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Chapter 27 Normal Anatomy: Intraoral Images Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 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? Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 2 Dental Radiography Chapter 27 Reading Iannucci & Howerton (pp. 325-344) Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 3 Dental Radiography Chapter 27 Outline Normal Anatomy: Intraoral Films Definitions of general terms Normal anatomic landmarks Normal tooth anatomy Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 4 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 5 Definitions of General Terms Types of bone Prominences of bone Spaces and depressions in bone Miscellaneous terms Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 6 Types of Bone Cortical bone Iannucci & Howerton (pp. 326-327) (Figs. 27-1 through 27-3) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 7 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 8 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 9 Miscellaneous Terms Septum Iannucci & Howerton (pp. 327-328) (Fig. 27-11) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 10 Normal Anatomic Landmarks Iannucci & Howerton (pp. 328) Bony landmarks of the maxilla Bony landmarks of the mandible Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 11 Bony Landmarks of the Maxilla The upper jaw is composed of two paired bones, the maxillae. Iannucci & Howerton (pp. 328-329) (Fig. 27-12) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 12 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 13 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 14 Incisive Foramen (Nasopalatine Foramen) Description Iannucci & Howerton (pp. 329-330) (Fig. 27-13) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 15 Superior Foramina of the Incisive Canal Description Iannucci & Howerton (pp. 329-330) (Fig. 27-14) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 16 Median Palatal Suture Description Iannucci & Howerton (p. 330) (Fig. 27-15) The immovable joint between the two palatine processes of the maxilla Appearance A thin radiolucent line between the maxillary central incisors Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 17 Lateral Fossa Description Iannucci & Howerton (pp. 330-331) (Fig. 27-16) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 18 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 19 Nasal Septum Description Iannucci & Howerton (p. 331) (Fig. 27-18) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 20 Floor of the Nasal Cavity Description Iannucci & Howerton (p. 332) (Fig. 27-19) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 21 Anterior Nasal Spine Description Iannucci & Howerton (p. 332) (Fig. 27-20) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 22 Inferior Nasal Conchae Description Iannucci & Howerton (pp. 332-333) (Fig. 27-21) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 23 Maxillary Sinus Description Iannucci & Howerton (pp. 332-333) (Figs. 27-22, 27-23) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 24 Septa within the Maxillary Sinus Description Iannucci & Howerton (pp. 332-333) (Figs. 27-24, 27-25) 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. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 25 Nutrient Canals within the Maxillary Sinus Description Iannucci & Howerton (p. 334) (Fig. 27-26) Tiny, tubelike passageways through bone that contain blood vessels and nerves Appearance A narrow radiolucent band bounded by two thin radiopaque lines Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 26 Inverted Y Description Iannucci & Howerton (p. 334) (Fig. 27-27) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 27 Maxillary Tuberosity Description Iannucci & Howerton (p. 334) (Fig. 27-28) A rounded prominence of bone that extends posterior to the third molar region Appearance A radiopaque bulge distal to the third molar region Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 28 Hamulus Description Iannucci & Howerton (pp. 334-335) (Fig. 27-29) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 29 Zygomatic Process of the Maxilla Description Iannucci & Howerton (pp. 334-335) (Figs. 27-30, 27-31) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 30 Zygoma Description Iannucci & Howerton (pp. 335-336) (Figs. 27-32, 27-33) Articulates with the zygomatic process of the maxilla Appearance A diffuse, radiopaque band extending posteriorly from the zygomatic process of the maxilla Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 31 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 32 Bony Landmarks of the Mandible Iannucci & Howerton (pp. 335-340) Genial tubercles Lingual foramen Nutrient canals Mental ridge Mental fossa Mental foramen Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 33 Bony Landmarks of the Mandible Mylohyoid ridge Mandibular canal Internal oblique ridge External oblique ridge Submandibular fossa Coronoid process Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 34 Genial Tubercles Description Iannucci & Howerton (pp. 335-336) (Fig. 27-35) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 35 Lingual Foramen Description Iannucci & Howerton (p. 336) (Fig. 27-36) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 36 Nutrient Canals Description Iannucci & Howerton (pp. 336-337) (Fig. 27-37) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 37 Mental Ridge Description Iannucci & Howerton (p. 337) (Fig. 27-38) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 38 Mental Fossa Description Iannucci & Howerton (pp. 337-338) (Fig. 27-39) A scooped-out, depressed area of bone located on the external surface of the anterior mandible Appearance A radiolucent area above the mental ridge Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 39 Mental Foramen Description Iannucci & Howerton (pp. 337-338) (Figs. 27-40) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 40 Mylohyoid Ridge Description Iannucci & Howerton (pp. 337-338) (Fig. 27-41) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 41 Mandibular Canal Description Iannucci & Howerton (p. 338) (Fig. 27-42) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 42 Internal Oblique Ridge Description Iannucci & Howerton (pp. 338-339) (Figs. 27-43) 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. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 43 External Oblique Ridge Description Iannucci & Howerton (p. 339) (Figs. 27-44, 27-45) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 44 Submandibular Fossa Description Iannucci & Howerton (p. 339) (Fig. 27-46) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 45 Coronoid Process Description Iannucci & Howerton (pp. 339-340) (Fig. 27-47) 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 46 Normal Tooth Anatomy Tooth structure Supporting structures Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 47 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 48 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 Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 49 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. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 50 Lamina Dura Iannucci & Howerton (p. 341) (Fig. 27-53) Description The wall of the tooth socket Made of dense cortical bone Appearance A dense radiopaque line that surrounds the root of a tooth Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 51 Alveolar Crest Description Iannucci & Howerton (pp. 341-342) (Fig. 27-54) The most coronal portion of the alveolar bone found between teeth Appearance Appears radiopaque, typically 1.5 to 2.0 mm. below the cementoenamel junction Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 52 Periodontal Ligament Space Description Iannucci & Howerton (pp. 341-342) (Fig. 27-55) The space between the root of the tooth and the lamina dura Appearance A thin radiolucent line around the root of a tooth Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 53 Shape and Density of Alveolar Bone Iannucci & Howerton (pp. 341-342) (Fig. 27-56) Anterior regions Normal alveolar crest appears pointed and sharp between the teeth. The alveolar crest appears as a dense radiopaque line in the anterior region. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 54 Shape and Density of Alveolar Bone Iannucci & Howerton (p. 342) (Fig. 27-57) Posterior regions Normal alveolar crest appears flat and smooth between the teeth. The alveolar crest appears less dense and less radiopaque than the alveolar crest seen in the anterior region. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 55
