unilocular and multilocular radiolucencies

important points only are covered..

1. SEMINAR ON UNILOCULAR AND MULTILOCULAR RADIOLUCENCY BY DR SOURAV MALHOTRA

2. Introduction Classification Anatomical radiolucencies Involving mandible Involving maxilla Involving both jaws Unilocular radiolucencies Multilocular radiolucencies References CONTENTS

3. What is radiolucency ? It express that the region/area/object didn’t absorb the radiation but is transparent/translucent thus more radiation reaches the sensor/film leading to a darker area. Introduction

4. What is unilocular radiolucency ? From the word uni : means one and lucular means lobes, it means the lesion appears as one mass.

5. Multilocular radiolucency is produced by multiple adjacent, frequently coalescing & overlapping pathologic compartments in bone. True multilocular lesion contains two or more pathologic chambers partially separated by septa of bone. Soap bubble appearance- Lesions consists of several circular compartments that vary in size & usually appear to overlap

6. Introduction Honeycomb- Lesions whose compartments are small & tend to be uniform in size Tennis racket- Lesions that are composed of angular rather than rounded compartments that result in formation of more or less septae. These compartments tend to be triangular rather, rectangular or square

7. UNILOCULAR RADIOLUCENCIES

8. Singapore Med J 2008; 49(2) : 165

9. ANATOMICAL RADIOLUCENCIES

10. Structures related to Mandible Mandibular Foramen Mandibular Canal Mental Foramen Lingual Foramen Submandibular Fossa Mental Fossa

11. Structures related to Maxilla Intermaxillary Suture Incisive Foramen Nasal Cavity Nasolacrimal duct/canal Maxillary sinus Structures common to both Jaws Periodontal ligament space Marrow Space Nutrient Canal Follicular Space

12. MANDIBULAR FORAMEN Usually situated just above the mid point in the medial surface of the ramus & just posterior to the mid point between the anterior & posterior borders. Seen on panographic & lateral oblique films Outline of foramen varies from triangular to oval to funnel shaped Radiographic image is usually upto 1 cm in diameter It is associated with relatively radiolucent mandibular canal that passes from it in an anteroinferior direction STRUCTURES RELATED TO MANDIBLE

13. MANDIBULAR FORAMEN Lingula may be detected as a triangular radiopacity of variable density at the foramen’s anterior border These associated structures, with mandibular canal & lingula, can be mistaken for pathology

14. MANDIBULAR CANAL/ INFERIOR DENTAL CANAL : Largest of the nutrient canals Seen on panoramic or periapical radiographs of molar region Appears as relatively radiolucent channel bounded by definite, thin radiopaque lines (cortical bones) through out its length Its course can be followed anteroinferiorly to a point where it frequently appears to sweep upward to meet the mental foramen

15. MENTAL FORAMEN Anterior limit of mandibular canal Mandibular canal send off the mental canal in the premolar region This smaller, short canal runs in superior buccal direction, terminating with the mental foramen It is usually located on the radiograph in the vicinity of premolar apices. It may be mistaken for periapical pathosis when it occurs at the apex of premolars

16. LINGUAL FORAMEN Seen in relation to lower central incisors often on periapical views Located well below the apices of these teeth in the midline Seen as radiolucency measuring usually 1-2mm in diameter surrounded by prominent radiopaque ring of cortical bone Occasionally 2 or more foramina are seen .

17. SUBMANDIBULAR GLAND FOSSA Submandibular fossa is concave area on the lingual side of the mandible below the molar area which accommodates the Submandibular salivary gland Lies between inferior alveolar canal & lower cortical margin of mandible This is seen as relatively radiolucent area with sparse trabecular pattern which is sharply limited superiorly by the lower border of mylohyoid ridge and inferiorly by lower border of mandible Shape is round, ovoid or triangular (rarely) Rarely occurs bilaterally

18. MENTAL FOSSA Depression on the labial aspect of midline of mandible just above the mental tubercle Due to relative thinness of bone over in this area, it may be seen as radiolucency over the incisor roots which may be mistaken for periapical pathology

19. MIDLINE SYMPHYSIS Seen on the midline of the mandible of infants Seen as radiolucent line which may be misinterpreted for fracture line Symphysis usually ossifies by age of 1 year & then is no longer apparent

20. MEDIAL SIGMOID DEPRESSION It is a radiolucency that appears below & just anterior to greatest depth of sigmoid notch of ramus Seen on approximately 10% of panoramic radiographs It is defined by temporal crest & crest of mandibular neck Its degree of expression is variable depending upon prominence of these two crests .

