PROSTH Flashcards
A complete denture patient presents to the first postinsertion visit with a chief complaint of soreness of the denture-supporting tissues. The MOST likely cause would be
A. excessive vertical dimension. B. overextension of the borders. C. unbalanced occlusion. D. overextended post-palatal seal. E. the denture needs a reline.
A. excessive vertical dimension:
The patient is complaining of generalized soreness is important. This is very common when there is excessive vertical dimension. Patients will often comment that they are having difficulty speaking, eating, and generalized intraoral discomfort. If the occlusion is unbalanced, there will be overloading and mucosal changes on the affected side only. An overextended postpalatal seal will cause the patient to complain of a sore throat. Lastly, overextension of the borders will cause soreness only in the border area.
The MOST common cause of porcelain separation from porcelain fused to metal restoration is
A. contamination of the metal before applying the porcelain. B. poorly supported porcelain in the crown. C. excessive compressive forces within the porcelain. D. all of the above.
A. contamination of the metal before applying the porcelain:
Contamination will cause the porcelain to have a poor fusion to the metal substructure. Contamination can be from an oxide layer, oils, water, etc. Poorly supported porcelain is a cause of failure, but is most common in the anterior region. It is not as common as contamination. Compressive forces are responsible for holding the porcelain and providing the strength of the porcelain.
All of the following are advantages to using an immediate full denture EXCEPT one. Which one is the EXCEPTION?
A. Helps protect the extraction sites during healing B. Allows the patient to maintain acceptable esthetics during treatment C. Allows the patient to maintain acceptable masticatory function during treatment D. Assists in the speech adaptation E. Provides less postoperative discomfort
E. Provides less postoperative discomfort:
The fabrication of an immediate denture does have several advantages. It allows the patient to maintain acceptable aesthetics during treatment. The patient is never without teeth. It also provides protection to the extraction sites; the patient is usually required to wear this denture for at least 24 hours after the oral surgery procedure, and the denture provides assistance in speech and masticatory adaptation. However, there can be significant pain following the multiple extraction of teeth and immediate placement of the denture. The temporary dentures will not do anything to assist with pain management.
Which of the sounds listed below will bring the mandible closest to the maxilla?
A. "V" sounds B. "Th" sounds C. "F" sounds D. "S" sounds E. None of the above
D. “S” sounds:
Phonic sounds are very important to the fabrication of complete dentures. These sounds will help determine the placement of the teeth in the acrylic.
- The “f” and “v” sounds are made between the upper incisors and the posterior of the lower lip.
- If the anterior teeth are set too high, the “v” will sound more like an “f”. Also, if the teeth are placed too low, the “f” will sound more like the “v”.
- The “th” sound will help in the labiolingual placement of the teeth.
- With the “s” sound, the important observation is the relationship between the maxillary and mandibular anterior teeth. When this sound is produced, the anterior teeth should approach each other but never touch.
What is the recommended range of occlusal reduction for an all-porcelain restoration?
A. 0.5-1.00 mm B. 1.0-1.5 mm C. 1.5-2.00 mm D. 2.0-2.5 mm
C. 1.5-2mm:
For an ALL CERAMIC crown:
- the incisal reduction should be 1.5 to 2 mm
- 1.2-1.5 mm reduction on the facial surface
- 1 mm on the lingual aspects are preferred.
- All line and point angles should be rounded. -
- The finish line should be 1.0-mm-wide.
For a PFM crown the recommended:
- incisal reduction is 2 mm for adequate material thickness to permit translucency in the completed restoration
- Posterior teeth generally require less (1.5 mm) because esthetics is not as critical.
- A minimum of 1.2mm of facial reduction is required and 1.5mm is preferable.
- Minimum 1mm reduction is required for lingual surface.
- The finish line should be 1 mm-wide.
Which of the following statements is TRUE concerning the posterior palatal seal?
A. It is used only during construction of a full denture and should be removed after the last post operative visit. B. The outline is the same for all patients. C. It should be used with all maxillary partial denture patients. D. It helps prevent food from becoming trapped under the denture. E. It should be at least 4 mm thick to provide proper retention.
