Developmental Disorders

Question 1

Achondroplasia

Answer 1

● Autosomal dominant bone growth disorder
● Most common cause of disproportionate short stature, also known as dwarfism
● Manifestations include limited range of motion at the elbows and brachydactyly (i.e., small fingers)

Question 2

Ankyloglossia

Answer 2

A congenital condition where a short lingual frenulum restricts tongue movement, potentially affecting
oral function and speech

Question 2

Apert syndrome

Answer 2

● Craniosynostosis (i.e., early closure of cranial sutures)
● Syndactyly (i.e., fusion of the fingers and toes)
● Acrocephaly (i.e., tall skull)
● Narrow, vaulted palate
● Intellectual disability
● Hypertelorism (i.e., wide-set eyes)
● Maxillary hypoplasia

Question 3

Cherubism

Answer 3

● Genetic disorder that typically appears between ages 2 – 5, with progression during childhood and
stabilization or regression after puberty
● Multilocular, bilateral, radiolucent (“soap bubble”) lesions in the mandible and sometimes the maxilla
● Jaw expansion leads to facial swelling and can cause tooth displacement, malocclusion, and delayed
eruption of teeth
● Lesions are histologically identical to those of a central giant cell granuloma

Question 4

Cleidocranial dysplasia

Answer 4

● Delayed closure of frontal sutures and impaired osteoblast differentiation
● Characterized by hypoplastic or absent clavicles, prominent skull, mandibular prognathism, and
hypertelorism
● Associated with supernumerary teeth, prolonged retention of primary teeth, and cleft palate

Question 5

Cleft lip/palate

Answer 5

● Cleft lip results from the failure of the maxillary and medial nasal processes to fuse during the 4th – 7th
week of embryonic development
● Cleft palate occurs when the palatal shelves fail to fuse, typically between the 8th – 12th week of gestation
● Higher frequency of cleft lip and/or palate seen in Pierre Robin sequence, Treacher Collins syndrome, fetal
alcohol syndrome, cleidocranial dysplasia, and nevoid basal cell carcinoma
● Genetic and environmental factors play a role (e.g., maternal smoking, alcohol, folic acid deficiency)

Question 6

Crouzon syndrome

Answer 6

● Genetic disorder characterized by craniosynostosis (i.e., early closure of cranial sutures)
● Brachycephaly (i.e., short skull), midface deficiency, frontal bossing, hypertelorism, and
proptosis/exophthalmos (i.e., bulging eyes)
● Supernumerary teeth

Question 7

Gorlin-Goltz syndrome
(nevoid basal cell carcinoma
syndrome)

Answer 7

● Odontogenic keratocysts (OKCs)
● Basal cell carcinomas, palmar or plantar pits, calcification of the falx cerebri
● Macrocephaly, cleft lip/palate, bifid ribs

Question 8

McCune-Albright syndrome

Answer 8

● Prototypical triad: fibrous dysplasia of bone, café-au-lait macules, and endocrine abnormalities
● Endocrine abnormalities include precocious (i.e., early) puberty, hyperthyroidism, and hyperparathyroidism

Question 9

Pierre Robin sequence

Answer 9

● Prototypical triad of micrognathia, glossoptosis, and airway obstruction
● Cleft palate, hearing loss, ear infections, and natal teeth

Question 10

Treacher Collins syndrome

Answer 10

● Underdeveloped cheekbones and lower jaw, hypodontia, cleft palate
● Small, malformed ears, downward slanting eyes, hearing loss, breathing difficulties

Question 11

Neurofibromatosis type 1
(Von Recklinghausen’s disease)

Answer 11

Benign neoplasms of Schwann cells and fibroblasts (i.e., neurofibromas)
● Café-au-lait macules and Lisch nodules on the eyes
● Crowe’s sign (i.e., axillary freckling)
● Most serious complication can be neurofibrosarcoma, a malignant transformation of neurofibromas

Question 12

Down syndrome
(Trisomy 21)

Answer 12

● Genetic condition caused by nondisjunction, resulting in an extra copy of chromosome 21
● Flattened facial profile, small ears, short neck, atrioventricular septal defect, prominent epicanthal (i.e.,
upper eyelid) folds
● Most common chromosomal abnormality
● Associated with maxillary hypoplasia, macroglossia, decreased muscle tone, and higher incidence of class
III malocclusion
● Delayed tooth eruption, hypodontia, supernumerary teeth, and increased risk of periodontal disease

