Chapter 27

Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.

Chapter 27Chapter 27

Normal Anatomy: Normal Anatomy:

Intraoral ImagesIntraoral Images

Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 2

Dental RadiographyDental Radiography

QuestionsQuestions What is the difference between cortical and What is the difference between cortical and

cancellous bone?cancellous bone? What normal anatomic landmarks of the maxilla What normal anatomic landmarks of the maxilla

and mandible are apparent on dental radiographs?and mandible are apparent on dental radiographs? What is the radiographic appearance of tooth What is the radiographic appearance of tooth

anatomy?anatomy?



Chapter 27 Reading Chapter 27 Reading Iannucci & Howerton (pp. 325-344)Iannucci & Howerton (pp. 325-344)



Chapter 27 OutlineChapter 27 Outline Normal Anatomy: Intraoral FilmsNormal Anatomy: Intraoral Films

Definitions of general termsDefinitions of general terms Normal anatomic landmarksNormal anatomic landmarks Normal tooth anatomyNormal tooth anatomy


IntroductionIntroduction

Iannucci & Howerton (pp. 326)Iannucci & Howerton (pp. 326) PurposePurpose

To review the normal anatomy of the maxilla and To review the normal anatomy of the maxilla and mandible as viewed on the skullmandible as viewed on the skull

To describe the normal anatomic landmarks seen To describe the normal anatomic landmarks seen on intraoral radiographson intraoral radiographs


Definitions of General TermsDefinitions of General Terms

Types of boneTypes of bone Prominences of boneProminences of bone Spaces and depressions in boneSpaces and depressions in bone Miscellaneous termsMiscellaneous terms


Types of BoneTypes of Bone

Iannucci & Howerton (pp. 326-327) (Figs. 27-1 Iannucci & Howerton (pp. 326-327) (Figs. 27-1 through 27-3)through 27-3)

Cortical boneCortical bone The dense outer layer of boneThe dense outer layer of bone Appears radiopaque on a radiographAppears radiopaque on a radiograph

Cancellous boneCancellous bone The soft, spongy bone located between two layers The soft, spongy bone located between two layers

of dense cortical boneof dense cortical bone Appears primarily radiolucentAppears primarily radiolucent

• Trabeculae appear radiopaque, marrow spaces appear Trabeculae appear radiopaque, marrow spaces appear radiolucentradiolucent


Prominences of BoneProminences of Bone

Iannucci & Howerton (pp. 326-328) (Figs. 27-4 Iannucci & Howerton (pp. 326-328) (Figs. 27-4 through 27-8)through 27-8)

Process: marked prominence or projectionProcess: marked prominence or projection Ridge: linear prominence or projectionRidge: linear prominence or projection Spine: sharp, thornlike projectionSpine: sharp, thornlike projection Tubercle: small bump or noduleTubercle: small bump or nodule Tuberosity: rounded prominenceTuberosity: rounded prominence


Spaces and Depressions in BoneSpaces and Depressions in Bone

Iannucci & Howerton (pp. 328-330) (Figs. 27-9, Iannucci & Howerton (pp. 328-330) (Figs. 27-9, 27-10)27-10)

Canal – tubelike passageway through bone Canal – tubelike passageway through bone that contains nerves and blood vesselsthat contains nerves and blood vessels

Foramen – opening or hole that permits the Foramen – opening or hole that permits the passage of nerves and blood vesselspassage of nerves and blood vessels

Fossa – broad, shallow, scooped-out, or Fossa – broad, shallow, scooped-out, or depressed areadepressed area

Sinus – hollow space, cavity, or recessSinus – hollow space, cavity, or recess


Miscellaneous TermsMiscellaneous Terms

Iannucci & Howerton (pp. 327-328) (Fig. 27-11)Iannucci & Howerton (pp. 327-328) (Fig. 27-11) SeptumSeptum

A bony wall or partition that divides two spaces or A bony wall or partition that divides two spaces or cavitiescavities

