1. Developmental Disorders
Chapter 5
Developmental Disorders

2. Outline Embryonic Development of the Face, Oral Cavity, and Teeth
Developmental Soft Tissue Abnormalities
Developmental Cysts
Developmental Abnormalities of Teeth

3. Developmental Disorders
(pg. 156)
A failure during the process of cell division and differentiation into various tissues and structures
Some may be identified clinically, by radiographic examination, biopsy, or histologic examination.

4. Developmental Disorders (cont.)
(pg. 156)
Inherited disorder
Caused by an abnormality in genetic makeup
Congenital disorder
Present at birth
May be inherited or developmental
The cause of most congenital abnormalities is unknown.

5. Embryonic Development of the Face, Oral Cavity, and Teeth
Oral and Nasal Cavities
Teeth

6. Face
(pgs )
During the third week, ectoderm infolds to form the stomodeum, the primitive oral cavity.
The frontal process is above and the first branchial arch is below.
The first branchial arch divides into two maxillary processes and the mandibular process.

7. Face (cont.)

8. Face (cont.) Two pits develop on the frontal process.
They divide the frontal process into three parts.
The median nasal process
The right lateral nasal process
The left lateral nasal process
The median nasal process grows downward between the maxillary processes to form the globular process.
This will form the philtrum.

9. Oral and Nasal Cavities
(pg. 157)
Premaxilla
Forms from the globular process
Lateral palatine processes
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.

10. Teeth Odontogenesis (pgs. 157-158)
Takes place in about the fifth week of life
Involves ectoderm and ectomesenchyme
Begins with formation of a band of ectoderm in each jaw called the primary dental lamina
Ten small knoblike proliferations develop on the primary dental lamina in each jaw.
Each extends into underlying mesenchyme.

11. Teeth (cont.)

12. Teeth (cont.) The tooth germ has three parts. The enamel organ
Produces enamel
The dental papilla
Forms the dental pulp
The dental sac or follicle
The follicle provides cells that form cementum, the periodontal ligament, and alveolar bone.
Cementum is formed after the crown is complete.

13. Developmental Soft Tissue Abnormalities
(pgs )
Ankyloglossia
Commissural Lip Pits
Lingual Thyroid

14. Ankyloglossia
(pg. 158)
An extensive adhesion of the tongue to the floor of the mouth
Due to the complete or partial fusion of the lingual frenum
Some patients may have no adverse effects, while others may have difficulty with speech.
It may just involve mucosa, or it may be muscular and thick.
Treatment
Frenectomy
This works nicely with a laser.

15. Ankyloglossia (cont.)

16. Commissural Lip Pits
(pgs )
Epithelium-lined blind tracts located at the corners of the mouth (commissure)
May be shallow or several millimeters deep.
Congenital lip pits may also be observed near the midline of the vermilion border.
Treatment
None

17. Commissural Lip Pits (cont.)

18. Lingual Thyroid A small mass of thyroid tissue located on the tongue
(pg. 159)
A small mass of thyroid tissue located on the tongue
Results from the failure of the primitive thyroid tissue to migrate from its developmental location in the area of foramen cecum on the posterior portion of the tongue to its normal position in the neck

19. Lingual Thyroid (cont.)
Appears as a smooth nodular mass posterior to circumvallate papillae at the base of the tongue.
TreatmentS
It may be removed if it is obstructive, providing the patient has other functioning thyroid tissue.

20. Developmental Cysts Odontogenic Cysts NonodontogenicS Cysts
Pseudocysts

21. Developmental Cysts (cont.)
(pg. 159) (Box 5-1)
An abnormal fluid-filled epithelium-lined sac or cavity
Found throughout the body, including the head and neck region

22. Developmental Cysts (cont.)
Developmental cysts are classified as to whether they are odontogenic or nonodontogenic.
They are also classified according to location, cause, origin of the epithelial cells, and histologic appearance.

23. Developmental Cysts (cont.)
They can cause expansion of bone.
Intraosseous cysts
Occur within bone
Extraosseous cysts
Occur in soft tissue
Cysts within bone generally appear as well-circumscribed radiolucencies.
They may appear as unilocular or multilocular.

