Removable Test 3 Flashcards
How many impressions are required to make a tooth-supported RPD (e.g Kennedy C III)?
One, as long as it records the teeth and soft tissue in anatomic form
Does the edentulous ridge offer support for the RPD?
No, abutment teeth absorb the forces
Can a tooth-tissue supported RPD (Kennedy C I or Kennedy C II) be made from one impression?
No, must be made using corrected cast
What does a corrected cast do?
Captures teeth in their anatomic position and the residual ridge tissue in functional form
What are 3 requirements for a corrected cast?
- Record and relate tissues under uniform loading
- Distribute load over as large an area as possible
- Accurately delineate peripheral extension of denturebase
What type of bone displays an irregular surface that can irritate overlying soft tissue when stress is applied?
Cancellous
What are 5 factors influencing support of the distal extension base?
- Quality of soft tissue covering edentulous ridge
- Type of bone in denture bearing area
- Design of prosthesis
- Amount of tissue coverage of denture base
- Anatomy of denture bearing arch
Will the ridge give the denture base more or less support if its overlying soft tissue is thick and displaceable?
Less support
What soft tissue covering of the edentulous ridge offers the greatest support for the RPD?
Firm, tightly attached mucosa of moderate thickness (2-3 mm)
What are 2 improvements removal of redundant tissue, especially over the maxillary tuberosities, offers the RPD?
- Minimize vertical displacement
2. Improve resistance to lateral displacement
Cancellous or cortical bone: which is less able to resist vertical forces?
Cancellous because its irregular surface irritatesoverlying tissue
Where should a practitioner direct forces when considering underlying bone of the denture-bearing area?
To dense cortical regions, e.g. the buccal shelf
What is the most efficient method of controlling rotational movement of a distal extension?
The use of one or more indirect retainers anterior to the fulcrum line
If the RPD is a bilateral distal extension (Kennedy Class I), how many and where are the indirect retainers placed?
One indirect retainer on each side of the arch
How many and where are the indirect retainers placed in a unilateral distal extension?
One, anterior to the fulcrum line and on opposite sides of the arch from the distal extension
If the distal extension RPD denture base is overextended and impinges on movable tissues, orthodontic movement of teeth will occur where?
Anterior to the fulcrum line
What is the maxillary arch primary stress bearing area?
Crest of the ridge
Why can the maxillary arch vertical slope be used as a stress bearing area?
Not oriented perpendicular to vertical forces
The maxillary buccal slope resists what forces?
Lateral
What other part of the maxilla provides some resistance to displacement from vertical forces, but is prone to ulceration as its mucosa is thin?
Hard palate
What must be done is the maxillary crestal mucosa is not firm and dense?
Surgical correction
Can the mandibular crestal ridge be used as a primary stress-bearing area and why?
No, it is covered by cancellous bone
What is the mandibular primary stress-bearing area for distal extension?
Buccal shelf
What provides vertical force resistance in the mandible?
Buccal shelf, almost perpendicular to vertical forces
What provides resistance to horizontal forces on the mandibular distal extension?
Buccal and lingual slopes of ridge
If an acrylic resin covered distal extension framework is placed in the mouth and pressed down, and the indirect retainers or lingual plates lift away from the teeth, what must be done?
New framework created using dual impression technique
For which arch and why is a dual impression technique most often indicated?
Mandibular because only limited ridge area is stress-bearing
Why is it difficult to get the peripheral extension of the mandibular denture base recorded?
The floor of the mouth is distensible
Of the two arches, which one normally requires only a single impression?
Maxillary
What other RPD type requires a dual impression technique?
Long span anterior edentulous (at least 6 anterior teeth) (Kennedy C IV)
What is the impression technique that records the ridge portion of the cast in its functional form by placing an occlusal load on the impression tray during the impression procedure?
Physiological impression
What is the impression technique intended to equalize the support between the abutments and the soft tissues and to direct forces to the portions of the ridge that are most capable of withstanding such forces (done by relieving the tray in some areas and allowing ht tray to contact the ridge in other areas)?
Selected pressure impression
In the selected pressure impression technique, areas where the tray is not relieved will have greater or less soft tissue displacement?
Greater displacement
For the corrected cast impression, what is attached to the impression tray?
The RPD framework
Soft tissues are ____________ if insertion and wear to the prosthesis produces no adverse soft tissue response?
Minimally displaced
Soft tissues have been ______________ when they have an inflammatory response and accompanying bone resorption
Excessively displaced
What is an impression technique in which you use a custom tray for the edentulous area, make an impression with it, put that custom tray into an impression tray with hydrocolloid and take a full arch impression (think of the custom tray as a substitute for a framework)?