21. SUBLINGUAL GLAND DEPRESSION First reported by Richard & Ziskind (1957) It may develop to accommodate sublingual salivary gland tissue that lies in close proximity to the lingual cortex of mandible in canine region Most often associated with canines, followed by incisors & 2 nd premolars (rare), in apical 1/3 rd of root Average size-1.2 cm Trabeculation may be present within radiolucency Have punched out appearance or corticated margin

22. STRUCTURES RELATED TO MAXILLA

23. AIRWAY SHADOW Bilateral, relatively radiolucent Seen on panoramic, lat oblique & cephalomatric radiographs Results from lack of soft tissue between he posterolateral surface of tongue & region of soft palate & posterior pharynx

24. INTERMAXILLARY SUTURE Intermaxillary/ median suture between right & left maxillary bones, can be identified as thin vertical radiolucency in midline between central incisors Usually delineated by two thin, vertical radiopaque lines (cortical bone). Generally fuses later in life & then no longer seen on radiograph.

25. INCISIVE FORAMEN, Incisive foramen (anterior palatine foramen) frequently shows as a round, oval, diamond shaped or heart shaped radiolucency that is well defined on occlusal & periapical radiographs The position of foramen on radiograph ranges from between the roots of central incisors, close to alveolar ridge to the level of apices. Variability in position of foramen on radiograph is due to the angulation of the rays & position of foramen

26. SUPERIOR FORAMINA OF INCISIVE CANALS On radiograph they are seen as two round or oval radiolucent areas above the apices of central incisors in the floor of nasal cavity near its anterior border & both sides of nasal septum In IOPA their image be superimposed over apices incisors, which may be misinterpreted as periapical pathosis

27. NASOLACRIMAL DUCT/ CANAL Nasal & maxillary bones form The nasolacrimal canal Seen on maxillary occlusal radiograph , projected onto the posterior hard palate near the 1 st or 2 nd molar as well defined radiolucency bilaterally well defined by sharp radiopaque borders. On periapical radiographs it may be seen in the region above the apex of canine, especially if steep angulation is used.

28. MAXILLARY SINUS Appear as well defined radiolucency with thin, sharp radiopaque borders It shows considerable variation in size They enlarge in childhood, achieving mature size by age of 15 to 18 years Floors of maxillary sinus & nasal cavity are seen at approximately same level at age of puberty in radiograph In adults sinuses are usually seen to extend from the distal aspect of canine to the posterior wall of maxilla above tuberosity

29. In older individuals it may extend farther into the alveolar process & may extend upto the alveolar ridge in absence of teeth

30. STRUCTURES COMMON TO BOTH JAWS

31. MARROW SPACE Marrow spaces between trabeculae of bone appear as radiolucent region Varies greatly in shape, size & distribution Radiographically, in maxilla, they are generally relatively uniform in size In mandible marrow spaces are smaller & more numerous in the anterior portion & larger in the posterior portion

32. In some persons trabecular spaces just above & below the roots of molars are so large & trabeculae so sparse that the combined appearance may resemble & be misinterpreted as cysts & other pathosis These are referred as focal osteoporotic bone marrow defects

33. NUTRIENT CANAL Appear as ribbonlike radiolucencies of fairly uniform width Carry neurovascular bundles Seen more often on periapical mandibular radiographs Canals become more marked when teeth are missing

34. PERICORONAL/ FOLLICULAR SPACE The crowns of unerupted teeth are surrounded by dental follicle- remnant of reduced enamel epithelium It is composed of soft myxomatous to dense collagenous fibrous connective tissue or cords of odontogenic epithelium On radiograph it appears as homogeneous radiolucent halo

35. Surrounded by thin outer radiopaque border representing compact bone continuous with lamina dura Radiolucent halo merges with periodontal ligament space Width of halo varies because of varying thickness of the follicles & accumulation of fluid between the capsule of reduced enamel epithelium & tooth crown Normal follicular space – 1.5 to 2 mm