D. It helps prevent food from becoming trapped under the denture:
It is important to note that the posterior palatal seal plays a significant role in the success of the full maxillary denture. It serves to provide a seal, prevents food from becoming trapped under the denture, helps provide retention, and helps compensate for the shrinkage of the acrylic during the processing of the denture. Landmarks for the posterior palatal seal include the posterior outline, the vibrating line, and the anterior outline, which is formed by the blow line. The posterior palatal seal varies in outline and depth from patient to patient. Typically, the posterior palatal seal comes to a thin taper of about 1.5-2mm, any thicker may trigger the patient’ s gag reflexes.
In a complete denture case, which of the following is responsible for the path of the condyles in mandibular movements?
A. Centric relation B. The degree of compensating curve C. The amount of horizontal and vertical overlap D. The size and shape of the bony fossa E. The vertical dimension of occlusion
D. The size and shape of the bony fossa:
Condylar guidance is determined by the anatomical configuration of the patient’s condyles and condylar fossae. All of the remaining options are directly related to the teeth, which are missing in the complete denture patient. It is necessary to reproduce the condylar guidance on an articulator so that incisal guidance, the compensating curve, and the occlusal plane can all be developed within acceptable limits of the patient’s anatomically configured condylar guidance.
Tooth-borne removable partial dentures with both anterior and posterior abutments for all clasps, and the presence of anterior teeth are classified in Kennedy Class
A. I. B. II. C. III. D. IV.
C. Kennedy Class III:
is the best-known classification system for partial denture cases. While there probably will not be detailed questions on this system, you should know the major divisions.
- Class I: is bilateral distal extension
- Class II: is unilateral distal extension
- Class III: is the case of spaces with both mesial and distal abutments (tooth-borne partials)
- Class IV is the case of missing bilateral anteriors with posteriors remaining on both sides.
Modifications (Mod), refer to additional edentulous spaces. As an example, a case of bilateral distal extension, and a missing central incisor would be a Class I, Mod I case.
Which of the following denture teeth is BEST for a patient with opposing natural dentition?
A. Monoplane porcelain B. Anatomic porcelain C. Monoplane plastic D. Anatomic plastic
D. Anatomic plastic:
The anatomic teeth will be easiest to articulate properly with the natural dentition, and they will give the patient the best function. Plastic is the material of choice. Monoplane teeth will be difficult to articulate with the natural dentition. Porcelain has been found to be very destructive to the opposing dentition and the residual ridge under the denture.
In RPD clasp assemblies, support is located on the _____ third of the tooth, while retention is located on the _____ third.
A. occlusal, middle B. occlusal, gingival C. middle, middle D. middle, gingival E. none of the above
B. occlusal, gingival:
As a general rule, support, in the form of the occlusal rest and guiding plane of the clasp assembly, functions primarily in the upper third of the tooth. The middle third is usually the site of reciprocation from the reciprocating arm of the clasp. Retention is usually located in the gingival third, as the retentive arm descends to find an undercut in this third.
Answer: occlusal ⅓ and gingival ⅓.
Indirect retention in RPD frameworks is used primarily to
A. INCREASE retention of the framework. B. decrease damaging effects of forces towards tissue. C. decrease damaging effects of forces away from tissue. D. balance the forces of retentive arms in clasps.
C. decrease damaging effects of forces away from tissue:
Indirect retention is used primarily in distal extension partial dentures. The extension denture base can move away from the tissue base during function, especially chewing of sticky foods. In the maxilla, this movement is downward, and in the mandible it is upward. The denture exerts a strong torquing action on the distal abutment teeth, endangering their periodontal support. This can cause tissue trauma in some patients.
Indirect retention limits the torquing movement by adding rests on teeth more anteriorly. Typically, rests for indirect retention are placed on mesial/occlusal surfaces of premolars, or on cingulum or notch rests of canines. The retention is always placed in a prepared rest seat on the tooth most mesial to the denture fulcrum line, on a tooth with sufficient bony support. Retenative arms are designed with a tapered shape to minimize forces. Located above the height of contour (HOC), the clasps should be passive until the patient tries to remove the appliance. Incisors are seldom used for indirect retention.
