landmarks pinali

NORMAL RADIOGRAPHIC ANATOMICAL LANDMARKS

Dr. PINALI DAS1 st Year PG

Guided by:DR SANAT KUMAR BHUYANDEPT OF ORAL MEDICINE AND RADIOLOGY

CONTENTS

Introduction Tooth anatomy Supporting structures Anatomical landmarks

Radiographic Density

Radiopacity – light on film

Radiolucency - dark on film

Radiopaque vs. Radiolucent

Radiopaque: refers to a light area on the filmStructures that are absorbers of x-rays block

the x-rays from reaching the filmThe x-rays are attenuated (decreased in

intensity) by absorbing structuresFewer photons reach the emulsionDense structures are strong absorbers

Radiopaque vs. Radiolucent

Radiolucent: refers to a dark area on the filmStructures that are less dense are poor absorbers and allow more photons to reach the film emulsion

Tooth Anatomy

Teeth are composed primarily of dentin, with an enamel cap over the coronal portion and a thin layer of cementum over the root surface.

Radiographic Appearance of Enamel ENAMEL appears more radio-opaque than other

tissues.It is 90% mineral ;causes greater attenuation of X-ray photons.

enamel

RADIOGRAPHIC APPEARANCE OF DENTIN

75% mineral content ;less radiopaque than enamel. Radiopacity similar to bone. DENTINO ENAMEL JUNCTION appears as a distinctinterface separating these two structures.

Dentin DEJ

RADIOGRAPHIC APPEARANCE OF CEMENTUM 50%mineral content and it appears as a very thin

layer on the root surface. It is usually not so apparent radiographically.

CERVICAL BURNOUT Radiographs sometimes show diffuse radiolucent areas with ill defined borders

present on the mesial or distal aspects of the teeth in the cervical region.

These regions appear between the edge of the enamel cap and the crest of the alveolar ridge.

REASON FOR CERVICAL BURNOUT

Normal configuration of the affected teeth, results in decreased X-ray absorption in the areas in question.

Perception of these areas is due to contrast with the adjacent ,relatively radiopaque enamel and alveolar –bone.

It should not be confused with root caries which has similar appearance.

Supporting Structures

Periodontal ligament space

Lamina dura

Alveolar crest

Trabecular bone

Radiopaque structures common to maxillary and mandibular radiographs

1.ENAMEL2.DENTIN3.CEMENTUM4.LAMINA DURA5.ALVEOLAR CREST6.TRABECULAE OF BONE

Radioluscent structures common to maxillary and mandibular radiographs

1.PERIODONTAL LIGAMENT SPACE2.BONE MARROW SPACE3.PULP4.NUTRIENT CANALS

Radioopaque structues in maxillary

radiographs 1.MAXILLARY TUBEROSITY 2.CORONOID PROCESS OF MANDIBLE 3.ZYGOMATIC PROCESS 4.NASAL SEPTUM 5.ANTERIOR NASAL SPINE 6.SHADOW OF NOSE 7.FLOOR OF NASAL CAVITY 8.INFERIOR NASAL CONCHA 9.WALL,FLOOR AND SEPTA OF MAXILLARY SINUS 10.INVERTED Y OF ENNIS 11.NASOLABIAL FOLD 12.PTERYGOID PLATE AND HAMULAR PROCESS

Radioluscent structures in maxillary radiographs

1.MAXILLARY SINUS2.INCISIVE FORAMEN3.MEDIAN PALATAL SUTURE4.NASAL FOSSA,NASAL CAVITY5.SUPERIOR FORAMINA OF

NASOPALATINE CANAL6.LATERAL FOSSA7.NASOLACRIMAL CANAL

Radioopaque structues in mandibular radiographs

1.BORDER OF MANDIBLE2.EXTERNAL OBLIQUE RIDGE3.GENIAL TUBERCLE4.MENTAL RIDGE5.MYLOHYOID RIDGE6.MANDIBULAR CANAL WALLS

Radioluscent structures in mandibular radiographs

1.MANDIBULAR FORAMEN2.MANDIBULAR CANAL3.MENTAL FORAMEN,MENTAL FOSSA4.SYMPHYSIS5.LINGUAL FORAMEN6.NUTRIENT CANAL7.SUBMANDIBULAR FOSSA

