Chapter 5. Developmental Disorders. Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 1

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1 Chapter 5 Developmental Disorders Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 1

2 Outline Ø Embryonic Development of the Face, Oral Cavity, and Teeth Ø Developmental Soft Tissue Abnormalities Ø Developmental Cysts Ø Developmental Abnormalities of Teeth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 2

3 Developmental Disorders A failure during the process of cell division and differentiation into various tissues and structures Ø Some may be identified clinically, by radiographic examination, biopsy, or histologic examination Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 3

4 Developmental Disorders Inherited disorder Ø Caused by an abnormality in genetic makeup Congenital disorder Ø Present at birth May be inherited or developmental Ø The cause of most congenital abnormalities is unknown Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 4

5 Embryonic Development of the Face During the third week, ectoderm infolds to form the stomodeum, the primitive oral cavity Stomodeum Frontal process Maxillary and mandibular process Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 5

6 Embryonic Development of the Face Two pits develop on the frontal process Ø They divide the frontal process into three parts: The median nasal process The right lateral nasal process The left lateral nasal process Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 6

7 Embryonic Development of the Face The median nasal process grows downward between the maxillary processes to form the globular process Ø This will form the philtrum Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 7

8 Embryonic Development of the Oral and Nasal Cavities Premaxilla Ø Forms from the globular process Lateral palatine processes Ø Form from the maxillary process The lateral palatine processes fuse with the premaxilla, creating a Y- shaped pattern The body of the tongue develops from the first branchial arch The base of the tongue forms from the second and third branchial arches Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 8

9 Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 9

10 Embryonic Development of the Teeth Odontogenesis: Tooth development Ø Ø Ø Ø Takes place in about the fifth week of life Involves ectoderm and ectomesenchyme Begins with formation in each jaw of a band of ectoderm called the primary dental lamina Ten small knoblike proliferations develop on the primary dental lamina in each jaw Each extends into the underlying mesenchyme Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 10

11 Deposition of Enamel and Dentin Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 11

12 Embryonic Development of the Teeth: Cell Differentiation The tooth germ has three parts: Ø Enamel organ Ø Dental papilla Ø Dental sac or follicle Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 12

13 Embryonic Development of the Teeth: Month 5 of Gestation Deposition of enamel and dentin: Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 13

14 Development of the Teeth Dental sac or follicle forms the cementum, the periodontal ligament, and alveolar bone Cementogenesis occurs after crown formation is complete Hertwig s epithelial root sheath: Shapes the root and induces root dentin Cementum is produced after tooth eruption, when the tooth is in occlusion and functioning Root length is completed 1 to 4 years after eruption Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 14

15 Developmental Soft Tissue Abnormalities Ankyloglossia Commissural lip pits Lingual thyroid Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 15

16 Ankyloglossia An extensive adhesion of the tongue to the floor of the mouth Treatment Ø Frenectomy Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 16

17 Commissural Lip Pits Epithelium-lined blind tracts located at the corners of the mouth (commissure) Treatment Ø None Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 17

18 Lingual Thyroid A small mass of thyroid tissue located on the tongue Ø Results from the failure of the primitive thyroid tissue to migrate from its developmental location in the area of the foramen cecum on the posterior portion of the tongue to its normal position in the neck Treatment Ø It may be removed if it is obstructive, provided the patient has other functioning thyroid tissue Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 18

19 Developmental Cysts Odontogenic cysts Ø Ø Ø Ø Ø Ø Dentigerous cyst Eruption cyst Primordial cyst Odontogenic keratocyst Calcifying odontogenic cyst Lateral periodontal cyst and gingival cyst Ø Ø Ø Ø Ø Ø Ø Ø Ø Nonodontogenic cysts Nasopalatine canal cyst Median palatine cyst Globulomaxillary cyst Median mandibular cyst Nasolabial cyst Brachial cleft cyst Epidermal cyst Dermoid cyst and benign cystic teratoma Thyroglossal tract cyst Pseudocysts Ø Static bone cyst Ø Simple bone cyst Ø Aneurysmal bone cyst Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 19

20 Developmental Cysts An abnormal fluid-filled epithelium-lined sac or cavity Most common oral cyst: Ø Radicular cyst (periapical cyst) Residual cyst Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 20

21 Developmental Cysts Developmental cysts are classified as to whether they are odontogenic or nonodontogenic Ø Location Ø Cause Ø Origin of the epithelial cells Ø Histologic appearance Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 21

22 Developmental Cysts They can cause expansion of bone Intraosseous cysts: Occur within bone Extraosseous cysts: Occur in soft tissue Cysts within bone generally appear as wellcircumscribed radiolucencies They may appear as unilocular or multilocular Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 22