RadiopaqueRadiopaque SutureSuture

An immovable joint representing a line of union An immovable joint representing a line of union between adjoining bones of the skullbetween adjoining bones of the skull

A thin radiolucent lineA thin radiolucent line


Normal Anatomic LandmarksNormal Anatomic Landmarks

Iannucci & Howerton (pp. 328)Iannucci & Howerton (pp. 328) Bony landmarks of the maxillaBony landmarks of the maxilla Bony landmarks of the mandibleBony landmarks of the mandible


Bony Landmarks of the MaxillaBony Landmarks of the Maxilla

Iannucci & Howerton (pp. 328-329) (Fig. 27-12)Iannucci & Howerton (pp. 328-329) (Fig. 27-12) The upper jaw is composed of two paired The upper jaw is composed of two paired

bones, the maxillae.bones, the maxillae. The paired maxillae meet at the midline of the The paired maxillae meet at the midline of the

face.face. Forms the Forms the

Floor of the orbit of the eyeFloor of the orbit of the eye Sides and floor of the nasal cavitiesSides and floor of the nasal cavities Hard palateHard palate



Incisive foramenIncisive foramen Superior foramina of the incisive canalSuperior foramina of the incisive canal Median palatal sutureMedian palatal suture Lateral fossaLateral fossa Nasal cavityNasal cavity Nasal septumNasal septum Floor of the nasal cavityFloor of the nasal cavity Anterior nasal spineAnterior nasal spine



Inferior nasal conchaeInferior nasal conchae Maxillary sinusMaxillary sinus

Septa within the maxillary sinusSepta within the maxillary sinus Nutrient canals within the maxillary sinusNutrient canals within the maxillary sinus

Inverted YInverted Y Maxillary tuberosityMaxillary tuberosity HamulusHamulus Zygomatic process of the maxillaZygomatic process of the maxilla ZygomaZygoma


Incisive Foramen Incisive Foramen (Nasopalatine Foramen)(Nasopalatine Foramen)

Iannucci & Howerton (pp. 329-330) (Fig. 27-13)Iannucci & Howerton (pp. 329-330) (Fig. 27-13) DescriptionDescription

An opening or hole in bone that is located at the An opening or hole in bone that is located at the midline of the anterior portion of the hard palate midline of the anterior portion of the hard palate directly posterior to the maxillary central incisorsdirectly posterior to the maxillary central incisors

AppearanceAppearance A small ovoid or round radiolucent area located A small ovoid or round radiolucent area located

between the roots of the maxillary central incisorsbetween the roots of the maxillary central incisors


Superior Foramina of the Superior Foramina of the Incisive CanalIncisive Canal


Two tiny openings or holes in bone that are Two tiny openings or holes in bone that are located on the floor of the nasal cavitylocated on the floor of the nasal cavity

Join together to form the incisive canalJoin together to form the incisive canal AppearanceAppearance

Two small round radiolucencies located superior Two small round radiolucencies located superior to the apices of the maxillary central incisorsto the apices of the maxillary central incisors


Median Palatal SutureMedian Palatal Suture

Iannucci & Howerton (p. 330) (Fig. 27-15) Iannucci & Howerton (p. 330) (Fig. 27-15) DescriptionDescription

The immovable joint between the two palatine The immovable joint between the two palatine processes of the maxillaprocesses of the maxilla

AppearanceAppearance A thin radiolucent line between the maxillary A thin radiolucent line between the maxillary

central incisorscentral incisors


Lateral FossaLateral Fossa


A smooth, depressed area of the maxilla located A smooth, depressed area of the maxilla located just inferior and medial to the infraorbital foramen just inferior and medial to the infraorbital foramen between the canine and lateral incisorsbetween the canine and lateral incisors

AppearanceAppearance A radiolucent area between the maxillary canine A radiolucent area between the maxillary canine

and lateral incisorsand lateral incisors


Nasal CavityNasal Cavity

Iannucci & Howerton (p. 331) (Fig. 27-17)Iannucci & Howerton (p. 331) (Fig. 27-17) DescriptionDescription

A pear-shaped compartment of bone located A pear-shaped compartment of bone located superior to the maxillasuperior to the maxilla• The inferior portion is formed by the palatal processes of The inferior portion is formed by the palatal processes of

the maxilla and the horizontal portions of the palatine the maxilla and the horizontal portions of the palatine bones.bones.

