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220 Cards in this Set
- Front
- Back
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recommended isthmus width for inlay
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1/4 intercuspal distance
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proximo-occlusal inlay is indicated for what type of teeth
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PMs and Ms w/ minimal caries or previous restoration that needs MO or DO
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T/F: class 2 inlays can be used in any mouth, regardless of caries risk
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F: should be in mouth w/ low caries rate for some time preceeding restoration
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contraindications for placing class 2 inlay
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hx of caries, adolescents
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how deep should pulpal floor be for class 2 inlay?
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1.5mm
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T/F: in a class 2 inlay box, the line angles resist displacement
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F: box walls
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T/F: F and L walls of class 2 inlay box should be slightly divergent
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T
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what is minnasota ditch?
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V-shaped groove at junction of axial and gingival walls
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purpose of minnasota ditch
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resist displacement by occlusal forces
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how should B and L flares lean in class 2 inlay prep
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B slightly to the B, L slightly to the L, both slightly to center of tooth
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Is flare for class 2 inlay wider at gingival or occlusal end?
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occlusal
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gingival bevel for class 2 inlay should be at what angulation
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30-45 degreees
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where is occlusal bevel for class 2 inlay
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junction of occlusal 1/3 and gingival 2/3 of isthmus walls at angle of 15-20 degrees
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indication for class 1 inlay
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moderately sized O lesion in mouth of pt w/ mostly gold restorations
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where can you use class 3 inlay?
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D surface of canines
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where is dovetail in class 3 inlay
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1mm deep at incisal end of cingulum
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indication for class 5 inlay
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restore severe abrasion or erosion and large caries on gingivofacial aspect of molars
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how deep should class 5 inlay be
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1mm
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indications for MOD onlay
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1. broken down teeth w/ intact B and L cusps 2. MOD restorations w/ wide isthmuses 3. endo tx post teeth w/ sound B and L tooth structure
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T/F: MOD are more retentive than 3/4 crowns and can be used as FPD retainers
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F
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how does an MOD prep differ in mand than max?
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functional cusp bevel and occlusal shoulder are on buccal, and lingual bevel is wider and can be contrabevel due to esthetics
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what are the 3 ways destruction of tooth can be classified?
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peripheral (axial surfaces), central, or combined
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use the principle of substitution when compensating for what/
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1. mutilated or missing cusps 2. inadequate length 3. missing clinical crown
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what would be used to augment retention and resistance where axial walls have been shortened/
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grooves
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2 rules to avoid excessive tooth destruction while creating retention in weakened tooth
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1. keep away from core (pulp and 1mm surrounding dentin) 2. no dentinal wall should have thickness > height for retention
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requirements for grooves to be placed
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at least 1mm wide and deep and as long as possible to improve retention and resistance
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how do pins increase retention
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adding additional length internally and apically rather than externally
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step form increases retention without doing what?
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1. ecroaching upon pulp and 2. thinning and weakening tooth
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recommended pin depths
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cemented: 4mm, threaded: 2mm
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clinical recommendation for pin placement
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1 pin for each missing cusp, line angle, or axial wall
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how much more retentive are self-threading pins than cemented pins?
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5x
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purpose of cement bases
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1. protect pulp 2. elim undercuts
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good cements used for bases
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GI and polycarb
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indication for placing a core
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if half or more crown is destroyed
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steps to modify extremely damaged teeth
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1. eval pulpal health 2. assess periodontal condition 3. make prelim prep design 4. remove previous restorations and bases, all caries and unsupported enamel 5. eval strength of reminaing walls 6. finalize prep design
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what happens if a tooth w/ thickness: height is < 1:2
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fracture and should be shortened
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indications for RPD
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edentulous spaces > 2 posterior teeth, anterior spaces > 4 incisors, or spaces that include canine and 2 other contiguous teeth
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what would make a poor environment for a conventional FPD?