23 Odontogenic Cysts Dentigerous cyst Eruption cyst Primordial cyst Odontogenic keratocyst Calcifying odontogenic cyst Lateral periodontal cyst and gingival cyst Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 23

24 Odontogenic: Dentigerous Cyst (Follicular Cyst) Forms around the crown of an unerupted or developing tooth Ø The epithelial lining originates from the reduced enamel epithelium after the crown has formed and calcified Ø Most commonly occurs around the crown of an unerupted or impacted third molar Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 24

25 Odontogenic: Dentigerous Cyst (Follicular Cyst) Radiographic Ø A well-defined, unilocular radiolucency around the crown of an unerupted or impacted tooth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 25

26 Odontogenic: Dentigerous Cyst (Follicular Cyst) Histologic Ø The lumen is most characteristically lined with cuboidal epithelium surrounded by a wall of connective tissue Treatment Ø Removal of the cyst There is some risk of cystic transformation into a neoplasm Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 26

27 Odontogenic: Eruption Cyst Similar to a dentigerous cyst Found in the soft tissue around the crown of an erupting tooth Treatment Ø None Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 27

28 Odontogenic: Primordial Cyst Develops in place of a tooth Ø Ø Most commonly in place of a third molar Most often seen in young adults and discovered on radiographic examination Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 28

29 Odontogenic: Primordial Cyst Histologic Ø The lumen is lined by stratified squamous epithelium surrounded by parallel bundles of collagen fibers Ø It may prove to be an odontogenic keratocyst or a lateral periodontal cyst Treatment Ø Surgical removal Ø The risk of recurrence depends on the diagnosis Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 29

30 Odontogenic Keratocyst (OKC) Histologic Ø The lumen is lined by epithelium that is 8 to 10 cell layers thick and surfaced by parakeratin Most often seen in the mandibular third molar region Can move teeth and cause resorption Treatment Ø Because of the high recurrence rate, surgical excision and osseous curettage are recommended Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 30

31 Odontogenic Keratocyst (OKC): Keratocystic Odontogenic Tumor Radiographic Ø Frequently appears as a well-defined, multilocular, radiolucent lesion Ø High recurrence rate! Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 31

32 Calcifying Odontogenic Cyst (COC) A nonaggressive, cystic lesion lined by odontogenic epithelium Closely resembles an ameloblastoma Has a characteristic feature called ghost cells Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 32

33 Intraosseous: Lateral Periodontal Cyst Extraosseous: Gingival Cyst Lateral periodontal cyst is most often seen in the mandibular cuspid and premolar area It is an asymptomatic, unilocular or multilocular radiolucent lesion on the lateral surface of a tooth root Botryoid odontogenic cyst = multilocular variant of lateral periodontal cyst Lateral periodontal cyst is found most often in males Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 33

34 Intraosseous: Lateral Periodontal Cyst Extraosseous: Gingival Cyst Histologic Ø A gingival cyst has the same type of lining as the lateral periodontal cyst, but is located in the soft tissue Ø A thin band of stratified squamous epithelium lines the gingival cyst Treatment Ø Surgical excision Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 34

35 Intraosseous: Lateral Periodontal Cyst Extraosseous: Gingival Cyst Multilocular, Multicystic: Botryoid Odontogenic Cyst Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 35

36 Glandular Odontogenic Cyst (GOC) Microscopic appearance: Multicystic lesions Ø Eosinophilic cuboidal cells on the surface of the epithelium Ø Columnar cells with cilia Ø Intraepithelial microcysts Ø Epithelial thickenings show whorls of cells similar to lateral periodontal cyst and botryoid cyst Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 36

37 Glandular Odontogenic Cyst (GOC) Enlargement of bone Ø Posterior mandible Ø Anterior maxilla Male and female 50 to 59 years Appears similar to ameloblastoma or odontogenic keratocyst (OKC) High recurrence rate Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 37

38 Nonodontogenic Cysts Nasopalatine canal cyst Median palatine cyst Globulomaxillary cyst Median mandibular cyst Nasolabial cyst Branchial cleft cyst (lymphoepithelial cyst) Epidermal cyst Dermoid cyst and benign cystic teratoma Thyroglossal tract cyst Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 38

39 Nonodontogenic Cysts: Nasopalatine Canal Cyst (Incisive Canal Cyst) Located within the nasopalatine canal or the incisive papilla Ø Males Ø 40 to 60 years old Ø Usually asymptomatic Ø May see a small, pink bulge near the apices and between the roots of the maxillary central incisors on the lingual surface Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 39

