ion Techniques

8/2/2019 ion Techniques

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PRESENTED BY

DR.RUNUK SINGHIPG STUDENT (ORAL MEDICINEAND RADIOLOGY)

LOCALISATIONLOCALISATION

TECHNIQUETECHNIQUE


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Why Do We NeedRadiographs ?

Dental radiograph is a two dimensionalpicture of a three dimensional object.

IOPA - depicts the object in the superior-inferior and anterior-posterior relationship.However does not depict buccolingualrelationship or depth of the object.

Occlusal - depicts the object in anterior-posterior and buccolingual relationship.However does not depict superior-inferiorrelationship.


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IndicationsForeign bodies

Impacted teethUnerupted teeth

Retained roots

Salivary stonesOrientation of fracture lines

Broken needles and instruments

Root positions

Filling materialsCysts, or neoplasms

Position of vital structures eg. Floor of

sinus, Mandibular canal


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Especially useful in...

Endodontics

Orthodontics

Implantology


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Methods used to localiseobjects

Definition Evaluation

Buccal Object Rule (Tube Shift Technique Or

Clarks Rule)Right Angle Technique

Stereoradiography

CT and MRI


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Definition EvaluationStructures that lie closer to the X-ray film

have better radiographic definition thanthose that are farther than the film.

Because the intraoral film is positioned lingually,the superimposed structure that is more sharplydefined is positioned more lingually in relation toother structures.

Advantage- requires no further X-ray exposuresof the patient.

Disadvantage- least reliable and notrecommended.


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Tube Shift Technique

...if we wish to ascertain [where] a buried canine

is lying, three radiographs are taken: the firstdirectly over the suspected tooth, and which wewillcall the centralposition, and anothermesialto this position, while the third istaken distalof the first or central position.

Each of the three radiographs must be markedimmediately [after] they are taken, or confusionwill arise. With the three radiographs placed intheir relative position[s], we carefully note theposition of each tooth shown in the centralradiograph, and by comparing it with the othertwo the position of the buried tooth, whether it ison the palate or whether it is situated labially,can be ascertained readily with a little practice.


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Tube Shift Technique

It was described by Clark in 1910.The rationale for this procedure derives from the

manner in which the relative positions of

radiographic images of 2 separate objectschange when the position angle at which theimages were made is changed

It uses the principle of parallax which isdefined as the apparent displacement of

an object because of different positions ofthe observer


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Given two objects in a perfectly straightline with the observer the more distantobject will be hidden from sight due toother.

If the observer moves to the right, the

more distant object will apparently move tothe right

Similarly, if the distant object seems tohave moved to the left, it means the

observer moved to the left.So as the more distant object seems to

move towards the direction taken bythe observer, the nearer the object it

seems to move in opposite direction


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Method

Two radiographs of the object are taken.

First using the proper technique & angulationsand the second radiograph is taken keeping all

other parameters constant and equivalent tothose of the first radiograph, only changing thedirection of the central ray either with adifferent horizontal or vertical angulation.


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InterpretationWhen the dental structure or object seen in

the second radiograph appears to havemoved in the same direction as the shift ofthe position indicating device (PID), the

structure or the object in question is said tobe positioned lingually.

But if the object appears to have moved ina direction opposite to the shift of the PID,

then the object in question is said to bepositioned buccally


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SLOB Rule

Same sideLingual

Opposite sideBuccal


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HorizontalTube Shift: When the tubehead ismoved mesially, the beam must be directedmore distally (from the mesial). If the tubeheadis moved distally, the direction of the beammust be more towards the mesial (from thedistal).

Vertical Tube Shift: The SLOB rule also worksfor movement of the tubehead in a verticaldirection. Downward movement of the tubehead

requires that the beam be directed upward andwhen the tubehead is moved upward, the beammust be directed downward.


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In the diagram at left, thebuccal (yellow) and lingual(red) objects of interest aresuperimposed on each

other because the beam isdirected perpendicular toboth of them and they arein the same relativeposition mesiodistally andvertically. Both images arelocated above the secondmolar.

mesial

distal

mesialdistal

Horizontal

movement


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In the diagram at left, thetubehead is moveddistally and the beam isdirected mesially. On the

radiograph, the buccal objectof interest (yellow) movesmesially (opposite totubehead movement) in

relation to the second molarand the lingual object ofinterest (red) moves distally(same direction as tubehead)in relation to the secondmolar.

mesialdistal

mesial

distal

Horizontal movement


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In the diagram at right, thetubehead is movedmesially and the beam is

directed distally. On theradiograph, the buccal objectof interest (yellow) movesdistally (opposite totubehead movement) in

relation to the second molarand the lingual object ofinterest (red) moves mesially(same direction as tubehead)

in relation to the second

mesial

distal

mesialdistal

Horizontal

movement


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In the diagram at left, thebuccal (yellow) and lingual(red) objects of interest aresuperimposed on eachother because the beam isdirected perpendicular toboth of them and they are

in the same relativeposition mesiodistally andvertically. Both images aresuperimposed over the

mandibular second premolar.

Vertical movement


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In the diagram at left, thetubehead is movedupward and the beam isdirected downward. On the

radiograph, the buccal objectof interest (yellow) movesdown (opposite to tubeheadmovement) in relation to the

second premolar and thelingual object of interest(red) moves up (samedirection as tubehead) inrelation to the secondpremolar.

