Card Set Information

2012-04-30 02:24:59

Show Answers:

  1. Why do we mount the casts to the articulator?
    Because we want to duplicate the teeth and related structures as well as to simulate jaw movement in order to fabricate restorations that will work in the stomatognathic system
  2. What instruments do we use to mount the casts?
    • Facebow
    • Bitefork attachment
    • Nasion Relator
  3. Articulator
    A mechanical instrument that represents the TMJs and jaw, to which maxillary and mandibular casts may be attached to simulate some or all mandibular movements
  4. Class I Articulator
    • Non adjustable
    • Vertical motion
  5. Class II Articulator
    • Semi adjustable
    • Vertical and horizontal motions but not oriented to TMJ
  6. Class III Articulator
    • Semi adjustable
    • Simulates the condylar pathways
    • Arcon and non-arcon
  7. Class IV Articulator
    • Fully adjustable
    • Simulation of most mandibular movements
    • Condylar guidance/inclination can be adjusted
    • Inter codylar distance can be adjusted
  8. Arcon advantage
    • Condylar inclination of the mechanical fossae is at a fixed angle to the maxillary occlusal plane
    • With the non-arcon design, the angle changes as the articulator is opened
  9. Facebow
    • Caliper like instrument used to record the spatial relationship of the maxillary arch to some anatomic reference point and then transfer this to an articulator
    • Orients dental cast in same relationship to opening of the articulator
    • Anatomic references are usually the mandibular condyles, transverse horizontal axis and one other anterior point (nasion)
  10. Occlusion record
    • Registration of opposing occluding surfaces made at any maxillomandibular relationship
    • Centric record
    • Eccentric record
    • - protrusive record
    • - lateral excursive record
  11. Record Base
    • Supports occluding surfaces
    • Used when there is no 3 point contact
    • Stabilize base occlusion rims (SBOR)
    • Use of Triad or acrylic resin with registration material and/or wax
    • Interocclusal record use for partially edentulous case
  12. How do we mount maxillary cast?
    • Prepare the bite fork
    • Attach the baseplate wax to the bite fork
    • Make occlusal imprints on the wax
    • Place the bite fork on the patients maxillary arch
    • Prepare the facebow and attach the nasion relator
    • Insert the bitefork attachment assembly
    • Place the bitefork and hold steady
    • Insert the bitefork stem to the assembly
    • Position the ear piece
    • Adjust the nasion relator and tighten the post assembly
    • Verify position and hold steady
    • Loosen the large thumb screw and remove the facebow
    • Remove the bite fork attachment
    • Remove the incisal guide table and replace the mounting fixture
    • Attach the cast support and bite fork
    • Adjust the cast support
    • Orient the maxillary cast and place the mounting plate
    • Make the orientation grooves
    • Apply Vaseline on the orientation grooves
    • Moisten the maxillary cast with a wet paper towel
    • Mix mounting stone
    • Reinforce mounting stone
    • Remove excess and clean mounting by sandpaper
    • Remove the mounting fixture and replace with the incisal guide table
  13. Mandibular movements
    • Complex 3D movement that can be broken down into two basic components
    • Translation - when all points within thebody have identical motin
    • Rotation - when the body is turning about an axis
    • 3 perpendicular planes are frontal, sagittal, and horizontal
  14. Mandibular movements - Sagittal Plane
    • Mandible is capable of a purely rotational movement as well as translation
    • Rotation occurs around the terminal hinge axis
    • Rotational movement is limited to about 12mm of incisor separation before the TM ligaments and structure anterior to the mastoid process force the mandible to translate
  15. Mandibular movements - Horizontal Plane
    • Lateral movement - rotation on the horizontal plane occurs during lateral movement of the mandible. The vertical axis is situated in the condylar process. There is relatively little translation
    • Protrusive movement - mandible can make a straight protrusive (anterior) movement
  16. Mandibular Movements - Frontal Plane
    • Lateral movement - mediotrusive condyle moves down and medially whereas laterotrusive condyle rotates around the sagittal axis
    • Protrusive movement - condylar process moving downward
  17. Centric Relation
    • Condyles articulate with the thinnest avascular portion of their respective discs with the complex in the anterior-superior position againt the shapes of the articular eminence
    • Independent of tooth contact
    • Clinically discernable when the mandible is directed superiorly and anteriorly
    • Restricted to purely rotary movement about the transverse horizontal axis
  18. Techniques to get CR:
    • Bimanual manipulation: using both thumbs on the chin and the fingers on the inferior border of the mandible to guide the jaw
    • Anterior programming device: individually fabricated guide table that allows mandibular motion wihtout the influence of tooth contacts and facilitates the recording of maxillomandiublar relationships; also used for deprogramming
    • Deprogrammer: various types of devices or materials used to alter the proprioceptive mechanism during mandibular closure
    • Leaf gauge: set of blades or leaves of increasing thickness used to measure distance between two points or to provide metered separation
    • Lucia jig: anterior programming device
  19. Maximal Intercuspal Position
    • Complete intercuspation of the oppsosing teeth independent of condylar position
    • Sometimes referred to as the "best fit" of the teeth regardless of the condylar position
  20. CR vs MIP
    • CR is considered a reliable and reproducible reference position - so if MI coincides with CR, restorative tx is often straightforward
    • When MI doesn't coincide with CR, it is necessary to determine whether corrective occlusal therapy is needed before restorative tx
    • CR not the same as MI = 2 reference position options to choose from - choice is determined by clinical parameters given
