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RAD #7
| Question | Answer |
|---|---|
| Panoramic film | shows a wide view of the upper and lower jaws. Both film and tube head rotate around the patient, producing a series of images. |
| Uses of a PAN | used to supplement bite-wings and PA's. Impacted teeth, evaluate eruption patterns, growth, and development, detect diseases, lesions, examine the extent of large lesions, evaluate trauma. |
| PAN image | not as sharp as intraoral films. should not be use to evaluate and diagnose caries, perio diesease, periapical lesions, should not be used as a sub for intraoral films. |
| Rotation | film rotates in one direction while the tubehead rotates in the other direction. |
| Tomography | radipgraphic technique that allows the imaging og one layer or section of the body while blurring images from structures in other planes. |
| rotation center | the pivotal point, or axis, around which the cassett carrier and x-ray tubehead rotate |
| 3 basic rotation centers | double center roation, triple center rotation, moving center rotation. |
| Focal trough | three dimensional curved zone in which structures are clearly demonstrated on a pan radiograph. Structures within the trough are clear structures outside or inside the trough appear blurred |
| Size of focal trough | the closer the rotation center is to the teeth, the narrower the focal trough. Narrow in anterior and wide in posterior. |
| difference of units | PAN units differ n the number of the rotation centers, the size and shape od the focal trough, and the type of film transport mechanism used. |
| Main components of a unit | x-ray tube head, head positioner, exposure controls. |
| tubehead | similar to intraoral tubehead. Has a filament used to produce electrons and a target used to produce x-rays. |
| collimator | differs from intraoral. Is a lead plate with an opening in the shape of a narrow vertical slit |
| vertical angulation | is not varied. tubehead is fixed in position so that the x-ray beam is directed slightly upward. tubehead rotates behind the patients head and the film rotates in front of the patient. |
| exposure factors | determined by the manufacturer. The milliamperage and kilovoltage are adjustable. exposrue time is fixed and cannot be changed. |
| Screen film | sensative to light emitted from intensifying screens. It is placed between two intensifying screens in the casette holder. |
| Rare earth | faster and less x-ray exposure used than calcuim tungstate |
| cassette | device used to hold the extraoral film and intensifying screens. must be light tight. |
| Position | position the patients midsagittal plane perpendicular to the floor. and the Frankfort plane paallel to the floor. tongue on roof of mouth. |
| ghost image | a radiopaque artifact seen on a panoramic film that is produced when a radiodense object is penetrated twice by the x-ray beam. on opposite side of film, larger, and higher then actual counterpart. |
| chin is positioned too high | hard palate and floor of the nasal cavity apper superimposed over the roots of the max. teeth, there is loss of detail in the max. incisor region, max. incisors appear blurred and magnified, a "reverse smile line" is apparent. |
| chin is positioned too low | the mandibular incisors appear blurred, there is a loss of detail in the anterior apical regions, the mandibular condyle may not be visible, an "exaggerated smile line" is apparent. |
| anterior teeth are not positioned in the focal trough | they appear blurred, and skinny. |
| too far back on the bit block | teeth appear fat and out of focus |
| head is not centered | the side farthest from the film appears magnified and the side closest to the film appears smaller. |
| advantages of a PAN | field size-coverage of the mandible and maxilla in one film,simplicity-simple and requires a minimal amount of time and training, patient cooperation- accepted by patient, no discomfort, minial exposure- minimal exposure to patient. |
| disadvantages of a PAN | image quality- not as sharp as intraoral, focal trough limitations- objects of intrest outside the focal trough are not seen, distortion- magnification, distortion, and overlapping, equiptment cost- high cost. |
| extraoral radiography | image large areas of the skull and jaws |
| purpose and use | evaluate large areas of the skull and jaws, evaluate growth and development, impacted teeth, detect diseases, lesions, and conditions of the jaws, trauma, the TMJ. |
| equiptment standard unit | standard x-ray unit may be used for the transcranial and lateral jaw projections. |
| equiptment PAN | PAN can be used in conjunction with an extension device called a cephalostat |
| cephalostat | includes a film holder and head positioner that allow the dental radiographer to position both film and patient easily. |