McLean physiologic impression
What is the drawback of the McLean physiologic impression?
Related ridge and teeth in anatomic position as if masticating, so the base could cause compromised blood flow if retainers hold it down, or it could have premature occlusal contact if the retainers do not hold it in the anatomic position
What is a method that adds a new surface to the intaglio of the denture base?
Functional reline method
When doing a reline, what is placed on the cast to allow for new material to be added?
Thing layer of metal (Ash’s no 7 metal)
In the mouth, what is used as the final impression material for the functional reline?
Zinc Oxide Eugenol paste or light bodied polysulfide paste
For the reline, when will occlusal discrepancies be corrected?
After processing of base
When making an impression tray for the corrected cast procedure, what is used to make the new tray?
Framework on the master cast and resin placed over the framework, then tried in the mouth
When trying in the resin covered framework tray, the edge of the tray should be how far from the depth of the buccal vestibule in the patient’s mouth?
2-3mm
When trying in the resin covered framework tray, how far should the posterior portion of the tray reach?
2/3 the height of the retromolar pad
How is the distolingual fit of the framework tray assessed?
The patient places tongue to upper lip, if operator feels the tray lift, the distolingual extension should be shortened
An overextended tray will cause what on abutment teeth?
Constant force on abutment teeth as border tissues attempt to unseat denture
What are 2 bolder moldings that must be done on the distal extension framework tray?
- Anterior to posterior of buccal flange
2. Lingual and distolingual flanges
Proper border molding results in what?
Tongue and other tissues move without dislodging tray
What are 3 objectives of the fluid wax impression?
- Obtain maximum extension of peripheral borders without interfering with movable tissues
- Record stress bearing areas of ridge in functional form
- Record non-pressue bearing areas in their non-
functional form
What type of waxes are firm at room temperature and have the ability to flow at mouth temperatures (Iowa wax, Korrecta Wax No. 4)?
Fluid wax
Will a thin layer or a thick layer of fluid wax flow less readily?
Thin layer flows less readily
What is the temperature range for a fluid wax water bath?
51°C to 54°C
Fluid wax will not support itself beyond how many millimeters?
2mm
After 5 minutes in the mouth, the fluid wax will look dull or glossy in areas of tissue contact?
Glossy
What mouth position is required to do the buccal and distobuccal extensions of the fluid wax impression?
Wide open mouth to activate buccinators and pterygomandibular raphe
How long must the fluid wax impression be left in the mouth once the borders are verified and total tissue contact (all internal surface are glossy) is achieved?
12 min
What is an impression technique that seeks to direct forces to
those portions of the ridge able to absorb stress and to protect areas of the ridge least able to absorb stress (to do so, the intaglio surface of the tray is selectively relieved)?
Selected pressure
Which area is relieved on a mandibular distal extension tray?
Posterior crest of ridge. Relieved down to metal, allowing for minimal tissue displacement during impression
Does a more-viscous or less-viscous impression material result in greater tissue displacement?
Less viscous
What is the impression material of choice if residual ridge is
free of gross undercuts, or when soft, flabby tissue is involved?
Zinc oxide eugenol
What impression material is appropriate for ridges with
moderate to severe undercuts of the ridge (must use a tray adhesive and drill holes to prevent excess tissue
displacement)?
Polysulfide rubber base
What would be an indicator that the framework was not fully seated during the impression process?
Impression material under the rests
What is done with the original master cast to make the final corrected cast?
The old ridge is cut out
The framework impression is placed on the remaining teeth and fixed there with modeling plastic
Bead and box to give a 2-3 mm land area
What is the quality control for dental laboratories?
Competition
What is the minimum information required on an RPD work authorization?
- Signature and license number of dentist
- Date signed
- Description of service or material ordered
- Perhaps patient’s name and address
Work authorization is equal to what?
Prescription
Legal document
How long is a lab required to keep a work authorization?
2 yrs
What should always accompany a master cast to the lab?
Properly designed diagnostic cast
What should be clearly identified on the work authorization?
- Major connector to be used
- Teeth to be clasped
- Type of clasp to use
- Amount undercut each assembly engages
What are 3 things the dentist must provide the lab for a good RPD?
- Written work authorization describing RPD
- Properly surveyed diagnostic cast w/ RPD design
- Properly articulated master cast
What is the term for placing three easily identifiable marks on the the same horizontal plane, widely separated, and on anatomic portions of the diagnostic cast allowing for rapid orientation and reorientation of the diagnostic cast?
Tripodization
What is the term for the act of scraping the outline of the major connector into the master cast to a depth of 0.5 mm, producing a raised edge on the final framework to ensure positive contact of the major connector with palatal tissues?
