Periapical Periapical radiographyradiography

Main indicationsMain indications

Detection of periapical infectionDetection of periapical infection

Assessment of the periodontal statusAssessment of the periodontal status

After trauma to the teeth and associated alveolar After trauma to the teeth and associated alveolar bonebone

Assessment of the presence and position of Assessment of the presence and position of unerupted teethunerupted teeth

During endodonticsDuring endodontics

Preoperative assessment and Preoperative assessment and postoperative appraisal of apical surgerypostoperative appraisal of apical surgery

Detailed evaluation of bone lesionsDetailed evaluation of bone lesions

Implant evaluationImplant evaluation

Ideal positioning requirementsIdeal positioning requirements

The tooth under investigation and the film The tooth under investigation and the film packet should be in contact or ,if not packet should be in contact or ,if not feasible, as close as possiblefeasible, as close as possible

The tooth and the film packet should be The tooth and the film packet should be parallel to one another parallel to one another

The film packet should be positioned with The film packet should be positioned with its long axis vertically for incisors and its long axis vertically for incisors and canines, and horizontally for premolars canines, and horizontally for premolars and molars with sufficient film beyond the and molars with sufficient film beyond the apices to record the apical tissuesapices to record the apical tissues

The positioning should be reproducibleThe positioning should be reproducible

The X-ray tubehead should be positioned The X-ray tubehead should be positioned so that the beam meets the tooth and the so that the beam meets the tooth and the film at right angles in both the vertical and film at right angles in both the vertical and the horizontal planesthe horizontal planes

Positioning of the instrumentPositioning of the instrument

Theoretical basis of the bisected Theoretical basis of the bisected angle techniqueangle technique

Advantages of the paralleling Advantages of the paralleling techniquetechnique

Geometrically accurate images are Geometrically accurate images are produced with little magnification, produced with little magnification, foreshortening or elongationforeshortening or elongation

The shadow of the zygomatic buttress The shadow of the zygomatic buttress appears above the apices of the molar appears above the apices of the molar teethteeth

The horizontal and vertical angulations of The horizontal and vertical angulations of the X-ray tubehead are automatically the X-ray tubehead are automatically determined by the positioning devicedetermined by the positioning device

There is no cone cuttingThere is no cone cutting The radiographs are reproducibleThe radiographs are reproducible The technique is useful for some patients The technique is useful for some patients

with disabilitieswith disabilities

Disadvantages of the paralleling Disadvantages of the paralleling techniquetechnique

Positioning of the film packet for the Positioning of the film packet for the posterior teeth can cause gaggingposterior teeth can cause gagging

The anatomy of the mouth sometimes The anatomy of the mouth sometimes makes the technique imposible, e.g a makes the technique imposible, e.g a shallow, flat palateshallow, flat palate

The apices of the teeth can sometimes The apices of the teeth can sometimes appear very near the edge of the filmappear very near the edge of the film

The technique cannot be performed The technique cannot be performed satisfactory using a short focal spot to skin satisfactory using a short focal spot to skin distance because of the resultant distance because of the resultant magnificationmagnification

The holders need to be autoclavableThe holders need to be autoclavable Positioning the holders in the lower third Positioning the holders in the lower third

molar region can be very difficultmolar region can be very difficult

Advantages of the bisected angle Advantages of the bisected angle techniquetechnique

Positioning of the film packet is relatively Positioning of the film packet is relatively simple and comfortable for the patientsimple and comfortable for the patient

If the angulations are assessed correctly If the angulations are assessed correctly the image should be diagnosticablethe image should be diagnosticable

DisadvantagesDisadvantages

Incorrect vertical angulation results in Incorrect vertical angulation results in foreshortening or elongation of the imageforeshortening or elongation of the image

The shadow of the zygomatic buttress The shadow of the zygomatic buttress overlies the roots of the upper molarsoverlies the roots of the upper molars

Incorrect horizontal angulation results in Incorrect horizontal angulation results in overlapping of the crowns or cone cuttingoverlapping of the crowns or cone cutting

The periodontal bone levels are poorly The periodontal bone levels are poorly shownshown

It is not possible to obtain reproducible It is not possible to obtain reproducible viewsviews

The buccal roots of the maxillary The buccal roots of the maxillary premolars and molars are foreshortenedpremolars and molars are foreshortened