AppearanceAppearance A large radiolucent area above the maxillary A large radiolucent area above the maxillary

incisorsincisors


Nasal SeptumNasal Septum


A vertical bony wall or partition that divides the A vertical bony wall or partition that divides the nasal cavity into the right and left nasal fossaenasal cavity into the right and left nasal fossae

Formed by the vomer and a portion of the ethmoid Formed by the vomer and a portion of the ethmoid bone and cartilagebone and cartilage

AppearanceAppearance A vertical radiopaque partition that divides the A vertical radiopaque partition that divides the

nasal cavitynasal cavity


Floor of the Nasal CavityFloor of the Nasal Cavity


A bony wall formed by the palatal processes of the A bony wall formed by the palatal processes of the maxilla and the horizontal portions of the palatine maxilla and the horizontal portions of the palatine bonesbones

AppearanceAppearance A dense radiopaque band of bone above the A dense radiopaque band of bone above the

maxillary incisorsmaxillary incisors


Anterior Nasal SpineAnterior Nasal Spine


A sharp projection of the maxilla located at the A sharp projection of the maxilla located at the anterior and inferior portion of the nasal cavityanterior and inferior portion of the nasal cavity

AppearanceAppearance A V-shaped radiopaque area located at the A V-shaped radiopaque area located at the

intersection of the floor of the nasal cavity and the intersection of the floor of the nasal cavity and the nasal septumnasal septum


Inferior Nasal ConchaeInferior Nasal Conchae


Wafer-thin, curved plates of bone that extend from Wafer-thin, curved plates of bone that extend from the lateral walls of the nasal cavitythe lateral walls of the nasal cavity

Conchae Conchae means shell-shaped or scroll-shaped.means shell-shaped or scroll-shaped. AppearanceAppearance

A diffuse radiopaque mass or projection within the A diffuse radiopaque mass or projection within the nasal cavitynasal cavity


Maxillary SinusMaxillary Sinus


DescriptionDescription Paired cavities or compartments of bone located Paired cavities or compartments of bone located

within the maxillawithin the maxilla Located above the maxillary premolar and molar Located above the maxillary premolar and molar

teethteeth AppearanceAppearance

A radiolucent area located above the apices of the A radiolucent area located above the apices of the maxillary premolars and molarsmaxillary premolars and molars


Septa within the Maxillary SinusSepta within the Maxillary Sinus


DescriptionDescription Bony walls or partitions that appear to divide the Bony walls or partitions that appear to divide the

maxillary sinus into compartmentsmaxillary sinus into compartments AppearanceAppearance

Radiopaque lines within the maxillary sinusRadiopaque lines within the maxillary sinus Presence and number vary depending on the Presence and number vary depending on the

anatomy of the individual.anatomy of the individual.


Nutrient Canals within the Nutrient Canals within the Maxillary SinusMaxillary Sinus


Tiny, tubelike passageways through bone that Tiny, tubelike passageways through bone that contain blood vessels and nervescontain blood vessels and nerves

AppearanceAppearance A narrow radiolucent band bounded by two thin A narrow radiolucent band bounded by two thin

radiopaque linesradiopaque lines


Inverted YInverted Y


The intersection of the maxillary sinus and the The intersection of the maxillary sinus and the nasal cavitynasal cavity

AppearanceAppearance A radiopaque upside-down Y formed by the A radiopaque upside-down Y formed by the

intersection of the lateral wall of the nasal fossa intersection of the lateral wall of the nasal fossa and the anterior border of the maxillary sinusand the anterior border of the maxillary sinus

