Card Set Information

2012-12-10 21:53:41
Indirect Fall 2012

Indirect Fall 2012
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  2. Interocclusal record material characteristics?
    • Soft at room temp
    • Tenax, sheet wax, plaster, acrylic, silicon rubber, aluwax, An oxide eugenol, dead soft metal
    • Filled PVS (polyviylsiloxane)
  3. Should occlusal records capture soft tissue landmarks?
    • No, trim to just cusp tips
    • Remove axial and deep occlusal Vs
  4. Should occlusal record be taken before or after die spacer?
    Wait til after in order to avoid errors of thickness (pooling)
  5. What does the facebow do?
    • Approximate rotation center of the head of the condyle
    • CLOSED BITE mounting in ICP, OK
    • If the mounting is open bite use different technique to locate true terminal hinge or condylar rotation center?
  6. What does the protrusive record do?
    • Set semi/fully adjustable articulators to approximate ange of CONDYLAR EMINENCE
    • More accurate CUSP INCLINES for jaw movements of protrusion and lateral border positions
  7. What influences the path of the condyle?
    Eminence curve (bone contour and ligaments and muscles
  8. What innovation increased the use of double bite impressions?
    ADDITION SILICON: Higher viscosity heavy body elastomerics
  9. What are the indications for double bite impression?
    • 1-2 single crowns
    • Pt w/ stable bilateral occlusion, w/ at least 1 vertical stop on preparation side
    • Contra: multiple, FPD, abutments, unstable, changes in VDO, can’t close mouth with tray
  10. What are advantages of double bite?
    • Prep, adj teeth and opposing in 1 impression
    • Bite registration in impression
    • Economic & efficient
  11. What is the proper sprue angle?
    45, smooth improved flow with less air entrapment
  12. Where should pattern be in relation to ring?
    • Entered
    • Margins 6-8mm from closed end
    • Margins 2-4mm from open(top) end
    • Sprue length 4-6mm
  13. What is novocast w/p ratio?
    • 26ml / 75g
    • Hand mix 15, vacuum 30 at 27psi
    • Set 1 hour
  14. What temp is novacast patterns burnouted at?
    1200 F
  15. Which area of flame should be used to melt gold?
    • Ox, red, combustion, mixing
  16. What does prevox do?
    • Remove investment and dissolves surface oxides leaving higher noble content to surface metal
    • Use rubber or plastic to remove from prevox
  17. What is the contraction of gold as it shrinks?
  18. For metal restorations what expansions and contractions should be considered?
    • Gold shrinks 1.5%
    • Die stone: expands when setting
    • Investment: expands-> compressing ring liner, expands in oven
    • Investment: setting & thermal expansion
    • Net result, good fit
  19. What are advantages of gold?
    • Resists corrosion
    • Tensile strength-> durable thin margins
    • CTE = tooth
    • Wear rates on restoration and opposing teeth similar to enamel
    • High density & low oxide make predictable
  20. Should anesthesia be used during try-in and cementation?
    Typically no, patient can evaluate better
  21. What tools can be used to remove temp?
    • Backhaus towl clamp
    • GC pliers
    • Engage buccal/lingual and rotate
  22. What are the limitations of radiographically detecting open margins?
    Angle of beam
  23. What is the primary component of most dental wax?
    Paraffin CnH(2n+2)
  24. What are some modifiers of dental wax?
    • Beeswax: pliability
    • Carnuba: hardness, shine
    • Candelilla: hardness, no m.p.
    • Ceresin: reduce brittleness, increase hardness
    • Gum dammar and Rosin: increase brittleness
  25. What are the classes of dental wax?
    • Pattern:inlay, casting, baseplate
    • Processing: boxing, utility, stick
    • Impression: low MP, Iowa wax, bite registration (Aluwax)
  26. What are all mechanical properties of wax dependent on?
    • Temperature
    • Viscoelastic, modulus, proportional limit, strength, ductility
  27. What are the thermal properties of wax?
    • Low thermal conductivity
    • High heat capacity-> long working time
    • High CTE
    • Melting range dependent on composition
  28. What is the CTE?
    • Coefficient of thermal expansion
    • = d(L)/L(0) * d(Temp)