40 Nonodontogenic Cysts: Nasopalatine Canal Cyst (Incisive Canal Cyst) Radiographic Ø A well-defined, radiolucent lesion Ø May be oval or heart-shaped Histologic Ø Lined by epithelium varying from stratified squamous to pseudostratified ciliated columnar epithelium Treatment Ø Surgical excision Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 40

41 Nonodontogenic Cysts: Median Palatine Cyst A well-defined, unilocular radiolucency Located in the midline of the hard palate Histologic Ø Lined with stratified, squamous epithelium surrounded by dense fibrous connective tissue Treatment Ø Surgical removal Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 41

42 Nonodontogenic Cysts: Globulomaxillary Cyst A well-defined, pear-shaped radiolucency Located between the roots of the maxillary lateral incisor and cuspid Treatment Ø Surgical removal Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 42

43 Nonodontogenic Cysts: Median Mandibular Cyst A rare lesion located in the midline of the mandible Ø Lined with squamous epithelium Radiographic Ø A well-defined radiolucency below the apices of the mandibular incisors Treatment Ø Surgical removal Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 43

44 Nonodontogenic Cysts: Nasolabial Cyst A soft tissue cyst Thought to originate from the lower anterior portion of the nasolacrimal duct Observed in adults 40 to 50 years of age 4:1 ratio in favor of females Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 44

45 Nonodontogenic Cysts: Nasolabial Cyst Clinical Ø An expansion or swelling in the mucobuccal fold in the area of the maxillary canine and the floor of the nose Histologic Ø Lined with pseudostratified, ciliated columnar epithelium and multiple goblet cells Treatment Ø Surgical excision Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 45

46 Nonodontogenic Cysts: Branchial Cleft Cyst (Lymphoepithelial Cyst) Most commonly found in major salivary glands Ø A stratified squamous epithelial lining surrounded by a well-circumscribed component of lymphoid tissue Appears to arise from epithelium trapped in a lymph node during development Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 46

47 Nonodontogenic Cysts: Branchial Cleft Cyst (Lymphoepithelial Cyst) Most commonly found intraorally on the floor of the mouth and the lateral borders of the tongue Appears as a pinkish-yellow raised nodule Treatment Ø Surgical excision Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 47

48 Nonodontogenic Cysts: Epidermal Cyst A raised nodule on the skin of the face or neck May be noted intraorally on occasion Histologic Ø Lined by keratinizing epithelium that resembles the epithelium of the skin Ø The lumen is usually filled with keratin scales Treatment Ø Surgical excision Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 48

49 Nonodontogenic Cysts: Dermoid Cyst A developmental cyst often present at birth or noted in young children It is usually found on the floor of the mouth when it is located in the oral cavity May cause tongue displacement May have a doughy consistency when palpated Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 49

50 Nonodontogenic Cysts: Dermoid Cyst and Benign Cystic Teratoma Histologic Ø Lined by orthokeratinized, stratified squamous epithelium surrounded by a connective tissue wall Ø Ø The lumen is usually filled with keratin Hair follicles, sebaceous glands, and sweat glands may be seen in the cyst wall Benign cystic teratoma Ø Resembles a dermoid cyst + teeth, bone, muscles, and nerve tissue in the lesion wall Treatment Ø Surgical excision Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 50

51 Nonodontogenic Cysts: Thyroglossal Tract (Duct) Cyst Forms along the tract the thyroid gland follows in development Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 51

52 Nonodontogenic Cysts: Thyroglossal Tract (Duct) Cyst Found in young individuals (<20 years of age) No sex predilection Treatment Ø Excision of the cyst and tract Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 52

53 Pseudocysts Not true cysts because they are not lined by epithelium Ø Static bone cyst Ø Simple bone cyst Ø Aneurysmal bone cyst Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 53

54 Static Bone Cyst (Lingual Mandibular Bone Cavity, Stafne Bone Cyst) A pseudocyst Not a pathologic cavity Clinically: An anatomic depression on the posterior lingual area of the mandible Treatment Ø None Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 54

55 Static Bone Cyst (Lingual Mandibular Bone Cavity, Stafne Bone Cyst) A well-defined, cystlike radiolucency may be observed in this radiograph of the posterior region of the mandible inferior to the mandibular canal Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 55

56 Simple Bone Cyst (Traumatic Bone Cyst, Hemorrhagic Bone Cyst) A pathologic cavity in bone that is not lined with epithelium May be associated with trauma Treatment Ø Curettage on the wall lining the void Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 56