| Extraoral film sizes | 5x7 - 8x10 inch |
| cassette | front side made of plastic and back side made of mental. front side known as tube side. front side must always face the patient |
| grid purpose | a device ised to reduce the amount of scatter radiation that reaches an extraoral rilm during exposure. scatter causes film for and reduces contrast. |
| grid composition | compoed of a series of lead strips in a material that permits the passage of the x-ray beam. it is placed between the patients head and the film. to compensate for the lead strips found in the gird, an increased exposure time is needed. |
| lateral jaw uses | used to examine the posterior region of the mandible. ued in children and in patients with limited jaw opening due to fracture or swelling, and patients who cant tolerate introral films. |
| lateral jaw projection | PAN radiograph is prteferred. standard x-ray unit can be used. two projections: body of mandible, and ramus of mandible. |
| purpose of lateral jaw projection- body of mandible | to evaluate impacted teeth, fractures, and lesions located in the body of the mandible. premolar and molar regions and inferior border of the mandible. |
| placement for lateral jaw- body of mandible | cassette placed flat against patients cheek and centered over the body of the mandible. parallel with the body of the mandible. patient holds casette with thumb placed under the edge of the cassette and palm against the outer surface. |
| head position for lateral jaw- body of mandible | tipped about 15 degrees toward side being imaged. chin extended and elevated. |
| beam algnment for lateral jaw- body of mandible | directed to a point just below the inferior border of the mandible on the side OPPOSITE cassette. bean directed upeard (-15 to -20 degrees). perpendicular to the horizontal plane of the film. |
| purpose of lateral jaw- ramus of mandible | evaluate impacted third molars, large lesions, and fractures that extend into the ramus of the mandible. view from the ramus of the mandible from the angle of the mandible to the condyle. |
| film placement for lateral jaw- ramus of the mandible | cassette placed flat against patients cheek centered over ramus of the mandible. cassette parallel with ramus. patient holds cassette with thumb placed under the edge of the cassette and the palm against the outer surface. |
| head position for lateral jaw- ramus of mandible | tipped about 15 degrees toward the side being imaged. chin is extended and elevated. |
| beam alignment for lateral jaw- ramus of mandible | central ray directed to a point posterior to the third molar region on the OPPOSITE side the cassette. beam directed upward (-15 to -20 degrees) centered on ramus. beam directed perpendicular to the horizontal plane of film. |
| lateral cephalometric film placement | cassette pepindicular to floor. long axis of cassette horizontal |
| lateral cephalometric head position | left side near cassette. midsagittal plane perpendicular to floor and parallel with cassette. frankfort plane parallel to the floor. head centered over cassette. |
| lateral cephalometric projection | evluate facial growth and development, trauma, and disease. bones of the face and skull as well as the soft tissue profile. |
| lateral cephalometric beam alignement | center of cassette. perpendicular to cassette. |
| posterioranterior projection | evaluate facial growth and development, trauma, and disease. frontal and ethmoid sinuses, the orbits, ans the nasal cavity. |
| posterioranterior film placement | cassette perpendicular to floor. long axis of cassette positioned vertically. |
| posterioranterior head position | forehead ans nose touch cassette. midsagittal plane perpendicular to floor. frankfort plane positioned parallel with floor. head centered over cassette. |
| posterioranterior beam alignment | center of cassette. perpendicular to cassette. |
| waters projection | evaluate the maxillay sinus. frontal and ethmoid sinuses, the orbits, ans the nasal cavity. |
| waters film placement | cassette perpendicular to the floor. long axis of cassette vertical. |
| waters head position | chin touches cassette. tip of nose positioned 1/2 to 1 inch away from cassette. midsagittal plane perpendicular to floor. |
| waters beam alignment | center of cassette. perpendicular cassette. |
| submentovertex projection | identify the position of the condyles, demonstrate the base of the skull and evaluate fractures of the zygomatic arch.. sphenoid and ethmoid sinuses ans the lateral wall of the max. sinus. |
| submentovertex film placement | cassette perpendicular to floor. long axis of cassette vertical. |
| submentovertex head position | head tipped back. top of head touches cassette. midsagittal plane and frankfort plane perpendicular to floor. |
| submentovertex beam alignment | center of cassette. perpendicular to cassette. |