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gross soft tissue defect and dry mouth
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indication for resin-bonded tooth-supported FPD
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defect-free abutments in situations where there is a SINGLE missing tooth, usually incisor or PM
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when is a resin-bonded retainer okay to use on a molar?
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if muscles of mastication aren't well developed
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T/F: resin-bonded FPD requires an abutment on either side
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T
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what type of prep is shallow and restricted to enamel
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resin-bonded
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indications for implant-supported FPD
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where insufficient numbers of abutment teeth or inadequate strength in abutments to support conventional FPD, and good when no distal abutment is present
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are implants or natural teeth more able to survive in a dry mouth?
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implants
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the roots and supporitng tissues for abutments should be evaluated for what 3 factors?
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1. crown-root ratio 2. root configuration 3. periodontal ligament area
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optimum crown:root ratio for FPD abutment
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2:3, but 1:1 is acceptable
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what root configuration is preferable for an abutment
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wide F-L, widely separated, multirooted
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ante's law
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pontic span length should not exceed the combined MD width of abutment teeth
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have FPD failures from abnormal stresses been attributed to leverage and torque or overload?
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leverage and torque
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how are disloding forces for FPD compared to a single crown
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FPD: M-D disloding forces, single: B-L
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requirement for a secondary abutment
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must have at least as much root surface area as primary
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what happens when pontics lie outside interabutment axis line?
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pontics act as a lever arm which produce torquing movement
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when do you use a nonrigid connector
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short-span FPD replacing one tooth
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what does nonrigid connector due w/ the stress
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transfers it to supportign bone rather than connectors
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rigid connectors are more preferable for what type of teeth
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decreased periodontal attachment, since stresses are distributed more evenly
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where is a connector placed in a 5-unit pier-abutment restoration
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usually on middle abutment, since placing it on terminal abutments would form a lever arm
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what restorations can you do on a tilted mand 2nd molar abutment if the 3rd molar is present and drifted mesially
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ortho uprighting, proximal half crown, telescope crown, nonrigid connector on distal of PM
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when is the only time you can do proximal half crown
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if D surface is untouched by caries or decalc and low incidence of proximal caries in mouth
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is a max or mand FPD replacing a canine subject to more forces?
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max
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T/F: no FPD replacing a canine should replace more than one additional tooth
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T
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occlusal interferences
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1. centric 2. working 3. nonworking 4. protrusive
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premature contact that occurs when mandible closes w/ condyles in optimum position
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centric interference
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contact b/w max and mand post teeth on same side of arches as the direction in which mand has moved
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working interference
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occlusal contact b/w max and madn teeth on side of arches opposite direction in which mandible has moved
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nonworking interference
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type of occlusion where a max num of teeth should contact in all excursive positions - good in denture construction
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bilateral balanced occlusion
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type of occlusion where all teeth on working side to be in contact during a lateral excursion
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group function
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type of occlusion that is aka canine protected occlusion
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mutually protected occlusion
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protrusive incisal path inclination
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50-70 degrees
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condylar guidance inclination
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30.4 degrees
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in a healthy occlusion, the anterior guidance is approx 5-10
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luting cement primary purpose
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fill the gap and prevent entrance of fluids
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which cement is an example of a luting cement (no adhesion)
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zinc phosphate
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advantages of micromechanical bonding
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allows less extensive preps for restorations like ceramic veneers and resin-bonded FPDs
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how do you get deep irregularities necessary for micromechanical bonding in surfaces?
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etch: phosphoric acid on enamel, hydrofluoric acid on ceramics, electrolytic on metals, etc
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what are examples of cements that work by molecular adhesion
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polycarbs and GIs but have low compressive strength
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T/F: noble metal alloys are suited for direct molecular bonding
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F
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how should molecular bonding be viewed?
