DHE 116 lecture 3QUIZ

  1. Shadow casting rules applied to produce quality: (3 possibilities)
    • Target to Image/Duplicate
    • Target to Receptor
    • Object to Receptor
  2. ___ is cloudiness/unclear x-ray shadow cast….sharper image and slightly less magnification
  3. (shadow casting rule)_____ use smallest possible on the target (radiation source)
    focal spot
  4. function of the receptor?
    to recodr the shadow image
  5. ______to reduce the penumbra and magnification (tooth and radiation source)
    Far target-object distance
  6. (shadow casting rule)______— to reduce penumbra and magnification (tooth and Film/PSP/Sensor)
    Close object film distance
  7. (shadow casting rule)Object (tooth) and film/receptor  need to be ____ relationship— to prevent distortion of the image
  8. (shadow casting rule)Central ray and the object and film/receptor  — ____relationship. to prevent distortion of the image
  9. (Sharpness/Definition) Focal spot size
    smaller = sharper and vice versa
  10. (Sharpness/Definition)Target-image receptor distance = PID to film/sensor
    Longer the target-image-receptor the more parallel the beam = sharper image
  11. (Sharpness/Definition)Object-image receptor distance= teeth & receptor. place as close as possible to reduce penumbra. Magnification occurs with increased distance
  12. (Sharpness/Definition)
    Motion =
    loss of image detail
  13. (Sharpness/Definition) 
    Screen thickness=
    intensifying screen lower rad needed but decrease sharpness
  14. (Sharpness/Definition)Crystal/pixel size of intraoral image receptors=
    smaller crystals equal sharper image but needs increased time or rad. Digital depends on pixel sixe and #
  15. How to acquire a sharp image  What is IDEAL?
    • small focal spot on the target
    • a long target-image receptor distance
    • short object-image receptor distance
    • Plus;Parallel & Perpendicular
    • Image Upload 1
  16. How image sharpness is lost?
    • Large focal spot on the target and
    • Long object-film distance results
    • Penumbra
    • NO Parallel & Perpendicular
    • Image Upload 2
  17. Image Upload 3
    Image Upload 4
  18. Factors Affecting the Radiographic Image:
    Radiographic contrast
    • ¤Subject –different absorption
    • ¤kVp –high kVp = low contrast
    • ¤Scatter radiation- (Compton) reduces integrity
    • ¤Film/digital sensor type - manufacturer
    • ¤Exposure – over/under = film fogProcessing – temp. time. Manual/digital/PSP
  19. Factors Affecting the Radiographic Image:
    • Defined: Increase in the size of the image
    • Mostly influenced by the target-object distance
    • Object-image receptor distance
    • Target-object distance is determined by the length of the PID
    • Long PID = more parallel beam = less magnification
  20. Factors Affecting the Radiographic Image:
    • Different parts of the same object are magnified unequally
    • Central ray is NOT perpendicular the object and plane of receptor
  21. Effect of varying exposure factors on image density:
    Image Upload 5
  22. Exposure Time Variations:
    • Defined: x-ray machine is fully activated and x-rays are produced
    • If you change exposure time you change DENSITY
    • Increase = Darker
    • Decrease = Lighter
    • This is the easiest to control
    • Precalibrated machines (like PCC’s) kVp and mA can NOT be changed – only time can
  23. Milliamperage (mA) Variations
    • Defined = # of x-rays generated/produced in the machine
    • Increasing mA = Dark & Dense
    • Lower mA = Lighter
  24. Kilovoltage (kVp) Variations:
    • Defined = QUALITY of Wavelength energy produced
    • More/Increase =Image Upload 6
    • Lower/Decrease = Image Upload 7

    Direct influence on CONTRAST
  25. Effects of Variations in Distances:
    • 1 = x-ray source to skin
    • 2 = teeth to receptor
    • 3 = source to receptor plane
  26. Distance:
    • Target-surface distance
    • Target-object distance
    • Object-image receptor distance
    • Target-image receptor distance
    • Target=PID
    • surface=skin surface covering cheek
    • object=tooth
    • image receptor=sensor
  27. How does the Density change on the receptor as per the distance?
    • Closest (4 feet) = Most Dense  
    • (8 feet) = Less moderate dense 
    • (16 feet) = least dense
    • ======= distance changes photons 
    • Need to compensate for distance by increasing / decreasing the photons…>> How is this done?
    • Increase the time = allows more e- (photon) production in the tube (power stays the same)
    • Will allow the total # of photons to reach receptor
  28. The Bitewing Examination:
    • most frequently performed
    • crowns and alveolar bone of both the maxillary and mandibular teeth on a single radiograph
    • #1 = incipient caries:
    •    Hope for remineralization
    •    Embrasures
    • Primarily Molar an PM
  29. Which is the vertical bwx?
    Image Upload 8
  30. Which is the horizontal bwx?
    Image Upload 9
  31. BWX Principles:
    • The receptor is placed in the mouth “parallel to the crowns of both the upper and lower teeth”
    • The receptor is stabilized when the patient bites on the bitewing tab or beam alignment device.                                         
    • The central ray is directed through the contacts of the teeth, using a +10 degree vertical angulation.
