NORMAL RADIOGRAPHIC ANATOMICAL LANDMARKS

DR. DIVYA RANA

a

bc

a : enamel

B : dentin

C : pulp

Cervical burnout :Radiographs sometimes showDiffuse radiolucent areasWith ill defined borders Present on mesial n distal Aspects of teeth in cervical region

These regions appear between The edge of the enamel capAnd the crest of the alveolar Ridge.

It should not be confused withRoot caries.

Lamina dura:It is a thin radio-opaque Layer Of dense bone surrounding the Tooth socket.

It is thicker than the surrounding Trabecular bone and thickness Increases with increase in amount In the occlusal stress

Alveolar crest

The gingival margin of theAlveolar process that extendsBetween the teeth isApparant on radiographsAs radiopaque line calledAlveolar crest.

It is considered as normal If it is not > than 1.5 mm From cej of adjacent teeth.

Periodontal ligament spacePDL space is primarily composed of collagen, so appers as radiolucent Space between tooth root and lamina dura.

Cancellous bone : it lies between the cortical plates in both the jaws.It is composed of thin radiopaque plates and rods surronding manySmall radiolucent marrow spaces.

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Landmarks of maxilla

median palatine sutureNasal fossaNasal septumAnterior nasal spineIncisive foramenLateral fossaMaxillary sinusMalar boneMaxillary tuberosityHamular processNasolacrimal duct

Maxillary anterior region

Nasal septum

Nasal fossa

Nasal spine

Insicive foramen

Nose

Median palatine suture

A-Nasal septum

B-Nasal fossa

C-Anterior nasal spine

D-Incisive foramen

E-Median palatine suture

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b

c d

e

Nasal cavities Nasal septum

Anterior nasal spine

Median palatine suture

1 .Nasal septum (17): appears as a

radio-opaque line that separates

the two nasal fossa in the

midline.

2. Anterior nasal spine (16): appears

as a V-shaped radio-opaque

structure in the midline above

the incisive foramen.

3. Incisive foramen (12): or the anterior

palatine fossa, it usually appears

as a prominent radiolucent area

above or between roots of two

central incisors, it usually appears

round or oval in shape and doesn’t

exceed 6mm in diameter.

Palatal view

Median palatine suture

Median palatine suture

Appears as a vertically orientedRadiolucent line in true image projections through the midline.Usually prominent between the two central incisor roots in Young individuals.

Palatal view

Incisive foramen

Red arrow points to periapical lesion

periapical cyst

Red arrow :mesiodens

mesiodens

Incisive canal cyst

Facial view

Nasal septum

Facial view

Nasal fossa

Soft tissues of nose

Red arrow : soft tissues of nose Green arrow :lip line

Floor of nasal fossa

Maxillary sinus

Lateral fossa

Nose

Maxillary canine

a: Floor of nasal fossa b: Maxillary sinus c: Lateral fossa

a

b

c

Floor of nasal fossa (red arrow) and anterior border of maxillary sinus (blue arrows),forming the inverted (upside down ) Y

Lateral fossa : the radiolucency results from a depression Above and posterior to the lateral incisor. To help rule Out a pathology, look for an intact lamina dura Surrounding the adjacent bone.

The maxillary sinus surroundsThe root of the canine,Which may be misinterpreted As pathology.

Black arrows indicate the floor of the nasal fossa ,the max sinus (red arrows) has pneumatized bet the 2nd PMAnd 1st molar.

Sinus septum

Zygomatic process

Maxillary sinus

Maxillary premolar region

a: Malar process c: Sinus septum d: Maxillary sinus

ac

da c

d

Maxillary sinus

zygoma

ptrygoid plate

Hamular process

Coronoid process maxillary tuberosity

Maxillary molar region

Maxillary sinus :

The maxillary sinus with Its thin bony walls, its thin mucosa, and its vastAir space, produce anExtremely dark imageDeep to the maxillary Teeth.

Its outlines, particularly its Floor, are clearly delineatedBy delicate radio-opaquelines

1- body of zygoma

6- apices of roots

7 - floor of the sinus

8- septum of the sinus

molar region

In general ,the floor of the sinus isApproximately coincidental with The location of the apices of the Roots of the upper teeth (bicuspidsAnd first two molars ).

But there is often as much as two Or even three mm of maxillary Bone between the root ends andSinus floor.

In other cases the sinus floor dips so deeply between the roots of theMaxillary teeth that the latter appear to project into it for as much as One half of their length

Pneumanization :expansion of sinus wall into surrounding bone, usually in an area where teeth have been lost prematurely.

It increases with age .

a

c

d

e

ge

g

d

c a

b

f

f

A :max tuberosity e : zygoma (dotted lines) B :coronoid process f : max sinusC : hamular process g :sinus recessD: pterygoid plates

Image of the imacted third molar superimposed

Malar (zygomatic) process. U or j- shaped Radio-opacity, often superimposed over the roots Of the molars, specially when using the bisecting Angle technique. The red arrows define the Lower border of the zygomatic bone.