Beading
Are bead lines used on mandibular major connectors?
No. Tissue will be irritated.
What is the overall shape of the blockout for tooth-tissue supported RPD (KennedyClass I and II)?
Parallel or tapered
What is the term for wax intended to make the framework stand away from the master cast, usually to allow 1 mm of space between the framework and the surface of the master cast to allow for resin to encompass the lattice work?
Relief (1 thickness of baseplate wax)
How far is a finish line to be placed from an abutment?
1.5 mm to ensure resin will not contact marginal ginigiva
What determines the ultimate fit of the framework as far as processing is concerned?
Refractory cast expansion
Refractory materials are also called what?
Investments
Gypsum-bonded refractory materials are called what type of investments? These are used to cast what materials?
- Low heat investments
2. Type IV partial denture gold and Ticonium
What is the temperature for low-heat investments?
704°C (1300°F)
Refractory materials used for Vitalium, Nobillium,
Jelenko’s LF, other chrome-cobalt alloys, titanium, and
titanium alloys are called what? What is their heating temp?
- High heat investments
2. 1037°C (1900°F)
A cast made from what material is the foundation for waxing and casting procedures?
Refractory material
How long must a refractory cast dry before trimming?
30-60 min at 93°C (200°F)
Why is the refractory cast trimmed within 6mm of the proposed design?
To ensure gas escapes during casting
What is the refractory cast dipped in to ensure smooth, dense surface and to eliminate need for soaking the cast prior to investment?
Hot beeswax (138°C-149°C [280°F-300°F]) for 15 sec
What is the most critical part of the design transfer to the refractory cast?
Individual clasp position
If a clasp is short, must it be thick or thin to ensure adequate flexibility?
Thin
What is the method of choice for RPD casting?
Induction casting
What is the term for casting based on the electric currents in a metal core induced from a magnetic field?
Induction casting
What is the term for rough finishing where atoms of metal from rough projections on the framework go into solution before those on smooth areas do giving a satin-like finish?
Electropolishing
Preliminary adjustment of occlusion of the RPD should be done where?
The lab
Wrought wire being round allows flexion in how many different directions?
All directions
What is the gauge of the most popular wrought wire?
18 and 19 gauge nickel-chromium-cobalt metals
In what situations is wrought wire used?
Interim RPD, transitional prosthesis, or repair of fractured or distorted clasps
What are 4 ways to attach wire clasps?
- Embed wire into denture resin
- Incorporate wire into wax pattern and cast metal to the wire
- Solder wire onto the framework
- Laser welding
What is the method of attaching wrought wire in a repair situation?
Embed the wire in resin
What is the most dependable method to attach wrought wire to RPD?
Solder the wire to the framework after the framework is complete
What is the disadvantage of incorporating the wire into the wax up and casting metal to it?
Adversely affect clasp longevity
What is the best method to attach wrought wire to the completed framework and why?
Solder onto lattice work well away from area where it will flex. Soldering limited to an area covered by denture base and heat will not affect the working part of the wrought wire
What is the laser used for laser-welding of the clasp to the framework?
Neodymium:yttrium aluminum-garnet (Nd:YAG)
Twin-flex clasp method provides what and how?
It provides a flexible clasp that is less noticeable to the patient by placing it in a measured undercut on a proximal surface of an abutment
What does placing the wrought wire on the cast then investing do on the RPD tissue surface?
Creates a channel into which the wire can be soldered
What percentage of RPDs do not fit on the day of insertion?
75%
Each completed RPD must be (pick one:) completely passive OR completely active in the mouth?
Passive
The tip of each retentive clasp is designed to (pick one:) lie passively OR lie actively in a measured undercut?
Lie passively
If the tip of the retentive clasp does not reach the undercut will it be passive or active?
Active
The tissue surface of the framework should be finished to what texture?
Fine matte
What are 2 requirements of internal and external finish lines on the framework?
- Sharply defined
2. Undercut to provide mechanical retention
What is the first and most important requirement of a major connector?
Rigidity
The framework is adjusted in what order: opposing occlusion first, then to the supporting arch or vice versa?
Fit to teeth and tissues of supporting arch first, then occlusion is adjusted second
Is spray type disclosing media indicated for intraoral framework fitting?
No
What is the greatest advantage of disclosing wax over other disclosing agents for framework fitting?
The three dimensional nature of the wax
Should a framework be forced into position if significant resistance is met?
No
When checking a distal extension framework, should any pressure be placed over the distal extension area?
No, it would cause the framework to rock and give inaccurate disclosing wax readings
Areas of show-through in disclosing wax indicate what?
