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Flashcards in Exam 2 Deck (196):
1

What is HERS?

At the base of the tooth crown, the confluence of the inner and outer enamel epithelium elongate to form a bilayered Hertwig's epithelial root sheath. It is an extension formed by the free edge of the enamel organ on the developing tooth which goes beyond the DEJ and molds the dental papilla to form the root of the tooth. It also initiates formation of dentin in the root of a tooth by causing the differentiation of odontoblasts from the mesenchyme of the dental papilla.

2

What is given to babies with cleft lip or palate to help them eat?

Obturator

3

What has cleft lip been attributed to?

Underdevelopment of the mesenchyme of the maxillary swelling, which results in inadequate contact of the maxillary swelling with the intermaxillary process.

4

What happens during inductive stage of amelogenesis?

Dentin is not mineralized, and the IEE has a cuboidal or low columnar appearance, with centralized nuclei and poorly developed Golgi. The IEE cells then elongate and become preameloblasts, but no Tomes process yet. It is at this stage that the ameloblasts send a signal across the DEJ to stimulate dentinogenesis.

5

From what three pairs of cartilaginous precursors does the chondocranium develop from?

1. Ethmoid prechordal cartilage 2. Sphenoid hypophyseal cartilage 3. Occipital parachordal cartilage

6

What innervates the taste component of the anterior 2/3 of the tongue?

It is supplied by the chorda tympani branch of CN VII-facial nerve, which innervates all taste buds except the circumvallate papillae.

7

What kind of heart defects can accompany DiGeorge syndrome?

Because of lack of blood, you can get a ventricular septal defect, only one large vessels instead of two (truncus arteriosus), or four abnormal heart structures (tetralogy of Fallot)

8

What is minor clefting?

Involves only the soft tissue of the lip and results in a notch in the vermillion border of the lip just lateral to the philtrum called a partial cleft.

9

What is the oronasal membrane?

It separates the nasal sac from the oral cavity, similar to the nasal fin, but forms when vacuoles develop in the nasal fin, fuse with the nasal sac, enlarging it and thinning the fin to a thin membrane called the oronasal membrane.

10

Dentinogenesis takes place throughout our entire lives. True or False?

True. Secondary dentin production happens.

11

What ends up forming the anterior two thirds of the tongue?

Distal tongue buds

12

Artificial saliva can also help stimulate salivary gland production. True or False?

False. Just helps lubricate and replace moisture lost.

13

What are the three kinds of amelogenesis imperfecta?

1. Hypoplastic - defect in amount of enamel (pitted). Pitted-Has normal thickness, pitted surface, normal hardness. Generalized-reduced thickness, smooth surface, normal hardness 2. Hypomaturation - defect in final growth and maturation of enamel crystallities and hypomineralization. Has normal thickness, chipped surface, less hardness, opaque white coloration. 3. Hypocalcified - defect in initial crystallite formation followed by defective growth and hypomineralization. Has normal thickness, smooth surface, less hardness.

14

What do the maxillary swellings do during the fifth week?

They enlarge and grow ventrally and medially simultaneously.

15

What is the name of the midline swelling that the third and fourth pharyngeal arches give rise to that overgrows the copula on the tongue?

Hypopharyngeal eminence

16

What is the name of the area between the epiphysis and diaphysis that is made up of uncalcified cartilage?

Epiphyseal plate (growth plate). This is the major center for growth in long bones. While periosteum plays a role in adding thickness and reshapes external contours.

17

What are the main four drugs that influence neural crest cell migration?

1. Alcohol 2. Thalidomide 3. Accutane 4. Retinoic acid

18

What does sagittal synostosis result in?

Bitemporal narrowing and prominence in frontal and occipital.

19

What is another name for the small areas of cartilage that represent the old chondocranium?

Synchondroses

20

What is distraction osteogenesis?

A technique that uses a device to pull the midface slowly forward after surgery and move it further forward than a single surgery can.

21

What is the name of the muscle that attaches to the posterior aspect of the maxillary palatal shelves?

Superior pharyngeal constrictor muscle, every time we swallow this muscle pulls on the separated palatal shelves. The orbicularis oris muscle is also involved.

22

What ends up forming the posterior one third of the tongue?

Hypopharyngeal eminence

23

What are other causes of enamel defects?

Vitamin A deficiency, measles, antibiotics, fluorosis

24

What are the five principle stages in craniofacial development?

1. Germ layer formation 2. Neural tube formation and initial formation of the oropharynx 3. Origin, migration, and interactions of cell population, especially neural crest cells 4. Formation of organ systems, especially the pharyngeal arches and the primary palate and secondary palates 5. Final differentiation of tissues

25

What causes a facial cleft?

Complete or partial failure of fusion between any of the five facial swellings. Can be unilateral or bilateral.

26

What are the five facial swellings that all originate from the first pharyngeal arch?

1. unpaired frontonasal process 2. Two maxillary swellings 3. Two mandibular swellings

27

What changes with growth with mineralized tissues?

Hyperplasia, hypertrophy, and secretion of extracellular material can only occur on the surface, not within the mineralized mass. Direct addition of new bone occurs through the activity of cells in the periosteum, and is called direct or surface apposition of bone.