  29. CTE of waxes order?
    Paraffin, beeswax, hard wax, carnauba
  30. What is the modulus?
    • Elastic deformation slope of linear stress(y) strain (x) curve
  31. What are ways to minimize wax pattern distortion?
    • Uniform heat
    • Immediate investing
    • Store at low temp
  32. How much gold is needed for a wax pattern?
    Weight(wax) * 16.2
  33. What must investment material expand to compensate for?
    Gold shrinkage
  34. What is refractory in investment material?
    • Heat resistant, SiO2 polymorphs
    • Quartz, Tridymite, Cristobalite
  35. What is the composition of investment material?
    • Refractory: heat resistant (SiO2)
    • Binder: gypsum, phosphate, SiO2
    • Modifiers: NaCl(regulate expansion), C, Cu reducing
  36. What are the properties of gypsum bonded investments?
    • CaSO4 hemihydrate-> dehydrate & heat
    • Ultimate Setting expansion(after initial contraction) due to multidirectional crystal growth
    • Heat causes thermal expansion of wax
  37. What is hygroscopic expansion?
    Increased expansion when investing setting under water -> uninterrupted crystal growth
  38. What does increasing spatulation time or speed do?
    • Breaks up crystal nuclei-> more growth, interation, setting expansion
    • Decreases setting time
  39. What does increasing H2O temp do for investments?
    • Faster setting time
    • Inc thermal expansion
  40. What does increasing the water/powder ratio do?
    • Increase setting time
    • Decrease setting expansion, strength
  41. What is thixotropy?
    Softening, viscosity reducing by rapid shear stress (vibrate)
  42. What are the classifications of investments?
    • I: inlay, thermal
    • II: inlay, hygroscoic
    • III: partial denture, thermal-> less expansion, higher compressive strength
  43. What happens to CaSO4 bonded investments above 700C?
    • Decomposition in presence of carbon
    • Embrittle metal castings
  44. What are the types of high-heat investments?
    • Phosphate-bonded: higher melting alloys (PFM), stronger than gypsum, harder to work with
    • silica-bonded: flammable, expensive
  45. What does silica sol in water do to phosphate bonded investment?
    Increase setting expansion and investment hardness
  46. What is silicosis?
    Reduced lung function from chronic SiO2 exposure, could be carcinogenic
  47. What are the differences of hard and soft waxes for crowns?
    • Hard: more heat, distortion (high when cooling, low when cooled), subject to fracture, easier to smooth and polish
    • Soft: withdraw past small undercuts without fracture/distortion
  48. What is the most important thing when removing crown?
    Safety to patient, prevent damage to remaining tooth, pulp, periodontium
  49. What tool is used to remove a crown?
    • Richwil: adhesion
    • Posterior: Centric
    • Anterior: protrusion
  50. When sectioning crown with a bur, should you cut all the way through?
    • No leave 2mm to prevent aspiration
    • Then use T-bar
  51. What is silicone wash used for?
    Intraoral crown fit checking
  52. What burs should be used to adjust crown occlusion?
    • Gold: 7404-012
    • Porcelain: diamond stone
  53. What is the difference between GC Fuji I and Plus?
    • I: single, dowel, FPD
    • Plus(Resin enforced): single
    • Not for ceramics
  54. What is the order of supragingival margin finishing?
    • 1. Medium garnet (enamel only)
    • 2. Fine Sand
    • 3. Fine Cuttle
    • 4. Brownie points (grooves)
    • 5. Pumice: rubber cup
    • 6. Greenie points (grooves)
