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Dental Materials
Cements and Bonding
| Question | Answer |
|---|---|
| What is the most commonly used etchant or conditioner for tooth bonding? | phosphoric acid |
| What is the concentration of the most commonly used etchant? | 10-38% |
| When a resin bonding agent hardens, it creates projections that lock into the tooth, creating what type of bond? | mechanical |
| What type of bond is formed when other resins placed over it, such as composite resin? | chemical |
| When acid etching for bonding, it is desirable to have a _____ surface energy. | high |
| When acid etching for bonding, it is desirable to have a _____ angle of contact. | low |
| Why would a bonded restoration with a deep preparation have a lower level of success over a shallow bonded restoration? | Wetter dentin with more holes is more difficult to bond to consistently than shallower dentin. |
| How will the etched surface of a permanent tooth look when dried? | frosty or chalky |
| Why should primary teeth be etched for longer than permanent teeth? | the surface of the enamel has a prism pattern that is not well structured, and the enamel is considered aprismatic |
| Are primary or permanent teeth more resistant to deep resin tag formation? | primary |
| What needs to happen if saliva contamination occurs during etching? | The surface must be re-etched. |
| How does a smear layer interfere with the bonding process? | It cannot be washed off using an air/water syringe and it plugs the openings of the dentinal tubules preventing a hybrid layer |
| Where does the smear layer form? | It forms on the surface of the cut dentin and enamel |
| How long should dentin be etched? | 10 seconds |
| Why is it important to not scrub the enamel surface with a hard instrument? | it could break enamel rods, lower bond strength, and decrease formation of resin tags |
| Where is the oxygen-inhibited layer that is a very thin coating of uncured resin found? | on the surface of the polymerized bonding resin |
| What is the correct dual-cure process for resin bonding agents? | can be activated by light or can cure chemically without application of the curing light |
| How are silanes used when working with ceramic restorations? | Acts as a coupling agent that reacts with glass in the ceramic leaving a vinyl coating. |
| Which etch or tooth conditioner is used when seating or repairing ceramic restorations? | Hydrofluoric acid |
| Etching dentin with what type of acid dissolves the smear layer first? | Phosphoric acid |
| Which bonding method is best suited for placement of orthodontic brackets? | Self cured, dual cured, or light cured are all acceptable |
| What is an acceptable method of preparing a tooth with a root canal for a restoration? | composite resin core, amalgam core, and bonded post are all acceptable |
| What can overdrying of the dentin after etching cause? | tooth hypersensitivity |
| When rinsing off the phosphoric acid used to etch, how is the excess water removed? | paper point |
| Know the first step in the sequence for tooth preparation before cementation of a post in an endodontically treated tooth? | The prepared canal is etched with phosphoric acid and then the acid is rinsed off |
| Know the last step in the sequence for tooth preparation before cementation of a post in an endodontically treated tooth? | Self-curing or light curing composite resin cement is applied to both the canal and the post |
| What is the purpose of a dental bonding? | To provide adhesion |
| What is the wavelength of the curing light? | blue |
| How long should a tooth be etched when cementing a CAD/CAM designed restoration? | 15 seconds |
| What are the factors that contribute to microleakage? | Poorly sealed margins, contaminants, percolation, and shrinkage |
| The primer portion of the dental bonding agent is _____ to water. | hydrophilic |
| What is the thin coating of uncured resin on the surface of the polymerized bonding resin called? | oxygen-inhibited layer. |
| When would microleakage occur? | When contaminants are not removed |
| What may occur when odontoblasts are irritated by procedures or chemicals associated with composite resin restorations? | hypersensitivity |
| What is the strength of cement as compared with other restorative materials? | inferior |
| What is the solubility of cement as compared with other restorative materials? | high |
| What is a good cement to use as a direct pulp-capping agent when very small exposures of the pulp are suspected? | calcium hydroxide |
| Why are high-strength bases placed in a thickness of 0.75 mm or greater? | Provide protection from the thermal conduction of metal restorations |
| What is a best practice when the cavity preparation is so deep that there is 2 mm or less of remaining dentin over the pulp? | provide mechanical support for the restoration by first placing a cement base. |
| What property does the provisional material used prior to placing a permanent restoration have that is beneficial to the pulp? | sedative |
| Which cements is the highest in mechanical strength? | resin cement |
| What properties of a cement would be modified when adding additional powder to the mix creating a secondary consistency? | viscosity and strength |
