Anatomical landmarks in Periapical and Orthopantomogram X-ray

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Anatomical landmarksin

PA and OPG

Rizgar S.

Ishık University School of DentistryDiagnostic Department

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Anatomical landmarksin PA

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• Introduction: • Periapical radiograph is a type of Intra oral

view in which the film is placed inside patient’s mouth and radio graphed using various techniques. . (Bisected angle, paralleling. .)

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• The interpretation of radiographs plays an important role in the dental office. Several abnormalities are diagnosed solely by or with help of radiographs. For this reason the training in the interpretation of dental radiographs plays an import-ant role in the curriculum of dental students and hygienists.

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Peiapical Films Show:• Teeth• Dental Germ

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• Tooth Consists of:– Enamel(RO)– Dentine(RO but less than enamel)– Cementum(RO & Similar density to dentine)– Pulp chamber & root Canals (RL)

RO=Radio opaque RL=Radiolucent

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Investing Structures Are: Cancellous Bone (Mixed RO & RL) Lamina Dura (RO) . . Normally it appears

surrounding and parallel to root of tooth as RO line . . Periodontal Membrane Space Is The RL between Then . . It Should Be Of Uniform Thickness Normally

Cortical Crest (RO) . . .Anteriorly It In Knife Edge Appearance

Posteriorly . . Flattened

RO=Radio opaque RL=Radiolucent

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Normal Maxillary Anatomical Landmarks:

1-Anterior Region:

• Radolucent Structures:

Nasal Fossa

W Shaped Radiolucency . . . May Be MisInterpretated As Soft Tissue Tumor . . .To Make Sure It Is Nasal Fossa use Shift Skitch TechniqueIf Lesion Persists In Place : It Is Pathosis If Changes its Position: It Is Nasal Fossa

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Incisive Foramen:

It is the opening in the midline of the palate just posterior to the central incisors.  it gives  passage  to  the nasopalatine artery and nerve  .

It  should  not  be  misdiagnosed  As Dental Infection Or Cyst. 

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Median Palatine Suture:

• is the line down the center of the maxilla where embryonic palatal shelves joined at the midline to form the hard palate.It Should Not be misdiagnosed As fracture line nor fistulous tract . . .

• To diffrentiate . . .• Fracture line will be acoompaigned by 

history of trauma, it will be irregular RL Line, Will not be bordered By 2 RO Lines . . .

• Fistulous tract: by applying RO material through the lesion . . . the tortuous course of the tract can be observed

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Incisive Fossa:

• Also Called Canine Fossa . . And It Is the indentation between the roots of the central and lateral incisors, and the canine fossa is between the roots of the lateral incisor and canine.

• It should not be Misdiagnosed As pathological condition. . If So Radiograph the other side for comparison. .

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• Nasopalatine Canals: If Exaggerated vertical Angle is used 

they may appear as projections of maxillary Incisors . . .

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Rdiopaque Structures:Median Nasal Septum:

It is the thin wall of bone in the midline of the face that separates the right and left nasal fossae. . In Some cases unusual density may denote supernumerary tooth, mesiodens, or a retained root . . .

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• Anterior Nasal Spine:

It is the triangular protuberance of bone that extends forward from the inferior aspect of the nasal cavity at the midline. . .

It Should Not Be MisInterpretated As remaining root, Odon tome , Impaction, Foreign Body . . .

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Nasal Turbinates:

Cartilaginous radiopacity that may appear on anterior maxillary radiographs is the inferior conch or inferior nasal turbinate. There are actually three turbinates on each side of the nasal antrum; however, only the most inferior of these is routinely projected onto the periapical view of the incisor region.

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Nasal Cartilage:

It is the soft tissue of the tip of the nose. .It Appears as RO Shadow superimposed over incisors’ Roots . . It Is Uniform Opacity With Sharp Borders. .

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Rdiopaque Structures:

Malar Bone:

It Is where Zeugmatic Bone Attach To Maxilla …It Appears As Well Defined RO Area super Imposed over Maxillary Molar Roots. . So Interpretation of this view is difficult . . . But effort may be exerted and different angulations may be

used to shift this zygomatic shadow. . It may be misdiagnosed as impacted teeth or foreign

bodies

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4-Regions Posterior To Upper Third Molar

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Normal Mandibular Anatomical Landmarks:

Radiopacities

1. Genial Tubercles

The genial tubercles are small bony spines found on the lingual aspect of the mandible adjacent to the midline at the attachment of the geniohyoid and genioglossus muscles.