57 Simple Bone Cyst (Traumatic Bone Cyst, Hemorrhagic Bone Cyst) Radiographic Ø A well-defined unilocular or multilocular radiolucency Ø Characteristically shows scalloping around roots of teeth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 57

58 Aneurysmal Bone Cyst A pseudocyst Consists of blood-filled spaces surrounded by multinucleated giant cells and fibrous connective tissue Radiographic Ø Multilocular appearance: Honeycomb, soap bubble Ø Usually seen in persons less than 30 years old Ø Slight predilection for females Treatment Ø Surgical excision Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 58

59 Developmental Abnormalities of Teeth Abnormalities in the number of teeth Abnormalities in the size of teeth Abnormalities in the shape of teeth Abnormalities of tooth structure Abnormalities of tooth eruption Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 59

60 Abnormalities in the Number of Teeth Anodontia Hypodontia Supernumerary teeth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 60

61 Anodontia The congenital lack of teeth Total anodontia is lack of all teeth May be associated with ectodermal dysplasia Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 61

62 Hypodontia The lack of one or more teeth The most common missing permanent teeth are: Ø Mandibular and maxillary third molars Ø Maxillary lateral incisors Ø Mandibular second premolars The most common missing deciduous tooth is the mandibular incisor Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 62

63 Hypodontia Tends to be familial May be a component of a syndrome Treatment Ø May require prosthetic replacement Ø Orthodontic evaluation and treatment may be necessary Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 63

64 Supernumerary Teeth Extra teeth May result from formation of extra tooth buds in the dental lamina or from the cleavage of already existing tooth buds May occur in either deciduous or permanent dentition Most often seen in the maxilla Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 64

65 Supernumerary Teeth Mesiodens Ø The most common supernumerary tooth Ø Located between the maxillary incisors Ø May be inverted when seen on radiographs Distomolar Ø The second most common supernumerary tooth Ø Located distal to the third molar Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 65

66 Supernumerary Teeth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 66

67 Supernumerary Teeth Treatment Ø Erupted teeth may require removal if they cause crowding, malposition of adjacent teeth, or noneruption of normal teeth Ø Nonerupted teeth should be extracted because a risk exists for cyst development around the crown Multiple supernumerary teeth may be associated with cleidocranial dysplasia or Gardner syndrome Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 67

68 Abnormalities in the Size of Teeth Microdontia Macrodontia Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 68

69 Microdontia Microdontia: In which one or more teeth are smaller than normal Microdontia involving a single tooth is far more common: Ø Maxillary lateral incisor and maxillary third molar are the most commonly involved teeth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 69

70 Microdontia True generalized microdontia Ø Seen in a pituitary dwarf; all teeth are smaller than normal Generalized relative microdontia Ø Normal-sized teeth appear small in a large jaw Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 70

71 Macrodontia One or more teeth are larger than normal Ø True generalized macrodontia Seen in cases of pituitary gigantism Ø Relative generalized macrodontia Large teeth in a small jaw Ø Macrodontia affecting a single tooth May be seen in cases of facial hemihypertrophy Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 71

72 Abnormalities in the Shape of Teeth Gemination Fusion Concrescence Dilaceration Enamel pearl Talon cusp Taurodontism Dens in dente Dens evaginatus Supernumerary roots Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 72

73 Gemination A single tooth germ attempts to divide in two Appears as two crowns joined together by a notched incisal area Radiographically, usually one single root and one common pulp canal exist The patient has a full complement of teeth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 73

74 Gemination Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 74

75 Fusion The union of two normally separate adjacent tooth germs Appears as a single large crown that occurs in place of two normal teeth Radiographically, either separate or fused roots and root canals are seen The patient is usually short one tooth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 75

76 Concrescences Two adjacent teeth are united by cementum Usually discovered on radiograph Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 76

77 Dilaceration An abnormal curve or bend in the root of a tooth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 77

78 Dilaceration Ø Usually discovered on radiograph Ø May cause a problem if the tooth must be removed or a root canal performed Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 78

79 Enamel Pearl A small, spherical enamel projection on a root surface Ø Ø Ø Usually found on maxillary molars Radiographically, it appears as a small, spherical radiopacity Removal may be necessary if periodontal problems occur in the furcation Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 79

80 Talon Cusp An accessory cusp located in the cingulum area of a maxillary or mandibular permanent incisor Contains a pulp horn May interfere with occlusion Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 80

81 Taurodontism The teeth have elongated pulp chambers and short roots Ø May occur in both deciduous and permanent dentition Ø Identified on radiographs Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 81