In a removable partial denture design, the reciprocal arm of a clasp is designed to
A. run along the mucosa, cross the gingival margin of the abutment tooth and approach the undercut from the gingival direction. B. be located below the height of contour. C. contact the abutment tooth immediately after the retentive arm reaches its position on the retentive area. D. contact the abutment tooth simultaneously with the retentive arm.
D. contact the abutment tooth simultaneously with the retentive arm:
The primary function of the reciprocal clasp is to counter the horizontal forces transferred to the abutment tooth by the retentive arm. The reciprocal arm also serves to stabilize the partial denture along with the other rigid components of the partial denture framework. The reciprocal arm is placed above the height of contour and, therefore, does not act as a direct retainer. The approach arm is designed to run along the mucosa, cross the gingival margin of the abutment tooth and approach the undercut from the gingival direction.
What is the proper way to remove a polyvinyl Siloxane® impression for the mouth?
A. Slow steady pressure B. Quick snapping pressure C. Walking one side of the impression out and then the other D. Apumping up-and-down movement
B. Quick snapping pressure:
A quick snapping motion will allow for minimal distortion of the impression material.
Slow removal or pumping of the impression material will likely cause the material to exceed its modulus of elasticity, which will result in permanent distortion of the impression material. Walking or rocking the impression material out of the mouth will also likely exceed the modulus of elasticity. This permanent distortion of the impression material will result in a poor-fitting cast restoration.
Which of the following forces is MOST damaging to a porcelain restoration?
A. Compressive B. Lateral C. Tensile D. All of the above
B. Lateral forces:
will likely produce shearing forces on a porcelain restoration. Porcelain has very POOR shear strength but is very good against compressive forces. Porcelain restorations rarely will undergo tensile strain, but porcelain’s tensile strength is still better than its shear strength.
Which of the following would be considered an indication for a cast post and core?
A. Perforation of the root B. Endodontically treated teeth C. Teeth with severe loss of coronal tooth structure D. Desire to strengthen the remaining tooth structure E. All of the above
C. Teeth with severe loss of coronal tooth structure:
A cast post and core is used in the restoration of endodontically treated teeth. Very often, teeth that have been endodontically treated have lost much of the coronal tooth structure as a result of caries, previously placed restorations, or in preparation of the endodontic access cavity. In this case, a cast post and core is the treatment of choice. It consists of a core, which replaces the part of the destroyed crown, and a post, which fits into the root canal and provides retention for the core. Generally, as a separate procedure, a cast crown is placed over the post and core to restore form, function, and esthetics. It should be noted that this procedure does not strengthen the tooth, but provides only a means of retaining the core.
Recall visits for a patient with cast restorations should be at least every
A. 3 months. B. 4 months. C. 6 months. D. 9 months. E. 12 months.
C. 6 months:
Patients who received treatment that included cast restorations should be recalled at least every 6 months. Failing to adhere to this recall schedule could lead to an oversight of recurrent caries or the development of periodontal disease. Patients who completed treatment plans that included more extensive fixed prostheses should consider a more frequent recall schedule (~3 months), especially if periodontal disease was present initially.
Which type of major connector should be used for a mandibular removable partial denture in a patient with mobile anterior teeth or periodontal involvement of the anterior teeth?
A. A lingual plate B. A lingual bar C. A labial bar D. Double lingual bar
A. Lingual plate (LP):
is similar to the lingual bar thinned out to extend onto the lingual surfaces of the teeth with a scalloped edge. Superior border of this major connector (MC) rests on the lingual surfaces of the teeth above the cingula (knife edge). It Must close the interproximal spaces at the level of contact point. Inferior border is placed as low as possible without interfering with the function of the floor of the mouth. It is the MC of choice when there is insufficient vertical space and periodontally compromised teeth.
Lingual bar is the most frequently used major connector (MC), it is half-pear shaped in cross section, the broadest portion of the bar is located at the inferior border. At least 8 mm of vertical space should be available between the Free Gingival Margin (FGM) and the floor of the mouth, allowing for 5 mm height of the bar and 3 mm space between the FGM and the bar.
Double Lingual Bar (Kennedy Bar) provides minimum coverage. It displays characteristics of both lingual bar and plate, it is basically two bars not joined by a continuous sheet of metal. The advantages of this MC design are that it preserves the health of the remaining dentition. The two most common disadvantages are that it may be a potential food trap and may irritate the tongue.