Located above the maxillary canineLocated above the maxillary canine


Maxillary TuberosityMaxillary Tuberosity


A rounded prominence of bone that extends A rounded prominence of bone that extends posterior to the third molar regionposterior to the third molar region

AppearanceAppearance A radiopaque bulge distal to the third molar regionA radiopaque bulge distal to the third molar region


HamulusHamulus


A small hooklike projection of bone extending from A small hooklike projection of bone extending from the medial pterygoid plate of the sphenoid bonethe medial pterygoid plate of the sphenoid bone

AppearanceAppearance A radiopaque hooklike projection posterior to the A radiopaque hooklike projection posterior to the

maxillary tuberosity areamaxillary tuberosity area


Zygomatic Process of the MaxillaZygomatic Process of the Maxilla


DescriptionDescription A bony projection of the maxilla that articulates A bony projection of the maxilla that articulates

with the zygoma or malar (cheek) bonewith the zygoma or malar (cheek) bone AppearanceAppearance

A J- or U-shaped radiopacity located superior to A J- or U-shaped radiopacity located superior to the maxillary first molar regionthe maxillary first molar region


ZygomaZygoma


DescriptionDescription Articulates with the zygomatic process of the Articulates with the zygomatic process of the

maxillamaxilla AppearanceAppearance

A diffuse, radiopaque band extending posteriorly A diffuse, radiopaque band extending posteriorly from the zygomatic process of the maxillafrom the zygomatic process of the maxilla


Bony Landmarks of the MandibleBony Landmarks of the Mandible

Iannucci & Howerton (pp. 335-336) (Fig. 27-34)Iannucci & Howerton (pp. 335-336) (Fig. 27-34) The largest and strongest bone of the faceThe largest and strongest bone of the face Divided into three main partsDivided into three main parts

RamusRamus• Vertical portion found posterior to the third molarVertical portion found posterior to the third molar

BodyBody• Horizontal U-shaped portion from ramus to ramusHorizontal U-shaped portion from ramus to ramus

Alveolar processAlveolar process• Encases and supports the teethEncases and supports the teeth



Iannucci & Howerton (pp. 335-340)Iannucci & Howerton (pp. 335-340) Genial tuberclesGenial tubercles Lingual foramenLingual foramen Nutrient canalsNutrient canals Mental ridgeMental ridge Mental fossaMental fossa Mental foramenMental foramen



Mylohyoid ridgeMylohyoid ridge Mandibular canalMandibular canal Internal oblique ridgeInternal oblique ridge External oblique ridgeExternal oblique ridge Submandibular fossaSubmandibular fossa Coronoid processCoronoid process


Genial TuberclesGenial Tubercles


Tiny bumps of bone on the lingual aspect of the Tiny bumps of bone on the lingual aspect of the mandiblemandible

Attachment sites for genioglossus and geniohyoid Attachment sites for genioglossus and geniohyoid musclesmuscles

AppearanceAppearance A ring-shaped radiopacity below the apices of the A ring-shaped radiopacity below the apices of the

mandibular incisorsmandibular incisors


Lingual ForamenLingual Foramen


A tiny opening or hole in bone located on the A tiny opening or hole in bone located on the internal surface of the mandibleinternal surface of the mandible

AppearanceAppearance A small radiolucent dot inferior to the apices of the A small radiolucent dot inferior to the apices of the

mandibular incisorsmandibular incisors


Nutrient CanalsNutrient Canals

Iannucci & Howerton (pp. 336-337) (Fig. 27-37) Iannucci & Howerton (pp. 336-337) (Fig. 27-37) DescriptionDescription

Tubelike passageways through bone containing Tubelike passageways through bone containing nerves and blood vessels that supply the teethnerves and blood vessels that supply the teeth

Most often seen in anterior mandibleMost often seen in anterior mandible AppearanceAppearance