Maxillary tuberosity : the rounded elevation located at the posterior aspect of both sides of the maxilla.

Malar bone : or the zygomaticProcess. The inferior portion Of the malar bone appears As a radio-opaque, U shaped structureRelated to the roots of the first Maxillary molar. It represents theAttachment of the zygomatic boneTo the maxilla.

Maxillary tuberosity: appears As a radio-opaque structure that Extends distally and upward from Posterior to maxillary sinus. It Represents the end of maxilla.

Black arrows : hamular processPurple arrows : pterygoid plates

Coronoid process : it is seen as a radio-opaque structure in maxillay molar iopa.

Hamular process: It is a bony spine extending from Pterygoid process of the sphenoid Bone. It appears as a radio-opaqueSpine that is recorded on radiographsDistal to the tuberosity of maxillaAnd extends downward.

Coronoid process of the mandible:Appears as a triangular radio-opaque structure projected into the same general area of max periapical film projections distal to the maxillary teeth.

The zygomatic process (green) is a U shaped rationality. Normally the Zygomatic bone posterior to this is very dense and radio-opaque. In this, however the max sinus has expanded into the zygomatic bone and makes the area more radiolucent (red). The coronoid process (orange), the pterygoid plates (blue) and the max tuberosity (pink) are also identified .

Nasolacrimal duct : It is seen in occlusal view of the maxilla as a round radiolucent area superimposed on the posterior region of the hard palate.

Landmarks of mandible

Lingual foramenGenial tuberclesMental ridgeMental foramenMental fossaExternal oblique lineInternal oblique lineMylohyoid lineMandibular foramenInferior alveolar canalSubmandibular gland fossaNutrient canals

Mandibular symphysis In a new born infant

Symphysis Fracture

Mandibular incisor region

mental fossa

Lingual foramen Genial tubercle

Mental ridge

ab

cd

C :mental ridge D: mental fossa

A: lingual foramen b: genial tubercles

Lingual foramen : radiolucent ‘hole ’ in centre of genial tubercles. Lingual nutrient vessels pass through this foramen .

Lingual foramen

It is set in the midline deep To the apices of theAnterior teeth.

It appears as a small Radiolucent dot at the Symphysis area usuallySurrounded by a radioOpaque structure.

Genial tubercles : radio-opaque area in the midline surrounding The lingual foramen

Genial tubercles:They appear as radio Opaque circle that surrounds the lingual foramen just below the apices of the Of the incisors.

mental ridge

Mental ridge :it is a bony prominence found on the labial Aspect of the mandible near its inferior border and extendedFrom the premolar region to the symphysis area on wchichIt takes an upward turn as it approaches it. It appears as a Radio opaque line below the apices of anterior teeth.

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

Nutrient canals :

The arrows above identify nutrientCanals.They are most often seen inPersons with thin bone and inThose with high blood pressure Or advanced periodontitis.

Nutrient canals

Mental foramen (3)

It appears as a radiolucent, ill defined area between the apices of bicuspids.

it represents the anterior Terminates of the mandibular canal.

6- caries

7- prepared cavity

8- enostosis

9 –mental foramen

Mandibular premolar region

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

b -Mandibular canal

d -Mental foramen

a- Mylohyoid ridge

c -Submandibular gland fossa

db a

c

mental foramen

Mandibular molar region

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

A -External oblique ridge

c -Mandibular canal

B - Mylohyoid ridge

D -Submandibular gland fossa

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c

b

d

External oblique ridge - a continuation of the anterior border of ramus passing downward and forward on the buccal side of the mandible. It apperas as a radio-opaque line which usually ends anteriorly in the Area of the first molar. The red arrow points to the mylohyoid ridge.

The external oblique ridge (red) and the mylohyoid ridge (blue)Usually run parallel to each other , with the external oblique ridgeAlways being higher on the film .

Internal oblique ridge -

It appears as a radio opaque Line, descending downwardsAnd forward from coronoid Process, in a horizontalPosition, stop at the third Molar area or become cotinuousWith the mylohyoid lineIts placed below the externalOblique ridge.

Mylohyoid ridge (internal oblique) – located on the lingual Surface of the mandible , extending from third molar area to Premolar region

Mandibular canal : arises at the mandibular foramen on the Lingual side of the ramus and passes downward and forward, Moving from the lingual side in the third molar region to the buccal Side in the premolar region.It contains the inferior alveolar nerves and vessels.

The mandibular canals (red arrows) usually runs very close to the molars

Green arrow showing dilaceration of roots.

The other film shows impaction at the superior border of the canal .

Bifid mandibular canal: a) cone beam sectionb) Cross section

Submandibular gland fossa

Submandibular gland fossa -

It is a depression on the lingualAspect of the mandible on whichSubmandibular glands arePresent.

It appears as a zone of Radiolucency below theLower molars

A – external oblique ridge B – mylohyoid ridge c – mandibular canal D – submandibular gland fossa

ab

c

d

THANK YOU

PRESENTED BY: DR. DIVYA RANA