The Labial Bar runs on the facial surface of the mandibular teeth. It is only used when the placement of the lingual major connector is impossible due to the presence of an interference such as large mandibular tori. It is also indicated when teeth have extreme lingual inclination. Advantages: It is MC of choice in situations where other MC cannot be used. The Disadvantages are: Poor patient acceptance, poor aesthetics and uncomfortable to the patient.
Ante’s law is associated with the
A. crown to root ratio. B. degree of tipping allowable in an abutment tooth. C. degree of taper of the walls of a crown preparation. D. amount of curvature acceptable in the plane of occlusion. E. degree of periodontal surface area.
E. degree of periodontal surface area:
Ante’s law is a generalized rule that focuses on the periodontal surface area of the abutment teeth and the teeth to be replaced. It states that the pericemental area of the roots of the abutment teeth must equal or surpass the original pericemental surface area of the roots being replaced by the fixed prosthesis. This law is designed to assure that the load on the abutment teeth does not overburden the supporting structures. For example, when a patient may have lost a mandibular right first molar and second premolar, a four-unit FPD would be indicated, as long as the abutments have a healthy periodontium, because the second molar and first premolar abutments have root surface areas approximately equal to those of the missing teeth. However as per Ante’ s law, if the first molar and both premolars are missing, an FPD may be a risk because the missing teeth have a greater total root surface area than the potential abutments (canine and the second molar).
The altered cast technique is used to obtain
A. a static impression of the edentulous ridge. B. a static impression of selected supporting areas and an anatomic impression of non-supporting areas. C. an anatomic impression of the edentulous ridge. D. a preliminary impression.
C. an anatomic impression of the edentulous ridge:
It is possible that the residual ridge will not support a partial denture when the denture is under occlusal loading. This will leave all stress being transferred to the abutment teeth as if the distal extension was cantilevered from the abutment tooth. The objective is to ensure that both the residual ridge and the abutment teeth support the prosthesis, allowing the stresses to be shared between the two support systems. This cannot be achieved by the use of a single impression. The altered cast technique will relate the extension base functionally to the supporting teeth to provide a much more stable denture.
In casting a complete gold crown, ________________ softens the alloy and increases malleability for finishing.
A. the lost wax technique B. investment C. soldering D. quenching E. crucibles
D. Quenching:
involves rapidly cooling a casting in water, which serves to soften the alloy and increase the malleability for finishing.
The lost wax technique is the overall technique in which a wax mold is invested in ceramic, heated to melt the wax, and molten metal is inserted into the empty space left behind.
Investment can be gypsum-bonded, phosphate-bonded, or silica-bonded depending on the types of metals used.
Soldering is the procedure in which metal components are joined by heating a piece of metal that melts at a temperature slightly lower than the metals that are to be joined together.
Crucibles are the vessel used to hold everything together and should only be used with one type of alloy to prevent contamination.
Inadequate interocclusal distance with complete dentures could result in all of the following except:
A. muscle soreness. B. facial distortion. C. soreness of the denture-supporting tissues. D. a clicking sound during normal conversation. E. angular cheilitis.
E. Angular cheilitis.
Excess interocclusal distance (excess freeway space, collapsed occlusal vertical dimension = low VDO) can lead to angular cheilitis, temporomandibular joint damage, facial distortion and loss of muscle tone.
Inadequate interocclusal distance (excessive occlusal vertical dimension = high VDO) leads to a stretched appearance (facial distortion), the lips do not touch when the patient is at rest, elevator muscles cannot complete their contraction, hence, they become sore. This also results in damage to the denture supporting tissues causing their soreness, ischemia and resorption and speech problems (clicking of the teeth when the patient speaks).
Shade selection should NOT be conducted under fluorescent light BECAUSE fluorescent light is heavier in which wavelengths?
A. Red and yellow B. Blue and violet C. Red and blue D. Blue and green E. None of the above
D. Blue and green:
Shade should ideally be selected under color-corrected light, and under at least one other type of light. Color-corrected light has a balance of wavelengths in equal proportion and represents the same light as natural sunlight. Other types of light can show how the crown will appear in different conditions. Indoor fluorescent lighting tends to have strong blue and green wavelengths. Incandescent lighting will have strong red and yellow wavelengths and will bring out the red and yellow tones of a shade when the crown is observed under that light. It is important to remember that metamerism cannot always be avoided, regardless of using more than one light source during shade selection.
