Wk 9 Normal Radiographic Anatomy PDF

Normal radiographic anatomy on All the chapter is important with pictures 1 Oral Sciences Department Thu. Oct. 24. 2024 oct TEETH Composed of enamel, dentin, cementum and pulp Enamel is more radiopaque Dentin is smooth and homogeneous (compared t...

Normal radiographic anatomy on All the chapter is important with pictures 1 Oral Sciences Department Thu. Oct. 24. 2024 oct TEETH Composed of enamel, dentin, cementum and pulp Enamel is more radiopaque Dentin is smooth and homogeneous (compared to bone) Enamel and dentin can be differentiated at DE junction Cementum is not seen due to low mineral content Pulp is radiolucent and can be traced from chamber to apical foramen Cervical burn out –phenomenon at the cemento-enamel junction Divergent appearance at apex- developing root (crypt) ALVEOLAR CREST Gingival extension of alveolar process between teeth Levels up to 1.5 mm below CE junction of adjacent teeth Crest of bone is continuous with lamina dura LAMINA DURA Thin radiopaque layer of dense bone Mineral content is same as that of trabeculae of cancellous bone Thickens with heavy occlusal forces In multi-rooted teeth double image may be seen  PERIODONTAL LIGAMENT SPACE Appears as radiolucent line between lamina dura and root Begins at alveolar crest, extends around the roots within the alveolus & returns to the alveolar crest on opposite of the tooth Width varies from patient to patient & tooth to tooth Thinner in the middle of the root Thickness is related to the degree of function of the tooth  CANCELOUS BONE Lies between the cortical plates Composed of thin radiopaque plates and rods (trabeculae) surrounding numerous radiolucent marrow spaces Examine trabecular distribution, size & density and compare them in both the jaws  Maxilla Trabeculae in anterior maxilla are thin-numerous forming fine, granular, dense pattern In posterior maxilla the marrow spaces are slightly larger  mandible In anterior mandible, the trabeculae are thicker than maxilla Trabecular plates are oriented horizontally In posterior mandible the plates are oriented mainly horizontally in periradicular region Under the apical area trabeculae decreases in number Significance of alveolar bone Thicker the cortical plate-fewer the trabeculae Absence of trabeculae may reveal a disease condition Examination of previous radiograph or repeating a radiograph should be done for verification  MAXILLARY LANDMARKS INTERMAXILLARY SUTURE (Median palatal suture) ANTERIOR NASAL SPINE NASAL FOSSA INCISIVE FORAMEN MAXILLARY SINUS ZYGOMATIC BONE/PROCESS  INTERMAXILLARY SUTURE (Median palatal suture) Appears as a thin radiolucent line in the midline Extends from alveolar crest between central incisors Continues posteriorly between palatine process up to the posterior aspect of hard palate  ANTERIOR NASAL SPINE Located in midline Frequently seen on maxillary central incisor radiograph Lies 1.5 to2 cm above the alveolar crest Just below the junction of lower end of nasal septum and inferior outline of nasal fossa  NASAL FOSSA Seen on maxillary central incisor projections Radiolucent area bounded by radiopaque lines extending bilaterally away from ANS Sometimes nasal conchae are seen extending from lateral wall of nose (hazy image) Sometimes the floor of nasal fossa is seen in maxillary canine projections  INCISIVE FORAMEN Oral end of nasopalatine canal Lies behind the central incisors in midline Image is projected between the roots of central incisors Marked variation in shape and size Use of different angulations make variations Sometimes mistaken as pathology Sometimes lateral walls of nasopalatine canal may be seen  MAXILLARY SINUS ▪ Air-filled cavity with mucosal lining ▪ The border appears as a thin, delicate weak radiopaque line- thin layer of cortical bone ▪ In adults sinus extends from distal of canine to the posterior wall of maxilla above the tuberosity ▪ Shows considerable variations in shape and size ▪ Both sinuses are symmetric, but in some individuals may appear asymmetric ▪ On periapical radiograph of canine, floors of sinus and nasal fossa get superimposed and sometimes they cross each other to form an inverted Y shape ▪ Roots of molars lie in close proximity of sinus ▪ Small elevations into the sinus cavity due to anatomic projections of apices ▪ Thin layer of bone covering apices is seen as lamina dura ▪ Several radiopaque lines may be seen traversing sinus, vertically, called as septa  ZYGOMATIC PROCESS AND ZYGOMATIC BONE ▪ It is an extension of lateral maxillary surface seen on apices of molars ▪ On periapical projections, zygomatic process appears as ‘U’ shaped radiopacity with its open ends directed superiorly ▪ The enclosed rounded end is seen near the apices of molars ▪ Size, width and definition is variable ❖Inferior portion of the zygomatic bone may be seen extending posteriorly from the inferior border of the process ❖Appears as uniform radiopacity over the apices of molars ❖Shadow of molar apices may get superimposed over the zygomatic bone MANDIBULAR LANDMARKS GENIAL TUBERCLE MENTAL FORAMEN MANDIBULAR CANAL MYLOHYOID RIDGE SUBMANDIBULAR GLAND FOSSA EXTERNAL OBLIQUE RIDGE CORONOID PROCESS  GENIAL TUBERCLE Located on lingual surface of slightly above the inferior border in midline Bony, spine-shaped protuberance Provide attachment to muscles As right and left; and inferior and superior prominences Seen as single radiopaque mass Seen on occlusal radiograph  MENTAL FORAMEN Anterior limit of inferior alveolar canal Variable image, not seen often due its superior and posterior direction Seen halfway between the lower border & crest of alveolar process in second bicuspid apex region May be mistaken as periapical pathology  MANDIBULAR/INFERIOR ALVEOLAR CANAL Appears as dark linear shadow with thin radiopaque superior and inferior borders Relation of canal to the apices of molars vary Usually canal is in proximity with roots of third molars Distance increases as progresses in anterior direction  MYLOHYOID RIDGE An irregular crest of bone on lingual surface of body Extends from third molar area up to lower of chin Image runs downward, forward in apical region of molars Ill-defined margins More prominent with excess negative angle  SUBMANDIBULAR GLAND FOSSA Depression in bone on lingual side below mylohyoid ridge in molar area Accommodates submandibular gland Appears as radiolucent area with sparse trabeculation Limited superiorly by mylohyoid ridge and inferiorly by inferior border of mandible  EXTERNAL OBLIQUE RIDGE Continuation of anterior border of ramus Runs antero-inferiorly lateral to alveolar process Further it flattens and disappears below the first molar Shadow is cast superior to mylohyoid ridge  CORONOID PROCESS Seen on periapical radiographs of maxillary third molar region Appears due to downward and forward movement of mandible while opening Shadow is homogeneous  Examination is an orderly process: – Mandible – Maxilla – Zygoma – Soft tissue shadows – pharyngeal air spaces – Teeth  Examine the borders of the bone first Next, examine the medullary bone Check the internal structures such as canals, foramina, and sinuses Check the soft tissue shadows Examine the pharyngeal air spaces Evaluate the teeth Red Arrow – Mandibular condyle Blue arrow – Inferior alveolar canal Green Arrow – angle of mandible Pink arrow – sigmoid notch 1. Hard palate double image 2. Infraorbital margin 3. Orbit 4. Posterior wall of Maxillary sinus 5. Zygomatic process 6. Hard palate (true) 7. Linea innominate 8. Zygomatic arch 9. Mandibular foramen 10.Styloid process 11.Ramus 12.Inferior alveolar canal 13.Mental foramen 14.Hyoid bone – body 15.Hyoid bone – greater cornua Thank You