36. UNILOCULAR RADIOLUCENCIES

37. PERIAPICAL ABSCESS The primary abscess develops in a periapical region that is normal on radiographic examination. The infection is usually acute and exudative, involving the periodontal tissues at the apex of the tooth with necrotic pulp. The infection and inflammation in the apical area forces the tooth slightly from its socket, creating an increased periodontal ligament space around the entire root that is usually apparent on the radiograph. The secondary abscess may be of the chronic or the acute type

38. Related tooth shows features such as deep restorations, caries, narrowed pulp chamber, or canals which suggest that the pulp is non-vital. The roots of these teeth may show resorption at the apex. The tooth is painful on percussion and the patient complains that it seems ‘high’ to bite on. Tooth doesnot respond to electric pulp test. The tooth may demonstrate increased mobility. In untreated cases the abscess may penetrate the cortical plate at the thinnest and closest point to the apex and form a space infection in the adjacent soft tissue.

39. Periapical radiolucency is a feature of the secondary abscess. The radiolucency may vary from small to quite large to involve much of the jaw. The initial periapical lesion may cause expansion of cortical plate.  In case of acute lesion the margins of the radiolucency may be well defined with possibly a hyperostotic border. The borders are poorly defined in case of chronic conditions. Sometimes the radiolucency is represented as a blurred area of somewhat lessened density than that of surrounding bone. Radiographic Features

40. Represents between 69.7% & 94% of all pulpoperiapical lesions It is a result of successful attempt by the periapical tissue to neutralize & confine the irritating toxic products that are escaping from the root canal Continual discharge of chronic irritating products from the canal into the periapical tissue is sufficient to maintain a low grade inflammation in the tissues which results in formation of periapical granuloma PERIAPICAL GRANULOMA

41. Well circumscribed radiolucency somewhat rounded & surrounding apex of tooth May be surrounded by thin radiopaque ( hyperostoic ) border Cannot be differentiated from radicular cyst radiographically alone Cysts tend to be larger than granulomas but differentiation on basis of size is not possible as some cysts are small & granulomas large Granulomas are rarely larger than 2.5cm in diameter Involved tooth is non vital & asymptomatic Radiographic Features

42. Synonyms- Periapical cyst Apical periodontal cyst Dental cyst Most common type of cyst in jaw It results when cell rests of Malassez in the PDL are stimulated to proliferate & undergo cystic degeneration by inflammatory products by non vital tooth Usually asymptomatic unless secondary infection occurs Incidence is greater in 3 rd to 6 th decade with slight male predilection RADICULAR CYST

43. Most radicular cysts involve apices of permanent teeth 58% involve lateral incisors History & clinical features are similar to those of periapical granuloma Studies by Lalonde show that such a lesion is more likely to be a radicular cyst if the periapical radiolucency tends to be atleast 1.6cm in diameter

44. An untreated cyst may enlarge slowly & cause expansion of cortical plates. In these cases a domelike swelling is seen on the alveolus over the periapical region of alveolus of involved tooth Swelling is initially bony hard on palpation but later it may demonstrate crackling sound ( crepitus) as cortical plate is thinned In these cases swelling is rubbery & fluctuant because of cystic fluid

45. Radiographic Features LOCATION Most common site- maxilla (60%) especially incisors (58%) & canines In deciduous teeth most commonly molars are involved Epicenter is located at the apex of nonvital tooth Occasionally it appears on the mesial or distal surface of root, at the opening of accessory canal, or infrequently in a deep periodontal pocket

46. PERIPHERY & SHAPE Usually has well defined cortical border When cyst becomes secondarily infected due to inflammatory reaction of surrounding bone, cortex may be lost or become more sclerotic Outline is usually curved or circular

47. EFFECT ON SURROUNDING STRUCTURES If cyst is large, displacement & resorption of roots of adjacent teeth may occur Outer cortical plate of maxilla or mandible my expand in curved or circular shape Cyst may displace the inferior alveolar canal in an inferior direction.

