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Chapter 27

Chapter 27. Normal Anatomy : Intraoral Images. Dental Radiography. Questions What is the difference between cortical and cancellous bone? What normal anatomic landmarks of the maxilla and mandible are apparent on dental radiographs? What is the radiographic appearance of tooth anatomy?.

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Chapter 27

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  1. Chapter 27 Normal Anatomy: Intraoral Images

  2. Dental Radiography • Questions • What is the difference between cortical and cancellous bone? • What normal anatomic landmarks of the maxilla and mandible are apparent on dental radiographs? • What is the radiographic appearance of tooth anatomy?

  3. Dental Radiography • Chapter 27 Reading • Iannucci & Howerton (pp. 325-344)

  4. Dental Radiography • Chapter 27 Outline • Normal Anatomy: Intraoral Films • Definitions of general terms • Normal anatomic landmarks • Normal tooth anatomy

  5. Introduction • Iannucci & Howerton (pp. 326) • Purpose • To review the normal anatomy of the maxilla and mandible as viewed on the skull • To describe the normal anatomic landmarks seen on intraoral radiographs

  6. Definitions of General Terms • Types of bone • Prominences of bone • Spaces and depressions in bone • Miscellaneous terms

  7. Types of Bone • Iannucci & Howerton (pp. 326-327) (Figs. 27-1 through 27-3) • Cortical bone • The dense outer layer of bone • Appears radiopaque on a radiograph • Cancellous bone • The soft, spongy bone located between two layers of dense cortical bone • Appears primarily radiolucent • Trabeculae appear radiopaque, marrow spaces appear radiolucent

  8. Prominences of Bone • Iannucci & Howerton (pp. 326-328) (Figs. 27-4 through 27-8) • Process: marked prominence or projection • Ridge: linear prominence or projection • Spine: sharp, thornlike projection • Tubercle: small bump or nodule • Tuberosity: rounded prominence

  9. Spaces and Depressions in Bone • Iannucci & Howerton (pp. 328-330) (Figs. 27-9, 27-10) • Canal – tubelike passageway through bone that contains nerves and blood vessels • Foramen – opening or hole that permits the passage of nerves and blood vessels • Fossa – broad, shallow, scooped-out, or depressed area • Sinus – hollow space, cavity, or recess

  10. Miscellaneous Terms • Iannucci & Howerton (pp. 327-328) (Fig. 27-11) • Septum • A bony wall or partition that divides two spaces or cavities • Radiopaque • Suture • An immovable joint representing a line of union between adjoining bones of the skull • A thin radiolucent line

  11. Normal Anatomic Landmarks • Iannucci & Howerton (pp. 328) • Bony landmarks of the maxilla • Bony landmarks of the mandible

  12. Bony Landmarks of the Maxilla • Iannucci & Howerton (pp. 328-329) (Fig. 27-12) • The upper jaw is composed of two paired bones, the maxillae. • The paired maxillae meet at the midline of the face. • Forms the • Floor of the orbit of the eye • Sides and floor of the nasal cavities • Hard palate

  13. Bony Landmarks of the Maxilla • Incisive foramen • Superior foramina of the incisive canal • Median palatal suture • Lateral fossa • Nasal cavity • Nasal septum • Floor of the nasal cavity • Anterior nasal spine

  14. Bony Landmarks of the Maxilla • Inferior nasal conchae • Maxillary sinus • Septa within the maxillary sinus • Nutrient canals within the maxillary sinus • Inverted Y • Maxillary tuberosity • Hamulus • Zygomatic process of the maxilla • Zygoma

  15. Incisive Foramen (Nasopalatine Foramen) • Iannucci & Howerton (pp. 329-330) (Fig. 27-13) • Description • An opening or hole in bone that is located at the midline of the anterior portion of the hard palate directly posterior to the maxillary central incisors • Appearance • A small ovoid or round radiolucent area located between the roots of the maxillary central incisors

  16. Superior Foramina of the Incisive Canal • Iannucci & Howerton (pp. 329-330) (Fig. 27-14) • Description • Two tiny openings or holes in bone that are located on the floor of the nasal cavity • Join together to form the incisive canal • Appearance • Two small round radiolucencies located superior to the apices of the maxillary central incisors

  17. Median Palatal Suture • Iannucci & Howerton (p. 330) (Fig. 27-15) • Description • The immovable joint between the two palatine processes of the maxilla • Appearance • A thin radiolucent line between the maxillary central incisors