24. Odontogenic Cysts Dentigerous Cyst Eruption Cyst Primordial Cyst
Odontogenic Keratocyst
Calcifying Odontogenic Cyst
Lateral Periodontal Cyst and Gingival Cyst

25. Dentigerous Cyst (Follicular Cyst)
(pgs )
Forms around the crown of an unerupted or developing tooth
The epithelial lining originates from the reduced enamel epithelium after the crown has formed and calcified.
Most commonly around the crown of an unerupted or impacted third molar

26. Dentigerous Cyst (Follicular Cyst) (cont.)

27. Dentigerous Cyst Radiographic Histologic Treatment (pgs. 160-161)
A well-defined, unilocular radiolucency around the crown of an unerupted or impacted tooth
Histologic
The lumen is most characteristically lined with cuboidal epithelium surrounded by a wall of connective tissue.
Treatment
Removal of the cyst
There is some risk of cystic transformation into a neoplasm.

28. Dentigerous Cyst (cont.)

29. Eruption Cyst Similar to a dentigerous cyst Treatment (pg. 160)
Found in the soft tissue around the crown of an erupting tooth
Treatment
None

30. Primordial Cyst Develops in the place of a tooth (pgs. 160-161)
Most commonly in place of a third molar
Most often seen in young adults and discovered on radiographic examination

31. Primordial Cyst

32. Primordial Cyst (cont.)
Histologic
The lumen is lined by stratified squamous epithelium surrounded by parallel bundles of collagen fibers.
It may prove to be an odontogenic keratocyst or a lateral periodontal cyst.
Treatment
Surgical removal
The risk of recurrence depends on the diagnosis.

33. Odontogenic Keratocyst (OKC)
(pgs )
Characterized by histologic appearance and frequent recurrence
The lumen of the cyst contains perakeratin.
Most often seen in the mandibular third molar region
Can move teeth and cause resorption

34. Odontogenic Keratocyst
(pgs )
Histologic
The lumen is lined by epithelium that is 8 to 10 cell layers thick and surfaced by parakeratin.
Radiographic
Frequently appears as a well-defined, multilocular, radiolucent lesion

35. Odontogenic Keratocyst (cont.)
(pgs )
Treatment
Due to a high recurrence rate, surgical excision and osseous curettage are recommended.

36. Calcifying Odontogenic Cyst (COC)
(pg. 163)
A nonaggressive, cystic lesion lined by odontogenic epithelium
Closely resembles an ameloblastoma
Has a characteristic feature called ghost cells

37. Lateral Periodontal Cyst and Gingival Cyst
(pgs )
Most often seen in the mandibular cuspid and premolar area
An asymptomatic, unilocular or multilocular radiolucent lesion on the lateral surface of a tooth root
Found most often in males

38. Lateral Periodontal Cyst and Gingival Cyst (cont.)
(pgs )
Histologic
A gingival cyst has the same type of lining, but is located in the soft tissue.
A thin band of stratified squamous epithelium lines the cyst
Treatment
Surgical excision

39. Lateral Periodontal Cyst and Gingival Cyst (cont.)

40. 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

41. Nasopalatine Canal Cyst (Incisive Canal Cyst)
(pg. 164)
Located within the nasopalatine canal or the incisive papilla
Most commonly seen in men between 40 and 60 years old
Usually asymptomatic
May see a small, pink bulge near the apices and between the roots of the maxillary central incisors on the lingual surface

42. Nasopalatine Canal Cyst
(pg. 164)
Radiographic
A well-defined, radiolucent lesion
May be oval or heart-shaped
Histologic
Lined by epithelium varying from stratified squamous to pseudostratified ciliated columnar epithelium
Treatment
Surgical excision

43. Nasopalatine Canal Cyst (cont.)

44. Median Palatine Cyst A well-defined, unilocular radiolucency
(pgs )
A well-defined, unilocular radiolucency
Located in the midline of the hard palate
Histologic
Lined with stratified, squamous epithelium surrounded by dense fibrous connective tissue
Treatment
Surgical removal