Interferences
What is the most common area of interferences?
- The shoulders of circumferential clasps
2. Interproximal extensions of lingual plate
What is the difference between an interference and a guiding surface on the disclosing wax?
Guiding surfaces thin the wax
How will disclosing wax appear when evenly displaced on alloy frameworks?
Grayish
What must occur when the framework is tried in with respect to occlusion?
Natural tooth occlusion should remain the same as when framework is absent
Are maxillary and mandibular frameworks placed and adjusted at the same time?
No, done individually. Once each arch is good, they are placed simultaneously and occlusion is checked
What should be used to ensure that undue thinning of the framework does not occur during try-in?
Use a metal thickness gauge (Iwanson gauge)
After the framework try-in, what would be required if the patient does not have enough teeth or distribution of teeth to permit accurate hand articulation?
Jaw relations record
What will be required after the framework try-in if the patient will have a mandibular distal extension RPD, a long-span maxillary distal extension RPD, or a long-span anterior RPD?
Corrected cast impression procedure
What will be required after framework try-in for a patient having anterior teeth replaced with denture teeth on a denture base?
Esthetic try-in
What is required when the opposing casts cannot be accurately hand articulated or when the RPD will be constructed at a position other than MIP?
Jaw relations record
When is a jaw relations record normally taken?
After corrected cast procedure for a Kennedy CI or C II RPD
What is the desired occlusal scheme for a complete denture?
Bilaterally balanced
What is the desired occlusal scheme for a fixed partial dentures?
Disclude posterior teeth
What is the goal for an RPD occlusal scheme?
Establish and maintain harmonious relationship b/w oral structures and provide effective, esthetic mastication
What are 2 general arbitrary points for vertical dimension measurement?
- Top of the patient’s nose
2. Patient’s chin
What are 2 important vertical dimensions?
- Physiologic rest
2. Occlusal vertical dimension
What is the term for the vertical dimension when the patient is upright, completely at rest, and the maxillary and mandibular teeth are slightly separated?
Physiologic rest
What determines the mandibular position in physiologic rest position?
Muscle balance between muscles of mastication,
postcervical muscle group, infrahyoid muscles, suprahydoid muscles
What is the term for the measure of the vertical dimension when the patient’s teeth are in MIP?
Occlusal vertical dimension
Which is greater: physiological rest dimension or occlusal vertical dimension?
physiologic rest dimension > occlusal vertical dimension
The difference between physiologic rest dimension and Occlusal vertical dimension is what range (in mm)?
2-4mm
When should changing the vertical dimension be considered?
When the patient has a significant vertical dimension decrease
Does excessive occlusal wear or a deep overbite always mean there has been a loss of vertical dimension?
No
Greater than ____ mm interocclusal rest space, should be a consideration for increasing the vertical dimension?
4mm
How should an increase in interocclusal height be accomplished?
Using a temporary removable device of acrylic resin, worn 24 hrs/day for 1-3 months
A bone to bone relationship of the mandible to maxilla where both condyle-disc assemblies are stabilized against the posterior slopes of the articular eminences?
Centric relation
Generally, MIP is usually_____and _____ to CR
Anterior and inferior
In what percentage of patients do CR and MIP not coincide?
90%
What is an articulator that opens and closes around a fixed horizontal axis?
Nonadjustable
What is the greatest requirement for a hinge articulator?
It must be rigid
What type of articulator has adjustable horizontal condylar paths, adjustable lateral condylar paths, and adjustable guide pin tables?
Semiadjustable
Hanau articulators are adjusted using what type of jaw relation records?
Protrusive
What is the Hanau formula to set the condylar elements?
L= (H/8) + 12
Whip-Mix condylar guidance is adjusted using what jaw relation records?
Lateral
When adjusting a Whip Mix condylar element, which element is loosened when the lateral jaw relation record is put in?
Elements opposite of side of jaw relation (e.g. if aright side jaw relation, release the left side elements)
Where are the condylar balls located on an arcon articulator?
Upper member of the articulator
What is the advantage of an arcon articulator?
Accurate relationship b/w maxillary cast and horizontal condylar guidance on opening and closing
What articulator should be selected?
The simplest instrument that meets the requirements of treatment
Which articulator type is commonly used for Kennedy classIII partially edentulous arches?
Simple hinge or non-adjustable
Which articulator type is commonly used for Kennedy C I,II, and IV arches?
Semiadjustable
What relates the maxillary cast to the opening and closing axis of the articulator as well as places the maxillary cast in the proper relationship to the horizontal plane?
Facebow
What is the Frankfort horizontal?