  18. Lateral Fossa • Iannucci & Howerton (pp. 330-331) (Fig. 27-16) • Description • A smooth, depressed area of the maxilla located just inferior and medial to the infraorbital foramen between the canine and lateral incisors • Appearance • A radiolucent area between the maxillary canine and lateral incisors

  19. Nasal Cavity • Iannucci & Howerton (p. 331) (Fig. 27-17) • Description • A pear-shaped compartment of bone located superior to the maxilla • The inferior portion is formed by the palatal processes of the maxilla and the horizontal portions of the palatine bones. • Appearance • A large radiolucent area above the maxillary incisors

  20. Nasal Septum • Iannucci & Howerton (p. 331) (Fig. 27-18) • Description • A vertical bony wall or partition that divides the nasal cavity into the right and left nasal fossae • Formed by the vomer and a portion of the ethmoid bone and cartilage • Appearance • A vertical radiopaque partition that divides the nasal cavity

  21. Floor of the Nasal Cavity • Iannucci & Howerton (p. 332) (Fig. 27-19) • Description • A bony wall formed by the palatal processes of the maxilla and the horizontal portions of the palatine bones • Appearance • A dense radiopaque band of bone above the maxillary incisors

  22. Anterior Nasal Spine • Iannucci & Howerton (p. 332) (Fig. 27-20) • Description • A sharp projection of the maxilla located at the anterior and inferior portion of the nasal cavity • Appearance • A V-shaped radiopaque area located at the intersection of the floor of the nasal cavity and the nasal septum

  23. Inferior Nasal Conchae • Iannucci & Howerton (pp. 332-333) (Fig. 27-21) • Description • Wafer-thin, curved plates of bone that extend from the lateral walls of the nasal cavity • Conchae means shell-shaped or scroll-shaped. • Appearance • A diffuse radiopaque mass or projection within the nasal cavity

  24. Maxillary Sinus • Iannucci & Howerton (pp. 332-333) (Figs. 27-22, 27-23) • Description • Paired cavities or compartments of bone located within the maxilla • Located above the maxillary premolar and molar teeth • Appearance • A radiolucent area located above the apices of the maxillary premolars and molars

  25. Septa within the Maxillary Sinus • Iannucci & Howerton (pp. 332-333) (Figs. 27-24, 27-25) • Description • Bony walls or partitions that appear to divide the maxillary sinus into compartments • Appearance • Radiopaque lines within the maxillary sinus • Presence and number vary depending on the anatomy of the individual.

  26. Nutrient Canals within the Maxillary Sinus • Iannucci & Howerton (p. 334) (Fig. 27-26) • Description • Tiny, tubelike passageways through bone that contain blood vessels and nerves • Appearance • A narrow radiolucent band bounded by two thin radiopaque lines

  27. Inverted Y • Iannucci & Howerton (p. 334) (Fig. 27-27) • Description • The intersection of the maxillary sinus and the nasal cavity • Appearance • A radiopaque upside-down Y formed by the intersection of the lateral wall of the nasal fossa and the anterior border of the maxillary sinus • Located above the maxillary canine

  28. Maxillary Tuberosity • Iannucci & Howerton (p. 334) (Fig. 27-28) • Description • A rounded prominence of bone that extends posterior to the third molar region • Appearance • A radiopaque bulge distal to the third molar region

  29. Hamulus • Iannucci & Howerton (pp. 334-335) (Fig. 27-29) • Description • A small hooklike projection of bone extending from the medial pterygoid plate of the sphenoid bone • Appearance • A radiopaque hooklike projection posterior to the maxillary tuberosity area

  30. Zygomatic Process of the Maxilla • Iannucci & Howerton (pp. 334-335) (Figs. 27-30, 27-31) • Description • A bony projection of the maxilla that articulates with the zygoma or malar (cheek) bone • Appearance • A J- or U-shaped radiopacity located superior to the maxillary first molar region

  31. Zygoma • Iannucci & Howerton (pp. 335-336) (Figs. 27-32, 27-33) • Description • Articulates with the zygomatic process of the maxilla • Appearance • A diffuse, radiopaque band extending posteriorly from the zygomatic process of the maxilla

  32. Bony Landmarks of the Mandible • Iannucci & Howerton (pp. 335-336) (Fig. 27-34) • The largest and strongest bone of the face • Divided into three main parts • Ramus • Vertical portion found posterior to the third molar • Body • Horizontal U-shaped portion from ramus to ramus • Alveolar process • Encases and supports the teeth

  33. Bony Landmarks of the Mandible • Iannucci & Howerton (pp. 335-340) • Genial tubercles • Lingual foramen • Nutrient canals • Mental ridge • Mental fossa • Mental foramen