Vertical radiolucent lines readily seen in areas of Vertical radiolucent lines readily seen in areas of thin bonethin bone


Mental RidgeMental Ridge


A linear prominence of cortical bone located on A linear prominence of cortical bone located on the external surface of the anterior portion of the the external surface of the anterior portion of the mandiblemandible

AppearanceAppearance A thick radiopaque band that extends from the A thick radiopaque band that extends from the

premolar region to the incisor regionpremolar region to the incisor region Often appears superimposed over the mandibular Often appears superimposed over the mandibular

anterior teethanterior teeth


Mental FossaMental Fossa


A scooped-out, depressed area of bone located on A scooped-out, depressed area of bone located on the external surface of the anterior mandiblethe external surface of the anterior mandible

AppearanceAppearance A radiolucent area above the mental ridgeA radiolucent area above the mental ridge


Mental ForamenMental Foramen

Iannucci & Howerton (pp. 337-338) (Figs. 27-40)Iannucci & Howerton (pp. 337-338) (Figs. 27-40) DescriptionDescription

An opening or hole in bone located on the external An opening or hole in bone located on the external surface of the mandible in the region of the surface of the mandible in the region of the mandibular premolarsmandibular premolars

AppearanceAppearance A small ovoid or round radiolucent area located in A small ovoid or round radiolucent area located in

the apical region of the mandibular premolarsthe apical region of the mandibular premolars Frequently misdiagnosed as a periapical lesionFrequently misdiagnosed as a periapical lesion


Mylohyoid RidgeMylohyoid Ridge


A linear prominence of bone located on the A linear prominence of bone located on the internal surface of the mandibleinternal surface of the mandible

AppearanceAppearance A dense radiopaque band that extends downward A dense radiopaque band that extends downward

and forward from the molar regionand forward from the molar region


Mandibular CanalMandibular Canal


A tubelike passageway through bone that travels A tubelike passageway through bone that travels the length of the mandiblethe length of the mandible

Houses the inferior alveolar nerve and blood Houses the inferior alveolar nerve and blood vesselsvessels

AppearanceAppearance A radiolucent band outlined by two thin radiopaque A radiolucent band outlined by two thin radiopaque

lines that represent the cortical walls of the canallines that represent the cortical walls of the canal


Internal Oblique RidgeInternal Oblique Ridge

Iannucci & Howerton (pp. 338-339) (Figs. 27-43)Iannucci & Howerton (pp. 338-339) (Figs. 27-43) DescriptionDescription

A linear prominence of bone located on the A linear prominence of bone located on the internal surface of the mandible the ramusinternal surface of the mandible the ramus

AppearanceAppearance A radiopaque band that extends downward and A radiopaque band that extends downward and

forward from the ramusforward from the ramus When both appear, the external oblique ridge is When both appear, the external oblique ridge is

superior to the internal oblique ridge.superior to the internal oblique ridge.


External Oblique RidgeExternal Oblique Ridge

Iannucci & Howerton (p. 339) (Figs. 27-44, 27-45)Iannucci & Howerton (p. 339) (Figs. 27-44, 27-45) DescriptionDescription

A linear prominence of bone located on the A linear prominence of bone located on the external surface of the body of the mandibleexternal surface of the body of the mandible

AppearanceAppearance A radiopaque band extending downward and A radiopaque band extending downward and

forward from the anterior border of the ramus of forward from the anterior border of the ramus of the mandiblethe mandible


Submandibular FossaSubmandibular Fossa


A scooped-out, depressed area of bone located on A scooped-out, depressed area of bone located on the internal surface of the mandible inferior to the the internal surface of the mandible inferior to the mylohyoid ridgemylohyoid ridge

AppearanceAppearance A radiolucent area in the molar region below the A radiolucent area in the molar region below the

mylohyoid ridgemylohyoid ridge


Coronoid ProcessCoronoid Process


A marked prominence of bone on the anterior A marked prominence of bone on the anterior ramus of the mandibleramus of the mandible

