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139 Cards in this Set
- Front
- Back
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types of intraoral radiographs
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periapical
bitewing occlusal |
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how many pas is used in FX?
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18-24 PAs but at OUCOD 20
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What sould be seen with correct periapical radiograph?
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OUTLINE, POSITION, MESIODISTAL EXTENT, SURROUNDING STRUCTURES, FULL LENGTH OF TOOTH, AND 2-4 MM OF NORMAL BONE SURROUNDING IT
INTERPROXIMAL CONTACTS SHOULD BE OPEN |
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WHAT DOES BITEWING RADIOGRAPHS RECORD?
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OUTLINE, POSITION, MESIODISTAL EXTENT, CORONAL PART OF TOOTH AND BONE OF BOTH ARCHES
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WHAT ARE INDICATIONS OF BITEINGS?
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EVAL OF INTERPROXIMAL TOOTH SURFACES
EVAL OF INTERPROXIMAL BONE |
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CENTRAL RAY
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MOST CENTRAL PORTION OF XRAYS COMING OUT OF BID
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VERTICAL BEAM ANGULATION
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UP AND DOWN MOTION OF TUBE IN RELATION TO OCCLUSAL PLANE CAN BE + OR -.
+ IS ABOVE 0 (OCCLUSAL PLANE) AND - IS BELOW |
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HORIZONTAL BEAM ANGULATION
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MOTION OF TUBE AROUND PTS HEAD IN RELATION TO MIDSAGITTAL PLANE
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wHAT CAUSES CLOSED CONTACTS?
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WRONG HORIZONTAL ANGULATION
central ray in center |
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WHAT DOES XCP HAVE FOR ORIENTATION?
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ANTERIOR AND POSTERIOR BITE BLOCK
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XCP INSTRUMENTS
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EXTENSION CONE PARALLELING
EXTERNAL GUIDE USED TO POSITION THE XRAY BEAM VERTICALLY AND HORIZONTALLY TO THE FILM ESTABLISHED A POINT OF ENTRY FOR THE BEAM |
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WHAT DOES XCP CONSIST OF?
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ANTERIOR AND POSTERIOR BITE BLOCKS
INDICATOR ROD AIMING RING (this allows lining up of the BID) |
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describe disposable bite blocks/stabes
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size 0,1,2 films
anterior and posterior exposures front section breakable for posterior and pedo exposure |
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advantages of bitewing loops and adhesive tabs
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ready to use
made of heavy duty paper board adjustable to bite |
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describe snap-a-ray film holder
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sturdy molded plastic
can be autoclaved elminates manual retention of film pkt for anterior and posterior xrays used esp. for endo xrays |
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what allows us to determine if we have the correct vertical and horizontal angulation?
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ring and rod
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is dot on film toward or away from xray and object?
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for periapical xrays the dot is toward the area of interest and the xray beam
for bitewings the dot is toward the lower edge of the film |
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advantages of film holders
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facilitates retention and film placement
relates film to beam indicating device collimates beam reduces dose to pt |
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types of BID
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long round open
long rectangular open short round open |
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advantages of XCP device
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prevents BID or cone cuts
aiming ring is compatible with rectangular and round BID indicator arm guides BID for proper alignment reduce distortion can be autoclaved |
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4 basic principles of intraoral radiography
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1. pt head position
2. location of long axes of teeth 3. xray beam angulation 4. point of entry of xray |
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Pt head position
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pt should be upright
mid sag plane perpendicular tothe floor occlusal plane or ala tragus line should be parallel to the floor |
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ala tragus line
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parallels tips of maxillary teeth from canine to third molar
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long axis of maxilla teeth
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tilted facially
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descibe long axis of teeth in the mandible
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ant teeth are tilted facially
premolars are vertical molars are inclined lingually |
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what is wrong if in xray teeth appear shortened or cramped in superior-inferior diminsion?
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BID too hi and too far up (over angulation) towards the head so you need to brind the BID down to correct this
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What is wrong w/xray if teeth appear elongated in superior-inferior dimension?
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BID is too lo (under angulation) which causes elongation of teeth. operator must bring BID up a bit to correct
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how does under angulation appear?
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elongation of teeth
apices cut off no periapical bone seen |
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how does over angulation appear in xray?
