Panoramic Imaging

Panoramic Imaging

Panoramic ImagingIt is a technique for producing a single tomographic image of the facial structures that includes both the maxillary and mandibular dental arches and their supporting structures.

Or Pantomography

Panoramic ImagingOr Pantomography

Panoramic ImagingAdvantages:Broad coverage Low patient radiation doseConvenience of the examinationUseful in patients who are unable to open their mouthsShort time required: 3-4 minsUseful visual aid

Panoramic ImagingIndications:Evaluation of traumaLocation of third molarsExtensive dental or osseous diseaseKnown or suspected large lesionsTooth developmentRetained teeth or root tipsTMJ painStudy of sinusesDevelopmental anomalies

Panoramic ImagingDisadvantages:Magnification, Geometric distortion & overlapped images.Resolution of fine anatomic details of peri-apical area and periodontal structures is less.The spinal cord superimpose the anterior region.Common to have overlapped teeth images especially in premolars.Expensive

Principles of Panoramic Image FormationFirst described by Numata and independently by Paatero in the late 1940sMovement of the film and objects about 2 fixed centers of rotation.

Principles of Panoramic Image Formation

Movement of the film and objects (A, B, C, and D) about two fixed centers of rotation. Pb, Lead collimator

Principles of Panoramic Image Formation

Movement of the film and x-ray source about one fixed center of rotation. Pb, Lead collimator

Principles of Panoramic Image Formation

Movement of the film and x-ray source about a shifting center of rotation. Pb, Lead collimator

Principles of Panoramic Image Formation

Movement of the x-ray source and beam.

Image Layer

Is a 3-D curved zone, or focal trough where the structures lying within this layer are reasonably well defined on final panoramic image.The images seen on the OPG consists largely of anatomic structures located within the focal troughObjects out of focal trough are blurred, magnified, reduced or distorted.The shape of the focal trough varies with the brand of equipments used.Or Focal Trough

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Image LayerFactors that affect image layer size:Arc pathVelocity of the receptor and x-ray tube headAlignment of the x-ray beamCollimator width

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Image Layer

Mandible supporting a metal ring positioned at the center of the focal trough. The incisal edges of the mandibular teeth are indexed by a bite rod-positioning device. The Mandible is positioned at the center of the trough.

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Image LayerRing 5 mm anterior to Focal Trough

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Image LayerRing 5 mm posterior to Focal Trough

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Image LayerThis distortions result from the reciprocal horizontal movements of the receptor and x-ray source.

When the mandible is displaced to the lingual side of its optimal position in the image layer, the beam passes more slowly through it. The images of the structures are elongated horizontally thus, appear wider.

When the mandible is displaced toward the buccal, the beam passes at a rate faster than normal through the structures, thus appear thinner.

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Interpreting the Panoramic ImageThe FOUR Diagnostic Regions in a Panoramic Image:Maxillary Region

Mandibular RegionDentoalveolar RegionTMJ, including retromaxillaryand cervical region

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Interpreting the Panoramic ImageMaxillary Region:

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Interpreting the Panoramic ImageMaxillary Region:

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Interpreting the Panoramic ImageMandibular Region:

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Interpreting the Panoramic ImageMandibular Region:

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Interpreting the Panoramic ImageDentoalveolar Region:

Shape and angulation of rootsAlveolar bone and periodontiumShows gentle curve of occlusal planeMissing 3rd molarsPresence of metallic restorations

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Interpreting the Panoramic ImageSoft Tissue Images:

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Interpreting the Panoramic ImageSoft Tissue Images:

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Interpreting the Panoramic ImageAirspace:

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Interpreting the Panoramic ImageAirspace:

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