48. Periapical granuloma & radicular cyst cannot be distinguished radiographically alone, although radiolucency with well defined corticated border more than 2cm diameter , it is more likely to be cyst. Differential Diagnosis

49. Periapical cementoosseous dysplasia : Difficult to distinguish radiographically from periapical granuloma & radicular cyst in its early lytic stage. Tooth is vital in PCOD Lower teeth especially incisors more commonly involved

50. Traumatic bone cyst : Teeth associated with lesion are vital Most commonly seen in mandibular region in molar, premolar & incisor region Periapical granuloma does not have predilection for lower jaw & more common in anterior region Lamina dura is intact in traumatic bone cyst

51. Dentigerous Cyst Synonym- Follicular cyst Most common type of cyst that is formed around crown of an unerupted tooth Begins with accumulation of fluid in the layers of reduced enamel epithelium or between the epithelium and the crowns of unerupted or supernumerary tooth Typically patient has no pain or discomfort

52. Location Mandibular 3 rd molar or maxillary canines are most commonly involved Epicenter is found just above the crown of involved tooth Cyst is attached to the CEJ Some cyst are eccentric developing from the lateral aspect of crown so that they occupy an area besides the crown instead of above the crown Radiographic Features

53. Periphery and Shape It has well defined cortex with a curved or circular outline Cortex may be missing if infection is present Internal Structure Completely radiolucent except the crown of involved tooth

54. Effects on Surrounding Structure Displaces tooth involved usually in apical direction It may also resorb the adjacent teeth The floor of maxillary antrum may be displaced as the cyst invaginates the antrum & displace inferior alveolar canal in inferior direction It tends to expand outer cortex of involved jaw

55. Hyperplastic follicle Size of normal follicular space is 1.5-2mm If follicular space exceeds 5mm, it is more likely to be dentigerous cyst. Tooth displacement & expansion is associated with dentigerous cyst DIFFERENTIAL DIAGNOSIS

56. Odontogenic cyst Sometimes associated with unerupted tooth with lesion present at pericoronal position Does not cause expansion of bone Less likely to resorb teeth May attach further apically on root than at CEJ

57. Ameloblastic fibroma May be present around the crown of an unerupted tooth Difficult to differentiate radiographically

58. Unicystic ameloblastoma Unilocular ameloblastoma located around the crown of an unerupted tooth is difficult to differentiate Causes apical displacement of teeth

59. Adenomatoid odontogenic tumour When completely radiolucent & associated with impacted tooth difficult to differentiate Attached apical to CEJ

60. Unicystic Ameloblastoma Synonyms Mural Ameloblastoma Cytogenic Ameloblastoma Cystic variant of Ameloblastoma Cystic Ameloblastoma Intracystic Ameloblastoma Arises from the wall of cyst 2 nd most frequently occurring pathologic pericoronal radiolucency Represents approximately 5% of all ameloblastomas

61. It is associated with following cysts Dentigerous cysts (85%) Residual cysts Radicular cysts Globulomaxillary cysts Primordial cysts Shortly after induction, the tumour begins as mural (within wall) When it infiltrates the connective tissue wall of cyst it invades between the medullary spaces of bone. It than behaves like conventional ameloblastoma.

62. Approximately 20% are associated with the crown of mandibular 3 rd molar. Seen in younger age (average age- 21 years) Associated with impacted, displaced tooth showing incomplete root formation Present as painless swelling

63. Mandible is more commonly involved 77% were in molar ramus region, 10% in premolar area, 13% in symphysis There is pericoronal radiolucency associated with an unerupted mandibular 3 rd molar Associated teeth is displaced RADIOGRAPHIC FEATURES

64. Adjacent erupted 2 nd or 3 rd molar may show knife edge pattern of root resorption Expansion is often present, which tends to be greatest on buccal aspect There may be perforation of anterior margins of ramus or at retromolar pad area

65. Adenamatoid Odontogenic Tumour SYNONYMS Adenoameloblastoma Ameloblastic adenomatoid tumour AOT is uncommon, benign and noninvasive tumour Makes up approximately 3% of all odontogenic tumours CLASSIFICATION Central Follicular (73%) Extrafollicular Peripheral

66. Age- 2 nd decade Female predilection (2:1) Follicular type is associated with unerupted tooth Unerupted teeth frequently associated with tumour in order of frequency are maxillary canine, lateral incisor & mandibular premolar Presents as slow growing painless swelling

67. Location 75% occurs in maxilla especially in incisor- canine- premolar region Has follicular relationship with impacted tooth but doesnot attach at CEJ, most often canine is involved or sclerotic border RADIOGRAPHIC FEATURES

68. Periphery Lesion is well defined with corticated or sclerotic border Internal structure 1/3 rd of cases show completely radiolucent lesions In rest radiopacities are present within the lesion

69. Effect on surrounding structures Causes displacement of teeth Root resorption rare May inhibit eruption of tooth Expansion of jaw may occur