  21. Is there a difference between mounting diagnostic casts and mounting working casts?
    • YES
    • Diagnostic casts - always mount on CR
    • Working casts - mount position depends on the requirement of tx
  22. MIP
    • Complete intercuspation of opposing teeth
    • Independent of condylar position
    • Sometimes referred to as best fit of teeth
  23. Centric Occlusion
    • Occlusion of opposing teeth when the madnible is in centric relation
    • Position may or may not coincide with MIP
  24. Static Occlusal Relationships
    • MIP
    • CR
    • CO
  25. Dynamic Occlusal Movements
    • Protrusion
    • Lateral Excursive Movements
    • - working - a lateral mandibular movement away from the maxillary midline
    • - non-working - toward the maxillary midline
    • Working side condyle pivots, non working translates
  26. Angle Classification Molar Classification
    • System of occlusion based on the interdigitation of the 1st molar teeth
    • Anteroposterior classification
    • Class I - neutrocclusion
    • Class II - distocclusion, division 1 and 2
    • Class III - mesiocclusion
  27. Class I Occlusion
    MB cusp of Mx 1st molar aligns with buccal groove of Mn 1st
  28. Class II Occlusion
    • Division I: bilateral distal retrusion with protruding maxillary incisors
    • Division II: retruded maxillary central incisors and labially malopposed maxillary lateral incisors, excessive vertical overlap
    • Buccal groove is posterior to MB cusp
  29. Class III Occlusion
    Buccal groove is anterior to MB cusp
  30. Morphologic Characteristics of Ideal Occlusion
    • Anteroposterior plane: horizontal overlap 2-4mm
    • Vertical plane: anterior teeth overlap 30-50%
    • Transverse plane: dental midlines aligned, posterior teeth with normal, good cusp to fossa relationship
  31. Mutually Protected Occlusion
    • Posterior teeth prevent excessive contact of anterior teeth in maximum intercuspation
    • Anterior teeth disengage the posterior teeth in all mandibular excursive movements
    • Simultaneous contact of posterior teeth
    • Axial loading of posterior teeth
    • Light contact of anterior teeth
    • Working - no posterior interferences; disocclude canines
    • Protrusive - anterior teeth disocclude posterior teeth
    • Non-working - no contacts
  32. What are the occlusal variations of ideal?
    • Cross bite
    • Arch size discrepancy
    • Disrupted occlusal plane
    • Anterior open bite
    • Unfavorable functional contacts
  33. Levels of excursive guidance
    • Canine
    • Group function
    • Posterior
    • Fully balanced (good for dentures)
    • Nonworking
  34. Objectives for occlusal equilibration
    • maximum number of posterior holding contacts
    • slight decrease in VDO
    • once all posterior contacts have been acheived, never grind out of contact
    • keep contacts off of inclined planes
    • During protrusion, distribute contacts over as many anteriors as possible - at least 2 centrals!