Maxillary IncisorNasal septum

Inferior concha

Nasal fossa

Nasal spine

Incisive foramen

Nose Median palatine suture

Nasal septum

facial view

a

Inferior concha

facial view

Nasal fossa

facial view

Anterior nasal spine

facial view

Incisive foramen

palatal view

Median palatal suture

palatal view

Soft tissue of the nose

a

db

Red arrows = lip line

Superior foramina of the nasopalatine canals (red arrows). These foramina lie in the floor of the nasal fossa. The nasopalatine canals travel downward to join in the incisive foramen.

The red arrows point to the soft tissue of the nose. The green arrows identify the lip line.

Maxillary Canine

Floor of nasal fossa

Maxillary sinus

Lateral fossa

Nose

a = floor of nasal fossab = maxillary sinusc = lateral fossa

(a & b form inverted Y)

a

cb

a

c

b

facial view

Lateral fossa. The radiolucency results from a depression above and posterior to the lateral incisor. To help rule out pathology, look for an intact lamina dura surrounding the adjacent teeth.

facial view

Soft tissue of the noseRed arrows point to nasolabial fold.

The maxillary sinus surrounds the root of the canine, which may be misinterpreted as pathology.

The black arrows indicate the floor of the nasal fossa. The maxillary sinus (red arrows) has pneumatized between the 2nd premolar and first molar

Zygomatic process

Sinus septumSinus recess

Maxillary sinus

Maxillary Premolar

Maxillary Sinus. An air-filled cavity lined with mucous membrane. Communicates with nasal cavity through 3-6 mm opening below middle concha. Red arrows point to neurovascular canal containing superior alveolar vessels and nerves.

facial view

Malar (zygomatic) process. U or j-shaped radiopacity, often superimposed over the roots of the molars, especially when using the bisecting-angle technique. The red arrows define the lower border of the zygomatic bone.

facial view

Sinus septum. This septum is composed of folds of cortical bone that arise from the floor and walls of the maxillary sinus, extending several millimeters into the sinus. In rare cases, the septum completely divides the sinus into separate compartments.

facial view

Sinus recess. Increased area of radiolucency caused by outpocketing (localized expansion) of sinus wall. If superimposed over roots, may mimic pathology.

facial view

Maxillary Molar Maxillary sinus

Sinus recessZygoma

Pterygoid plate

Hamularprocess

Coronoid process Maxillary tuberosity

g

d

a

e

f

a = maxillary tuberosity* e = zygoma (dotted lines)b = coronoid process f = maxillary sinusc = hamular process g = sinus recessd = pterygoid plates

* image of impacted third molar superimposed

c

b

facial view

d

ba

e

c f

g

Maxillary Tuberosity. The rounded elevation located at the posterior aspect of both sides of the maxilla. Aids in the retention of dentures.

facial view

Hamular process (black arrows) and pterygoid plates (purple arrows). The hamular process is an extension of the medial pterygoid plate of the sphenoid bone, positioned just posterior to the maxillary tuberosity.

facial view

Zygomatic (malar) bone/process/arch. The zygomatic bone (white/black arrows) starts in the anterior aspect with the zygomatic process (blue arrow), which has a U-shape. The zygomatic bone extends posteriorly into the zygomatic arch (green arrow).

facial view

The zygomatic process (green arrows) is a prominent U-shaped radiopacity. Normally the zygomatic bone posterior to this is very dense and radiopaque. In this patient, however, the maxillary sinus has expanded into the zygomatic bone and makes the area more radiolucent (red arrows). The coronoid process (orange arrow), the pterygoid plates (blue arrows) and the maxillary tuberosity (pink arrows) are also identified.

Mandible

symphysis

Radiolucent line to the midline of the jaw between the central incisors .

This suture usually fuses by the end of the first year of life – after which it is no longer radiographically apparent.