Radiographic appearanceRadiographic appearance A triangular radiopacity superimposed over, or A triangular radiopacity superimposed over, or

inferior to, the maxillary tuberosity regioninferior to, the maxillary tuberosity region


Normal Tooth AnatomyNormal Tooth Anatomy

Tooth structureTooth structure Supporting structuresSupporting structures


Tooth StructureTooth Structure

Iannucci & Howerton (p. 340) (Figs. 27-48, 27-49, Iannucci & Howerton (p. 340) (Figs. 27-48, 27-49, 27-50)27-50)

Enamel – the outermost radiopaque layer of Enamel – the outermost radiopaque layer of the crown of a tooththe crown of a tooth

Dentin – comprises most of the tooth Dentin – comprises most of the tooth structure, not as radiopaque as enamelstructure, not as radiopaque as enamel

Dentinoenamel junction – the junction Dentinoenamel junction – the junction between dentin and enamelbetween dentin and enamel

Pulp Cavity – a pulp chamber and pulp Pulp Cavity – a pulp chamber and pulp canalscanals


Supporting StructuresSupporting Structures

Iannucci & Howerton (pp. 340-341) (Figs. 27-51)Iannucci & Howerton (pp. 340-341) (Figs. 27-51) Anatomy of alveolar boneAnatomy of alveolar bone

Lamina duraLamina dura Alveolar crestAlveolar crest Periodontal ligament spacePeriodontal ligament space

Shape and density of alveolar boneShape and density of alveolar bone Anterior regionsAnterior regions Posterior regionsPosterior regions


Anatomy of Alveolar BoneAnatomy of Alveolar Bone

Iannucci & Howerton (pp. 341) (Fig. 27-52)Iannucci & Howerton (pp. 341) (Fig. 27-52) Anatomic landmarks of the alveolar process Anatomic landmarks of the alveolar process

include the lamina dura, alveolar crest, and include the lamina dura, alveolar crest, and periodontal ligament space.periodontal ligament space.


Lamina DuraLamina Dura


The wall of the tooth socketThe wall of the tooth socket Made of dense cortical boneMade of dense cortical bone

AppearanceAppearance A dense radiopaque line that surrounds the root of A dense radiopaque line that surrounds the root of

a tootha tooth


Alveolar CrestAlveolar Crest


The most coronal portion of the alveolar bone The most coronal portion of the alveolar bone found between teethfound between teeth

AppearanceAppearance Appears radiopaque, typically 1.5 to 2.0 mm. Appears radiopaque, typically 1.5 to 2.0 mm.

below the cementoenamel junctionbelow the cementoenamel junction


Periodontal Ligament SpacePeriodontal Ligament Space


The space between the root of the tooth and the The space between the root of the tooth and the lamina duralamina dura

AppearanceAppearance A thin radiolucent line around the root of a toothA thin radiolucent line around the root of a tooth


Shape and Density of Alveolar BoneShape and Density of Alveolar Bone

Iannucci & Howerton (pp. 341-342) (Fig. 27-56)Iannucci & Howerton (pp. 341-342) (Fig. 27-56) Anterior regionsAnterior regions

Normal alveolar crest appears pointed and sharp Normal alveolar crest appears pointed and sharp between the teeth.between the teeth.

The alveolar crest appears as a dense radiopaque The alveolar crest appears as a dense radiopaque line in the anterior region.line in the anterior region.


Shape and Density of Alveolar BoneShape and Density of Alveolar Bone

Iannucci & Howerton (p. 342) (Fig. 27-57)Iannucci & Howerton (p. 342) (Fig. 27-57) Posterior regionsPosterior regions

Normal alveolar crest appears flat and smooth Normal alveolar crest appears flat and smooth between the teeth.between the teeth.

The alveolar crest appears less dense and less The alveolar crest appears less dense and less radiopaque than the alveolar crest seen in the radiopaque than the alveolar crest seen in the anterior region.anterior region.

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