Web viewThe name must indicate where the focus of radiograph is, What are the teeth appear in the radiograph

21\7\2014 radiology #7 ali jawad + Jacob ismail

Intraoral RadiologyMost radiographs taken by dentists are intraoral radiograph

When you write prescription! For radiograph you need to know the nomenclature!

1. Location first : anterior set, posterior set2. The name must indicate where the focus of radiograph is, What are the teeth appear in the

radiograph (e.g.) in anterior set: central projection, lateral-canine projection In posterior set: premolar projection, molar projectionAll these called periapical radiograph which focus on the apex and the anatomy around the apex.The other type bitewing which the patient bite on a wing, the upper and lower teeth appear in the same radiograph as molar projection and premolar projection

- When we put all these intraoral radiographs together it called : full mouth series in general its 18(14 periapical and 4 bitewing)

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- Full mouth series: group of radiographs complete each other, at the end you must see all teeth and structures around the apex, surfaces of the teeth, all apices!, and beyond.

- Surfaces is important thing if the teeth are superimposed on each other so we cant see initial caries, all surfaces mean proximal surfaces.

Performance criteria:- Image quality: does the radiograph clear enough to be good diagnostic tool or not

1. Density of radiograph (adjust (mA) , (kVp) the highest kilo voltage used in producing a radiograph).

2. Positioning! : every position has set up and holder.

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- Image mounting!: that’s mean when you see a radiograph for upper central you must know that this tooth is upper central, that’s why anatomy is importantIf you see sinus then its maxillaIf you see mental foramen, incisive foramen, internal oblique ridge then its mandible.

Periapical radiograph

General consideration of PA, what make PA is a good one:- 2-3 mm of alveolar bone visible beyond the apex- All around teeth- Occlusal plane parallel to edge of receptor not to be crooked because of the dimension of the

receptor fixed so any angle produced(not parallel) we will loss part of the apical or the crown of the tooth

- Projection:1. Centeral projection:

Centrals in center and as much as possible of the lateral.The contact between centrals incisor must appear open contact(mesial surface of right central and mesial surface of left central) these surfaces must not superimposed to detect small carious lesion.In severe crowded teeth we may not open contact.We put the receptor in the holder inside patient mouth and the cone of x-ray machine on the extra oral part of the holder, you put the cone against the film in the orientation you need and set up the x-ray machine and that’s it.

The holder in the clinic color coded for anterior teeth, posterior teeth, Endo treatment, bitewing radiograph.the holder save the orientation of thing to keep it in the angle we need parallel or perpendicular.2-Lateral-canine projection:

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Open contact must appear (distal surface of lateral tooth and mesial surface of canine )

3-Posterior set, mainly the Premolar projection:

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distal surface of canine must appear, and premolars, we have to open two contact, the contact between canine and first premolar and the contact between two premolars

4-Molar projection:

We go more distal, challenge to show distal surface of last tooth,Open contact between first molar and second molar

Anterior teeth long so when we take anterior projection we put the film vertical Posterior teeth wide so when we take posterior projection we put the film horizontal

Bitewing radiograph

These radiograph have equal distrupution between maxilla and mandible and parallel

used to detect proximal caries

Premolar bitewing I have to see the distal of canine and the premolar and the open contact between 3 and 4, 4 and 5.

favor maxillary contact to be open because its wider contact than mandibular one, and maxillary

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interproximal caries harder to detect on examination.

Projection: 90 degree on contact (perpendicular to contact) to see the two adjacent teeth separate.

In the premolar bitewing the 90 degree in the maxilla not the same as in mandible, and if you can’t open both open the maxillary periapical radiograph of maxilla appear at real step angle

In the periapical of mandible not really, so the geometry in the maxilla in periapical very distorted.

So, here the bitewing radiograph open contact in the maxillary teeth and to open the contact in mandibular teeth we take periapical radiograph because its already opened contact.

Why we take premolar bitewing and molar bitewing?

As we take in prosto lab the premolar found in the A line differ from the molar angle so when we take the premolar bitewing we have to open contact between premolar and maybe cant open it between molar and visa versa to molar bitewing.

-bitewing is very easy and simple to the patient and the doctor.- why do we have vertical and horizontal projections ?- the structures we need to radiograph are the teeth and the bone, some times we use horizontal projection but the will not appear in radiograph so we change to vertical projection to include the bone in the image for example in periodontits patients we make vertical projection to detect if there's a bone loss.the doc displayed radiographs for central, lateral-canine, molar projections and bitewing radiograph.

-Now how I will get the open contact and prevent the distortion?by the paralleling technique.

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in the paralleling technique: 1-the receptor must be parallel to the long axis of the tooth2-the central ray must be perpendicular to both the long axis of the tooth and the receptorbut how we could do that? By film holders we can hold the receptors and then we put the other part of the holder (circle) on the x-ray tube this will adjust the angle automatically at 90 degree

film holder film holder on Dexter

this will ensure that there's no distortion and we can adjust the open contact as we need-object to film distance:must be small as possible but not zero and less by the definition from source to object distance(the tooth and the film must not be attached to each other because if they attached this will break the parallelism ).

-Source to object distance: must be large as possible as we can to make the rays of the beam parallel when reach the object(teeth) so we have long cones (xray tube) to increase this distance- film holders are manufactured for regular mouth dimensions, if we some anatomical considerations like sharp palate, tori and sometimes lower anterior could be challenging -we can use cotton rolls to get more space and prevent the patient from biting all away the teeth, we learn more about this in the clinics but in general we don't put rolls up against the teeth we want to radiograph; when we take a bitewing for the mandible we put the rolls between the bite block of the holder and the maxilla- by adding these rolls we violate on the 90 degrees a little bit but if we don't use these rolls the patient may bite and injure himself or bent the film which is too bad.-IF we have a tori we must put the film behind this tori-same thing in the floor of the mouth we add cotton rolls and make a vertical angulation even if we violate the 90 degree because this will get us more space and prevent patient injury

there is another technique which is bisecting technique and we use it when we don't have holders.-it's derived from Pythagoras theorem -in bisecting angle technique we direct the central ray at right angle to the imaginary line that bisects the angle between the tooth and the film, this method results in an image with same length of the object (tooth)

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-this technique much harder than paralleling technique and may cause more distortion because of :1- you must be familiar enough with the anatomy and orientation of the teeth2-the film must be fixed in the right place3-you must determine the bisecting line by yourself -in this technique we should also think about the horizontal angulation and the vertical angulationthe horizontal angulation you must be at the right place horizontally (left and right )and perpendicular at same time thus prevent the overlap between teeththe vertical angulation must be also perpendicular :if we have angle between the rays and the bisecting line more positive we will get foreshortened image but if we have the angle more negative we will have elongated image.-film ending causes the elongation of the tooth image-in endo treatment we use special type of holders which have baskets to allow the files and the cones to get inside it while biting to take the radiograph so the patient actually bites in the proximal teeth of the endo treated tooth

endoray holder with basketsocclusal radiography : we use large films so it show more structures and it considers a supplementary, it is either maxillary or mandibular there is no bitewing here

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There is subtypes of the occlusal radiographs :

1-cross sectional: the rays are perpendicular on the film 2- topographical : the rays are not perpendicular and the are sensitive to the anatomy which may interfere with some structures the maxilla can only be radiographed by topographical and not cross sectional because if we want to take a cross sectional at 90 degree there will be many structures in the image and this doesn't make sense we usually use occlusal radiograpghs when we look for something big like cyst , trauma ,fractures or stones in the salivary glands

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Web viewThe name must indicate where the focus of radiograph is, What are the teeth appear in the radiograph