| submentovertex exposure factors | for the zygomatic arch, the exposure time is reduced to about 1/3 the normal time. |
| reverse towne projection | identify fractures of the condylar neck and ramus. |
| reverse towne film placement | cassette perpendicular to the floor. long axis of cassette vertical. |
| reverse towne head position | head tipped down. mouth wide open. top of forehead touches cassette. midsagittal plane perpendicular to the floor. |
| transcranial projection | evaluate the superior surface of the condyle and the articualr eminence. evaluate movement of the condyle while the mouth is opened and to compare the joint spaces. |
| transcranial film placement | casette flat against ear. centered over TMJ. |
| transcranial head position | midsagittal plane perpendicular to floor and parallel with cassette. |
| transcranial beam alignment | 2 inches above and 0.5 inch below the ear canal opening. vertical engulation +25 degrees. horizontal angulation 20 degrees. |
| TMJ tomography | radiographic technique used to show structures located within a selected plane of tissue while blurring structures outside the selected plane. |
| Cone beam imaging | use of a cone shaped x-ray beam to acquire an image. a 360 rotation around the patients head. |
| benefits of cone beam technology | lower radiation dose, quick scanning time, high degree of patient cooperation, production of anatomically true images, optimized computer to scan the tissues of the oral and maxillofacial complex. |
| mastoid process | prominence of bone located posterior and inferior to the TMJ. appears as a rounded radiopacity located posterior and inferior to the TMJ. not seen on a PA |
| styloid process | long, pointed, and sharp projection of bone that extends downward from the inferior surface of the temporal bone. anterior to mastoid. appears as a long radiopaque spine that extends from the temporal bone anterior to the mastoid process. not seen on a PA |
| external auditory meatus | hole or opening in the temporal bone located superior and anterior to the mastoid process. appears as a round ovoid radiolucency anterior and superior to the mastoid process. not seen on a PA. |
| glenoid fossa | concave, depressed area of the temporal bone. located anterior to the mastoid process and the external auditory meatus. appears as a concave radiopacity superior to the mandibular condyle. not seen on a PA. |
| articular eminence | rounded projection of the temporal bone located anterior to the glenoid fossa. appears as a rounded radiopaque projection of the bone located anterior to the glenoid fossa. not seen on a PA. |
| lateral pterygoid | wing shaped bony projection of the sphenoid bone located distal to the maxillary tuberosity. appears as a radiopaque projection of bone distal to the maxillary tuberosity. not seen on a PA. |
| pterygomaxillary fissure | narrow space that seperates the lateral pterygoid plate and the maxilla. appears as a radiolucent area between the lateral pterygoid plate and the maxilla. not seen on a PA. |
| maxillary tuberosity | rounded promininence of bone that extends posterior to the third molars. appears as a radiopaque bulge distal to the third molars. |
| infraorbital foramen | a hole or opening in bone found inferior to the border of the orbit. appears as a round or ovoid radiolucency inferior to the orbit. not seen on PA. |
| orbit | bony cavity that contains the eyeball. appears as a round radiolucent compartment with radiopaque borders located superior to the max. sinus. only the inferior border of the orbit is visible, where it appears as a radiopaque line. |
| incisive canal | passageway through bone that extends from the superior foramina of the incisive canal to the incisive foramen. appears as a tubelike radiolucent area with radiopaque borders. |
| incisive foramen | opening in bone that is located at the midline of the anterior portion of the hard palate directly posterior to the maxillary central incisors. appears as a small, ovoid radiolucency located between the roots of the maxillary central incisors. |
| anterior nasal spine | sharp bony projection of the maxilla located at the anterior and inferior portion of the nasal cavity. appears as a v-shaped radiopaque area located at the intersection of the floor of the nasal cavity and the nasal septum. |
| nasal cavity | a pear-shaped compartment of bone located superior to the maxilla. appears as a large radiolucent area above the maxillary incisors. |
| nasal septum | vertical bony wall that divides the nasal cavity into the right and left nasal fossae. appears as a vertical radiopaque partition that divides the nasal cavity. |
| hard palate | bony wall that seperates the nasal cavity from the oral cavity. appears as a horizontal radiopaque band superior to the apices of the maxillary teeth. |