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foreshortening of teeth
crowns cut off too much periapical is seen |
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describe horizontal beam placement to get open contacts
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CR must be parallel to interproximal space to get open contacts if CR is not parallel to interproximal space, you get operlaps
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2 intraoral PA xray tecniques
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paralleling
bisecting angle |
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advantages of paralleling tecnique for taking PA xrays
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better anatomical detail
minimizes undesirable unsharpness,magnification, and shape distortion |
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Rules for paralleling technique
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1.film parallel to long axes of tooth
2.CR perpendicular to long axes of tooth and film plane |
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paralleling tecnique procedure
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place film in holder (dot in slot)
position film to cover area of interest in mouth position film plane parallel to teeth vertical angulation of BID (must be vertically parallel to indicator rod) CR perpendicular to long axes of teeth Center xray beam |
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bisecting angle tecnique for taking PAs
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angle that is formaed by plane of tooth and plane of film is bisected and the central ray is directed through the paex of the tooth perpendiular to the bisecting line
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vertical angulation tecnique with bisecting tecnique
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CR through center of filed
perpendicular to bisecting line formed between film and long axes of teeth |
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errors seen with wrong vertical angulation
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elongation
foreshadowing angle varies w/each view |
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horizontal angulation
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CR perpendicualr to facial surface of teeth in region
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main error seen with wrong horizontal angulation
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overlapping
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poing of entry
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center of region
obj should be completely covered |
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why is long cone recommended?
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bc it decreases magnification and unsharpness
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BID cut/cone cut
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only get a partial image
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problem with bisecting angle
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hard to master
cant see long axes of teeth so have to estimate have to imagine bisecting angle film placement not accuarately seen causes errors like film bending or imporoper film plalcement |
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which direction of BW shows more alveolar bone?
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vertical BW show more alveolar bone than horizontal BW
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With which xray is alveolar bone best shown?
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on BW
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areas where PAs are taken for FMX
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central lateral incisor
canine region premolar molar |
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how are PAs of max central-lateral incisor region taken?
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place size one film vertically in bite block
align central and lateral contact w/center of film place film in posteror of mouth pt should be biting of end of block away from film direct CR to pass through the central-lateral contact |
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characteristics of ideal PA of max central-lateral incisor region
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contact between central-lateral incisor should be open and centered on film
2-4 mm of bone beyond apices incisal edge of teeth should be a bit above lower edge of film contact between two centrals should be seen on r and l central lateral films |
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how are PAs of max canine region taken?
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place size 1 film vertically in bite block
align midline of canine w/center of film place film in posteror of mouth, away from lingual surfaces under tongue pt should bite on end of block away from film direct CR through mesial contact of canine |
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Characteristic of ideal PA of max canine region
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canine should be centered on film
mesial contact of canine should be open 2-4 mm of NORMAL bone beyond teeth incisal edge of teeth should be a bit below edge of film |
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How are PAs of max premolar region taken?
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place size 2 film horizontally in midline of palate parallel to long axis of teeth
anterior border of film shold over premolars and distal contact of canine CR is directed to pass through contact between 1st and 2nd premolar or 2nd premolar and 1st molar |
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characteristics of ideal PA of max premolar region
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2nd premolar should be centered on film
contact between premolar and distal contact of canine should be seen and open 2-4 mm of NORMAL bone beyond teeth occlusal plane of teeth a bit above lower edge of film buccal and lingual cusps should be superimposed |
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how are PAs of max molar region taken?
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place size 2 film horizontally in midline of palate,parallel to long axis of teeth, second molar should be centered on film
posteror border of film should cover maxillary tuberosity and distal part of last molar in mouth CR is diected to pass through the contact between the 1st and 2nd molar |
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characteristics of ideal PA of max molar region
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2nd molar should be centered on film
contact between molars should be open max tuberosity should be seen in 3rd molar area 2-4 mm of bone beyond apices occlusal plane of teeth a tad above lower edge of film buccal and lingual cusps superimposed |
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where is film holder in relation to tooth?