Which of the following is NOT TRUE of base metal partial denture frameworks, as compared to gold alloy frameworks?
A. They are MORE ductile. B. They require higher melting temperatures. C. They are MORE difficult to grind during adjustment. D. They are less expensive. E. They are stiffer.
A. They are MORE ductile:
Ductility is the ability of the metal to be drawn into wire. Gold is very ductile, but base metal alloys are much less so. The most common partial denture frameworks are made with base metal alloys. An example of a common brand name is Vitalliumreg. The alloys usually contain nickel, cobalt and chromium in varying degrees. Chromium, in particular, is valuable in helping the alloy to resist tarnish. Base metal alloys tend to be harder and more brittle. They have a high modulus of elasticity (high stiffness), lower yield strength (can break under less force) and are lower weight than are noble alloys. They are more difficult to adjust and polish, and care must be taken in bending base metal clasps. They require special casting equipment and much higher temperatures than gold. Their cost is significantly less than gold. Tin is not commonly used in these frameworks.
What is the anatomical landmark commonly used to signify the location for the posterior border of a maxillary denture?
A. Tensor veli palatini B. Fovea palatini C. Tuberosity D. Vibrating line
B. Fovea Palatini:
They are two small pits or depressions in the posterior palate, one on each side of the midline. They may be useful in identification of the vibrating line because they occur within 2 mm of vibrating line.
Tensor veli palatini: The tendon of the muscle runs across the hamulus to reach the soft palate. It is not clinically discernible.
Tuberosity: An important denture support area. It also provides resistance to horizontal movements of the denture. The denture posterior border extends beyond the tuberosity.
Vibrating line: is not a true anatomical landmark. It is an imaginary line that extends through the hamular notches bilaterally and marks the junction of the movable and immovable tissues of the palate However, it is the maximum posterior limit of the maxillary denture.
Please also note: Hamular Notch - This narrow cleft extends from tuberosity to the pterygoid muscles. Capturing of the hamular notch in the impression is critical to the retention of the maxillary denture. Improper molding of this area could lead to soreness and the loss of retention. The posterior extent of the denture (the vibrating line) runs bilaterally through the hamular notches.
Which of the following cements requires the use of a cavity varnish or liner prior to placement?
A. Zinc phosphate B. Glass ionomer C. Zinc polycarboxylate D. Zinc oxide/eugenol E. Resin composite
A. Zinc phosphate cement:
has good compressive strength but has a very low pH at the initial mixing. When zinc phosphate is used as a luting agent, it is recommended that it be mixed in small increments over a large area of a glass slab to dissipate the heat generated during the exothermic reaction. Also, it is recommended that a thin layer of cavity varnish/liner be applied over the preparation prior to cementation of the crown or bridge, especially if the preparation is close to the pulp.
Which of the following direct retainers should be considered when esthetics is of concern?
A. Intracoronal attachment B. Wrought wire C. Bar clasp D. Circumferential clasp
A. Intracoronal attachment:
One of the disadvantages of treatment planning a traditional metal clasp partial is the compromise in esthetics. Many times, it is difficult to place the clasps in an area that is aesthetically pleasing. Patients with this problem should consider a fixed partial denture. In cases where this cannot be the treatment of choice, another option would be to place intracoronal attachments. These can be either semi-precision or precision attachments. This type of attachment is built into the contour of a crown, and it produces both a mechanical and frictional retention.
Which of the following is an acceptable reason to use solder on a cast crown?
A. To add contact B. To fill in an occlusal opening C. To repair a marginal gap D. All of the above E. None of the above
A. to add contact:
On occasion, it is necessary to add solder to a cast restoration to increase the contact with the adjacent teeth. In the case of a full cast crown, the entire crown would be heated with solder attached; the solder melts and becomes incorporated as part of the restoration. The solder will melt due to the fact that its melting point is lower than that of alloy in the cast crown. It is important to remember that solder cannot be used to repair marginal gaps. When used as a means to increase the contact between teeth, solder can be modified with a disk or polished down until the proper fit is attached. Also, it is not recommended to be used to fill occlusal openings. These openings or holes may indicate the lack of occlusal reduction.
