fpd,rpd and implant
TRANSCRIPT
FPD,RPD and implant .
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3-A ceramometal posterior fixed partial denture pontic should. 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
walls. 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 minimum. B. maximum number of artificial teeth can be
placed. 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 tooth-supported 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 important.
• 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. D. zygoma.
• 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 chapter13 page212.
• 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 commonlyprocessed in a brass flask using a compression moldingtechnique (dough technique). The polymerand monomer are mixed in the proper ratio of 3:1by volume or 2.5:1 by weight. The mixed materialgoes through four stages: first, a wet, sandlike stage;second, a tacky fibrous stage as the polymer dissolvesin the monomer; third, a smooth, doughlikestage, 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 agypsum mold. The flasks are placed, under
pressure, in a time-temperature controlled water bath to initiate polymerization of the resin.
The polymerization reaction is exothermic in nature and should be carefully controlled to avoid a marked increase in temperature, which may exceed
the boiling point of un reacted monomer (100.8˚C),leading to denture porosity. Gaseous porosity dueto rapid heating and monomer evaporation appearsas fine, uniform spherical pores, localized moreoften in the thicker portions of the denture
Inadequate pressure during flask closure, aninsufficient amount of dough present on packing ofthe mold, or improper mixing of powder/liquidcomponents may also result in denture porosity.The resulting porosity will inevitably compromisethe physical properties and denture esthetics andmay promote the accumulation of denture deposits,which could adversely affect the health of thedenture-supporting tissues.Prothodontic treatment of edentulous patient Chapter 12 page 190
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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
bite. C. warpage. D. porosity due to boiling of the monomer. E. crazing of the denture base around the necks of the teeth.
• Like previous answer In general, heat-activated acrylic resins arepolymerized 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 inaccuraciesin the fit of the denture base.