mandibular landmarks of radiograph

EKLAVYA DENTAL COLLEGE AND HOSPITAL

DEPARTMENT OF ORAL MEDICINE AND

RADIOLOGYTOPIC : RADIOGRAPHIC MANDIBULAR LANDMARKS

GUIDED BY

SUBMITTED BYDR. SWATI GOEL(M.D.S) – HOD AND READERDR. VISHESH YADAV(M.D.S.) – SENIOR LECTURER

A. AFSANAFINAL YEARBATCH 2016-17

RADIOGRAPHIC NORMAL

ANATOMICAL LANDMARKS OF

MANDIBLE

RADIOPAQUE STRUCTURES

1. ENAMEL2. DENTIN3. CEMENTUM4. LAMINA DURA5. ALVEOLAR CREST6. CANCELLOUS BONE7. GENIAL TUBERCLES8. MENTAL RIDGE9. MYLOHYOID RIDGE10.INTERNAL OBLIQUE RIDGE11.EXTERNAL OBLIQUE RIDGE12.INFERIOR BORDER OF MANDIBLE

RADIOLUCENT STRUCTURES

1.PULP2.PERIODONTAL LIGAMENT SPACE3.NUTRIENT CANALS4.LINGUAL FORAMEN5.SYMPHYSIS6.MENTAL FOSSA7.MENTAL FORAMEN8.MANDIBULAR CANAL9.SUBMANDIBULAR FOSSA

TOOTH STRUCTURE

ENAMEL : The densest structure and seen as the outer most radiopaque layer of the crown of a tooth on the radiogragh.

DENTIN : It is found beneath the enamel layer and appears radiopaque and comprises most of the tooth structure. It is less radiopaque than enamel.

CEMENTUM – it is not usually apparent on the radiograph because the cemental layer is very thin.

SUPPORTING STRUCTURE

1. LAMINA DURA2. ALVEOLAR CREST

3. PERIODONTAL SPACE4. CANCELLOUS BONE

Lamina dura

Definition: It is the wall of the tooth socket that surrounds the root.

On Radiograph : Thin radiopaque line that

surrounds the root.

It is continuous with the shadow of the cortical bone at the alveolar crest

Double lamina dura - appears if the mesial and distal surfaces of root present in the path of x-ray beam

Intact lamina dura around tooth - a vital pulp.

Definition: This is the most coronal portion of the alveolar bone found between the teeth.

Alveolar Crest

On Radiograph :•Radiopaque line•Located 1.5-2mm below CEJ•Appears - A point of bone in anterior teeth; flat in posterior. •Recede apically with age •Markable resorption with periodontal disease

•Continuing with lamina dura and forms a sharp angle → Rounding angle indicative periodontal disease

Definition: I t i s the space be tween the roo t and the l amina dura and i t con ta ins connec t ive t i s sue f iber s , b lood vesse l s and lymphat ics .

Periodontal ligament space

On Radiograph :•Thin Radiolucent line•Its of uniform thickness and presents around the root.•Width of PDL varied by individual, teeth & location; thinner in the middle of the root, slightly widened near the alveolar crest & apex.•Its thickness less around – roots of embedded tooth and those lost their antagonists.

Periodontal ligament space

Definition: This is the spongy bone located between two layers of dense cortical bone

Cancellous Bone

On Radiograph :It appears predominantly radiolucent with the trabeculae appearing radiopaque in a criss-cross pattern.

Anteriorly – trabeculae are thicker, coarser and fewer

Posteriorly – trabeculae are fine, and have larger marrow spaces than anterior region.

Cancellous Bone

Structures of mandible• Symphysis• Genial tubercle• Lingual foramen• Nutrient canals• Mental ridge• Mental fossa• Mental foramen• Mandibular canal• Mylohyoid ridge• Submandibular gland fossa• External oblique ridge• Inferior border of mandible• Coronoid process

Symphysis

• It is the suture in the midline of the mandible.

• It fuses by the end of first year of life, after which it is not radiographically evident.

• On Radiograph : appears radiolucent line through the midline of jaw

Mandibular symphysis In a new born infant Mandibular symphysis

fracture

Genial Tubercles

• These are tiny bumps of bone on the lingual side of the mandible, approximately in the midline.

• serves as attachment for the genioglossus and the geniohyoid muscles.