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film holder must be used to keep film parallel to long axis of tooth
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purpose of long BID
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increases source film distance to increase magnification and decrease image distortion
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Occlusal xrays
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cross section of arches to see incisal and occlusal sufaces of teeth
used to see impacted teeth,fractures,and foreign bodies, jaw lestions, and salivary stones |
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vertical angle of maxillary occlusal xray
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Direct central ray at vertical angulation of 60-65
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CR of occlual xray mandibular view
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direct the central ray at the midline through the floor ofthe mouth approx 3 cm below the chin at right angle to the center of the film
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anatomic variations
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tori
edentulous ridges apprehensive pt tongue size depth of palate hi muscle attachments |
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different exposure time with edentulous ridge
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25% less exposure time
do only 14 PA film with size 2 films (1 midline, 2 lateral canine, 2 premolar, 2 molar) no BW needed |
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simplest, fastest, and least uncomfortable alternative to intraoral
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pano
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ways to reduce pain and hypersensitivty so we can take xray on pt
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tissue protectors
topical anesthetics film bending tranquilizers |
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edge ease comfort cushions
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developed by DH
pt bit hader on film holder improves pt comfort bc procts soft tissue from film abrasion reduces no of retakes |
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managing gagging pt
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reduce psychic stimuli
pleasant conversation anterior films taken first divert pt attention premed Reduce tactile stimuli mimimal film motion in moth minimal contact w/mucosa flm holders/cusion desensitizers procedure quick get help combine intra/extraoral |
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what is a good radiograph?
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has proper visual characteristics and minimal projection geometry
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what does diagnostic quality depend on?
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proper visual characteristics
(contrasts and density) minmial projection geometry (geometric unsharpness, motion unsharpness, screen unsharpness) anatomical accuracy adequate covreage of anatomical area of interest |
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visual characteristics
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density
contrast |
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density
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degree of blackness on the film
depends on amt of radiation; greater the amount of xrays reaching film, greater the density |
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what is the correct density?
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faint outline of soft tissues should be seen along with hard tissues
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useful range of film density
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0.3 v.lt to 3.0 v.dark
beyond this the film is either too light or too dark |
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primary factors controlling radiographic density
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milliamper seconds mAs
kVp source film distance |
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secondary factors controlling radiographic density
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dev. conditions
film type intensifying screens grids obj density |
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how does mAs control density?
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blackness varies directly and proportionally w/current and exposure time. the higher the mAs the greater the density
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how does kVp control density?
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greater the kVp, more speed and more penetration of xray. the more xrays strike the film emulsion and make a greater density
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how does source film distance control density?
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beam intensity varies inversely to square of source film distance
shorter the distance, the greater the intensity of the beam and the higher the film density |
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what is the correct density?
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faint outline of soft tissues should be seen along with hard tissues
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what does doubling the distance do to density?
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decreases it by four
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useful range of film density
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0.3 v.lt to 3.0 v.dark
beyond this the film is either too light or too dark |
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what does halving the distance do to density?
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four times greater density
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primary factors controlling radiographic density
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milliamper seconds mAs
kVp source film distance |
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what does dev time do to density?
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underdev produces lo density image (either due to depletion of dev sln or temp is too cold for processing)
over dev can make hi density (fog) |
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what is the correct density?
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faint outline of soft tissues should be seen along with hard tissues
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secondary factors controlling radiographic density
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dev. conditions
film type intensifying screens grids obj density |
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how does film type affect density?
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hi spped film require less mAs to make density change compard w/slower film
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useful range of film density
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0.3 v.lt to 3.0 v.dark
beyond this the film is either too light or too dark |
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primary factors controlling radiographic density
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milliamper seconds mAs
kVp source film distance |
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what mAs does hi speed intensifying screnns require to maintain density?
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less mAs
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what mAs does grip require to maintain constant density?
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more mAs
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secondary factors controlling radiographic density
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dev. conditions
film type intensifying screens grids obj density |
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how does mAs control density?
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blackness varies directly and proportionally w/current and exposure time. the higher the mAs the greater the density
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how does mAs control density?
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blackness varies directly and proportionally w/current and exposure time. the higher the mAs the greater the density
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radiographic contrast
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differences in densities on film
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how does kVp control density?
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greater the kVp, more speed and more penetration of xray. the more xrays strike the film emulsion and make a greater density
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what primarilily affects radiographic contrast?
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primarily affected by kVp
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how does kVp control density?
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greater the kVp, more speed and more penetration of xray. the more xrays strike the film emulsion and make a greater density
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how does source film distance control density?
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beam intensity varies inversely to square of source film distance
shorter the distance, the greater the intensity of the beam and the higher the film density |
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what does doubling the distance do to density?