  34. Bony Landmarks of the Mandible • Mylohyoid ridge • Mandibular canal • Internal oblique ridge • External oblique ridge • Submandibular fossa • Coronoid process

  35. Genial Tubercles • Iannucci & Howerton (pp. 335-336) (Fig. 27-35) • Description • Tiny bumps of bone on the lingual aspect of the mandible • Attachment sites for genioglossus and geniohyoid muscles • Appearance • A ring-shaped radiopacity below the apices of the mandibular incisors

  36. Lingual Foramen • Iannucci & Howerton (p. 336) (Fig. 27-36) • Description • A tiny opening or hole in bone located on the internal surface of the mandible • Appearance • A small radiolucent dot inferior to the apices of the mandibular incisors

  37. Nutrient Canals • Iannucci & Howerton (pp. 336-337) (Fig. 27-37) • Description • Tubelike passageways through bone containing nerves and blood vessels that supply the teeth • Most often seen in anterior mandible • Appearance • Vertical radiolucent lines readily seen in areas of thin bone

  38. Mental Ridge • Iannucci & Howerton (p. 337) (Fig. 27-38) • Description • A linear prominence of cortical bone located on the external surface of the anterior portion of the mandible • Appearance • A thick radiopaque band that extends from the premolar region to the incisor region • Often appears superimposed over the mandibular anterior teeth

  39. Mental Fossa • Iannucci & Howerton (pp. 337-338) (Fig. 27-39) • Description • A scooped-out, depressed area of bone located on the external surface of the anterior mandible • Appearance • A radiolucent area above the mental ridge

  40. Mental Foramen • Iannucci & Howerton (pp. 337-338) (Figs. 27-40) • Description • An opening or hole in bone located on the external surface of the mandible in the region of the mandibular premolars • Appearance • A small ovoid or round radiolucent area located in the apical region of the mandibular premolars • Frequently misdiagnosed as a periapical lesion

  41. Mylohyoid Ridge • Iannucci & Howerton (pp. 337-338) (Fig. 27-41) • Description • A linear prominence of bone located on the internal surface of the mandible • Appearance • A dense radiopaque band that extends downward and forward from the molar region

  42. Mandibular Canal • Iannucci & Howerton (p. 338) (Fig. 27-42) • Description • A tubelike passageway through bone that travels the length of the mandible • Houses the inferior alveolar nerve and blood vessels • Appearance • A radiolucent band outlined by two thin radiopaque lines that represent the cortical walls of the canal

  43. Internal Oblique Ridge • Iannucci & Howerton (pp. 338-339) (Figs. 27-43) • Description • A linear prominence of bone located on the internal surface of the mandible the ramus • Appearance • A radiopaque band that extends downward and forward from the ramus • When both appear, the external oblique ridge is superior to the internal oblique ridge.

  44. External Oblique Ridge • Iannucci & Howerton (p. 339) (Figs. 27-44, 27-45) • Description • A linear prominence of bone located on the external surface of the body of the mandible • Appearance • A radiopaque band extending downward and forward from the anterior border of the ramus of the mandible

  45. Submandibular Fossa • Iannucci & Howerton (p. 339) (Fig. 27-46) • Description • A scooped-out, depressed area of bone located on the internal surface of the mandible inferior to the mylohyoid ridge • Appearance • A radiolucent area in the molar region below the mylohyoid ridge

  46. Coronoid Process • Iannucci & Howerton (pp. 339-340) (Fig. 27-47) • Description • A marked prominence of bone on the anterior ramus of the mandible • Radiographic appearance • A triangular radiopacity superimposed over, or inferior to, the maxillary tuberosity region

  47. Normal Tooth Anatomy • Tooth structure • Supporting structures

  48. Tooth Structure • Iannucci & Howerton (p. 340) (Figs. 27-48, 27-49, 27-50) • Enamel – the outermost radiopaque layer of the crown of a tooth • Dentin – comprises most of the tooth structure, not as radiopaque as enamel • Dentinoenamel junction – the junction between dentin and enamel • Pulp Cavity – a pulp chamber and pulp canals

  49. Supporting Structures • Iannucci & Howerton (pp. 340-341) (Figs. 27-51) • Anatomy of alveolar bone • Lamina dura • Alveolar crest • Periodontal ligament space • Shape and density of alveolar bone • Anterior regions • Posterior regions

  50. Anatomy of Alveolar Bone • Iannucci & Howerton (pp. 341) (Fig. 27-52) • Anatomic landmarks of the alveolar process include the lamina dura, alveolar crest, and periodontal ligament space.

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