Recognizing Normal Radiographic Anatomy Chapter 22 Recognizing Normal Radiographic Anatomy

Objectives Define the key words. Provide three rationales for why it is important to recognize and identify normal anatomical landmarks of the face and head. Describe and identify the facial and cranial bones. Differentiate between the lamina dura and the periodontal ligament space.

Objectives Describe and identify the radiographic appearance of all structures of the teeth. Name significant anatomical landmarks of the maxilla and mandible. Identify significant anatomical landmarks normally seen on intraoral radiographs of the maxilla and mandible.

Key Words Alveolar bone Alveolar process Alveolus Angle of mandible Anodontia Anterior nasal spine Apical foramen Cancellous bone

Key Words Cementum Condyle Coronoid process of the mandible Cortical bone Dentin Dentition Enamel

Key Words Exfoliation External auditory meatus (foramen) Frontal bone Genial tubercles Hamulus Impacted teeth

Key Words Incisive (anterior palatine) foramen Inferior border of mandible Inverted Y Lamina dura Lateral fossa Lingual foramen

Key Words Mandible Mandibular canal Mandibular foramen Mastoid process Maxilla Maxillary sinus

Key Words Maxillary tuberosity Median palatine suture Mental foramen Mental fossa Mental ridge

Key Words Mylohyoid ridge Nasal bones Nasal conchae Nasal fossa (cavity) Nasal septum Nutrient canal Nutrient foramen

Key Words Oblique ridge Occipital bone Periodontal ligament (PDL) Permanent teeth Primary teeth Pterygoid plates

Key Words Pulp chamber Ramus Septum Sphenoid bone Styloid process Submandibular fossa

Key Words Supernumerary teeth Suture Symphysis Temporal bone Torus mandibularis (lingual torus) Trabecular bone

Key Words Tuberosity (maxillary) Zygoma Zygomatic arch Zygomatic process

Introduction The importance of learning to identify normal radiographic anatomy may be summarized as follows: To evaluate the image receptor for correct positioning so that the areas of interest and anatomical structures are clearly visible, enhancing the diagnostic value of the radiograph

Introduction The importance of learning to identify normal radiographic anatomy may be summarized as follows: To assist with determining into which frame of the x-ray mount each radiograph is to be mounted To assist in interpreting radiographs and recognizing a deviation from the normal that would require referral to the dentist for evaluation

Figure 22-1 Frontal view of the skull.

Figure 22-2 Lateral view of the skull.

Figure 22-3 Frontal view of the nose.

Figure 22-4 Palatal view of maxilla.

Figure 22-5 Lateral view of detached mandible.

Figure 22-6 Lingual view of detached mandible.

Radiographic Appearance of the Alveolar Bone and Tooth Area Lamina dura Periodontal ligament space Nutrient canals Teeth Dentition

Figure 22-7 Drawing of mandibular premolar–molar area.

Figure 22-8 Radiograph of mandibular premolar area showing (1) dentin, (2) enamel, (3) pulp chamber, (4) periodontal ligament space, (5) lamina dura, (6) pulp (root) canal, and (7) cancellous (trabecular) bone. Note that because only a very thin layer of cementum covers the root, it is radiographically indistinguishable from the underlying dentin.

Figure 22-9 Radiograph of mixed dentition in mandibular canine area showing (1) primary canine, (2) primary first molar with partially resorbed roots, (3) permanent canine, and (4) permanent first premolar with incomplete root formation.

Figure 22-10 Facial bones recorded on radiographs Figure 22-10 Facial bones recorded on radiographs. Note the position of the PID when exposing a maxillary posterior periapical radiograph. The zygomatic arch will most likely be recorded on this radiograph.

TABLE 22-1 Radiopaque and Radiolucent Features

Figure 22-11 Sequence for interpreting normal radiographic anatomy.

Anatomy Basics, Intraoral Radiographs Anatomy observed on intraoral radiographs of the maxillary anterior region

Figure 22-12 Drawing of maxillary midline area illustrating (1) outline of nose, (2) incisive foramen (anterior palatine foramen), (3) lateral fossa, (4) nasal fossa, (5) nasal septum, (6) border of nasal fossa, (7) anterior nasal spine, and (8) median palatine suture.