70. Dentigerous cyst Associated with impacted teeth but radiolucent lesion is more apical than CEJ DIFFERENTIAL DIAGNOSIS Odontogenic keratocyst Difficult to differentiate pericoronal OKC from AOT radiographically

71. Synonym Soft odontoma Soft Mixed Odontoma Mixed Odontogenic Tumour Fibroadmantoblastoma Granular Cell Ameloblastic Fibroma Ameloblastic Fibroma

72. These are benign, true mixed odontogenic tumours , containing nests & strands of odontogenic & ameloblastic epithelium in primitive dental papilla Calcified odontogenic structures are not present Age – below 20 years Manifests as painless, slow growing expansion & displacement of involved tooth May be associated with missing tooth

73. Location Mandibular premolar- molar region most common site Tumour may involve ramus in some cases Common location is crest of alveolar process or in follicular relationship with an unerupted tooth It can also arise in an area where tooth failed to develop RADIOGRAPHIC FEATURES

74. Periphery Borders are well defined & corticated Internal Structure More commonly present as unilocular radiolucency but may be multilocular with indistinct curved septa

75. Effects on Surrounding Structure Large lesion can cause expansion of cortical plates without bone destruction Associated tooth may fail to erupt or displaced apically

76. Hyperplastic Follicle Dentigerous cyst Not possible to differentiate either entity radiographically from ameloblastic fibroma DIFFERENTIAL DIAGNOSIS

77. Multilocular radiolucencies

78. Ameloblastoma Cherubism Odontogenic myxoma Central hemangioma Aneurysmal bone cyst Central giant cell granuloma Odontogenic keratocyst Hyperparathyroidism

79. Ameloblastoma SYNONYM - Admantinoma Adamtoblastoma Odontomes Embryolastiques Epithelial Odontomes It is true neoplasm of odontogenic epithelium, is a persistent, locally invasive tumour; it has aggressive but have benign growth characteristics

80. Represents about 1% of all odontogenic epithelial tumours & 11% of all odontogenic tumours Slight male predilection More common in blacks Age- 20 to 50 years Slow growing Frequently discovered on routine radiographs Teeth in involved region may be displaced or become mobile

81. Location About 80% develop in mandibular molar– ramus region & may extend into the symphyseal region In maxilla 3 rd molar area is involved & extends in the maxillary sinus & nasal floor RADIOGRAPHIC FEATURES

82. Periphery Well defined & delineated with a cortical border Border is often curved & in small lesions it may be indistinguishable from a cyst Maxillary lesion are more ill defined

83. Internal Structure Varies from totally radiolucent to mixed with bony septae creating internal compartments These septae are usually coarse & curved & originate from the normal bone that has been trapped within the tumour

84. Internal Structure Since ameloblastoma frequently has internal cystic components, these septae are often remodeled into curved shape giving a honeycomb or soap bubble appearance Generally loculations are larger in posterior mandible than in anterior part

85. Effects On Surrounding Structures Causes extensive root resorption & tooth displacement Common point of origin is occlusal to tooth; teeth may be displaced apically Occlusal radiograph may show cyst like expansion & thinning of adjacent cortical plate, leaving a thin eggshell of bone

86. In late stages perforation of bone into surrounding soft tissues or anatomic spaces occurs Unicystic types may cause extreme expansion of mandibular ramus

87. Odontgenic keratocyst Grows along the bone without expansion of bone Differential diagnosis

88. Giant Cell Granuloma Occurs anterior to molars Younger age group More granular & ill defined septae

89. ODONTOGENIC MYXOMA Both more common in mandible Ameloblastoma is common in molar- ramus region Odontogenic myxoma in premolar & molar region & rare in ramus Straight thin septa seen in odontogenic myxoma whereas curved coarse in ameloblastoma Ameloblastoma causes extensive root resorption Odontogenic myxoma tends to grow in length of bone

90. Ossifying Fibroma Septae are wide granular & ill defined

91. SYNONYM Familial fibrous dysplasia Cherubism is rare, inherited developmental abnormality that causes bilateral enlargement of jaws, giving child a cherubic facial appearance It is inherited as autosomal dominant trait It is composed of giant cell like granuloma- like tissue & does not form bone matrix Lesion regress with age Cherubism