    • 7. 15mu Al2O3
    • 8. Super greenie
    • 9. 1mu AlO2
  55. Which burs are good for crown sectioning?
    • H34-010
    • 330
  56. What are recommendend depth of cutbacks for PFM?
    • .7mm minimum
    • 1.0 Ideal
    • 2.0 Maximum
  57. What are the margins in PFM?
    • Porcelain butt joint
    • Metal collar
    • “disappearing margin
  58. What is minimum shoulder width for PFM?
  59. How much more wear does porcelain cause than gold?
  60. What does insufficient cusp reduction lead too?
    Thin porcelain or overcontour in final crown
  61. How long does heavy/light body take to set?
    5 mins from start of mix
  62. What are the main differences of ceramic in/onlays?
    • Bulk: strength
    • Proximals: greater extension for finishing
    • Internal angles: rounded
    • Divergence: greater
    • Bonded
  63. Does bonding restoration increase strength of remaining structure?
  64. Why ceramic vs composite?
    • Easier to contour
    • More durable
    • More conservative than PFM
  65. When is ceramics contraindicated?
    • Heavy occlusal forces (fracture)
    • Cannot isolate (dry for adhesion)
    • Deep subgingival: poor bonding to cementum and hard to impress/finish
    • Uncontrolled caries
  66. What are the main differences between gold & ceramic in/onlays?
    • Gold: 1-2mm occ clearance, sharp internal angeles, beveled shoulders in box and functional cusp, 6-10 occlusal divergence, minimal proximal, luted
    • Ceramic: 2mm, rounded internal, 90 degree finish lines, 12-15 degree divergence, greater proximal, bonded
  67. What is the order of all ceramic preps?
    • Dam, remove caries/old rest, block out w ionomer
    • Occlusal, boxes, covered cusps, margins
  68. What are the requirements for cements?
    • Non-toxic
    • Insoluble
    • Good mechanics (compressive)
    • Protective (thermal, electrical, chemical
    • Adhere to tooth and restoration
    • Bacteriostatic
    • Obtundent to pulp
  69. What does increasing powder/liquid ratio do?
    • More viscous
    • Faster setting
    • High strength
    • Low solubility, acidity
  70. What factors do operator control for cements?
    • P/L ratio
    • Rate of powder incorporation
    • Mixing temp
    • Spatulation
    • Water contamination
  71. What kind of cement is used for temps?
    • Zinc-oxide(powder)
    • Eugenol(liquid)
    • ->zinc eugenolate
    • Some liner applications
  72. What are the biological effects of zinc-eugenol?
    • Bland and obtundent on pulp
    • Mild irritant to CT
  73. What are the advantages of zinc-eugenol?
    • Good for pulp, temporary seal
    • Disadvantages:
    • Low strength, abrasion resistance, anticariogenic action
    • Soluble in oral fluids
  74. What is zinc-eugenol reinforced with?
    • Natural/synthetic resins or AlO3
    • Increases compressive strength, marginal use for permanent retention
    • Can be used for temporary fillings
  75. What are the properties of non-eugenol zinc oxide cements?
    • Liquid is aromatic oil and organic acid NOT eugenol
    • Used for temps where resin or resin ionomer luting will be used for permanent
  76. What is the composition of most permanent cements?
    • Glass ionomer
    • Powder: aluminosilicate glass
    • Acid: polyacylic(vs phosphoric)
  77. What are the biological effects of zinc phosphate cements
    • Zinc oxide & phosphoric acid
    • Initial pulpal irritation from acidity, osmotic effects
    • May permit marginal leakage
  78. What are the advantages of zinc phosphate cements?
    • easy handling
    • durable
    • moderate strength
    • low film thickness
    • Pulp irritation, poor adhesion to tooth, not anticariogenic, brittle, soluble long term
  79. What is a polycarboxylate cement?
    • Powder: Zn oxide
    • Acid: polyacrylic
    • Uses: luting temps, interim luting on sensitive teeth, luting restorations, base
    • Decreased use for permanent and base
  80. What is the composition of glass ionomer?
    • Powder: Ca-F-Al-Si-ate glass
    • Liquid:50% aqueous polyacrylic-itaconic acid
    • ⇒ Calcium Aluminoacrylate gel
    • High compressive strength for lining, luting, base
    • Bonding: good w/clean enamel, dentin and stainless steel
    • Good for luting metal, PFM, decreasing use as liner, base, restorative
  81. What are the advantages/disadvantages of glass ionomer?
    • Adv:
    • High strength, low solubility than ZnPO4
    • Minimal pulpal rxn(technique dependent)
    • Adhesion
    • Fluoride release
    • Disadvantages:
    • Technique, proportion sensitive
    • Moisture contamination
  82. What are resin cements?
    • similar to restoratives but less filler and LOW viscosity
    • BisGMA or UDMA diluted
    • Setting rxn: addition polymerization
    • Curing: chemical, light, dual
    • Applications: bonding ceramic or resin resorations, luting metal or PFM
    • Types: adhesive (MDP phosphates, 4-Meta)or non-adhesive
  83. What are the biological effects of resin cements?
    • Sensitivity: polymer contraction, marginal leakage
    • Pulp protection
  84. What are the adv/disadv of resin cements?
    • Adv: high strength, low solubility
    • Disadv: moisture contamination, thick film, difficult handling, pulp irritation, high wear on occlusal margins
  85. What type of cement is Fuji Plus?
    Resin Ionomer Luting cements
  86. What is the composition of resin ionomer luting cements?
    • Powder: F-Al-Si-ate glass, chemical or light initiator
    • Liquid: polyacrylic acid with pendent methacrylate groups
  87. What are the adv/disadv of resin ionomer luting cements?
    • High compressive strength
    • Lower solubility than GI
    • F-release
    • Inherently adhesive
    • Disadvantages: rapid set, excess difficult, cause fracture
  88. Where is die spacer placed for inlays?
    Pulpal floor and axial wall
  89. For gypsum bonded investments list the W/P ratios from smallest to largest.
    • DO,MO,O inlays (15)
    • FGC (15.5)
    • 7/8, 2/4, MOD onlays (18)
    • MOD inlays (18.5)
  90. What is the purpose of blockout?
    Allows ideal preparation, keeping internal conservative
  91. For a mesial box of an MO inlay which hand instruments are used to create the bevels?
    • External Tucker 233 GMT
    • Internal Tru-bal 232 GMT
  92. What are the prep guidelines for PFM anterior?
    • * Incisal Reduction-2 mm
    • * Lingual Clearance-1.0-1.5 mm
    • * Facial Reduction
    • * Shoulder-1.0-1.2 mm wide
    • * Axial-1.5 mm
    • * Finish Lines
    • * Facial-shoulder
    • * Lingual-chamfer
    • * Proximal-shoulder-beveled shoulder-chamfer
  93. What are the restorative reqs for graduation?
    • • Minimum Clinical Experiences (all prescriptive procedures
    • • 30 Direct, 4 sealants)
    • • Skills Assessment Evaluations (need 3.0 average on each)
    • • Student Teaching Experiences (2nd year/4th year operative and crown)
    • • RVU’s totaling 1200 points
  94. What are the components of the ceramic tooth interface
    • A. Glass ceramic
    • B. Etched intaglio surface
    • C. Silane primer
    • D. Unfilled resin
    • E. Filled resin cement
    • F. Bonding resin
    • G. Etched enamel
    • H. Hybrid layer
  95. Describe enamel vs dentinal bonding
    • Enamel: etch 30-60 secs, micromechanical, more stable
    • Dentin: smear layer removal etch 10-15 secs, keep wet, primer, hybrid layer, less constistent, stable
  96. What are differences btwn self etch and total etch?
    • Self: ONLY sealed areas, less post-op sensitivity, faster, weaker
    • Total: may penetrate non-sealed->post-op sensitivity, stronger, longer time
  97. Describe the different curing modes of resin cements
    • • Auto cure
    • • Appropriate for metal and opaque ceramic restorations
    • • Dual cure
    • • Allows accelerated clean up for posterior or full coverage ceramic restorations where light penetration is limited
    • • Light cure
    • • More color stable for thin translucent anterior porcelain veneers
  98. Advantages of resin cements?
    • • Essentially low viscosity composite materials with similar properties to composite:
    • • Good strength
    • • Resistance to wear better than acid/base cements
    • • Low solubility
    • • Tooth colored
    • • Can optically connect tooth & overlying ceramic
    • • Compatible with enamel and dentin bonding techniques
  99. Disadvantages of resin cements?
    • • Clean up can be very difficult
    • • Can bond to unprotected adjacent tooth surface
    • • Inhibition of set by oxygen means that proximal cement will set before cement on more accessible surfaces
    • • Tooth color and adhesion make removal from root surfaces difficult
    • • Contribution to periodontal disease
    • • Post operative sensitivity from aggressive removal
  100. Which types of glass ceramics are etchable?
    Felspathic porcelain(60-120 secs, 7-10%), leucite reinforced glass ceramic, LiSiO4 (20 secs 4-5%)