45. Median Palatine Cyst (cont.)

46. Globulomaxillary Cyst
(pg. 165)
A well-defined, pear-shaped radiolucency found between the roots of the maxillary lateral incisor and cuspid
Was once thought to be a fissural cyst, now believed to be of odontogenic epithelial origin
Treatment
Surgical removal

47. Globulomaxillary Cyst (cont.)

48. Median Mandibular Cyst
(pg. 165)
A rare lesion located in the midline of the mandible
Lined with squamous epithelium
Radiographic
A well-defined radiolucency below the apices of mandibular incisors
Treatment
Surgical removal

49. Nasolabial Cyst A soft tissue cyst (pgs. 165-166)
Thought to originate from the lower anterior portion of the nasolacrimal duct
Observed in adults from 40 to 50 years of age
4:1 ratio in favor of females

50. Nasolabial Cyst (cont.)
(pgs )
Clinical
An expansion or swelling in the mucobuccal fold in the area of the maxillary canine and the floor of the nose
Histologic
Lined with pseudostratified, ciliated columnar epithelium and multiple goblet cells
Treatment
Surgical excisions

51. Nasolabial Cyst (cont.)

52. Branchial Cleft Cyst (Lymphoepithelial Cyst)
(pgs )
Most commonly found in major salivary glands
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

53. Branchial Cleft Cyst (Lymphoepithelial Cyst) (cont.)

54. Branchial Cleft Cyst (Lymphoepithelial Cyst) (cont.)
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
Surgical excision

55. Epidermal Cyst Treatment
(pg. 166)
A raised nodule on the skin of the face or neck
May be noted intraorally on occasion
Histologic
Lined by keratinizing epithelium the resembles the epithelium of the skin
The lumen is usually filled with keratin scales
Treatment
Surgical excision

56. Dermoid Cyst and Benign Cystic Teratoma
(pg. 166)
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 have a doughy consistency when palpated

57. Dermoid Cyst Histologic Treatment
Lined by orthokeratinized, stratified squamous epithelium surrounded by a connective tissue wall
The lumen is usually filled with keratin
Hair follicles, sebaceous glands, and sweat glands may be seen in the cyst wall
Benign cystic teratoma
Resembles a dermoid cyst
Treatment
Surgical excision

58. Thyroglossal Tract Cyst
(pgs )
Forms along the tract the thyroid gland follows in development
Most often found in young individuals under 20 years of age
No sex predilection
Treatment
Excision of the cyst and tract

59. Thyroglossal Tract Cyst (cont.)

60. Pseudocysts
Static Bone Cyst
Simple Bone Cyst
Aneurysmal Bone Cyst

61. Static Bone Cyst (Lingual Mandibular Bone Cavity) (Stafne Bone Cyst)
(pgs. 166, 168)
A pseudocyst (not a true cyst)
A well-defined cystlike radiolucency may be observed on radiograph in the posterior region of the mandible inferior to the mandibular canal.
Caused by a lingual depression in the mandible
Treatment
None

62. Static Bone Cyst (Lingual Mandibular Bone Cavity) (Stafne Bone Cyst) (cont.)

63. Simple Bone Cyst (Traumatic Bone Cyst)
(pg. 168)
A pathologic cavity in bone that is not lined with epithelium
May be associated with trauma
Radiographic
A well-defined unilocular or multilocular radiolucency
Characteristically shows scalloping around roots of teeth
Treatment
Curettage on the wall lining the void

64. Simple Bone Cyst (Traumatic Bone Cyst) (cont.)

65. Aneurysmal Bone Cyst A pseudocyst (pg. 168)
Consists of blood filled spaces surrounded by multinucleated giant cells and fibrous connective tissue

66. Aneurysmal Bone Cyst (cont.)
Radiographic
Multilocular appearance “honeycomb,” “soap bubble”
Usually seen in persons less than 30 years old
Slight predilection for females
Treatment
Surgical excision

67. 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

68. Abnormalities in the Number of Teeth
Anodontia
Hypodontia
Supernumerary Teeth

69. Anodontia The congenital lack of teeth (pgs. 168-169)
Total anodontia is lack of all teeth.
May be associated with ectodermal dysplasia

70. Hypodontia The lack of one or more teeth
(pg. 169)
The lack of one or more teeth
May affect either deciduous or permanent teeth
The most common missing permanent teeth are
Mandibular and maxillary third molars
Maxillary lateral incisors
Mandibular second premolars
The most common missing deciduous tooth is the mandibular incisor.