  35. Equilibration limitations
    • Enamel thickness/restoration - 2-2.5mm at cusp tips, less in fossa
    • Tooth position
    • Skeletal relationship
    • Guideline - rule of thirds
  36. Rule of Thirds
    • Occlusal Adjustment
    • Restorative Treatment
    • Orthodontic Treatment
  37. Occlusal Equilibration Technique
    • Raise incisal pin
    • Ensure centric lock is engaged
    • Adjustments in CO
    • Excursive adjustments (adjust lingual of mx incisors rather than shortening mn incisors)
  38. Adjustments in CO
    • Cusp Repositioning: identify contact on incline plane, determine desired direction of contact movement, adjust opposite slope of the opposing cusp that created the contact
    • Selection of Fossae: centric fossae= ideal, minimalizes excursive interferences
    • Fossae Repositioning: some fossa may not be attainable w/o gross reduction of teeth, flatten incline plane to allow for axial loading
    • Ideal Contact Position/Adjustment Incomplete: shorten cusp, deepen fossa
  39. Goals of Prosthodontics
    • Correction of abnormalities (peg lateral)
    • Restore function (deteriorating restorations)
    • Restore impaired appearance
    • Maintenance of remaining tooth and supporting structures
    • Prevention of further injury
  40. Diagnosis
    • Systematic evaluation of the condition of patient when he/she presents for treatment
    • Problem identification
  41. General problems and concerns of patient seeking prosthodontic service
    • Function
    • Comfort
    • Esthetics
    • Longevity
    • Cost
  42. Treatment Plan
    • Aims to re-establish a well functioning oral relationship that is biologically and mechanically sound as well as esthetically pleasing
    • A blue print to acheive prosthodontic goals
    • Problem solution
  43. Dentist must haves
    • ability to communicate w/pt (talk and listen)
    • ability to perform diagnostic procedures
    • Ability to integrate and process information to ID problem and generate a viable solution
    • Ability to support diagnosis and tx plan w/ scientific and clinical evidences
  44. Restorative Options for a single tooth
    • Amalgam/composite
    • Inlays/Onlays
    • Partial Crowns (3/4, 7/8)
    • Laminate veneers
    • Full crown (FGC, PFM, Ceramic)
    • Post and Core restorations
  45. Alginate Working Time
    • Working Time = Mixing time + loading time
    • Initial Setting Time = 2 min 15 sec
    • Setting Time: 3 min 30 sec
  46. What are rim blocks for?
    To hold alginate in once set
  47. Diagnostic Cast
    • Life size reproduction of part or parts of the oral cavity and/or facial structures for the purpose of study and treatment planning
    • Permits the analysis of hard and soft tissue contours
  48. Master Cast
    • Definitive Cast
    • Replica of tooth surfaces, residual ridge areas, and/or other parts of the dental arch and/or facial structures used to fabricate a dental restoration or prosthesis
  49. Adequate Base Height
  50. Mandibular Rotation
    Rotation is movement between the superior surface of the condyle and the inferior surface of the articular disc
  51. Horizontal rotation
    • Opening and closing motion
    • Hinge axis
    • Pure rotational movement
    • Terminal hinge axis when the condyles are in their most anterior superior position
  52. Frontal/Vertical Rotation
    • One condyle moves anteriorly out of the terminal hinge position
    • Opposite condyle remains in terminal hinge position
  53. Sagittal Rotation
    • One condyle moves inferiorly out of the terminal hinge position
    • Opposite condyle remains in terminal hinge position
  54. Mandibular Translation
    • Occurs when the mandible moves forward
    • Teeth and mandible all move in the same direction to the same degree
    • Occurs within the superior cavity of the joint
  55. Sagittal Plane Border Movements
    • Posterior and anterior limits: determined by ligaments and morphology of TMJs
    • Superior limits: determined by occlusal and incisal surfaces of teeth
    • Functional limits: determined by neuromuscular system
  56. Envelope of Motion
    • Combine all three border movements
    • Maximum range of motion
    • Characteristic shape
    • Vary with individual
    • Superior borders- tooth
    • Ant/Post borders - ligaments and joint anatomy
  57. Purpose of diagnostic wax up
    • Space analysis
    • Correct Proportion
    • Esthetics
    • Establishing/Re-establishing occlusal scheme
    • Determining position of final restoration
    • Establishing room for restoration/substructure
    • Determine other treatment needs (crown lengthening, ortho)