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only as a way to enhance mechanical and micromechanical retention and reduce microleakage, not as primary bondign mechanism
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T/F: cements based on zinc oxide and eugenol are not indicated for permenant cementation
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T
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cement that has high compressive strength but widely blamed for pulpal irritation
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zinc phosphate
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cement that has higher tensile strength than zinc phosphate, but low compressive strength
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polycarb
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polycarb has low pH, but why doesn't it irritate the pulp?
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b/c large size of polyacrylic acid molecules don't penetrate dentinal tubules
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T/F: polycarb has moderately high bond strength to enamel AND dentin
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T
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T/F: polycarb will bind to stainless steel and gold
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F: will bind to SS but not gold
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cement that is used largely for provisional cementation that deteriorates rapidly in the mouth
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ZOE
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T/F: ZOE causes virtually no pulpal inflammation
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T as long as no direct contact w/ pulp
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cement w/ fluoride content ranging from 10-16% by weight, good compressive and tensile strength and bond to tooth structure comparable to polycarb
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GI
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cement that is bacteriostatic during its setting phase
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GI
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how does GI cement inhibit secondary caries?
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reduces solubility of adjacent enamel
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disadvantages of GI cement
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lower pH than ZP, postcementation hypersensitivity
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what should be placed along with GI to areas close to pulp
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calcium hydroxide
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what weakens GI cement and what produces shrinkage cracks
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early exposure to moisture weakens and desiccation produces shrinkage
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what should you use w/ zinc phosphate to avoid irritation?
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varnish - copalite
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how is zinc phosphate mixed?
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add powder to liquid and mix over large area which neutralizes acid rxn and retards setting time
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how do you knwo zinc phosphate is right consistency?
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string up 10mm from slab
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how do you avoid dessicating margins when using GI cement?
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coat w/ petrolatum during setting
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how do you mix GI?
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mix quickly, little heat liberation so can mix over smaller area
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how long should you mix GI?
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60s
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working time for GI
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3m
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the tendency is to undermix GI cement, so what does this cause?
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microleakage
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5 preparatory procedures done on casting after fabrication
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1. prelim finishing 2. try-in and adjustment 3. pre-cementation polishing 4. cementation 4. post cementation finishing
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where do onlays protect teeth from stress?
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walls and line angles
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2 acceptable finish lines for MOD onlays
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occlusal shoulder and heavy chamfer
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how wide shoudl gingival flares be on MOD onlays?
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0.5-0.7mm
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3 requirements of a good cast
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1. bubble free 2. distortion free 3. trimmed to insure access for carving wax pattern margins
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what does working cast establish?
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1. interprox contacts 2. B/L contours 3. occlusion w/ opposing teeth
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what is simplest working cast systems?
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working cast w/ separate die
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disadvantage of using separate die
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wax pattern must be transferred from one to another
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what types of stone are used to make the die
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high strength type 4 or high expansion type 5
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how tall should the handle of the die be?
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1 in
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angulation of handle to tooth
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parallel long axis of tooth
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how thick should die spacer be?
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20-40 microns
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max num of post teeth safely rplaced
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3 only under ideal conditions
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when can 3rd molars be used as abutments?
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1. upright - little or no mesial inclination 2. long, distinctly separate roots 3. completely erupted 4. surroudned by healthy attached, keratinized gingiva
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favorable crown:root ratio, favorable abutment-pontic ratio
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both 1.0
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what retainers can be used if resin-bonded aren't acceptable due to carious involvement
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MCR adn all metallic
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what pontics are used in anterior/esthetic zone?
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modified ridge lap
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pontics used in posterior
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hygienic
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what abutments are used when replacing canines?
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double anterior abutments
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T/F: laterals make good abutments
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F
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if a lateral abutment is compromised through caries, bone loss or tilting, what shoudl you do?
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consider extraction and include as pontic
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retainer suggested for abutments when replacing 1 tooth, esp canines
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MCR
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complex FPD replacing 2 teeth usually require what type of abutments?
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double abutments on one or both sides of edentulous space, MCRs or metallic crowns
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what are generally indicated for pier abutments?