What metal may sometimes cause unsightly “greening” of porcelain?
A. Gold B. Silver C. Nickel D. Platinum E. Palladium
B. Silver:
Gold, platinum, palladium, and silver are the major components of noble metal casting alloy. Zinc, tin, and indium are trace elements useful for aiding the bonding between metal coping and porcelain. Silver and palladium “whiten” the alloy, and alloys with high silver/palladium content are silver/white in appearance. High silver content can cause a detrimental greening of porcelain, as can copper, though copper is not commonly used in these alloys. This is because silver tends to tarnish or have a reaction to moisture overtime.
Which of the following describes brightness when color is being discussed?
A. Chroma B. Value C. Hue D. Intensity E. Translucency
B. Value:
The three dimensions of color are its hue, chroma, value, and translucency. Value is the relative lightness (brightness) or darkness of the hue (color). Value decreases as the darkness increases.
Chroma is the intensity or saturation of the color tone (hue), i.e. light green or dark green. It is used to describe, the orange or yellow hue of a tooth or a restoration.
Hue is the color tone, i.e. red, blue, yellow, green. The term “hue” is the same as the term “color”, and it is used to describe the color of a tooth or a prosthesis.
As the teeth age, the enamel becomes thinner. The intensity of the basic hue can be different in allowing the dentin to dominate the shade of the tooth.
Translucency is the three-dimensional representation of value. Highly translucent teeth tend to be lower in value, since they allow light to transmit through the tooth and pick up the darkness of the oral cavity and the surrounding environment. More opaque teeth allow less light transmittance; they are more reflective in nature and, therefore, appear brighter.
The cervical third of a tooth contains the highest chroma and the lowest value, whereas the slightly lower chromas are at the middle third. The transition to transparency at the incisal 1/3rd minimizes the chroma, thereby letting the opulence effects to take place at the incisal edge.
What is the BEST way to INCREASE the strength of cold cure acrylic resin used in repairing a broken denture?
A. Placing the cold cure resin in hot water B. Placing the cold cure resin in cold water C. Allowing the resin to cure on the bench top D. Placing the cold cure resin in a pressure pot
D. Placing the cold cure resin in a pressure pot:
Placing the curing resin under pressure will cause the resin to increase in density.
Placing the resin in hot water will cause the reaction to increase and the resin to cure more quickly-but if the water is too hot, the uncured monomer will boil, resulting in voids in the cured resin. If the resin is placed in cold water, the reaction rate will be slowed, but the final product will be the same. Letting the resin cure naturally on the benchtop will not have much effect on the strength.
The preparation of a full gold crown involves the occlusal reduction of
A. 1 to 1.5 mm. B. 2.0 to 2.5 mm. C. 2.5 to 3.0 mm. D. 3.0 to 3.5 mm. E. none of the above.
A. 1 to 1.5 mm:
The object of preparing a tooth for a full cast gold crown is to provide a tooth surface free of undercuts, allowing complete seating of the casting and providing sufficient occlusal and proximal reduction for adequate thickness of restorative material. The minimum recommended clearance is 1 mm. It is recommended that occlusal reduction follow normal anatomic contours to conserve tooth structure. Axial reduction should parallel the long axis of the tooth while allowing for the recommended 6 degrees of taper or convergence between opposing axial surfaces.
The first step in taking a face-bow transfer record would be to
A. establish centric relation. B. equilibrate the plane of occlusion. C. establish the vertical dimension of occlusion. D. set the articulator condylar inclination. E. establish the location of the hinge axis point.
E. establish the location of the hinge axis point:
The face-bow is designed to relate the maxillary cast to the condylar elements of the articulator in the same way that the maxillary arch is related to the temporomandibular joint. The condyles are placed in centric relation through manipulation at the time of occlusal registration with the protrusive relation being verified with a check bite. If the face-bow transfer is done correctly, the arc of closure should be identical to that seen in the patient. Therefore, because this is a record of the patient’s maxilla/hinge axis relationship, it is necessary to establish the location of the axis point.
