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Bisecting-the-Angle.
DentRad2: Bisecting-the-Angle, BW Techniques
Question | Answer |
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The bisecting technique aka | Bisecting-the-angle technique; short-cone technique |
Definition of Bisecting-the-angle technique | An intraoral radiographic technique that provides a complete image of the tooth or teeth and 3-4 mm of surrounding tissue; |
Advantages of Bisecting-the-Angle Technique | More comfortable for the pt, since small bite blocks can be used instead of bulky receptor holders that are necessary for the paralleling technique |
Disadvantages of Bisecting-the-Angle Technique | The image projected on the receptor has dimensional distortion; More bodily tissues are exposed as a result of greater vertical angulation (lens of the eye, thyroid) |
Dimensional Distortion with the Bisecting-the-Angle Technique | Paralleling: dimensional accuracy; Bisecting-the-angle: *dimensional distortion; *foreshortening of objects farthest from the film |
Angle, Definition | Figure that is formed by two lines diverging or separating from a common point; |
Bisect, Definition | To divide into two equal parts; |
Long Axis of the Tooth, Definition | Imaginary Line that divides the tooth vertically into two equal parts; |
Central Ray, Definition | Central portion of the primary beam from the x-ray tubehead |
Bisecting-the-Angle Technique is based on the | rule of isometry (two triangles are equal if they have two equal angles and share a common side) |
Principles of the Bisecting-the-Angle Technique | Theintraoral rcptr is placd alongthe lingl srfce oftooth (edge ofthrcptr touches theincsl/occl portion ofthetooth) *the radigrphr must vislze a line that divds/bisects theangle formed bythe image receptr & thelong axis ofthetooth(line is imagnry bisector) |
The central ray in bisecting-the-angle technique is directed... | perpendicular to the imaginary bisector |
Snap-A-Ray receptor holding device can be used for what techniques/ areas of the mouth | Snap-A-Ray can be used for bisecting, or paralleling in the mandibular premolar area |
Correct Horizontal Angulation | Central ray is directed through the contact areas of the teeth to open the contacts (Paralleling, bisecting, and bitewing techniques all follow this principle) |
Incorrect Horizontal Angulation results in | Overlapped contact areas Superimposition of tooth surfaces |
Bisecting Technique. Vertical Angulation | Vertical angulation is determined by the imaginary bisector *Central ray is directed perpendicular (at a right angle) to the imaginary bisector *When vertical angulation is correct, the image formed on the film is the same length as the tooth. |
Foreshortening in Bisecting-the-Angle technique is caused by | excessive vertical angulation |
Elongation in Bisecting-the-Angle technique is caused by | insufficient vertical angulation; |
Bisecting-the-Angle Technique. Errors associated with receptor positioning | *Not touching the edge of the receptor to the lingual surface of the tooth Result: distortion of image(s) |
Bisecting-the-Angle Technique: Errors associated with cone (PID) positioning | *Incorrect vertical angulation (elongation, foreshortening) *Incorrect horizontal angulation (Overlapping, Cone cutting) |
Bisecting-the-Angle Technique: Patient Positioning | Occlusal plane parallel with the floor for both maxillary and mandibular films |
Receptor Positioning | Film is positioned close to the tooth with the incisal or occlusal end of the film touching the tip of the tooth |
Bitewing Radiographs, definition | Intraoral radiographic technique that produces an image of the maxillary and mandibular teeth in occlusion, and the crestal alveolar bone |
Bitewing Radiographs, purpose | To detect interproximal caries and examine the interproximal crestal bone levels |
Interproximal, define | between two adjacent surfaces |
Bitewing image, define | Receptor used in the interproximal examination that has a “wing” or tab |
Crestal Bone (alveolar crest) | Coronal portion of alveolar bone that is located between the teeth; |
Coronal portion of the alveolar bone that is located between the teeth; | Crestal bone (alveolar crest) |
Contact area | Area of the tooth that touches an adjacent tooth |
Principles of the Bitewing Technique | *Receptor is placed parallel to the crowns of the max & mand teeth; *Receptor is stabilized when the pt bites down on the tab: *Central Ray of the X-Ray beam is directed to open the contact areas between the teeth, using a +8 degree vertical angulation |
Patient Positioning for Posterior Bitewing Technique | Occlusal plane of the maxilla parallel w/the floor |