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non-rigid connectors on the distal of pier/lone standing abutment
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what type of connector is used when replacing a mand CI and LI on opposite side
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rigid
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when is rigid connector indicated
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when span lengths are long (ex max incisors and PMs)
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when can cantilevers be used?
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only if there are little stresses imposed on the pontic and ideal abutments (canines are great)
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joining/fusing metals together w/ filler (solder), there is no fusion or alterations in metals
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soldering
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process where fillr metal melting temp is >450
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brazing
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bonding is dependent on wetting by solder not the melting of metals
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wetting
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fusion or alterations in metals being joined w/o having solder
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welding
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prime prerequisite for soldering
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cleanliness
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flux for noble metals
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borate
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flux for base metal alloys
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fluoride
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what is the best form for flux to come in and why?
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petrolatum paste b/c it keeps air out of the flux adn leaves no residues
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examples of antiflux
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graphite and rouge
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low fineness has what type of flow?
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low
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good dental solder should have what properties?
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1. corrosion resistant 2. lower fusing than alloy 3. nonpitting 4. strong 5. free flowing 6. same color
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how thin should the disc be to separate a bridge before soldering
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.009in or .23mm
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indirect wax pattern technique advantages
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1. can be done away from chair 2. complete visualization of restoration 3. access to margins 4. technician can fabricate pattern
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type 1 and 2 wax uses
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1 used for intra oral wax patterns - 2 used extraorally and has lower melting point
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requirements of an inlay wax
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1. flow readily when heated 2. rigid when cooled 3. can be carved precisely w/o chipping, distorting or smearing
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what should the shape of the axial surface interproximally
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flat (easiest to floss) or slightly concave and not encroach on interdental papilla
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overcontouring axial surfaces results in what?
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gingival inflammation
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Height of contour on facial surface of all posteriors
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.5mm
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lingual HOC on max teeth and mand 1st PMs
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.5mm
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lingual HOC on mand 2nd PMs
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.75mm
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lingual HOC on mand molars
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1mm
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part of axial contour that extends from base of gingival sulcus past free margin of gingiva
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emergence profile
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is it better to under/overcontour the emergence profile?
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under
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one tooth to one tooth arrangement
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cusp to fossa
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ideal occlusal arrangement but rarely found in natural teeth
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cusp to fossa
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problem when margin breaks off when wax is removed from die resulting in short/shy margin - if it doesn't break it may preven tseating
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overwaxed margins
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problem when there is not an adequate seal
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short margin
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problem with margin when there is a collecting point for plaque whch can irritate gingiva
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ripples
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thick margins result in what?
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poor sealing/poor axial contours - creates perio probs
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best product to make pontic out of
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porcelain - b/c easily cleaned and hygienic
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what types of materials for pontics are preferred for tissue contact
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glazed or highly polished porcelain or gold with mirror-like finish
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why should the pontic not match the apical half of facial surface of lost tooth?
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b/c it will look too long and artifical
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straight line b/w retainers prevents what?
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torquing of retainers/abutments
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area of pontic that contacts ridge should only contact what?
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keratinized gingiva
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saddle pontic is aka
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ridge lap pontic
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why do we never use saddle/
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not cleansable
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most commonly used pontic in appearance zone in both arches
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mod ridge lap
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pontic w/ nearly all convex surfaces for cleansability and contacts ridge nor further lingually than midline
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mid ridge lap
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hygienic aka
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sanitary
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where is hygienic used?