    • Demonstration for the patient
  58. Diagnostic wax up and set up- why?
    • Analyze space availability
    • Correct proportion/esthetics
    • Establish occlusal scheme
    • Determine other treatment needs
    • Serve as a model for the patient
    • Provide for preparation guide
    • Provide for provisional crown
  59. Custom Tray
    • Individualized impression tray made from a cast recovered from a prelimiary impression
    • Used in making a final impression
    • Improves accuracy of elastomeric impression material by limiting the volume of material
  60. Provisional Crown
    Fixed or removable prosthesis designed to enhance esthetics, stabilization, and/or function for a limited period of time after which it is replaced by a definitive dental or maxillofacial prosthesis
  61. Biologic, mechanical, and esthetic requirements of provisional
    • Pulp protection: well adapted margin, prevent temp extremes conduction, prevent saliva leakage
    • Positional stability: need proximal contact, keeps tooth from drifting while final restoration is fabricated
    • Occlusal function: presence of occlusal contact, for patient comfort, prevention of drifting, prevent joint or neuromuscular damage
    • Easily cleaned: Adequate embrasure, keep gums healthy
    • Non-impinging margins: No overhang (could cause gum inflammation otherwise)
    • Strength and Retention: Adequate thickness
    • Esthetics:
  62. Difference between direct and indirect provisionals
    • Use of duplicate cast (Indirect requires duplicate cast, direct doesn't)
    • For multiple teeth best to use indirect b/c chair time can be saved
  63. Purposes of gingival displacement
    • Control bleeding
    • Provide access of margins for impression
  64. Gingival retraction techniques
    • Single cord: placed in sulcus and then removed before impression
    • Double cord: 2 cords placed one above the other (can remove both or just one)

    Leave cord in for 10 min
  65. Final Impression
    Impression that represents the completion of the registration of the surface or object
  66. Acceptable Impression
    • Exact record of all aspects of prepared tooth
    • Also included are adjacent unprepared teeth and cervical contour of the prepared tooth margin
    • All teeth in the arch and the soft tissues
  67. Impression material
    • Irreversible hydrocolloid
    • Reversible hydrocolloid
    • Polysulfide polymer
    • Addition silicone
    • Condensation silicone
    • Polyether
  68. Clinical properties of impression materials
    • Hydrophilicity, wetting, and contact angles
    • Consistency
    • Surface detail
    • Setting and working time
    • Others
  69. Wettability
    Ability of a liquid to spread over a surface
  70. Contact angle
    Measure of wetting
  71. Hydrophilicity
    Affinity to surface moisture
  72. Surface detail (impressions)
    • Ability of an impression material to accurately reproduce the surface of an object and is related to the viscosity of the material
    • Low viscosity - better detail
    • High viscosity- poorer detail
  73. Working and Setting Time of Impression Materials
    • WT - mixing to loading in tray - affected by temperature
    • ST - placed in oral environment, linear shrinkage during polymerization, compensated by expansion of the dental stone during pouring