  32. Bite-Wing Receptors size:
    • Size 0
    • For posterior teeth of children with primary dentition
    • Size 1
    • For the posterior teeth of children with mixed dentitions
    • Size 2
    • For posterior teeth of adults, placed horizontally or vertically
  33. Correct horizontal angulation BWX?
    The central ray is directed perpendicular to the curvature of the arch and through the contact areas of the teeth.
  34. The positioning of the PID in a vertical or up- and-down plane
    • Positive
    • The PID is positioned above the occlusal plane and the central ray is directed downward.
    • Negative
    • The PID is positioned below the occlusal plane and the central ray is directed upward.
  35. Vertical Angulation for BWX
    correct and incorrect?
    • Correct vertical angulation: +10-degree
    • Incorrect vertical angulation:Results in a distorted image
  36. Avoid Overlapping on BWX:
    • Primary beam is directed toward the mean tangent
    • Predetermined area
    • Point of entry  :Occlusal/incisal plane
    • Correct (+10) vertical angle : +5 for children, Error is unequal arches
  37. Modifications in Bitewing Technique:
    Edentulous Spaces
    A cotton roll must be placed in the area of the missing tooth to support the bite-wing tab or beam alignment device.
  38. Modifications in Bitewing Technique:
    Bony Growths
    The receptor must be placed between the tori and the tongue.
  39. Most common reason for exposing dental radiographs?
    caries detection
  40. Radiographs in the Detection of Dental Caries
    Pathological process:
    • Localized destruction of hard dental tissues
    • Organic acid from microorganisms
    • Process is progressive demineralization
    • Deeper/advanced caries = more radiolucency
    • May go without clinical detection (proximal)
  41. Occlusal relationships:
    Class I & III
    - receptor placement to the mandibular canine and 2nd PM
  42. Occlusal relationships:
    Class II
    - receptor placement to the maxillary canine and 2nd PM
  43. What about the “Tilting/Slanted” image?
    Results from a failure to place the image receptor far enough lingually (in toward the tongue) to avoid being pushed down by the palate.
  44. Vertical Angulation:
    • 1) Excessive vertical angulation prevents viewing proximal surface carious lesion
    • (2) Proper vertical angulation shows the proximal surface caries
  45. Horizontal Angulation:
    • (1) Incorrect horizontal angle = overlapping between adjacent teeth
    •      prevents viewing for interproximal caries
    • (2) Improved horizontal angulation but caries difficult to view
    • (3) Correct horizontal angulation clearly images caries
  46. Area to examine for interproximal caries?
    • Two adjacent teeth contact
    • Apical to where the gingival margin is (boxed area)
    • Cervical burnout(optical illusion) the region apical to the gingival margin
  47. 4 caries locations:
    • Occlusal:
    • Chewing/posterior surface
    • Break through to DEJ can be imaged
    • Seen as a flat radiolucent line
    • PFSjQuery11010485798970662775_1506878021409
    • Proximal (mesial and distal)
    • Impossible clinically to examine
    • Demineralized
    • Buccal/lingual
    • Most easily detected clinically
    • Issue: 2D of a 3D (depth?)
    • Cemental (root surface) 
    • Bone loss / recession
    • May appear on B,L,M,D
    • Ill defined radiolucent
    • Below CEJ
    • Crescent shape
  48. Recurrent / Secondary Caries Occurs around:
    • restoration margins
    • Poor cavity preps
    • Defective margins
    • Incomplete caries removal
  49. Rampant Caries Occurs around:
    • “growing rapidly”
    • Spreading unchecked
    • Multiple teeth
    • radiolucent
  50. Arrested Caries Occurs around:
    • “stopped or Inactive”
    •   Cause: shift  in oral environment
    • Slow down in caries process
    • Incipient enamel caries can be remineralized or reversed
  51. Conditions Resembling Caries
    • Nonmetallic restorations
    • Mimic decay
    • Composite silicate resin
    • Key: straight boarders
    • Prepared look
    • Even radiolucency
    • Radiopaque base material
    • Mach band effect
    • Optical illusion
    • Radiolucency caused by overlapping teeth images
    • Radiolucent lines
  52. Conditions Resembling Caries
    Cervical burnout
    • Presents as a diffuse radiolucent area on the interproximal surfaces of the root apical to the cemento-enamel junction.
    • Created by decreased x ray attenuation of the cementum as it is very thin and unable to stop x rays from reaching the image receptor.
    • Attenuation is when the quantity of x rays is reduced by either absorption or scatter as it travels through matter
    • No visible tooth structure missing in this area.
Card Set
DHE 116 lecture 3QUIZ
DHE 116 lecture 3 QUIZ