| maxillary sinus and floor of the maxillary sinus | paired cavities or compartments of bone located within the maxilla and are located above the maxillary premolar and molar teeth. appear as paired radiolucent areas located above the apices of the maxillary premolars and molars. radiopaque line. |
| zygomatic process of maxilla | bony projection of the max. that articulates with the zygoma or cheekbone. appears as a J or U- shaped radiopacity located superior to the maxillary first molar region. |
| zygoma | articulates with the zygomatic process of the max. appears as a radiopaque band that extends posteriorly from the zygomatic process of the max. |
| hamulus | small, hooklike projection that extends from the medial pterygoid plate of the sphenoid bone. appears as a radiopaque hook-like projection posterior to the maxillary tuberosity. |
| mandibular condyle | rounded projection of bone extending from the posterior superior border of the ramus. appears as a bony, rounded radiopaque projection extending from the posterior border of the ramus. not seen on PA. |
| coronoid noch | scooped-out concavity of bone located distal to the coronoid process. appears as a radiopaque concavity located distal to the coronoid process on the superior border of the ramus. not seen on PA. |
| coronoid process | marked prominence of bone found on the anterior superior ramus of the mandible. appears as a triangular radiopacity posterior to the maxillary tuberosity. |
| mandibular foramen | round or ovoid hole in bone on the lingual aspect of the ramus of the mandible. appears as a round or ovoid radiolucency centered within the ramus of the mandible. not seen on PA. |
| lingula | small, tongue-shaped projection of bone seen adjacent to the mandibular foramen. appears as an indistinct radiopacity anterior to the mandibular foramen. not seen on PA. |
| mandibular canal | tubelike passageway through bone that travels the length og the mandible. goes from mand. foramen to mental foramen. appears as a radiolucent band outlined by two thin radiopaque lines representing the walls of the canal. |
| mental foramen | opening in bone located on the external surface of the mandible in the region of the mand. premolars. appears as a small, ovoid radiolucency located in the apical region of the mandibular premolars. |
| mental ridge | linear prominance of bone located on the external surface of the anterior portion of the mandible, extends from the premolar region to the midline. appears as a thick radiopaque band that extends from the mandibular premolar region to the incisor region. |
| mental fossa | scooped-out depressed area of bone located on the external surface of the anterior mandible above the mental ridge in the mand. incisor region. appears as a radiolucent area above the mental ridge. |
| lingual foramen | tiny openings in bone located on the internal surface of the mand. near the midline. appears as a small radiolucent dot located inferior to the apices of the mand. incisors. |
| genial tubercles | tiny bumps of bone located on the lingual aspect of the mand. appears as a ring-shaped radiopacity surrounding the lingual foramen. |
| inferior border of mandible | linear prominance of cortical bone that defines the lower border of the mand. appears as a dense radiopaque band that outlines the lower border of the mand. |
| mylohyoid ridge | linear prominance of bone located on internal surface of the mand. that extends from molar region downward and forward to the lower border of the mand. symphysis. appears as a dense radiopaque band that extends downward and forward from the molar region. |
| internal oblique ridge | prominance of bone on the internal surface of the mand. extends down and forward from ramus. appears as a dense radiopaque band that extends down and forward from ramus. |
| external oblique ridge | prominance of bone on the external surface of the body of the mand. appears as a dense radiopaque band that extends down and forward from the anterior border or the ramus of the mand. |
| angle of the mandible | where the body meets the ramus. appears as a radiopaque body structure where the ramus joins the body of the mand. |
| palatoglossal air space | space between the palate and tongue. appears as a horizontal radiolucent band above the apices of the max. teeth. |
| nasopharyngeal air space | portion of the pharynx located posterior to the nasal cavity. appears as a diagonal radiolucency located superior to the radiopaque shadow of the soft palate and uvula. |
| glossopharyngeal air space | portion of the pharynx located posterior to the tongue and oral cavity. appears as a vertical radiolucent band superimposed over the ramus of the mand. |
| tongue | movable muscular organ attached to the floor of the mouth. appears as a radiopaque area superimposed over the maxillary posterior teeth. |
