INTRODUCTION

Radiographic recognition of disease requires knowledge of radiographic appearance of normal structures.

RADIOLUCENT LANDMARKS OF MAXILLA

Tooth- Pulp

Periodontal structures Periodontal ligament spaceBone marrow spaces

Incisive foramen

Intermaxillary suture

Nasal fossa

Nasopalatine canals

Lateral fossa

Naso lacrimal canal

Maxillary sinus

RADIOPAQUE LANDMARKS OF MAXILLA

Tooth- Enamel, Dentin

Periodontal structures Cementum, lamina dura ,Trabecular pattern

Anterior nasal spine

Naso labial fold

Zygomatic process of maxilla

Zygomatic arch

Pterygoid plates

Hamulus

Maxillary tuberosity

Nasal septum

Coronoid process

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 greator attenuation of X-ray photons.

RADIOGRAPHIC APPEARANCE OF DENTIN

75% mineral content less radiopaque than enamel. Radiopacity similar to bone.

ENAMELODENTINAL JUNCTION appears as a distinct interface separating these two structures.

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.

.

Radiographic Appearance of the Pulp

It is composed of soft tissues so it appears radiolucent.

Pulp chambers and root canals extend from the interiors of the chamber till the root apices.

It is seen radiographically also as apical foramen.

ENAMEL

PULP

DENTIN

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

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.

Lamina Dura -hard layer –radiographic terminology.Anatomically – edge of cortical bone.Appears –radiopaque.

Double lamina dura- buccal and lingual eminences on the mesial surface of mandibular 1st molar roots.

Periodontal ligament space-Appears as radiolucent space between lamina dura and the root .

Alveolar crest- Appears as radiopaque . Normal level-1.5 mm from CEJ . It is the radiopaque gingival margin of the alveolar

process which surrounds the teeth.

Flat proximal tooth surface- Convex tooth surface-

narrow alveolar crest flat alveolar crest

Cancellous bone or Trabecular bone or Spongiosa

Appears as thin radiopaque plates (trabeculae ) surrounding small radiolucent marrow spaces.

Anterior maxilla-mesh or network pattern

Thin ,numerous,fine ,granular ,dense .With smaller marrow spaces and numerous

Posterior maxilla-mesh or network pattern

Similar to anterior maxilla with marrow spaces slightly larger

Anterior mandible- (Trajectory pattern)(Stepladder pattern-central incisors)

Thicker ,coarser .oriented more horizontally .fewer with large marrow spaces

Posterior mandible-Trajectory pattern or linear pattern)(Stepladder pattern-1st molar)

Comparable to anterior mandible ,with larger marrow spaces ,sparse trabeculation inferiorly.

RADIOLUCENT LANDMARKS OF MAXILLA Intermaxillary suture/Median maxillary suture/Mid

pallatine sutureAppears between two portions of premaxilla May terminate as V shape widening at alveolar crest

Incisive foramen or Nasopalatine or Anterior palatine foramen –

Location-behind maxillary central incisorsSize –varies- 2mm – 1cm or more

Average-3*3 mm

Normal limits- <6 mm Shape-varies-slit like, round ,oval ,heart shape ,diamond

shape

Nasal fossa –Appears on IOPA of maxillary anterior teeth .

Superior foramen of nasopalatine canal-Viewed in maxillary occlusal radiograph

Lateral fossa or incisive fossa- Depression in maxilla near apex of lateral incisor Appears diffuse radiolucent.

Nasolacrimal canal –

Commonly seen in occlusal films.Oval shaped in the region of molars.

Occlusal radiograph

NASOLACRIMAL CANALThe nasal and maxillary bones form the

nasolacrimal canal.

It runs from the medial aspect of the antero inferior border of the orbit inferiorly, to drain under the inferior conchae into the nasal cavity.

RADIOGRAPHIC FEATURES OF MAXILLARY SINUSMAXILLARY SINUS is an air containing cavity

lined by mucous membrane.Appears as the three sided pyramid .

Base -formed by mesial wall adjacent to nasal cavity.

Apex –extending laterally into the zygomatic process of maxilla.

Maxillary sinus /Antrum

Floor of maxillary sinus Small maxillary sinus does not appear on radiograph

Maxillary sinus extending into alveolar bone Large maxillary sinus extending int maxillary

tuberosity area

Inverted Y

Formed by bony structures between Formed by anterior wall of maxillary

maxillary sinus and nasal cavity sinus and floor of nasal fossa

RADIOPAQUE LANDMARKS OF MAXILLA

Anterior nasal spine –Located in midline 1.5 -2 cm above alveolar crestUsually V shaped .

Inferior nasal concha-Appears as hazy shadow extending from the right and left lateral walls for varying distance towards the septum

Nasal septum-Appears as radiopaque arising in the midline from the anterior nasal spine.

Ref: Oral radiology –white and pharoah 6thedition

Nasal mucosa-Appears as hazy

shadow on each side

of nasal septum.

Floor of nasal fossa-Radiopaque line extending bilaterally away from the base of anterior nasal spine.

Ref: Oral radiology –white and pharoah 6thedition

Nasolabial fold –Appears in canine –premolar region

Shadow of tip of noseAppears over roots of central incisors

Zygomatic bone (Malar bone)U shaped

Zyomatic arch-Appears as uniform opacity over the apices of molars

Coronoid process of mandible-Triangular area of opacity Superimposed on maxillarym tuberosity

Maxillary tuberosity-Terminal protuberance

Pterygoid plates-Lies immediately posterior to tuberosity of maxilla Hamular process-extends inferiorly from medial

pterygoid plate.

CONCLUSIONA good diagnosis mandateed appreciation of a wide

range of variation in the appearance of normal structures

Most patients demonstrates many of the normal radiological landmarks , but it is a rare patient who shows them all .

Hence absence of one or several landmarks in any individual should not be necessarily considered abnormal.

REFERENCESText book of dental and maxillofacial radiology-

karjodhkar 2nd editionOral radiology –white and pharoah 6th editionEssentials of dental radiography and radiology-Eric

Whites 4th edition