92. Age- 2- 6 years Presents as painless, firm, bilateral enlargement of lower face. Occasionally whole mandible is involved Maxillary sinus, orbital floor & tuberosity region may be involved causing stretching of skin of cheeks, which depresses the lower eyelids, exposing thin line of sclera ( eyes in heaven appearance ) Cherubism

93. Lesions grow slowly, expanding but not perforating cortex Enlargement of submandibular lymph nodes may occur By age of 8-9 years of age , growth of pathologic lesion may stop At puberty lesion may begin to regress Usually bony architecture returns to normal by age of 30 years

94. Location Lesion is bilateral Often both the jaws are affected When present in only one jaw, mandible is more commonly affected Epicenter is always in posterior part of jaws, in ramus of mandible, or tuberosity of maxilla Lesion grows in anterior direction In severe cases may extend upto midline RADIOGRAPHIC FEATURES

95. Periphery Well defined & in some instances corticated Internal Structure Fine granular bony & wispy trabeculae present giving a soap bubble appearance

96. Effects On Surrounding Structure Expansion of maxillary & mandibular cortex occurs resulting in severe enlargement of jaws Maxillary lesion enlarges into maxillary sinus Teeth are displaced in anterior direction as epicenter is placed in posterior part of jaw Degree of expansion can be severe resulting in destruction of tooth buds & incipient follicles

97. GIANT CELL GRANULOMA Internal structure has fine, wispy trabeculae as in cherubism Cherubism is bilateral with epicenter in ramus DIFFERENTIAL DIAGNOSIS

98. MULTIPLE ODONTOGENIC KERATOCYST Cherubism shows bilateral symmetry with anterior displacement of teeth & has multilocular appearance DIFFERENTIAL DIAGNOSIS

99. Odontogenic Myxoma SYNONYM Myxoma Myxofibroma Firbomyxoma Account for 3- 6% of odontogenic tumours These are benign, intraosseous neoplasm that arises from odontogenic ectomesenchyme & resemble mesenchymal portion of dental papilla Non encapsulated & tend to infiltrate the surrounding cancellous bone

100. Age- 10 – 30 years Slight female predilection Slow growing painless lesion If left untreated it grows large & may invade maxillary sinus Recurrence rate – 25% (noncapsulated, poorly defined boundaries, extension of nests or pockets of myxoid tumour into trabecular spaces)

101. LOCATION Most commonly affects mandible (3:1) Occurs in premolar & molar areas & rarely in ramus & condylar area In maxilla, alveolar process in premolar & molar regions & zygomatic process is involved PERIPHERY May be well defined & corticated or poorly defined (in maxilla) RADiographic features

102. INTERNAL SRTUCTURE It may produce several pattern Unicystic Multilocular Pericoronal Radiolucent – radiopaque Residual bone trapped within the bone remodels into curved or straight, coarse or fine septae giving multilocular appearance

103. INTERNAL SRTUCTURE Characteristically septae are straight & thin (tennis racket or step ladder appearance) but this pattern is rarely seen Majority of septae are curved & coarse, but finding one or two of these straight septa helps in identification

104. EFFECTS ON SURROUNDING STUCTURE Causes displacement & loosening of teeth but rarely resorption Lesion frequently scallops between the roots of adjacent structure Tendency to grow along the bone without causing much expansion

105. AMELOBLATOMA Both more common in mandible Ameloblastoma is common in molar- ramus region Odontogenic myxoma in premolar & molar region & rare in ramus Straight thin septa seen in odontogenic myxoma whereas curved coarse in ameloblastoma Ameloblastoma causes expansion of bone but odontogenic myxoma grows along the length of bone Differential DIAGNOSIS

106. CENTRAL GIANT CELL GRANULOMA Both occur in mandible but CGCG occurs anterior to 1 st molar septae are ill- defined & wispy & some are at right angles to the periphery CGCG causes expansion of jaws

107. CENTRAL HEMANGIOMA Mandible common site but posterior body , ramus & inferior alveolar canal is involved Shows coarse trabecular pattern

108. OSTEOGENIC SARCOMAS In odontogenic myxoma a small area of expansion with straight septae may be projected over an intact bony cortex & give spiculated appearance resembling osteogenic sarcoma But outer cortex is destroyed in odontogenic sarcoma

109. Hemangioma is a proliferation of blood vessels Most frequently noticed in skin & subcutaneous tissues Central hemangioma is more commonly seen in vertebrae & skull Rarely develops in jaws Lesion may be developmental or traumatic in origin More prevalent in females (2:1) Age- 1 st decade Central Hemangioma

