Paralleling Technique (Slides)

What is paralleling technique?

• used for periapical radiographs

• more diagnostic than bisecting

• easier than bisecting

• used to referred to as “long cone technique” because narrow beams reduces magnification that otherwise results from this technique

Is paralleling more diagnositic than bisecting?

yes-also easier

What does the receptor placement cover? (anatomy of tooth)

incisal edge to apex

Does the receptor placement contact the teeth?

no-place towards midline of palate/floor of mouth

What is the receptor parallel to?

long axis of tooth

The central ray is _____ to long axis of tooth and receptor

perpendicular

What happens if VA is incorrect?

alters where shadow hits receptor

• cuts off incisals/apices-might be due to RP or might be due to incorrect VA

• might get distortion especially if receptor isn’t perfectly parallel to long axis

Horizontal Angulation:

• Direct beam through target teeth

• Note: PM image, don’t worry about molar contacts!

• Opening of PID runs parallel with buccal surfaces of target teeth

• Canine PA, aim through mesial - Why?

You can’t aim through mesial & distal at same time Distal is in premolar image

Where should you aim the PID?

very center of receptor- beam alignment devices help a lot with this

What color are anterior holders?

blue

What color are posterior holders?

yellow-must switch from UR/LL to UL/LR

where should the identification dot (a) be on PSP? hint-should never cover apex

lower right, must always be on occlusal edge of film- put the “dot in the slot”

What side of the PSP should you see when looking through the ring?

black side “in plain sight”`

Do maxillary or mandibular teeth lean more?

maxillary

Do anterior or posterior teeth lean more?

anterior

How many points of contacts must there be?

2-edge of film against palate/floor of mouth and bite block resting on incisal/occlusal edge

Should you increase the distance between tooth and receptor?

yes to allow more room/height to work with making it possible to get parallel and ensure coverage of apex

Failure to establish a 2-point contact results in…

root cut off, with lots of blank space below incisals

PID must be ____ with ring in all directions

parallel

Maxillary Molar:

• film centered on second molar. no premolars in molar periapical

• film equidistant from lingual surfaces of teeth; this opens contacts between teeth

• film in center of palate

Maxillary Premolar:

• front edge of film anterior to middle of canine; approximately centered on 2nd premolar

• film equidistant from lingual surfaces of teeth; this opens contacts between teeth

• film in center of palate

Maxillary Canine:

• film centered on lateral and canine

• film placed in highest part of palate

• premolar overlapping is fine

Maxillary Incisor:

• centered on contact between central and incisors

• film places far back in patient’s mouth where it’s wider

Mandibular Molar:

• centered on second molar

• film equidistant from lingual surfaces of teeth; in this area the film will usually contact lingual of molars

Mandibular Premolar:

• front edge of film anterior to middle of canine; approximately centered on 2nd molar

• film equidistant from lingual surface of teeth; film placed toward center of mouth, displacing tongue

Mandibular Canine:

• film centered on canine

• film positioned away from teeth, pushing tongue back slightly

Mandibular Incisor:

• film centered on midline

• film positioned way from teeth where there’s more room, pushing tongue back

roots for days:

Some patients (such as unusually tall patients and African American patients) have longer than normal roots - even with proper RP, you’ll still end up with missing apices

Use VA to “shrink” tooth and move where shadow hits receptor - causes crown to be cut off though!