71. Hypodontia (cont.)

72. Hypodontia (cont.) Treatment
Usually identified during clinical and radiographic examination
Tends to be familial
Treatment
May require prosthetic replacement
Orthodontic evaluation and treatment may be necessary
May be a component of a syndrome

73. Supernumerary Teeth Extra teeth found in the dental arches
(pgs )
Extra teeth found in the dental arches
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
Most are found on radiographs

74. Supernumerary Teeth (cont.)

75. Supernumerary Teeth (cont.)
(pgs. 169, )
Mesiodens
The most common supernumerary tooth
Located between maxillary incisors
May be inverted when seen on radiographs
Distomolar
The second most common supernumerary tooth
Located distal to the third molar

76. Supernumerary Teeth (cont.)

77. Supernumerary Teeth (cont.)
Treatment
Erupted teeth may require removal if they cause crowding, malposition of adjacent teeth, or noneruption of normal teeth.
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.

78. Abnormalities in the Size of Teeths
Microdontia
Macrodontia

79. Microdontia One or more teeth are smaller than normal.
(pgs. 170, 172) (Fig. 5-24)
One or more teeth are smaller than normal.
True generalized microdontia
Seen in a pituitary dwarf; all teeth are smaller than normal
Generalized relative microdontia
Normal-sized teeth appear small in a large jaw.
Microdontia involving a single tooth
Maxillary lateral incisor and maxillary third molar are the most commonly involved teeth.

80. Microdontia (Cont.)

81. Macrodontia One or more teeth are larger than normal. (pg. 170)
True generalized macrodontia
Seen in cases of pituitary giantism
Relative generalized macrodontia
Large teeth in a small jaw
Macrodontia affecting a single tooth
May be seen in cases of facial hemihypertrophy

82. Abnormalities in the Shape of Teeths
Gemination
Fusion
Concrescence
Dilaceration
Enamel Pearl
Talon Cusp
Taurodontism
Dens in Dente
Dens Evaginatus
Supernumerary Rootsss

83. Gemination Occurs when a single tooth germ attempts to divide in two
(pgs , 173)
Occurs when 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.

84. Gemination (cont.)

85. Fusion The union of two normally separate adjacent tooth germs
(pgs )
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.

86. Fusion (cont.)

87. Concrescences Two adjacent teeth are united by cementum.
(pgs. 172, 174)
Two adjacent teeth are united by cementum.
Usually discovered on radiograph
If one of the teeth needs to be removed, both usually come out (two for the price of one).

88. Concrescences (cont.)

89. Dilaceration An abnormal curve or bend in the root of a tooth
(pgs. 172, )
An abnormal curve or bend in the root of a tooth
Usually discovered on radiograph
May cause a problem if the tooth must be removed or a root canal performed

90. Dilaceration (cont.)

91. Enamel Pearl A small, spherical enamel projection on a root surface
(pgs. 174, 176)
A small, spherical enamel projection on a root surface
Usually found on maxillary molars
Radiographically, it appears as a small, spherical radiopacity.
Difficult to instrument with curettes or scalers
Removal may be necessary if periodontal problems occur in the furcation.

92. Enamel Pearl (cont.)

93. Talon Cusp
(pgs. 174, 176)
An accessory cusp located in the cingulum area of a maxillary or mandibular permanent incisor
Contains a pulp horn
May interfere with occlusion

94. Talon Cusp (cont.)

95. Taurodontism The teeth have elongated pulp chambers and short roots.
(pgs. 174, 176)
The teeth have elongated pulp chambers and short roots.
May occur in both deciduous and permanent dentition
Identified on radiographs

96. Taurodontism (cont.)

97. Dens in Dente
(pgs. 175, 177)
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
A restoration can be placed in the pit if the tooth is vital.