If radiolucency found- it is abnormal (# or cleft).

Genial tubercles

Located on lingual surface , above the inferior border and in the midline.

Bony protuberances , spine shaped divided into right , left, superior and inferior protuberances.

Genioglossus muscle attached at the superior tubercles. Geniohyoid muscles attached at the inferior tubercles.

Mental fossa

It is a depression on the labial aspect of mandible extending laterally from the midline and above the mental ridge.

Image may be similar to submandibular fossa and may be mistaken for periapical disease involving the incisors.

Mental fossa. This represents a depression on the labial aspect of the mandible overlying the roots of the incisors. The resulting radiolucency may be mistaken for pathology.

facial view

The orange arrows above identify nutrient canals. They are most often seen in older persons with thin bone, and in those with high blood pressure or advanced periodontitis.

Mandibular Incisor

Mental ridge

Genial tubercles Lingual foramen

Mental fossa

c

b = mandibular canald = mental foramen

a = mylohyoid ridge (internal oblique)c = submandibular gland fossa

facial view lingual view

c

add b

Mylohyoid (internal oblique) ridge. This radiopaque ridge is the attachment for the mylohyoid muscle. The ridge runs downward and forward from the third molar region to the area of the premolars.

lingual view

facial view

Mandibular canal. (Inferior alveolar canal). Runs downward from the mandibular foramen to the mental foramen, passing close to the roots of the molars. More easily seen in the molar periapical.

lingual view

Submandibular gland fossa. The depression below the mylohyoid ridge where the submandibular gland is located. More obvious in the molar periapical film.

Mental foramen. Usually located midway between the upper and lower borders of the body of the mandible, in the area of the premolars. May mimic pathology if superimposed over the apex of one of the premolars.

facial view

Mandibular Molar

a = external oblique ridgeb = mylohyoid ridgec = mandibular canald = submandibular gland fossa

facial view lingual view

b

c

ab

a = external oblique ridgec = mandibular canal

b = mylohyoid ridged = submandibular gland fossa

dd

ab

cdd

a = external oblique ridgeb = mylohyoid ridgec = mandibular canald = submandibular gland fossa

External oblique ridge. A continuation of the anterior border of the ramus, passing downward and forward on the buccal side of the mandible. It appears as a distinct radiopaque line which usually ends anteriorly in the area of the first molar. Serves as an attachment of the buccinator muscle. (The red arrows point to the mylohyoid ridge).

facial view

The external oblique ridge (red arrows) and the mylohyoid ridge (blue arrows) usually run parallel with each other, with the external oblique ridge always being higher on the film.

facial view

Mandibular (inferior alveolar) canal. Arises at the mandibular foramen on the lingual side of the ramus and passes downward and forward, moving from the lingual side of the mandible in the third molar region to the buccal side of the mandible in the premolar region. Contains the inferior alveolar nerve and vessels.Its positon in relation to impacted tooth is important during disimpaction.

lingual view

Submandibular gland fossa. A depression on the lingual side of the mandible below the mylohyoid ridge. The submandibular gland is located in this region. Due to the thinness of bone, the trabecular pattern of the bone is very sparse and results in the area being very radiolucent. The fact that it occurs bilaterally helps to differentiate it from pathology.

Restorative materials

Vary in their radiographic appearance , depending primarily on their thickness, density, and anatomic number. ( the anatomic number is most influential).

Silver amalgam is Most commonly seen, is completely radiopaque.

Gold is equally opaque to x-rays, whether cast as a crown or inlay or condensed as gold foil.

TEST

Nasal septum

A. The radiopacity identified by the blue arrows is the ?

B. The orange arrow identifies the ?

Blue-mylohyoid ridgeOrange-mandibular canal

Nutrient canals

.

Mental ridge

A. The red arrow points to the ?B. The white arrows identify the ?C. The blue arrow points to the ?D. The yellow arrow identifies the ?

A. Coronoid process B. Maxillary sinus (pneumatized into maxillary tuberosity) C. Sinus septum D. Zygomatic process

Mental foramen

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