3-A ceramometal posterior fixed partial denture
A. be constructed to have an occlusal surface one
quarter the width of the tooth it replaces.
B. be constructed to have an occlusal surface wider
than the width of the tooth it replaces.
C. cover as much mucosa as possible.
D. provide adequate embrasure spaces
• The mesial, distal, and lingual gingival
embrasures of the pontic should be wide open
to allow the patient easy access for
cleaning,3^.12.'620 and the contact between
• pontic and tissue must allow the passage of
floss from one retainer to the other.
• Schillenberg page 478
• An occlusal rest preparation should be
A. angular and box shaped with parallel vertical
B. rounded and spoon shaped.
C. flat and with an obtuse angle to the proximal
surface of the tooth.
• The outline form of an occlusal rest seat
should be a rounded triangular shape with the
apex toward the center of the occlusal
surface. It should be as long as it is wide, and
the base of the triangular shape (at the
marginal ridge) should be at least 2. 5 mm for
both molars and premolars.
• mcckrRPD chapter 6 ,PAGE 70
6-The base of a distal extension partial denture
should cover the maximum support area because
A. the force per unit area will be kept to a
B. maximum number of artificial teeth can be
C. phonetics is improved.
D. strength of the base is increased.
• Distal Extension Partial Denture Base
• In a distal extension partial denture, the
denture bases other than those in toothsupported modifications must contribute to
the support of the denture. Such support is
critical to the goal of minimizing functional
movement and improving prosthesis stability.
• Although the abutment teeth provide support for
the distal extension base, as the distance from
the abutment increases, the support from the
underlying ridge tissue becomes increasingly
• Maximum support from the residual ridge may
• be obtained by using broad, accurate denture
bases, which spread the occlusal load equitably
over the entire area available for such support
• The snowshoe principle, which suggests that
broad coverage furnishes the best support with
the least load per unit area, is the principle of
choice for providing maximum support. Therefore
support should be the primary consideration in
selecting, designing, and fabricating a distal
extension partial denture base. Of secondary
importance (but to be considered nevertheless)
are esthetics, stimulation of the underlying
tissue, and oral cleanliness
• mcckrRPD Chapter9 page 130
8-The primary stress bearing area of the
maxillary complete denture is the
A. hard palate.
B. alveolar ridge.
C. median palatal raphe.
• the horizontal portion of the hard palate lateral
to the midline provides the primary support area
for the denture. In the area of the rugae, the
palate is set at an angle to the residual ridge and
is rather thinly covered by soft tissue. This area
contributes to the stress-bearing role, though in a
secondary capacity. The submucosa covering the
• incisive papilla and the nasopalatine canal
contains the nasopalatine vessels and nerves.
• Prothodontic treatment for edendulous patient
• Both the maxillae and the palatine bone provide
support for an upper denture.Individual
differences in form determine how forces should
be directed to these bones during function. A,
Spiny projections that would irritate tissues under
a denture. B, Rough and irregular bone of the
maxillary ridges. C, Incisive foramen, which
comes to lie closer to the crest of the ridge as
resorption takes place. Thus the location of the
incisive papilla, which covers the incisive
foramen, in relation to the crest of the ridge is a
guide to the amount of resorption that has
occurred. D, Greater palatine foramen, which
often has a spiny
9-In the processing of methyl methacrylate,
denture porosity is most likely to appear in the
A. thickest portion.
B. thinnest portion.
C. buccal surface.
D. palatal area.
Heat-Activated PMMA These resins are commonly
processed in a brass flask using a compression molding
technique (dough technique). The polymer
and monomer are mixed in the proper ratio of 3:1
by volume or 2.5:1 by weight. The mixed material
goes through four stages: first, a wet, sandlike stage;
second, a tacky fibrous stage as the polymer dissolves
in the monomer; third, a smooth, doughlike
stage, suitable for packing into a mold; and fourth,
a stiff, rubberlike stage.
Dough formation is assisted by internal
plasticizers chemically attached to the
polymer beads that locally softens them and
facilitates monomer diffusion.
After wax elimination, the dough is packed in a
gypsum mold. The flasks are placed, under
pressure, in a time-temperature controlled
water bath to initiate polymerization of the
The polymerization reaction is exothermic in nature
and should be carefully controlled to avoid a
marked increase in temperature, which may
the boiling point of un reacted monomer (100.8˚C),
leading to denture porosity. Gaseous porosity due
to rapid heating and monomer evaporation appears
as fine, uniform spherical pores, localized more
often in the thicker portions of the denture
Inadequate pressure during flask closure, an
insufficient amount of dough present on packing of
the mold, or improper mixing of powder/liquid
components may also result in denture porosity.
The resulting porosity will inevitably compromise
the physical properties and denture esthetics and
may promote the accumulation of denture
which could adversely affect the health of the
Prothodontic treatment of edentulous patient Chapter 12
1-In processing (polymerizing) an acrylic denture
in a water bath, a correct temperature control is
desired because of the possibility of
A. shrinkage of the denture.
B. volumetric expansion of the denture causing an open
D. porosity due to boiling of the monomer.
E. crazing of the denture base around the necks of the
• Like previous answer
In general, heat-activated acrylic resins are
polymerized by placing the flasks in a constant
temperature water bath at 74˚C (165˚F) for 8
hours or longer with or without a 2- to 3-hour
terminal boil at 100˚C. A shorter cycle involves
processing the resin at 74˚C for approximately 2
hours then boiling at 100˚C for 1 hour or longer.
Prothodontic treatment of edentulous patient Chapter
12 page 190
After the polymerization procedure, the denture flasks
are cooled slowly to room temperature toallow
adequate release of internal stresses and thus
minimize warpage of the bases. Deflasking thenfollows
and should be done carefully to avoid fracture or
flexing of the dentures.
The popularity and relative simplicity of the
compression molding technique are usually
overshadowed by the high-processing stresses that
are induced in the resins during polymerization.
These stresses result from various factors. First,
polymerization shrinkage, which occurs as polymer
chains are formed, accounts for a volumetric shrinkage
of about 7%. Second, thermal shrinkage follows as the
resin cools. In addition, differences in thermal
contraction of the resin and gypsum mold collectively
yield stresses in the resin. It is tempting to assume that
the release of such cumulative stresses
may give rise to dimensional changes and inaccuracies
in the fit of the denture base.
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