98. Dens in Dente (cont.)

99. Dens Evaginatus
(pgs )
An accessory enamel cusp found on the occlusal tooth surface
Most often seen on mandibular premolars
May cause occlusal problems

100. Dens Evaginatus (cont.)

101. Supernumerary Roots May involve any tooth (pgs. 176-177)
Most commonly, maxillary and mandibular third molars if multirooted teeth are involved.
May become clinically significant if removal or endodontia is necessary

102. Supernumerary Roots

103. Abnormalities of Tooth Structure
Enamel Hypoplasia
Enamel Hypocalcification
Endogenous Staining of Teeth
Regional Odontodysplasia

104. Enamel Hypoplasia The incomplete or defective formation of enamel
(pgs )
The incomplete or defective formation of enamel
Can affect either deciduous or permanent dentition
May be due to many factors
Amelogenesis imperfecta
Febrile illness (measles, chickenpox, scarlet fever)
Vitamin deficiency
Infection of a deciduous tooth
Ingestion of fluoride
Congenital syphilis
Birth injury, premature birth
Idiopathic factors

105. Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency
(pgs )
Ameloblasts are one of the most sensitive cell groups in the body.
Any serious systemic disease or severe nutritional deficiency can produce enamel hypoplasia.
One or more horizontal rows of tiny, deep pits are seen traversing the affected tooth surface.

106. Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency (cont.)

107. Enamel Hypoplasia Resulting from Local Infection or Trauma
(pg. 178)
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.

108. Enamel Hypoplasia Resulting from Fluoride Ingestion
(pg. 178)
Affected teeth exhibit a mottled discoloration of enamel.
Ingestion of water with 2 to 3 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.

109. Enamel Hypoplasia Resulting from Fluoride Ingestion (cont.)

110. Enamel Hypoplasia Resulting from Congenital Syphilis
(pgs )
Congenital syphilis is transmitted from an infected mother to her fetus via the placenta.
This may result in enamel hypoplasia of adult incisors and first molars.
Hutchinson incisors are shaped like screwdrivers.
Mulberry molars have a berrylike appearance.

111. Enamel Hypoplasia Resulting from Congenital Syphilis (cont.)

112. Enamel Hypoplasia Resulting from Birth Injury, Premature Birth, or Idiopathic Factors
(pg. 179)
Enamel hypoplasia may occur due to trauma or injury at the time of birth.
Even a mild illness or systemic problem can result in enamel hypoplasia.

113. Enamel Hypocalcification
(pg. 179)
A developmental anomaly resulting in a disturbance or 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.

114. Endogenous Staining of Teeth
(pg. 179)
The result of deposition of substances circulating systemically during tooth development
May be due to
Tetracycline stain
Erythroblastosis fetalis – Rh incompatibility
Neonatal liver disease
Congenital porphyria – an inherited metabolic disease

115. Regional Odontodysplasia (Ghost Teeth)
(pgs )
One or several teeth in the same quadrant exhibit a marked reduction in radiodensity and a characteristic ghostlike appearance.
Very thin enamel and dentin are present
May affect primary or adult dentition
Usually treated by extraction

116. Regional Odontodysplasia (Ghost Teeth) (cont.)

117. Abnormalities of Tooth Eruption
(pgs )
Impacted and embedded teeth
Impacted teeth cannot erupt due to an obstruction.
Embedded teeth do not erupt due to lack of eruptive force.
Ankylosed teeth

118. Impacted and Embedded Teeth
(pg. 180)
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.

119. Impacted and Embedded Teeth (cont.)

120. Impacted and Embedded Teeth (cont.)
Impacted teeth may be surgically removed to prevent odontogenic cyst and tumor formation or damage to adjacent teeth.
Partially impacted third molar teeth are removed to prevent infections.
The optimal time is between 12 and 24 years of age.

121. Ankylosed Teeth Tooth cementum fused to bone (pgs. 180-181)
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 (kind of a dull thud).

122. Ankylosed Teeth (cont.)

123. Ankylosed Teeth (cont.)
The periodontal ligament space is lacking.
Difficult to extract
Removal of deciduous teeth is necessary for eruption of the adult successor.
Removal of adult teeth may be necessary to prevent malocclusion, caries, and periodontal disease.

124. 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?