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nonappearnce zone, exp mand 1M
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purpose of hygienic
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restores occlusal function and stabilizes adjacent and opposing teeth
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all convex configuration of hygienic
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"fishbelly"
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hygienic w/ F-L extension that is concave w/ loss of gingival embrasures
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Perel pontic
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pontic that replaces teeth over thin ridges in nonappearance zone
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conical
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pontic w/ round end design used in esthetic areas mainly on broad flat ridge
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ovate
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pontic that sits 1/4 of way into an extraction site to give illusion of growing from ridge
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ovate
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pontic w/ greatest esthetic potential
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metal ceramic pontic - stronger b/c bonded to metal
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class I ridge classification
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loss of F-L ridge w/ normal apicocoronal height
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class II ridge classification
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loss of ridge height w/ normal width
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class III ridge classification
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loss o both ridge width and height
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when is FVC mandatory?
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when abutment tooth is small or when edentulous span is long
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contraindications for FVC?
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uncontrolled caries
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how thick is the resin to make a template?
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.02 in thick
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modifications are made from classic crown prep for fixed bridge abutments in order to:
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1. increase retention and resistance 2. make provisions for accessible margins adjacent to pontic 3. create space for precision attachments
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T/F: inlays and onlays are NEVER indicated as abutments
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T
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when is it okay to use 3/4 crown for abutments?
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when replacing one tooth or 2 small teeth, and when abutment teeth are relatively intact and have adequate crown length
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when do you use 7/8 crowns for abutments
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longer spans or bridges w/ 2+ abutments
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what features are placed to resist displacement around a F-L axis resulting from pontic flexing down as force is applied
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F-L grooves
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what features are placed when pontic is located on a curved portion of dentition placing pontic facial to straight line connecting 2 abutments which creates torque around M-D axis on abuts
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M and D grooves
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T/F: it's okay to place finish line for abutments at or below gingival crest on short teeth in area of pontic
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T - so not to be encroached upon by connector
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advantages for RPD
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1. abutment requirement not as stringent 2. better esthetically and functionally in edentulous areas w/ high tissue loss
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contraindications for RPD
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pts w/ large tongues and muscular discoordination
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advantages of PMMA
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1. good marginal fit 2. good tx strength 3. good polishability 4. durability
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disadvantages of PMMA for provisionals
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1. high exothermic rxn 2. low abrasion resistance 3. free monomer toxic to pulp 4. high volumetric shrinkage (8%)
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what material for temps do we use in clinic?
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bis-acryl: protemp II, integrity
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advantages of bis-acryl
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good marginal fit, low exothermic rxn, low shrinkage, good abrasion resistance, good transverse strength
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disadv of bisacryl
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surface hardness, less stain resistant, limited shade selection, limited polishability, brittle
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techniques for custom provisional restoration
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1. overimpression fabricated 2. template fabricated 3. template VLC 4. shell fabriccated (from waxup before prep appt)
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what does polymerizing temp in pressure pot under 20 psi do?
|
decreases porosity and increase transverse strength 28%
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what is added to cement for easier removal and reduced strength?
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petrolatum
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what happens when you let resin to cure in air?
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monomer evaporates and formation of granulated frosted surface
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what happens when you let resin cure in hot water
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monomer boils = increased porosity
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techniques for prefabricated provisional restorations
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1. anterior polycarbonate crown 2. provisional crown for endodontically tx tooth 3. preformed anatomic metal crown (emergency - fractured molars)
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types of prefabricated provisional restorations
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1. stock aluminum cylinders 2. anatomic metal crowns 3. clear celluloid shells 4. tooth colored polycarbonate crown forms
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in extensively damaged teeth, when do you use a box form?
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only if caries dictates destruction of sound dentin, otherwise, use groove
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when a gold surface is polished, small particles of the polishing matrial are filled into surface irregularities on gold's surface = ?
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beilby layer
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basic component of carborundum disks and green stones
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silicon carbide
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gine siliceous polishing powder combined w/ wax binders to form cakes
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tripoli
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composed of iron oxide - softest extraoral polishing agent
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rouge
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used for final intraoral polishing
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tin oxide
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how big should the space be to solder?
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.008in or .2mm
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how think should the index be for soldering?
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6mm or .25 in
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how much of an apron around the index?
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3mm
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