2 condylar locations and the lowest part of the bony orbit (orbitale to tragion)
What should be used to aide in jaw relations to aide in mounting a partially edentulous case?
Fitted RPD framework
What is the greatest danger in using a wax record base?
Distortion
What are two ways to avoid wax record base distortion?
- Do not store more than 1 hr
2. Do not submit to changes in temp or humidity
Large record bases should be made of what?
Acrylic resin
Should a record base be polished?
No
An occlusion rim on a framework should be how high?
Approximately even with fossae of neighboring abutments
How high is the occlusion rim in the distalextension
2/3 up the retromolar pad
What is the most common jaw relations medium?
Polyether or polyvinylsiloxane
The occlusal rim or opposing occlusal rims should have how much space interocclusally?
1mm
Inclination of the condylar guidance is dependent on what?
Anatomy of glenoid fossae
What is the plane that passes through the tips of the
mandibular central incisors anteriorly and the MB cusps of the mandibular second molars posteriorly with the angle measured relative to the horizontal plane?
inclination of plane of orientation
What is the relative curvature of the occlusal plane in an anteroposterior direction (Curve of Spee)? (I have no idea what this question even means)
Inclination of incisal guidance
What is the term for the vertical distance from the cusp base to the cusp tip?
Cusp height
When is the only time that the Hanau quint is not predetermined by existing dentition in designing an RPD?
When RPD opposes complete denture
When both arches only have anterior teeth and their incisal relationship does not interfere with establishing desired occlusal scheme
What is a major problem when replacing anterior teeth?
Loss of restorative space due to drifting or tilting
What is the House technique for estimating the width of one central incisor?
divide pt’s bizygomatic width by 16
What is the house technique for estimating the length of one central incisor?
Divide the patient’s chin-to-hairline distance by 16
What are 4 basic tooth mold forms based on patient’s face shape?
- Square
- Tapering
- Square-tapering
- Ovoid
What is critical to transfer to the master cast, and is obtained either at framework try-in or jaw relations?
Midline
When placing posterior teeth, what is of greater concern: fitting into the current occlusion or putting in the correct number and type of teeth?
Fitting into existing occlusion
What is the only time porcelain teeth are indicated?
When they oppose other porcelain teeth
To determine arch length on a distal extension, measure from where to where?
Mand: Distal of natural canine to incline of mandibular ramus
Max: Distal of natural canine to mesial of tuberosity
What is the normal range of distal extension length?
28-32mm
What is a mold consideration for posterior teeth?
Choose a mold slightly longer than remaining natural teeth
Denture teeth are initially set at a height greater than or less than the proposed occlusal vertical dimension?
Greater than. Set incisal pin 0.5mm higher.
What is done with the incisal pin once the posterior teeth have been set a little high?
Reset pin to original height, adjust occlusion until pin touches table
What is used to mark the framework in order to mark a denture tooth that is next to a clasp assembly?
Graphite
What is the desired occlusal scheme when the patient is in MIP?
Simultaneous bilateral posterior occlusal contact with all natural teeth occluding
What is the desired occlusal scheme for a tooth-borne RPD?
Balanced (bilateral simultaneous contact of anterior and posterior in centric and eccentric)
What is the desired occlusal scheme in Class IV RPD(anterior)?
Light contact with opposing natural teeth
Should artificial teeth be positioned on the upward incline of the mandibular ridge?
No
Must the denture base be waxed to full contour for an esthetic try-in appointment?
No
What is a common sensation during esthetic anterior try-in?
Fullness at upper lip
What should be visible when lips are relaxed?
Edges of central incisors
Should a decreased number of teeth be placed if anterior drifting has occurred?
No
What are some problems if there is spacing after you have placed the denture teeth?
Food impaction, hygiene problems, phonetic problems
Should a patient be given a hand mirror or told to stand a few feet away from a wall mirror during esthetic try-in?
Wall mirror
What are 4 times when the jaw relation must be verified?
- If accuracy of mounting is in question
- RPD opposed by complete
- All posterior teeth in both arches replaced
- No opposing natural teeth and require verification of occlusal vertical dimension
Verifications are normally made at the same or an increased vertical dimension?
An increased vertical dimension
The mandible can maintain a non-translating arc for what range?
10-20mm
Are teeth allowed to contact during verification recordings?
No
What is the most common wax for jaw relations?
Baseplate wax
If baseplate wax is used, mounting should be completed how soon after recording?
30 min
Should a verification be made as soon as the RPD is placed?
No. The patient should wear for 3-5 mins and speak.
Should there be penetration through the recording medium during a jaw relations?
No
Acrylic resins are never finished to what type of edge?
Never to a fine edge
Should external finish lines be waxed heavy or light?