Vertical movemen


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In the diagram at left, thetubehead is moveddownward and the beam isdirected upward. On the

radiograph, the buccal objectof interest (yellow) moves up(opposite to tubeheadmovement) in relation to the

second premolar and thelingual object of interest (red)moves down (same directionas tubehead) in relation to thesecond premolar.

Vertical movement


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BUILD Rule

If in vertical tube shift method, the tubehead is as a rule moved down with thecentral ray pointing upwards, we can putthe BUILD Rule in use.

B uccal

U p

IL ingual

D own


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RIGHT ANGLE TECHNIQUE

This technique was suggested by DrFred Miller and later popularized byWinter.

Here two projections are taken at rightangles to each other which helps tolocalize an object in the maxilla ormandible.


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MethodA periapical radiograph is taken to show

the position of the object supero-inferiorlyand antero-posteriorly.

Next, an occlusal radiograph is taken which

will show the objects buccolingual andanteroposterior relationship.

Two radiographs when studiedtogether help to localise the object inall three dimensions.


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Various Combinations

Lateral and postero-anterior (PA)cephalometric radiographs.

Lateral, PA, and submentovertex(SMV) skullor facial view.

Panoramic, or paralleling periapical, andtrue mandibular occlusal views.

Panoramic, or paralleling periapical, andvertex occlusal.


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Stereoradiography

J.Mackenzie Davidson introduced it in 1898only 3 years after Roentgens discovery ofx-rays.

Over the next 30 to 40 years the techniquegrew in popularity among radiologist because ofits educational value ;understanding normal

anatomy is simplified with stereoscopic images

St di h f ll f f f


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Stereoradiography fell from favour forseveral reasons among which were theintroduction of more sophisticated and

less time consuming imaging technique& a greater awareness of the adverse effectof x-ray as the stereoscopy imagingdelivers twice the amount of radiation

to the patient

Stereoradiography requires the exposure of

two films, one for each eye, and thusdelivers twice the amount of radiation to thepatient. Between exposures the patient ismaintained in position, the film is changed,

and the tube shifted from the right eye to


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TechniqueIn this technique the tube is first centered over the

part to be taken and then shifted 11/4 inches tothe right; it is then tilted in such a manner thatthe direct rays will pass through the samepoint of entry they would pass through if thetube was centered then the exposure is made.

The tube is then moved back to the centre thenshifted 11/4 inches to the left ,where a similarprocedure is followed to that taken on the rightside.

Thus a total of 21/2 inches movement of thetube through the center is brought about which iscorresponding to the distance between thepupil of the normal eyes.


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Stereoradiographcurrently enjoys a renewed

interest for evaluation of

bony pockets in patients with periodontaldisease

morphology of the TMJ area

determination ofroot configuration ofteeth that require endodontic therapy

assessment of the relationship of themandibular canal to the roots of

unerupted mandibular third molarsand assessment ofbone shape when

placement of dental implants is considered.


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CT AND MRI

Tomography is a generic term formedfrom the Greek words tomos i.e. slice or

section and graphia i.e. picture.

MRI has proved superior to CT fordepicting soft tissues


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The axial ,coronal and sagittal sectiongives a 3-dimentional picture of anobject/tooth/structure and thus helps inlocalization

The axial sections give the antero-posterior location.The coronal section gives the superio-

inferior view

The sagittal section gives the locationfrom the midline


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Assessment Of ThePosition Of The Canine

Using the Clark's rule if two views of anunerupted canine are taken with the x-ray tubein two different positions the resultantradiographs will show a difference in the

position of the unerupted canine relative to theincisors as follows:

If the canine is palatally positioned it will appearto have moved in the same direction as the x-ray tubehead, where as if it is labiallypositioned, it will appear to have moved in theopposite direction.

If the unerupted canine is in the same plane asthe incisors i.e in the line of the arch,it will

appear not to have moved at all


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Assessment of mandibularthird molar

The main features to examine include

Angulation

The crownThe root

The relationship of the apices with theinferior dental canal

The depth of the tooth in the alveolar boneThe buccal or lingual obliquity

Radiographic views


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Radiographic viewsused :

Periapicals

OPGOblique laterals


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Assessment Of TheRoot Canals

Assessment of the root canals can bedone using the Clarks technique

At least two radiographs are taken usingdifferent horizontal x-ray tubeheadposition

Using SLOB rule the position of differentcanals can be located


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The SLOB procedure applies during accessIf a single canal is discovered initially on

access preparation, an instrument is placedin the canal

Then a radiograph is made either mesial ordistal

If the instrument is skewed considerably offcenter another canal must be presentThe location of the missed canal is

determined by applying SLOB rule

Identification ofundiscovered canal


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Localization Of ForiegnObject

The recommended radiographic techniqueare:

Maxillary area

1.Incisor zoneStereoscopicLateral profileOcclusal

2.Cuspid zoneStereoscopicLateral profileOcclusal


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3.Bicuspid and molar zone Periapical Occulusal

Mandibular area1. Incisor zone Periapical Lateral profile Occlusal2.Posterior zone Periapical Occulusal

3.Third molar zone Periapical Lateral oblique Occlusal


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Foreign Body Localization

In Maxillary SinusRecommended technique include

Orthopantomogram

Waters view

Lateral skull

Computed tomography

MRI


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