• Well visualized on standard occlusal film

Genial Tubercles

• On Radiograph : appear as ring shaped radiopacities below the apices of mandibular incisors

Lingual Foramen

• It is a tiny opening in the bone located on the internal surface of the mandible, near the midline and surrounded by the genial tubercles.

• On Radiograph : A small radiolucent dot inferior to the apices of the mandibular incisors.

Nutrient canals

• These are tube like passages through the bone that contain nerves and blood vessels that supply the teeth.

• On Radiograph : • Vertical radiolucent lines• More prominent in anterior

region and in edentulous mandible.

Mental ridge

• It is a linear bony prominence found on the labial Aspect (external portion) of the mandible

• Extends from the premolar region to the midline and slopes upward turn as it approaches it.

• It appears as a Radio opaque line below the apices of anterior teeth.

Mental fossa

• This is a scooped out depressed area of the bone located on the external surface of the anterior mandible.

On Radiograph : • radiolucent area above mental

ridge• More prominent in anterior

region and in edentulous mandible.

mental fossa : this represents the depression on the labial aspect of the mandible overlying the roots of the incisors. The resultant radiolucency may be mistaken for pathology

Mandibular incisor region

mental fossa

Lingual foramen Genial tubercle

Mental ridge

Mental Foramen

• Its an opening in the bone located on the external surface of the mandible, in the region of premolars.

On Radiograph : A small ovoid or round radiolucent area in the apical region of the premolars.

Mental foramen

Mylohyoid ridge

• located on the lingual surface of the mandible, extending from third molar area to Premolar region, serves as an attachment for the mylohyoid muscle.

On Radiograph : • Dense radiopaque band extends

downwards and forward from the molar region.

• It may appear continuous with internal oblique ridge.

Internal Oblique Ridge

• Linear prominence of bone located on the internal surface of the mandible.

• Extends downwards and forwards from the ramus

• It may end in the region of third molar or it may continue as the mylohyoid ridge.

• On Radiograph : Radiopaque band that extends

downwards and forwards from the ramus

Depending upon the technique used, the internal and external oblique ridges may appear superimposed on one another.

When the ridges appear seperate., then the superior band is external oblique ridge (white arrows) and the inferior radiopaque band (black arrows) is the

internal oblique ridge.

External Oblique Ridge

• Linear prominence of bone located on the internal surface of body of the mandible.

On Radiograph : • Radiopaque band that extends

downwards and forwards from anterior border of the ramus.

• It typically ends in the region of third molar.

Submandibular fossa • It’s a scooped out depressed

area of the bone located on the internal surface of the mandible inferior to the mylohyoid line.

• It houses the submandibular salivary gland.

On Radiograph : Radiolucent area in the molar

region below the mylohyoid ridge.

Mandibular premolar region

A – mylohyoid ridge B - mandibular canal c – submandibular gland fossa d – mental foramen

Mandibular molar region

A – external oblique ridgeB – mylohyoid ridge C – mandibular canalD- submandibular gland fossa

Mandibular Canal

• It is a tube like passage through the bone that travels the length of the mandible.

• Extends from mandibular foramen to mental foramen.

On Radiograph : A radiolucent band outlined by two thin radiopaque lines that represent the cortical walls of the canal.

• It may appear below or superimposed on the mandibular molar teeth.

Inferior border of the Mandible

• As the name suggests is the lower border of the mandible.

• Its rarely seen on the periapical projections.

On Radiograph : Dense Radiopaque band of bone

Coronoid process• Marked prominence of bone on

the anterior ramus of the mandible.

• It’s the site for attachment of the muscles of mastication.

• On Radiograph : A triangular radiopacity superimposed

over or inferior to the maxillary tuberosity region.

Its seen on IOPA of maxillary molar, not a mandibular periapical radiograph.

RESTORATIVE MATERIALSRADIOPAQUE• SILVER AMALGAM• GOLD• STAINLESS STEEL PINS• GUTTA-PERCHA• ORTHODONTIC

APPLIANCES• ZINC PHOSPHATE

CEMENT

RADIOLUCENT• SILICATES• COMPOSITE• PORCELAIN• CALCIUM HYDROXIDE

AMALGAM GUTTA PERCHA

CAST CROWNS ORTHODONTIC APPLIANCES

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