tubules, when the patient bites down, the restoration compresses the dentin, putting pressure on the air in the tubules.
Contaminants on the surface of the tooth can greatly affect the longevity of the restoration and may include?
saliva, blood, food
what to do if the enamel becomes contaminated
rinse and re-etch for 10-15 sec
micro leakage
Leakage of fluid and bacteria caused by microscopic gaps that occur at the interface of the tooth and the restoration margins.
When would it occur?
When contaminants are not removed.
3 modes of cure
- Self- process- (chemical) chemical reactions occur when two chemicals are mixed together
- Light cure- blue light
- dual cure- self cure and light
One primary reason for sensitivity (postoperative) is unsealed dentinal tubules. How do the unsealed dentinal tubules occur?
Phosphoric acid etching removes the smear layer and smear plugs in the tubules leaving open tubules. If they are not sealed during the bonding process, a number of things can influence the pressure on the fluid in the tubules and elicit a pain response.