Heavy enough to allow for loss of resin during finishing and polishing. Never below the level of the metal.
What should be waxed apical to the gingival margin of each posterior tooth in order to help control food flow?
Slight bulge
The gingival height is highest over which tooth?
Canine
What does waxing in a slight concavity between the gingival bulge and the periphery of the denture base do?
Aides retention by giving area for the cheek to fold into
If corrected cast was not made, what should be the thickness of the denture peripheral roll?
2mm
The lingual portion of a distal extension should have what?
A distinct concavity to allow for the floor of the mouth to rest in and aide retention
What are 2 places commonly requiring modification during finishing and polishing?
- DB flange of maxillary
2. DL flange of mandibular
The denture base should have what minimum thickness during wax up?
2mm
The borders of tooth-supported segments of RPD should be waxed ____ mm apical to the adjacent gingival margin?
5mm
What type of completed mold contains master cast and metal
framework in one portion of denture flask and artificial teeth are in the remaining portion of the denture flask?
Split mold investing
In a split mold, what amount of clearance should be between the occlusal surface of teeth and the top of the flask’s middle segment?
15mm
What dental stone is used in the first investment layer of a split mold?
Type III or Type IV
What type of dental stone is used in the second layer of a split mold?
Type III or Type IV
In a split mold, what amount of clearance should there be between the second layer and the top of the middle part of the flask?
7mm
In a split mold, the second layer covers everything except what?
All except waxed bases and denture teeth
In a split mold, what is put on the surface of the exposed wax before the third layer of gypsum added?
Surface tension-reducing agent
In a split mold, the third layer covers everything, leaving only what exposed?
The occlusal surface of the denture teeth
When is colorization of denture teeth done?
Before the placement of bulk denture resin
How long does the packed resin flask sit before processing?
1 hr
Heat-activated acrylic resin is processed at what temperature?
74°C(165°F)
What is a common cause of porosity in the denture base?
Rapid rise in temp causing monomer to boil
What is the safest curing cycle?
Room temp water brought to 74°C(165°F) in 1 hr
Maintain 74°C(165°F) for 7 hrs
At end of 7 hrs, boil for additional 30 mins
Should investment be allowed to dry after curing if it is not immediately deflasked?
No keep it wet
What is the temperature and length of time of a short cure?
74°C(165°F) maintained for 90 minutes
What mechanical retention features are placed in denture teeth prior to packing with resin?
Diatorics
When the mastercast and framework are remounted after processing a discrepancy of what length or less in the incisal pin is considered successful?
1mm
When removing partial from the master cast after investment, the abutments are cut off first, then how does sectioning of the cast proceed?
Perimeter inward
Should the facial surface of the anterior flange be polished to a high shine?
No
If a corrected cast impression was used to make the distal extension borders, will they need to be adjusted clinically?
No
Are resin-metal junctions at internal finish lines polished?
No
How is an RPD stored after finishing and polishing?
Disinfected and put in water
What is the principle goal of prosthodontic treatment?
- Replace missing teeth
2. Preserve dentoalveolar structures
A significant percentage of failed RPDs can be attributed to what?
Lack of mental preparation preceding delivery
What are 3 objectives of the insertion appointment?
- Eval correct fit of denture base
- Correct occlusion
- Adjust retentive clasps
What is a common area for denture bases to contact and require adjustment at delivery?
Lateral walls of ridge and no contact on crest of ridge
What type of base has slightly less distortion requiring less adjustment?
Chemically activated resins
What base type does not have polymerization shrinkage and usually does not require adjustment at insertion?
Chemically-activated resins
What base type does not have polymerization shrinkage and usually do not require adjustment at insertion?
Cast metal
What are the medium and makeup to assess the internal aspects of denture base at insertion?
Pressure indicating paste (PIP), which is zinc oxide powder with vegetable fat or shortening
Should the RPD be tried in without putting PIP on first, or should the first try in have PIP in the base?
Should have PIP in the base at the very first try-in
Where are the usual areas of heavy contact on the denture base?
Bony prominces like maxillary tuberosity and lingual surface of mandibular edentulous ridge in the mylohyoid region
What is mixed with disclosing wax to help it adhere while evaluating denture base flanges at the insertion appointment?
Petroleum jelly
What is the method of choice for evaluating the maxillary denture base flange extension?
Direct visual exam
On a tooth-supported RPD, how far and why must the denture base flange extend?
Only far enough to achieve positive soft tissue contact to prohibit food accumulation
The posterior denture base flange should be how thick?
2mm
In theory, the only components of an RPD permitted to contact oral tissues in areas of undercuts are what?
