Dental Materials Chapter 5
"Prime & Bond" is an example of an bonding agent w/ acetone and "Optibond Solo Plus" is an example
of an bonding agent with what? - ANSWER-Ethanol
A bonding resin can be viewed as what two components? - ANSWER-A resin primer, and an adhesive
resin
A primer is more important on dentin than enamel because the primer contains hydrophilic groups that
penetrate wet, etched dentin; water is removed from etched enamel when it is dried, but the dentin
remains moist (wet). True or false - ANSWER-True
A resin primer penetrates etched dentin and enamel and lays down a resin layer; The primer is
composed of monomers and molecules that allow it to penetrate what? - ANSWER-Water (it has
hydrophilic properties)
Acetone is a highly volatile solvent. True or false - ANSWER-True; Its rapid evaporation may require that
two or more coats of the bonding resin be applied to ensure adequate sealing of the dentin
Acid etching increases the ability of liquids to wet the surface of the tooth by creating a what? -
ANSWER-High surface energy; High surface energy can attract contaminants (such as saliva), so good
isolation is important, because it saliva contamination occurs, drying the surface will leave residues that
will interfere w/ the bond and the surface will need to be re-etched.
An adhesive resin is applied over the primer and the two resins chemically bond to each other, that is ,
the initial resin bonding material prepares (or primes) the tooth surface, and then the resin chemically
bonds to the primer. True or false - ANSWER-True; Many manufacturers however have combined the
primer & bonding resin into one bottle to eliminate one step in the process.
Because dentin is not as highly mineralized as enamel, it should be etched for shorter periods, typically
for 10 seconds. When one is etching both enamel and dentin as in a coronal cavity preparation, it is best
to do what? - ANSWER-Apply the acid to enamel first for 10 seconds, and then to the dentin for 10
seconds, that way the enamel will be etched for a total of 20 seconds and dentin for only 10 seconds.
Bonding agents are usually not very viscous (thick), so they will flow readily and wet the etched surface.
True or false - ANSWER-True
Bonding to enamel alone requires only a low-viscosity liquid resin monomer that will penetrate into the
spaces on and between the enamel rods created by the acid etching. The liquid may be simply an
unfilled resin or may include what? - ANSWER-Small amounts of very fine filler particles to enhance the
strength of the resin
Bonding to enamel usually achieves consistently high bond strengths of around 30 MPa (4500 psi). The
bond strength to dentin is usually less than to enamel and varies according to what? - ANSWER-To how
deep into the dentin the cavity preparation extends.
Conventional amalgam restorations leak at the interface between the tooth and the amalgam. Freshly
placed amalgams leak more than older amalgams do. True or false - ANSWER-True; As amalgam ages, it
begins to corrode and form corrosion products along the interface between the tooth and the amalgam
, Dental Materials Chapter 5
which reduces microleakage. Many clinicans prefer to bond their amalgam restoration to strengthen the
seal between the amalgam and the tooth structure and to reduce the potential for microleakage.
Enamel is composed of thousands of rods (prisms) that extend from the dentin to the tooth surface in
what type of fashion? - ANSWER-Radial fashion; each rod has many millions of crystals composed of
hydroxyapatite that has about 20% carbonate inclusions.
Etching dentin for 20 seconds or longer opens the tubules too wide and removes the hydroxypaptite
mineral too great a depth. True or false - ANSWER-True
Etching dentin w/ phosphoric acid dissolves the smear layer first, then portions of the hydroxypatite
crystals from the surface of the dentin, creating a porous surface and exposing collagen fibrils that are
part of the what? - ANSWER-dentin matrix
Etching of enamel creates a high-energy, low-tension surface that makes the surface easier to what? -
ANSWER-Wet
Etching of enamel removes a small portion of the surface, reduces the ends of the enamel rods, and
opens porosities between the what? - ANSWER-adjacent rods ( as seen in fig. 5-2 page 35)
Ethanol dries more slowly so it may require a longer drying time. True or false - ANSWER-True
Even though there is a difference in the length of the resin tags between end-etched rods and side-
etched rods, the bond strengths are not significantly different. True or false - ANSWER-True
For resin to penetrate through water, it must be dissolved in a solvent that can penetrate water and
carry the resin w/ it; the solvents allow the resins to penetrate water on the dentin and in the dentinal
tubules, and to penetrate around the collagen fibrils and into the porosities in the tooth surfaces
created by the etching. What solvents are primarily used? - ANSWER-Acetone, ethanol (ethyl alcohol), or
a combination of ethanol and water.
Good wetting increases the intimate contact of the bonding resin with the etched tooth structure,
improving what? - ANSWER-Penetration of resin to form tags and thereby improving the bond.
High surface energy helps to attract the resin to the etched surface. True or false - ANSWER-True
Hydrofluoric acid is a highly caustic solution. True or false - ANSWER-True; it can etch porcelain,
composite, and glass ionomer restorations, as well as tooth structures, and can burn soft tissues.
In dentistry, the term bond or bonding, is used to describe the process of attaching restorative
materials, such as a bonded amalgam or a bonded composite resin, to the tooth by what? - ANSWER-
Adhesion (attraction of atoms or molecules of two different contacting surfaces).
In general, the solvent is the largest portion of the bonding agent, making up 60% or more of the
material. True or false - ANSWER-True
Noble metals such as gold particularly need to be tin-plated for an effective bond to the resin. True or
false - ANSWER-True
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