Question 13

Ectodermal dysplasia

Answer 13

● Group of inherited conditions of ectodermal tissue
● Two or more tissues of ectodermal origin are affected (e.g., skin, sweat glands, hair, nails, teeth, mucous
membrane)
● Associated with fine, sparse hair, wrinkly skin, and conical-shaped teeth
● Prototypical triad:
1. Hypohidrosis (i.e., diminished sweating)
2. Hypotrichosis (i.e., reduced hair)
3. Hypodontia (i.e., fewer teeth)

Question 14

Gardner syndrome

Answer 14

● Multiple polyps of the colon, skin, and skeleton; associated with malignant transformation
● Osteomas in the jaws
● Cotton-wool appearance of the jaws
● Epidermoid cysts of the skin, supernumerary teeth, impacted teeth, and connective tissue growths

Question 15

Von Willebrand disease

Answer 15

● Autosomal dominant condition caused by deficiency of Von Willebrand factor
● Results in defective platelet adhesion to blood vessel wall and decreased factor VIII
● Excessive bruising, bleeding, and nosebleeds

Question 16

Sickle cell anemia

Answer 16

● Abnormal hemoglobin synthesis resulting in reduced oxygen levels
● Most common in Black Americans
● Moon-shaped red blood cells, swelling of extremities, and episodes of pain during vaso-occlusive crises
● Hair-on-end appearance of the skull, interproximal alveolar bone step ladder patterns
● May experience tonsillitis and adenotonsillar hypertrophy which can lead to airway obstruction and obstructive sleep apnea

Question 17

Hemophilia

Answer 17

● Inherited sex-linked bleeding condition, reduced clotting factors causing decreased clotting abilities
● Minor trauma can cause frequent nosebleeds and bruising
● Hemophilia A: deficiency of factor VIII, affecting the intrinsic pathway, tested with the partial thromboplastin time (PTT) test
● Hemophilia B: deficiency of factor IX
● Hemophilia C: deficiency of factor XI

Question 18

Factor V Leiden

Answer 18

● Inherited blood-clotting disorder characterized by a mutation in the factor V protein
● Leads to higher propensity for blood clots (i.e., prothrombotic state)
● Associated with an increased risk of osteonecrosis due to disrupted blood flow to the bone

Question 19

Papillon-Lefèvre syndrome

Answer 19

● Hyperkeratosis of palmar and plantar surfaces
● Associated with advanced, accelerated periodontal disease, resulting in early loss of both the primary
and permanent dentitions

Question 20

Sturge-Weber syndrome

Answer 20

● Vascular proliferations (i.e., lymphangiomas)
● Characteristic unilateral red/purple lesions (i.e., port wine stains)
● Intellectual disabilities and seizures
● Supernumerary teeth

Question 21

Tetracycline staining

Answer 21

● Tetracycline exposure during tooth mineralization binds to calcium ions, causing permanent tooth staining.
● Location and severity of the discoloration depend on the stage of tooth development at the time of
exposure.
● Staining typically appears as yellow, brown, or gray bands in affected teeth.
● Tetracycline is not recommended for children under age 8, as permanent tooth calcification is still
incomplete

Question 22

Turner’s hypoplasia

Answer 22

● Enamel defect that affects a single tooth, usually caused by local trauma or infection of a primary tooth
● Leads to underdeveloped enamel on permanent tooth

Question 23

Fetal alcohol syndrome

Answer 23

● Craniofacial abnormalities including microcephaly, smooth philtrum, thin upper lip, and flat midface
● Oral findings include delayed tooth eruption, malocclusion, and increased risk of cleft lip/palate
● Poor oral hygiene and increased caries risk due to developmental delays, which may impact dental treatment planning and behavior management

Question 24

Horner syndrome

Answer 24

● Condition that affects the face on one side of the body and can be caused by damage to the sympathetic tracts leading from the hypothalamus to the eyes and face ● Symptoms include ptosis (i.e., drooping of the upper eyelid), miosis (i.e., constriction of the pupils), anhidrosis (i.e., decreased sweating)