  74. Critical Errors with impression
    • Tissue contact with tray
    • Not enough wash material and tooth contact with tray
    • Not enough tray material
    • Voids and bubbles
    • Inadequate margins
    • Pulls and drags
    • Tearing
    • Inadequate tray adhesion
    • De-lamination/lack of co-adaptation
  75. How many times can a VPS impression be re-poured?
    • 1-2x max
    • IF it hasn't torn the margins or separated from the tray
  76. Master cast lab stone selection
    • Use type IV gypsum to proper proportions for all die work
    • Be sure vacuum mix bowl is clean of stone
    • Stone residue in bowl accelerates set
  77. Supernatant
    • Settled out water from model trimmer
    • 1 die soak 2-3 min - can just use plain H2O
    • 2+ use supernatant
    • I think you use this to soften die to trim margin with scalpel blade
  78. Light
    Visible EM energy whose wavelength is measured in nanometers
  79. Color is influenced by 3 main factors
    • Physical properties of the object
    • Assessment of the observer
    • Nature of incident light
    • - Relationship to other colored objects
  80. Pure white light
    • relatively equal quantities of EM energy over the VLS
    • When passed through a prism we see component colors of white light
    • Shorter wavelengths bend more than longer wavelengths
  81. Quality of Light/ 3 Types
    • Incandescent Light
    • Fluorescent Light
    • Natural Daylight
  82. Incandescent Light
    • Emits a high concentration of yellow waves
    • Not suitable for shade matching
    • Low color rendering index (CRI)
  83. Fluorescent Light
    • Emits high concentration of blue waves
    • Not suitable for shade matching
    • CRI= 50-80
  84. Natural Daylight
    • Northern daylight considered the best
    • Closest to emitting the full spectrum of white light
    • Used as the standard by which to judge other light sources
    • CRI close to 100
  85. Color Rendering Index
    • CRI= 0-100
    • Indicates how well a light source renders color as compared to a standard source
    • Northern daylight can by affected by:
    • - time of day
    • - cloud cover
    • - humidity
    • - pollution
  86. CRI and time of day
    • Morning and evening: shorter wavelengths scatter before penetrating atmosphere; daylight rich in yellow/orange, lacks blue/green
    • Mid-day: hours around noon=ideal, incident daylight is most balanced within VLS, full spectrum of colors visible
  87. Color Temperature
    • Another light source reference standard
    • Related to the color standard black body when heated
    • Reported in degrees Kelvin
    • 1000K= red
    • 2000K= yellow
    • 5555K= white
    • 6500K= northern daylight
    • 8000K= pale blue
  88. Color
    Quality of an object or substance with respect to light reflected by the object, usually determined visually by measurement of hue, chroma, and value
  89. Substractive Color
    • Used in pigments for making paints, inks, fabrics, etc
    • Primary subtractive colors: red, yellow, and blue
    • Secondary subtractive colors: green, purple, and orange
    • When subtractive primary colors are combined they produce black
    • "Subtracting light by laying color over it"
  90. Additive Color
    • These are the color obtained by emitted light
    • Associated with television and computer displays
    • Primary additive colors are: red, blue, and green
    • Secondary additive colors are: cyan, yellow, and magenta
    • When additive colors are combined they produce white
  91. Hue
    • Variety of color (red, green, yellow, etc)
    • Determined by the wavelength of observed light within the VLS
    • Reflected wavelength determines hue
  92. Chroma
    Intensity or saturation of a hue
  93. Value
    • Relative darkness or lightness of a color or brightness of an object
    • Range 0-10 (0=black, 10=white)
    • Amount of light energy an object reflects or transmits
    • Objects of different hues/chroma can be identical value
    • Restorations too high in value are easily detected
  94. Color Perception
    • Rods: scotopic, interpret brightness not color, highest concentration in peripheral retina
    • Cones: photopic vision, interpret color, more active under high light, highest concentration on central retina (macula)
  95. Color Adaptation
    • Color vision decreases rapidly as object is observed
    • Color viewed dulls, while its compliment increases in intensity (fatigue)
    • Viewing a pale blue or gray surface between shade matching will restore color vision
  96. Metamerism
    Two colors that appear to be a match under a given lighting condition but have different spectral reflectance= metamere
  97. Color Blindness
    • 8% males, 0.5% females
    • Achromatism: complete lack of color sensitivity
    • Dichromatism: sensitivity to two primary hues
    • Anomalous Trichromatism: sensitivity to all three hues with abnormality in retinal cones affecting one of primary pigments
  98. Shade Selection
    • Subjective evaluation with considerable variation
    • Subtle variations can exist without causing disharmony in smile (restoration contour, value of restoration)
    • Process improved by applying principles of light and color
  99. Principles of Shade Selection
    • Teeth to be matched must be clean
    • Remove bright colors from field of view (makeup, tinted eye glasses, bright gloves, neutral operatory walls)
    • View patient at eye level
    • Evaluate shade under multiple light sources
    • Make shade comparisons at beginning of appointment
    • Shade comparisons should be made quickly to avoid eye fatigue
  100. Vita Classic
    • A - red/yellow
    • B - yellow
    • C- grey
    • D- red/yellow/gray
    • Chroma is designated with numerical values
    • A3= hue of red-yellow, chroma of 3
  101. Recommended sequence for Vita Classic
    • Hue selection
    • Chroma selection
    • Value selection
    • Final check/revision
  102. Value best determined by
  103. Vita 3D Steps
    • Determine Value
    • Select Chroma
    • Determine Hue
  104. Hue Modification
  105. Chroma Modification
  106. Value Modification
  107. Extended range shade guides
    • bleach shades
    • dentin shades
    • custom shade guides
  108. Shade Mapping
    • Tooth divided into 3 regions/9 segments
    • Each region is matched independently
    • Further characterizations can be sketched