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• 2)-MENTAL RIDGE:

The mental ridges are elevated ridges of bone located along the anterior aspect of the mandible. The ridges are also known as the mental tubercles and fuse at the mid-line to form the mental protuberance, the anterior most aspect of the mandible. This periapical radiograph demonstrates the radiopaque margin of the mental ridges. Study these and compare the varying appearance of these landmarks.

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• 3)-Lingual Foramen:

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4)-Interdental Nutrient Canals:

They Contain Blood Vessels And Nerves That Supply teeth And Investing Structures . . They Appear as RL Lines of uniform width and sometimes exhibit RO margins . . .they are clearly seen In Patients with edentulous Mouth. .

They Should Not Be MisInterpretated As Fracture Lines . .If so They will be irregular lines with previous history of trauma . .

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2-Premolar Region:

The Most Important Structure In This Area Is Mental foramen.

• The best way to differentiate periapical disease from the mental foramen is to identify the periodontal membrane space to see if it is confluent with the radiolucent opening.

Periapical lesion - Mental foramen Mental foramen - Periapical lesion

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3-Molar Region:

Mandibular Canal:

The inferior alveolar nerve and artery pass through the mandible through a structure called the mandibular canal. The mandibular canal extends from the mandibular foramen, on the lingual aspect of the ramus, through the body of the mandible under the roots of the molar teeth.

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• SubMandibular Fossa:

Directly below the internal oblique ridge is a depression in the lingual aspect of the mandible called the submandibular fossa.

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Lower Border Of Mandible:

The lower border of the mandible is the thick cortical plate that forms the lower edge of the mandible. The solid thickness of bone along the inferior border of the mandible is seen in the radiograph as a uniform wide radiopaque band at the margin of the mandible.

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Intra Orally:

The internal oblique ridge (or mylohyoid line) is an eminence of bone extending along the lingual aspect of the mandible. It serves as the attachment point for the chief muscle of the mouth floor, the mylohyoid muscle. This drawing shows the location and direction of mylohyoid muscle, which is attached to the mandible at the internal oblique ridges.Radiographically the internal oblique ridge appears as a radiopaque band extending from the terminal molar region to the premolar area, as seen in this periapical projection. Note that part of the mandibular canal is visible just below the mylohyoid line and is often superimposed on the image of the internal oblique ridge.

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Extra Orally: 

• The external oblique ridge is a ridge of bone located along the facial of the mandible, which extends from the superior aspect of the posterior body of the mandible down to the necks of the molar teeth. It runs in the same direction as the internal oblique ridge, but is located on the facial, or external surface of the mandible. The external oblique ridge serves as the attachment point for the buccinator muscle, as demonstrated in this drawing. The next two periapical projections demonstrate the radiographic appearance of the external oblique ridge. To distinguish radiographically between the internal and external oblique ridges, note that the external ridge is always superior to the internal oblique ridge. In this image the external oblique ridge is denoted by white arrows while the internal oblique ridge is demarcated by black arrows.

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Anatomical landmarksin OPG -Orthopantomograph-

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Panoramic radiograph:

is a panoramic scanning dental X-ray of upper and lower jaw. It shows a two-dementional view of half-circle from ear to ear.

Abbrevuiatoins used are:PAN, OPT, DPR and OPG..

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Indications:

OPG is used to provide information about: Diagnosis and treatment planning of impacted wisdom teeth. diagnosis of developmental anomalies like cherubsim, cleido cranial

dysplasia Carcinoma in relation to the jaws. Periodontal bone loss plus periapical involvement. finding source of pain. assessment of for the placement of dental implants. orthodontic assessment Diagnosis of osteosarcoma, ameloblastoma, renal ostiodystrophy and

hypophoaphatemia. dentoalviolar fractures salivary stone TMJ problems and ankylosis..

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Projection of OPG

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Anatomical landmarks

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Soft tissues on OPG

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42Thanks