Termini of retentive clasps, but some denture bases actually go into limited soft tissue undercuts
Extraoral occlusal adjustment via a remounting is indicated in what 3 instances?
- RPD with long extension bases
- Extension base covers extremely mobile tissues
- RPD opposed by complete denture
Ultrathin articulating paper is how thin?
8µm
Remount procedures for occlusal adjustments are made how?
Irreversible hydrocolloid impression with RPD in the mouth
What are the goals for a clasp adjustment?
- Limit unnecessary force application to abutments
2. Assure sufficient RPD retention
Elongation measures what in an alloy?
The degree of plastic deformation that an alloy can undergo before fracture
Fracture of chromium-based alloys during adjustment is most often caused by what?
Excessive or repeated bending at one location
What are 2 plier types for clasp adjustments?
No 139 Bird beak
No 200 3 prong
How is the No 139 bird beak used?
Hold that clasp at the place to bend, then pull or push the RPD with the opposite hand
How is the No 200 three-prong used?
Hold the wire between the prongs and squeeze handle
What is the clasp type that most often requires adjustment?
Wrought wire
While wrought wire can be adjusted in any direction, how can half-round cast circumferential clasps be adjusted?
Only perpendicular to flat surface (toward or away)
What is the only plier that is to be used to adjust a half-round cast circumferential clasp?
No 139 Bird beak
What common error is made when adjusting an infrabulge T-clasp?
Bending vertical approach arm to try to get retentive terminus toward abutment
What plier type should be used to get the retentive terminus of the infrabulge T-clasp to engage an undercut?
No 200 3 prong, single prong in the inside flat surface
What is used if entire infrabulge T-claps is deformed (e.g. an accident bends it out)?
Use No 139 bird beak and bend entire approach arm medially
What are the oral hygiene instruction for RPD?
- Brush RPD out of mouth daily
- No toothpaste on RPD
- Hold over sink full of water while cleaning
- No soaks containing chlorine which will damage metal
- Remove at bedtime
- Store in water
When would an RPD be indicated for wear at night?
Pt bruxes on few remaining teeth. Wear of RPD at night can lessen that. Still have them take it out a few hours during the day
Which is harder for RPD: insertion or removal?
Insertion
Should the patient seat the RPD with biting pressure?
No
When is it acceptable to position a fingernail apical to a facial clasp arm on each side of dental arch and move the clasp occlusally?
Only with cast circumferential clasp
How should a wrought wire clasp retained RPD be removed?
Grasp acrylic resin denture base on each side of arch and withdraw
The patient should be informed that what are not part of RPD therapy?
Sore teeth and soft tissues
Patients should be seen how soon after the RPD insertion appointment?
24 hours
Laceration or ulceration is generally caused by what?
Overextended denture base
What is a useful aide to identify overextensions of the denture base?
- Circle ulceration or sore with indelible pencil.
- Place RPD in.
- Remove RPD and relieve the transfer.
What can hasten healing from laceration or ulceration?
1⁄2 tsp salt in 6 oz warm water.
Hold a bit in mouth until temp drops.
Repeat until 6 oz is used up.
Repeat every 4 hrs.
Redness/erythema is commonly caused how and how can find out?
Rough denture base. Rub gauze or finger over the denture base or use PIP
What is the greatest factor in prosthesis-related discomfort?
Lack of occlusal harmony
How do you check abutment teeth for soreness?
Use finger pressure with RPD not in
What must be done if teeth are sore?
Lack of occlusal harmony
How is the RPD marked to find areas irritating teeth?
Disclosing wax
If disclosing wax shows that the RPD is not causing tooth pain, what is the most logical reason for the pain?
Occlusal trauma
What usually causes occlusal trauma?
Occlusal interference between natural tooth in one arch and metal of prosthesis in opposing
When adjusting the metal of an RPD, what must always be considered?
Not making metal too thin. Last resort is to adjust opposing natural dentition
What is a common cause of gagging with an RPD?
Max palatal connector not adapted to palate or hitting soft palate
What is used to ensure that the maxillary RPD palate is not extending onto the soft palate?
Mark posterior with indelible pencil. Take out RPD, have pt say Ahhhh. If vibration occurs anterior of that line, posterior of RPD palate must be adjusted
What is one of the best methods to adapt to phonetics while wearing an RPD?
Reading aloud
Cheek biting is usually caused by what?
Insufficient horizontal overlap of Maxillary and mandibular posterior teeth
Tongue biting can be caused by what?
Denture teeth positioned too lingual
What are some other causes of cheek or tongue biting not associated with tooth placement of RPD?