Receptor Positioning for premolar bitewing | Include at least the distal surfaces of the cuspid (entire mandibular cuspid if possible) |
Receptor Positioning for molar bitewing | One tooth's width past the most posterior molar; |
Bitewing; Cone (PID) Positioning | Vertical Angulation, cone points slightly downward; |
Bitewing; Horizontal angulation (Cone (PID) positioning) must | open the contact areas between the teeth; determined by using the q-tip positioned between the guide teeth; |
How is horizontal angulation determined for premolar bitewing | Determined by using a Q-tip positioned between guide teeth; Place Q-tip between mandibular premolars |
How is horizontal angulation determined for molar bitewing? | Determined by using a Q-tip positioned between guide teeth; place Q-tip between maxillary first and second molars; |
Cone (PID) Positioning, Premolar BW; Covering the Entire Receptor | Premolar BW: Position the PID anteriorly enough to cover the maxillary and mandibular cuspids and lateral incisors; /commisure in the middle of the cone; *middle of the cone directed @ the level of the occlusal plane; |
Cone (PID) Positioning, Molar BW; Covering the Entire Receptor | Molar BW: Position the PID anteriorly enough to capture the maxillary and mandibular second premolars; *Anterior portion of the cone is at the commisure; *Middle of the cone directed at the level of the occlusal plane |
Common Errors associated w/the BW technique | *Incorrect Receptor Placement; *Cone positioning errors (Overlapping, Negative vertical angulation); *Overexposed receptor; *Underexposed receptor |
Common Errors associated w/the BW technique. INCORRECT RECEPTOR PLACEMENT | *Mesial surfaces of 1st premolars are missed; *Distal surfaces of most posterior molars are missed; *"uphill/downhill" caused by receptor rotation; |
Error characterized as such is caused by: *Mesial surfaces of 1st premolars are missed; *Distal surfaces of most posterior molars are missed; *"uphill/downhill" caused by receptor rotation; | BW Technique. Incorrect Receptor Placement |
Common Errors associated w/the BW technique. CONE POSITIONING ERRORS | *Overlapping (superimposition of tooth surfaces caused by incorrect horizontal angulation); *Negative vertical angulation |
Errors characterized as such are caused by: *Overlapping (superimposition of tooth surfaces caused by incorrect horizontal angulation); *Negative vertical angulation | Cone positioning errors |
BW Technique. Overlapping is caused by... | incorrect horizontal angulation |
BW Technique. Uphill/downhill is caused by | dropped receptor corner |
BW Technique. Negative Vertical Angulation, error characterized as: | *Cone (PID) was pointed upward; *Occlusal surfaces of maxillary teeth can be viewed; *Apical areas of mandibular teeth may be seen |
Overexposed Receptor appears... Causes" | Overexposed receptor appears dark. Causes: *Exposure time too long; *kVp setting too high; *mA setting too high |
Underexposed receptor appears... Causes: | Underexposed receptor appears light. Causes: *Exposure time too short; *kVp setting too low; *mA setting too low |
A conventional film exposed to light appears black after processing is... (what type of error? cause) | Exposure error. Cause: exposure to white light |
An unexposed film/receptor appears clear after processing/scanning (what type of error? cause) | Exposure Error; Cause: Electrical failure, x-ray machine wasn't turned on, malfunction of the machine |
Cone Cutting, describe | Entire receptor was not covered by PID; The border can appear fuzzy or have a distinct line; |
This describes what type of error: Entire receptor was not covered by PID; The border can appear fuzzy or have a distinct line; | Cone Cutting, it is a Technique Error |
Bent receptor causes distortion of images on the receptor. Cause: | Excessive bending of receptor due to curvature of hard palate; |
Excessive bending of receptor due to curvature of hard palate may cause: | Bent receptor causes distortion of images on the receptor; |
Film creasing (crease - складка, загиб,) caused by | Creased conventional film caused by cracked film emulsion |
Double exposure, describe, what type of error | The same receptor was exposed twice in more than one area; Technique error |
What type of error is this: The same receptor was exposed twice in more than one area; | Double Exposure, Technique error; |
Herringbone pattern and a light image appear when the film is placed in the mouth backwards, known as | Reversed Conventional Film, Technique Error |
Reversed Conventional Film, describe, what type of error | Herringbone pattern and a light image appear when the film is placed in the mouth backwards; |