110. Presents as slow, non tender expansion of jaws It is bony hard in consistency Pain, if present is probably throbbing type Some tumours are compressible or pulsate & bruit may be detected on auscultation Anesthesia of skin supplied by mental nerve occurs Bleeding may occur around gingiva around the neck of teeth

111. LOCATION Mandible twice more affected than maxilla Posterior body & ramus & within the inferior alveolar canal Gives a cart wheel apperaence . Radiographic features

112. PERIPHERY Periphery is well defined & corticated or ill defined Variation is related to the amount of residual bone around the blood vessels Formation of linear spicules of bone emanating from the surface of the bone in sunray- like appearance can occur when hemangioma breaks through the outer cortex & displace the periosteum

113. INTERNAL STRUCTURE Multilocular appearance is due to entrapment of residual bone trapped around the blood vessels Small radiolucent locules may resemble marrow spaces surrounded by coarse, dense & well defined trabeculae These trabeculae produces honeycomb pattern composed of small circular radiolucent spaces that represent blood vessels oriented in the same direction of x- ray beams

114. Width of inferior alveolar canal, if involved, is increased & shape becomes serpiginous Phleboliths are formed when soft tissue is involved They develop from thrombi that become organized & mineralized & consists of calcium phosphate & calcium carbonate

115. EFFECTS ON SURROUNDING STRUCTURES Roots of teeth are resorbed or displaced Width of inferior alveolar canal, if involved, is increased & shape changes to serpiginous path Mandibular & mental foramen may be enlarged Involved bone may be enlarged & have coarse internal trabeculae Developing teeth in contact with hemangioma may be larger & erupt earlier

116. Aneurysmal Bone Cyst Characterized as false cyst as it does not have epithelial lining Age- below 30 years Female predilection Usually presents as rapid bony swelling Pain is occasionally present Involved area may be tender on palpation

117. LOCATION Mandible is more commonly involved than maxilla (3:2) in molar & ramus region PERIPHERY & SHAPE Periphery is usually well defined & shape is circular. Radiographic features

118. INTERNAL SRTUCURE Small initial lesion may show no evidence of an internal structure Often internal structure is multilocular Septa is wispy & ill- defined & perpendicular to outer expanded border EFFECTS ON SURROUNDING STRUCTURES Causes expansion of outer cortical plates Displaces & resorbs teeth

119. CENTRAL GIANT CELL GRANULOMA Both have wispy, ill- defined trabeculae Expansion of cortex is more in ABC than CGCG ABC is found in molar & ramus area whereas CGCG in anterior to 1 st molar region DIFFERENTIAL DIAGNOSIS

120. AMELOBLASTOMA ABC causes cortical expansion & displaces & resorbs tooth as in ameloblastoma Molar – ramus region common site in both Septae are curved, coarse & well defined in ameloblastoma Occurs in older age DIFFERENTIAL DIAGNOSIS

121. CHERUBISM Both have ill defined, wispy trabeculae & causes expansion of jaws But cherubism is multifocal & bilateral DIFFERENTIAL DIAGNOSIS

122. Central Giant Cell Granuloma SYNONYM Giant cell reparative granuloma Giant cell lesion, giant cell tumour Slow growing lesion Affects mostly adolescents & young adults, usually below the age of 20 years Presents as painless swelling Area is tender on palpation Overlying mucosa is purple in colour

123. LOCATION More common in mandible (2:1) Epicenter of lesion is usually anterior to 1 st molar, although large lesion can extend posterior to ist molar Most maxillary lesion arise anterior to canines Lesions can cross midline PERIPHERY Well defined margin in mandible Lesions in maxilla have ill defined borders Radiographic features

124. INTERNAL STRUCTURE Small lesions are completely radiolucent Larger lesion show subtle granular pattern of calcification Occasionally these calcifications are organized into ill- defined wispy septa which are at right angles to the periphery of the lesion Sometimes these septa are well defined & divide the internal aspect into compartments, creating a multilocular appearance

125. EFFECTS ON SURROUNDING STRUCTURES Often displace & resorb teeth Resorption of roots not common but when it occurs, it may be profound & irregular in outline Lamina dura of involved teeth is absent Inferior alveolar canal may be displaced in an inferior direction