| What are type I cements used for? | luting agents, can be permanent or temporary |
| What are type II cements used for? | provisional or intermediate restorations or dental sealants |
| What are type III cements used for? | bases or liners for cavity preparations |
| Which type of cement is recommended for cementing thicker ceramic restorations where light would not penetrate adequately? | dual cure |
| Which type of cement should not be used under composites or as temporary cement before final cementation with hybrid glass ionomer or resin cements? | ZOE -zinc oxide eugenol |
| Why shouldn't ZOE be used under composites or as temporary cement before final cementation with hybrid glass ionomer or resin cements? | Eugenol may interfere with the polymerization process of resins |
| Which cement should be removed with alcohol or orange solvent once it has set? | ZOE |
| What cement could be removed with the use of ultrasonic cleaners or a solution of baking soda and water? | zinc phosphate |
| What can be done when mixing zinc phosphate cement to dissipate the heat produced by the reaction? | mix on a cool glass slab, add powder to the liquid in small increments, and mix over a large area |
| What is the initial acidity of zinc phosphate cement? | low |
| When does the acidity of zinc phosphate cement become neutral? | 24-28 hours |
| Which cement requires the user to add all of the powder to the liquid at once and mix for 30 seconds? | Zinc polycarboxylate cement |
| What type of retention methods does polycarboxylate cement use? | both chemical and mechanical |
| What type of restorations are polycarboxylate cements ideal for? | indirect restorations |
| How do you know when zinc polycarboxylate cement is no longer usable? | When it loses its gloss and becomes stringy |
| Which cement must be used immediately because of the short working time? | zinc polycarboxylate cement |
| Which cements form a chemical bond to tooth structure? | Zinc polycarboxylate and glass ionomer |
| What are the properties of glass ionomer cements? | It has an anticariogenic effect, fluoride released is bacteriostatic, and it may remineralize tooth structure. |
| The composition of hybrid ionomer cement is similar to that of glass ionomer cement, but it is modified with the addition what? | resin |
| Which dental cement causes expansion as it absorbs moisture which makes it a concern when cementing all ceramic indirect restorations? | resin-modified glass ionomer |
| What are some common uses for ZOE cements? | Provisional cementation, provisional restorations, periodontal dressings, and low-strength bases |
| How should the cement be mixed when it is being made to cement a permanent crown? | to a luting consistency |
| What cement would not be used as pulpal protection under a restoration? | Resin cement |
| Which two cements are often used together to protect the pulp in a deep preparation prior to placing an amalgam restoration? | ZOE and calcium hydroxide |
| Why would you place a high strength base? | Decrease thermal sensitivity |
| What is the advantage of using glass ionomer cement? | they release and replenish fluoride |
| How are dental cements mixed when placing provisional and intermediate restorations? | to secondary consistency |
| How can solubility of dental cements be lowered? | Increase the amount of powder |
| What are the advantages to using hybrid ionomer cements? | Insoluble, excellent film thickness, chemical adhesion to tooth |
| When cementing a permanent ceramic restoration, at which point should excess cement be removed? | Immediately after seating |
| What is micromechanical bonding? | Micromechanical bonding uses surface irregularities smaller than can be seen with the naked eye, surface roughness cannot be seen or felt. |
| What are some reasons for using bonding or adhesive? | retention and reduction of recurrent caries and microleakage, |
| What affects the setting time and consistency of cements? | Saliva, temperature, humidity |
| What is a reason for placing a liner when doing a dental restoration? | To protect the pulp from chemical irritation |
| What is the difference between a liner and a base? | A base is stronger and thicker than a liner |
| Which dental materials are suitable for use as a dental base? | some examples are zinc phosphate, glass ionomer, polycarboxylate |
| Which dental material can be used as an insulating and protective base, temporary restoration, permanent cement, and a permanent restoration? | glass ionomer |
| How will a cement base appear on a radiograph? | Less radiopaque than metal |
| What are examples of high strength bases? | Zinc phosphate, zinc polycarboxylate, glass ionomer, resin modified glass ionomer, resin, reinforced ZOE, |
| Why is ZOE not used often as a luting material? | It has low strength and high solubility |
| Which cements form a chemical bond to tooth structure? | Zinc polycarboxylate and glass ionomer |
| Expansion of which dental cement, as it absorbs moisture, is a concern when cementing all ceramic indirect restorations? | Resin-modified glass ionomer |
| Which of the following cements should not be used under composites or as temporary cement before final cementation with hybrid glass ionomer or resin cements? | ZOE |
Created by:
BrendaAlberts