Long absence of teeth has caused cheeks to sag in and tongue to broaden
How should patient be instructed initially for chewing to decrease frustration?
Avoid extremely tough, stringy, or sticky foods
How often should an RPD patient be seen?
Every 3-6 months, not longer than 12 months
What is the term for when the side to side or back and forth motion of an RPD is limited?
Stability
What is the term for when the up and down or rocking motion limited in RPD?
Retention
What is the term for when vertical forces are evenly placed between tissue and teeth?
Support
What is the term for a lack of movement that produces sore spots?
Comfort
What is the term for minimizing visible clasps and facial support?
Esthetics
Dr Moon considers the permanence of the RPD as concerned with what? (What does this question even mean?)
Bone loss
What is the major defect of RPD?
Stability
Which RPD type has more problems as the patient ages?
Mandibular because that is where the greatest bone loss occurs
A soft reline seeks to do what?
Ease soft tissue stress
A hard reline seeks to do what?
Replace bone loss
What are 4 functions of the RPD?
- Mastication
- Esthetics
- Phonetics
- Self-esteem
What is the term that describes >1mm movement of occlusal rests or indirect retainers upon application of unilateral or bilateral force to denture base or movement 1mm or greater upon application of unilateral or bilateral force to stress- bearing areas?
Loss of stability
What is the term for when the denture dislodges when the patient opens their mouth moderately wide but without strain?
Loss of retention
How should you examine an RPD?
Extraorally
What are 3 defect categories?
- Integrity
- Wear
- Reline
How can there be broken clasps, rests, or broken portions of the RPD framework?
Fatigue, dropping, cast voids
How can there be occlusal surface problems or missed or chipped teeth in an RPD?
Acrylic denture teeth wear readily
What are 6 things RPD alloy selection is based upon?
- Weight (density)
- Casting accuracy
- Availability/cost
- Versatility
- Clinical experience
- Mechanical properties
What are the 5 mechanical properties considered when choosing an RPD alloy?
- Hardness
- Yield strength
- Elastic modulus
- Fracture and fatigue strength
- Ductility (% elongation)
What is a problem with a light casting allow?
Less accurate casting because less weight to push metal into form when centrifuged
Drake labs makes our RPDs and uses what alloy and specs?
Vitalium 2000 Plus 0.2% Yield strength (680 MPa) 10% elongation Co 63.4%, Cr 28%, Mo 5.2% No nickel or beryllium Chrome keeps cobalt from rusting
What are the problems with stainless steel in RPD (18/8 stainless steel)?
Has nickel in it which some people are allergic to
What is the desired percent elongation?
Greater than 5%
Teeth will wear quicker and will take more grinding to adjust if you increase what mechanical property?
Hardness
Clasps will engage less undercut and you will get more retention and less elastic deformation when you increase what mechanical property?
Elastic modulus
Is it better to have a softer or stiffer major connector?
Stiffer, it distributes force across the arch better
What is increased by increasing yield strength?
- Clasp deflects elastically more before plastically deformed
- Can engage more undercut
What happens if you increase the fracture strength?
The alloy is less likely to fracture or fatigue
If you increase the ductility, the chances of what decrease?
There is less chance of fracture during adjustment or fatigue
Which is stiffer (has less elastic modulus): gold or CoCr?
CoCr, so Gold engages more undercut
Which distributes stress better across the arch while requiring less material, gold or CoCr?
CoCr
What is the drawback of reducing clasp size in order to increase flexibility?
Increase fracture and plastic deformation
Which have greater yield strenght: wrought wire or cast clasps?
Wrought wire
What does heating do to yield strength?
Lowers it
What increases the flexibility of a clasp without compromising strength?
Tapering the clasp to 1⁄2 its diameter where it started on the framework
What is the one advantage to Ti if you can even get it cast accurately?
It is light and less damaging to clasped teeth, especially in maxilla
What is the high noble alloys percentage?
60% (40% gold + platinum group)
What is the titanium alloys percentage?
85% titanium
What is the noble alloys percentage?
25% (gold + platinum group)
What is the predominantly base alloys percentage?
<25% (gold + platinum group)
1/3 of Nickel allergic patients are also allergic to what?
Palladium
Silver is added in alloy to do what?
Counteract orage effect of copper which is used to harden the gold
Pd-Ag alloys are majority used for what restoration and why?
PFM, it is corrosion-resistant and cheaper
What ADA Gold Crown and Bridge alloy is used for crown, bridge and RPD?
Type IV (> 75% Au)
Which is the harder titanium: Type I or Type IV?
Type IV, but internal oxides abrade teeth
Metal and porcelain thermal expansion must match within how much to prevent porcelain fracture?
+/- 7%