| soft palate and uvula | form a muscular curtain that sepertes the oral cavity from the nasal cavity. appears as a diagonal radiopacity projecting posteriorly and inferiorly from the max. tuberosity. |
| lipline | formed by the position of the patients lips. areas of the teeth not covered by the lips appear more radiolucent; areas covered by the lips are more radiopaque. |
| ear | appear as a radiopaque shadow that projects anteriorly and inferiorly fomr the mastoid process. |
| trauma | injury produced by an external force |
| fracture | the breaking of a part |
| root fractures | less common than crown fractures. occur most common in maxillary central incisors |
| x-ray beam root fracture | parallel with the plane of the fracture, the root fracture appears as a sharp radiolucent line on a PA. X-ray beam not parallel with the fracture, the adjacent areas of tooth structure obscure the fracture site; as a result the fracture cannot be seen. |
| jaw fractures | fractures of the mandible occur more often than fractures of any other bone of the face. appears as a radiolucent line at the site where the bone has been seperated. |
| luxation | abnormal distplacement of teeth |
| intrusion | abnormal displacement of teeth into bone |
| extrusion | abnormal displacement of teeth out of bone. |
| avulsin | complete displacement of a tooth from alveolar bone. |
| physiological resorption | procees that is seen with normal shedding of primary teeth. |
| pathologic resorption | regressive alteration of tooth structure that is observed when a toot is subjected to abnormal stimuli. |
| external resorption | seen along periphery of the root surface, associated with reimplanted teeth, abnormal mechanical forces, trauma, chronic inflammation, tumors, cysts, impacted teeth. roots appear blunted and the length appears shorter then normal. |
| internal resorption | occurs within the crown or root. involves pulp chamber, pulp canals, and dentin. caused by trauma, pulp capping, and pulp polyps. round-to-ovoid radiolucency in the midcrown to midroot area. |
| pulpal sclerosis | diffuse calcification of the pulp chamber and pulp canals of teeth that results in a pulp cavity of decreased size. associated with aging. pulp cavity reduced in size. |
| pulpal obliteration | production of secondary dentin which results in obliteration of the pulp cavity. |
| pulp stones | calcifications that are found in the pulp chamber or pulp canals. unknown cause. |
| periapical lesion | periapical granulomas, cysts, and abscesses. cannot be diagnosed by their radiographic appearances alone. |
| periapical granuloma | localized mass of chronically inflamed granulation tissue at the apex of a NONVITAL tooth. results from pulpal death. give rise to PA cyst or abscess. remocal of the tooth with curettage. |
| appearance of pariapical granuloma | seen as a widened periodontal ligament space at the root apex. with time the space enlarges and appears as a round, ovoid radiolucency. |
| periapical cyst | lesion that develops over a long period of time. results from pulpal death. most common tooth related cyst. comprises of 50%-70% of all cysts in the oral region. asymptomatic. endo or extraction curettage. round ovoid radiolucency. |
| periapical abscess | localized collection of pus in the PA region. |
| acute abscess | result from an acute imflammation of the pulp or an area of chronic infection such as PA granuloma. painful. throbbing, constant. nonvital, sensative to pressure, percussion, heat. no radiographic change. |
| chronic abscess | long standing, low grade, pus producing process. develop from an acute abscess or PA granuloma. asymptonmatic. gumboil may be seen. endo or drainage. appears as a round apical radiolucency with poorly defined margins. |
| periodontal abscess | results from bacterial infection within the walls of the perio tissues that typically results from a preexisting perio condition. therapy includes deep scaling and debridement of the perio tissues. |
| condensing osteitis | well defined rediopacity that is seen below the apex of a non vital tooth with a history of long-standing pulpitis. occurs in response to pulpal necrosis. vary in size and shape. not attached to tooth. |
| condenseing osteitis 2 | most common PA radiopacity. mos often is the mand. first molar. associated with nonvital teeth, and have a large carious leasion or large rastoration. no treatment. |
| sclerotic bone | well defined radiopacity seen below the apices of vital noncarious teeth. cause unknown. not attached to tooth. varies in size and shape. margins- smooth or irregular, diffuse. no radiolucent outline. asymptomatic. |
| hypercementosis | excess deposit of cementum on root. results from supraeruption, inflammation, trauma. no obvious cause. root appears large and bulbous. no sign or symptoms. no treatment. |
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