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decreases it by four
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how does source film distance control density?
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beam intensity varies inversely to square of source film distance
shorter the distance, the greater the intensity of the beam and the higher the film density |
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what does halving the distance do to density?
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four times greater density
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what does doubling the distance do to density?
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decreases it by four
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what does dev time do to density?
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underdev produces lo density image (either due to depletion of dev sln or temp is too cold for processing)
over dev can make hi density (fog) |
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what does halving the distance do to density?
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four times greater density
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what does dev time do to density?
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underdev produces lo density image (either due to depletion of dev sln or temp is too cold for processing)
over dev can make hi density (fog) |
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how does film type affect density?
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hi spped film require less mAs to make density change compard w/slower film
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what mAs does hi speed intensifying screnns require to maintain density?
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less mAs
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how does film type affect density?
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hi spped film require less mAs to make density change compard w/slower film
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what mAs does grip require to maintain constant density?
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more mAs
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what mAs does hi speed intensifying screnns require to maintain density?
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less mAs
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radiographic contrast
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differences in densities on film
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what mAs does grip require to maintain constant density?
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more mAs
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what primarilily affects radiographic contrast?
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primarily affected by kVp
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radiographic contrast
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differences in densities on film
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what primarilily affects radiographic contrast?
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primarily affected by kVp
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long scale contrast
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lo contrast
higher kVp (80-90) more penetrating xrays so density differences are small and contrast is low. there are few blacks and whites and many shades of gray |
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how do you go from long scale to short scale contrast?
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decrease kVp
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short scale contrast
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hi contrast
lower kVp (60-65) less penetrating xrays. density differences are large. hi contrast more blacks and whites with few shades of gray |
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optimal contrast of PAs
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should show lo contrast to see osseous changes
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optimal contrast of BW
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should have hi contrast to see dental caries detection
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if kVp increases, what must be decreased to maintain density?
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if kVp is increased, mAs or exposure time must be decreased to maintain previous density
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what does kVp affect
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speed of xrays and number of xrays produced
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will changing mAs only cause a change in contrast
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no. mainly just kVp causes change in contrast
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what does image sharpness measure?
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how well a boundary between two areas differeing radiodensity is revealed
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what can image unsharpness be due to?
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geometric unsharpness
motion unsharpness screen unsharpness |
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geometric unsharpness
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diffustion of detail
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penumbra
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unsharp margin surrounding the image. also known as edge gradient. unsharp margin or blurred zone on image is seen as xrays orinate from focal spot and travel in straight lines, their projectons of feature of an object do not occur at exactly the same location on the film
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3 reasons image unsharpness, distortion, and magnification occurs
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1.xrays originate from an area rather than a point
2.xrays travel in diverging straight lines as they radiate from the source 3.human structures have depth,width,and lenghth |
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5 rules for accurate image formation to minimize loss of image clarity
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1.effective focal spot should be as small as possible
2.distance between focal spot and obj should be as long as possible 3.film should be as close to obj as possible 4.long axis of obj should be parallel to film 5.central ray should be perpendicualr to film to record structures in true spatial relationships |
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what happens to penumbra and image definition as focal spot gets smaller?
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smaller the focal spot size, the smaller the nenumbra and the higher the image definition
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when are lingual cusps sharper?
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when closer to film
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how does obj film distance affect sharpness?
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longer the obj-film distance, the greateer the unsharpness
objects closer to the film have a sharper image |
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how can radiographic image magnification can be decreased?
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by using longer source-oject distance and shorter object-film distance
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how can shape distortion be minimized?
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by using radiographic intraoral paralleling tecnique
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what problem arises w/bisecting angle tecnique?
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inherent shape distortion
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when does an xray have anatomic accuracy?
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when it has....
proximal contacts open CEJ buccal and lingual cusps superimposed bccal and lingual portion of alveolar crest superimposed no superimpostion of zygomatic arch over roots of max teeth |
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what causes superimpostion of zygomatic arches over roots of max teeth?
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over angulation
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film coverage
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area of interest shown in xray
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PA film coverage
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2-4 mm of normal bone surrounding apices of teeth
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what does adequate film coverage depend on?
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proper alignment of film and radiation beam to area of interest
proper selectoin of film type proper selection of film-projection tecnique |