Figure 22-13 Radiograph of maxillary midline area showing (1) incisive (anterior palatine) foramen, indicated by an irregularly shaped, rounded radiolucent area, (2) outline of the nose, (3) lateral fossa, (4) nasal fossa (radiolucent), (5) nasal septum, (6) border of nasal fossa, (7) anterior nasal spine, and (8) median palatine suture.

Figure 22-14 Drawing of maxillary canine area Figure 22-14 Drawing of maxillary canine area. The drawing shows the (1) lateral fossa, (2) nasal fossa, (3) inverted Y (intersection of the borders of nasal fossa and maxillary sinus), and (4) maxillary sinus. (5) Note the dense radiopaque area caused by overlapping of the mesial surface of the first premolar over the distal surface of the canine. This overlapping is common in this region of the oral cavity because of the curvature of the arch.

Figure 22-15 Radiograph of maxillary canine area showing (1) lateral fossa, (2) nasal fossa, (3) inverted Y (intersection of the borders of the nasal fossa and maxillary sinus), (4) maxillary sinus, and (5) dense radiopaque area caused by overlapping of the mesial surface of the first premolar over the distal surface of the canine. This overlapping is common in this region of the oral cavity because of the curvature of the arch.

Figure 22-16 Soft tissue of the nose in the path of the x-ray beam Figure 22-16 Soft tissue of the nose in the path of the x-ray beam. Note that the soft tissue of the nose will be in the path of the x-ray beam in this exposure. The resultant radiograph will most likely show an image of the soft tissue, outlining the tip of the nose.

Figure 22-17 Soft tissue image of the nose Figure 22-17 Soft tissue image of the nose. (1) The resultant image of the soft tissue of the nose is often magnified to a large size. According to the rules of shadow casting (see Chapter 4), the further an object is from the image receptor, the more likely that object will appear magnified. The tip of the nose is at an increased distance from the intraoral image receptor, resulting in a magnification of the size of the nose.

Anatomy Basics, Intraoral Radiographs Anatomy observed on intraoral radiographs of the maxillary posterior region

Figure 22-18 Drawing of maxillary premolar area illustrating (1) border (floor) of maxillary sinus, (2) maxillary sinus, (3) septum in maxillary sinus dividing the sinus into two compartments, (4) zygomatic process of maxilla, (5) zygoma, and (6) lower border of zygomatic arch.

Figure 22-19 Radiograph of maxillary premolar area showing (1) border (floor) of maxillary sinus, (2) maxillary sinus, (3) zygomatic process of maxilla, (4) septum in maxillary sinus dividing the sinus into two compartments, (5) zygoma, and (6) inferior border of the zygomatic arch.

Figure 22-20 Drawing of maxillary molar area illustrating (1) border (floor) of maxillary sinus, (2) maxillary sinus, (3) zygomatic process of maxilla, (4) zygoma, (5) septum in maxillary sinus, (6) lower border of zygomatic arch, (7) hamulus (hamular process), (8) maxillary tuberosity, and (9) coronoid process (mandible).

Figure 22-21 Radiograph of maxillary molar area showing (1) border (floor) of maxillary sinus, (2) maxillary sinus, (3) zygomatic process of maxilla, (4) zygoma, (5) lateral pterygoid plate, (6) lower border of zygomatic arch, (7) maxillary tuberosity, and (8) coronoid process of the mandible.

Figure 22-22 Radiograph of maxillary molar area showing (1) hamulus (hamular process), a downward projection of the medial pterygoid plate, (2) lateral pterygoid plate, (3) coronoid process of the mandible, (4) maxillary tuberosity, and (5) maxillary sinus.

Figure 22-23 Coronoid process of the mandible may be recorded on intraoral radiographs of the maxillary posterior region. Note the position of the image receptor holder when exposing a maxillary posterior periapical radiograph. The coronoid process of the mandible will most likely be recorded on this radiograph.