126. EFFECTS ON SURROUNDING STRUCTURES Causes expansion of cortical boundaries of jaw Expansion is uneven or undulating in nature, which may give appearance of a double boundary when seen in occlusal radiograph Outer cortical plate is destroyed in some cases & is seen more often in maxilla

127. Differential diagnosis AMELOBLASTOMA Occurs posterior mandible Younger age group More curved, granular & well defined septa

128. CHERUBISM Internal structure has fine, wispy trabeculae as in cherubism Cherubism is bilateral with epicenter in posterior part of jaw

129. ODONTOGENIC MYXOMA Both occur in mandible but CGCG occurs anterior to 1 st molar septae are sharper & straighter in OM CGCG causes expansion of jaws

130. ABC Both have wispy, ill- defined trabeculae Expansion of cortex is more in ABC than CGCG ABC is found in molar & ramus area whereas CGCG is anterior to 1 st molar region

131. Odontogenic Keratocyst OKC is a noninflammatory odontogenic cyst that arises from dental lamina Accounts for about 1/10 th of all cysts in the jaws Age- 2 nd & 3 rd decade Male predominance Usually asymptomatic Pain may occur with secondary infection Aspiration may reveal thick, yellow cheesy material (keratin)

132. LOCATION Site- posterior body of mandible (90% occur posterior to canine) & ramus (> 50%) Epicenter is located superior to inferior alveolar canal RADIOGRAPHIC FEATURES

133. PERIPHERY & SHAPE Cortical border is intact unless they have become secondarily affected Has smooth round or oval shape

134. INTERNAL STRUCURE Most commonly radiolucent In some cases curved internal septa may be present, giving lesion a multilocular appearance

135. EFFECTS ON SURROUNDING STRUCURES Grows along the internal aspect of jaws, causing minimal expansion This occurs throughout the mandible except for the upper ramus & coronoid process, where considerable expansion may occur Can displace & resorb teeth Inferior alveolar canal may be displaced inferiorly In maxilla, it may invaginate & occupy maxillary antrum

136. Ameloblastoma Both have scalloped margins Ameloblastoma causes expansion of bone Differential diagnosis

137. Odontogenic myxoma Both shows minimal expansion of bone Straight septa present in odontogenic myxoma

138. It is endocrine abnormality in which there is an excess of circulating Parathyroid hormone (PTH) It causes increase in serum calcium by two processes An excess of serum PTH increases bone remodeling by osteoclastic resorption, which mobilizes calcium from skeleton PTH also increases renal tubular resorption of calcium & renal products of active vitamin D metabolite HYPERPARATHYROIDISM

139. Types Primary Secondary PRIMARY HYPERPARATHYROIDISM Occurs due to benign tumour (adenoma) of one of four parathyroid glands, which produces excess PTH Diagnosis can be made on basis of hypercalcemia & elevated serum PTH level

140. SECONDARY TYPE Results from compensatory increase in output of PTH in response to hypocalcemia Hypocalcemia may be due to Poor dietary intake Poor absorption of Vitamin D Deficient metabolism of Vitamin D in liver or kidney

141. RADIOGRAPHIC FEATURES OF JAWS Demineralization & thinning of cortical boundaries often occur in the jaws in cortical boundaries such as inferior borders, mandibular canal & the cortical outlines of maxillary sinuses The densities of the jaws is decreased, resulting in a radiolucent appearance that contrasts with density of teeth

142. The teeth stand out in contrast to the radiolucent jaws A change in normal trabeculae pattern may occur, resulting in ground- glass appearance of numerous small, randomly oriented trabeculae

143. Brown tumour appear more frequently in facial bones & jaws, particularly in long standing cases Lesions may be multiple within a single bone Have variably defined margins May produce cortical expansion

144. RADIOGRAPHIC FEATURES OF TEETH & ASSOCIATED STRUCTURES Lamina dura is lost (10%) giving tooth a tapered appearance because of decreased image contrast It may occur around one tooth or all teeth It may be either partial or complete

145. REFERENCES Differential diagnosis of Oral & Maxillofacial lesions- 5 th Ed,Wood & Goaz Oral Radiology -5 th Ed White & Pharoah- Diagnostic Imaging of Jaws- Langland, Langlais, Nortje Clinical Outline of Oral Pathology,Eversole Essentials of Dental Radiology & radiography,Eric Whaites Textbook of Oral Pathology- 4 th Ed ,Shafer, Hine, Levy