82 Dens in Dente Occurs when the enamel organ invaginates into the crown of a tooth before mineralization Radiographically, it appears as a toothlike structure within a tooth Vulnerable to caries, pulpal infection, and necrosis Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 82

83 Dens Evaginatus An accessory enamel cusp found on the occlusal tooth surface Most often seen on mandibular premolars May cause occlusal problems Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 83

84 Supernumerary Roots May involve any tooth Most commonly, maxillary and mandibular third molars if multirooted teeth are involved May become clinically significant if removal or endodontia is necessary Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 84

85 Abnormalities of Tooth Structure Enamel hypoplasia Enamel hypocalcification Endogenous staining of teeth Regional odontodysplasia Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 85

86 Enamel Hypoplasia The incomplete or defective formation of enamel May be due to many factors: Ø Amelogenesis imperfecta Ø Febrile illness (measles, chickenpox, scarlet fever) Ø Vitamin deficiency Ø Infection of a deciduous tooth Ø Ingestion of fluoride Ø Congenital syphilis Ø Birth injury, premature birth Ø Idiopathic factors Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 86

87 Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency Ameloblasts are one of the most sensitive cell groups in the body Any serious systemic disease or severe nutritional deficiency can produce enamel hypoplasia Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 87

88 Enamel Hypoplasia Resulting from Local Infection or Trauma Enamel hypoplasia of an adult tooth may result from infection of a deciduous tooth A single tooth is usually affected; it is referred to as a Turner tooth The color of the enamel may range from yellow to brown, or severe pitting and deformity may be involved Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 88

89 Enamel Hypoplasia Resulting from Fluoride Ingestion Affected teeth exhibit a mottled discoloration of enamel Ingestion of water with two to three times the recommended amount leads to white flecks and chalky opaque areas of enamel Four times the recommended amount of fluoride causes brown or black staining Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 89

90 Enamel Hypoplasia Resulting from Fluoride Ingestion Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 90

91 Enamel Hypoplasia Resulting from Congenital Syphilis Congenital syphilis is transmitted from an infected mother to her fetus via the placenta Mulberry molars have a berrylike appearance Hutchinson incisors are shaped like screwdrivers Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 91

92 Enamel Hypoplasia Resulting from Birth Injury, Premature Birth, or Idiopathic Factors Enamel hypoplasia may occur due to trauma or injury at the time of birth Ø Even a mild illness or systemic problem can result in enamel hypoplasia Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 92

93 Enamel Hypocalcification A developmental anomaly resulting in a disturbance in the maturation of the enamel matrix Usually appears as a chalky, white spot on the middle third of smooth crowns The underlying enamel may be soft and susceptible to caries Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 93

94 Endogenous Staining of Teeth The result of deposition of substances circulating systemically during tooth development May be due to: Ø Tetracycline stain Ø Erythroblastosis fetalis: Rh incompatibility Ø Neonatal liver disease Ø Congenital porphyria: An inherited metabolic disease Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 94

95 Regional Odontodysplasia (Ghost Teeth) Exhibit a marked reduction in radiodensity and a characteristic ghostlike appearance Very thin enamel and dentin are present Usually treated by extraction Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 95

96 Abnormalities of Tooth Eruption Impacted teeth cannot erupt because of an obstruction Embedded teeth do not erupt because of lack of eruptive force Ankylosed teeth Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 96

97 Impacted and Embedded Teeth Any tooth can be impacted Third molar impactions are classified according to the position of the tooth Teeth can be completely impacted in bone or they may be partially impacted Partially impacted teeth are prone to infection Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 97

98 Impacted and Embedded Teeth Impacted teeth may be surgically removed to prevent odontogenic cyst and tumor formation or damage to adjacent teeth The optimal time is between 12 and 24 years of age Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 98

99 Ankylosed Teeth Tooth cementum fused to bone Prevents exfoliation of the deciduous tooth and eruption of the underlying adult tooth The ankylosed deciduous tooth appears submerged and has a different sound when percussed (a kind of dull thud) Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 99

100 Ankylosed Teeth The periodontal ligament space is lacking Difficult to extract Ø Removal of deciduous teeth is necessary for eruption of the adult successor Ø Removal of adult teeth may be necessary to prevent malocclusion, caries, and periodontal disease Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 100

101 Discussion Questions What developmental soft tissue abnormalities may be observed within the oral cavity? What developmental cysts may be observed within the oral cavity? What developmental abnormalities of teeth may be observed within the oral cavity? Copyright 2014, 2009, 2004, 2000, 1996, 1992 by Saunders, an imprint of Elsevier Inc 101