Anatomy Basics, Intraoral Radiographs Anatomy observed on intraoral radiographs of the mandibular anterior region

Figure 22-24 Drawing of mandibular midline area illustrating (1) mental ridge, (2) nutrient canal, (3) nutrient foramen, (4) genial tubercles surrounding the (5) lingual foramen, and (6) inferior border of mandible.

Figure 22-25 Radiograph of the mandibular midline area showing (1) mental ridge, (2) nutrient canal, (3) nutrient foramen, (4) genial tubercles surrounding the (5) lingual foramen, and (6) inferior border of the mandible (radiopaque band of dense cortical bone).

Figure 22-26 Drawing of mandibular canine area illustrating (1) nutrient canal, and (2) torus mandibularis (lingual torus).

Figure 22-27 Radiograph of mandibular canine area showing (1) nutrient canal, (2) torus mandibularis (lingual torus).

Anatomy Basics, Intraoral Radiographs Anatomy observed on intraoral radiographs of the mandibular posterior region

Figure 22-28 Drawing of mandibular premolar area illustrating (1) torus mandibularis, (2) oblique ridge, (3) mylohyoid ridge, (4) submandibular fossa, (5) mandibular canal, and (6) mental foramen.

Figure 22-29 Radiograph of mandibular premolar area showing (1) submandibular fossa, (2) thin radiolucent line indicating the periodontal ligament space, (3) thin radiopaque line representing the lamina dura, and (4) the mental foramen.

Figure 22-30 Radiograph of mandibular premolar area showing (1) small torus mandibularis (lingual torus).

Figure 22-31 Drawing of mandibular molar area illustrating (1) oblique ridge, (2) mylohyoid ridge, (3) submandibular fossa, and (4) mandibular canal.

Figure 22-32 Radiograph of mandibular molar area showing (1) oblique ridge, (2) mylohyoid ridge, (3) mandibular canal (note the thin, parallel radiopaque lines representing the canal walls), and (4) submandibular fossa.

Review: Chapter Summary Knowledge of the anatomical landmarks of the face and skull is needed to properly position the image receptor, to clearly image the area of interest, to assist in mounting intraoral radiographs, and to develop the ability to interpret radiographs and recognize deviations from normal.

Review: Chapter Summary A systematic procedure is helpful to the beginning radiographer in learning to identify normal radiographic anatomy.

Recall: Study Questions General Chapter Review

Reflect: Case Study Your colleague is viewing a full mouth series of radiographs that he just finished mounting. As he is describing the following features, see if you can tell him the name of the anatomic landmark.

Reflect: Case Study A dense, vertical radiopacity separating two paired oval radiolucencies observed in the maxillary anterior region. Large, paired oval radiolucencies separated by a dense, vertical radiopacity observed in the maxillary anterior region. A thin radiolucent line resembling a fracture observed between the maxillary central incisors.

Reflect: Case Study A round or pear-shaped radiolucency observed between the maxillary central incisors. A broad, U-shaped radiopacity observed superimposed over the maxillary posterior teeth roots

Reflect: Case Study A radiopaque downward projection of bone that appears pointed or hook-like observed in the far posterior region of the maxilla. A large triangular shaped radiopacity observed superimposed over the maxillary tuberosity region.

Reflect: Case Study A large radiolucency outlined by a thin radiopaque border that is observed in almost all the periapical radiographs of the maxilla, from the canine posteriorly. A very small, round radiolucency observed in the midline apical (below) the mandibular incisors.

Reflect: Case Study A horizontal radiopaque line extending from the premolar region to the symphysis. A round radiolucency that resembles an abscess observed near the apex of the mandibular second premolar. A horizontal radiopaque line observed in the mandibular posterior region, superimposed across the molar roots.

Reflect: Case Study Another horizontal radiopaque line observed in the mandibular posterior region, but inferior to (below) the line described in #12 above. This line is observed inferior to the molar roots. A large, irregularly shaped radiolucency observed below the line described in #13 above.

Relate: Laboratory Application Proceed to Chapter 22, Laboratory Application, to complete this activity.