28

What does cephalocaudal gradient of growth mean?

It means that there is an axis of increased growth extending from the head toward the feet.

29

By what type of ossification do the maxilla, zyogmatic, and temporal bones form?

Intramembranous ossification

30

What forms the intermaxillary process?

By the end of week 7, the inferior tips of the medial nasal processes expand laterally and inferiorly and fuse to form the intermaxillary process.

31

What is a common side effect cleft palates?

Buildup behind the eardrum, which affects hearing.

32

PTH has no direct established activity on the intestine. True or False?

True, but indiretly it increases intestinal calcium and phosphorus absorption via stimulation of 1,25 dihydroxyvitamin D production.

33

What are the four main functions of saliva?

1. Buffering ability 2. Provides a cleansing effect 3. Has antibacterial action 4. Maintenance of oral environment

34

What are the two types of cementum? Characteristics? Which one forms first?

1. Cellular 2. Acellular -Acellular forms first as cementoblasts differentiate from the dental follicular cells, which only reach surface of tooth once HERS is gone. -Cellular cementum develops after most of tooth formation is complete, it forms around fiber bundles of the PDL, and their cementoblasts become trapped in the cementum they produce.

35

Amelogenesis takes place throughout our entire lives. True or False?

False. it only happens once, and ends once the ameloblasts are lost within eruption within the REE.

36

What does the tongue develop from?

From endodermal covered swellings on the floor of the pharynx.

37

What is ectodermal dysplasia?

Inherited disorders that affect the hair, nails, sweat glands, teeth. You need two of these to be considered. It is genetic, but you can be first in family due to a mutation. Teeth can be missing, pointed, widely spaced, prone to cavities because of defective enamel, multiple denture replacements are needed as child grows, implants may be an option as well, and ortho.

38

What does PTH do to the kidney and what does it act on?

PTH stimulates the 1-alpha hydroxylase activity in the kidney, resulting in an increase in 1,25 dihydroxyvitamin D production. It also increases the reabsorption of calcium in the distal renal tubules. It also decreases the reabsorption of phosphorus in the proximal renal tubules.

39

What is the definition of development?

An increasing degree of organization, complexity, or specialization.

40

What is the primitive choana?

It is formed when the oronasal membrane ruptures during the seventh week to form an opening called the primitive choana.

41

What forms the nasal fin?

The floor and posterior wall of the nasal sac proliferate to form a thickened, plate like fin of ectoderm separating the nasal sac from the oral cavity called the nasal fin.

42

What helps form the bony hard palate?

Mesenchymal condensations in the ventral portion of the secondary palate form the bony hard palate.

43

What does Vitamin D do with calcium?

It helps the intestines absorb calcium, but vitamin D must first be activated by PTH. Vitamin D also increases re-absorption of urinary calcium and phosphorus in the renal tubules. And Vitamin D has a direct effect on the parathyroid gland to suppress PTH secretion when we have too much of it.

44

What is a LeFort III fracture?

It passes through the nasal bridge medially, extending laterally through the medial orbital rim, nasolcarimal groove, ehtmoid bones, floor of orbit, lateral orbital wall, and zygomatic arch. They separate the entire midface from the cranium, and results in a bone fragment that includes the nasal complex, inferior half of orbit, zygoma, entire maxilla.

45

The maxilla grows more and later than the mandible. True or False?

False. Just think that the maxilla is closer to the brain, which also grows slower.

46

What is the bony cap on each end of a long bone called?

Epiphysis

47

What gives rise to the primary palate?

The floor of the nasal cavity is formed by a posterior extension of the intermaxillary process called the primary palate.

48

What is fetal alcohol syndrome?

FAS is a mild form of holoprosencephaly. Each year between 5,000 to 12,000 American babies are born with it. They may grow slower than other children, have facial abnormalities, mental retardation. Facial features include small eyes with drooping upper eyelid, short upturned nose, flattened cheek, small jaw, thin upper lip, flattened philtrum. FAS is due to deficiencies of midline tissue of the neural plate very early in embryonic development.

49

What is amelogenesis imperfecta?

It can be inherited as an x-linked autosomal recessive or AD condition. Mutations in AMELX, ENAM, and MMP20 genes cause it. These genes provide instructions for making proteins essential to tooth development.

50

What are the two most common missing teeth?

Maxillary lateral incisors and mandibular 2nd premolars

51

What happens to thymus gland with DiGeorge syndrome?

It is small or missing, and mature T cells are absent and results in poor immune function and frequent infections.

52

What are the two layers that make up the reduced enamel epithelium?

A layer of ameloblast cells and cuboidal cells from the outer enamel epithelium.

53

What is the timeline for addressing an infant with cleft lip and cleft palate?

3 months - repair of cleft lip 6 months - pre-surgical orthopedics 9 months - speech therapy begins 9-12 months - repair of cleft palate Age 1 -7 - orthodontic treatment Age 7-8 - alveolar bone graft 8+ - orthodontic treatment

54

What is osteogenesis imperfecta?

May be seen alone or with dentinogenesis imperfecta, and it is a genetic disorder where bones break for no apparent cause, and is caused by mutations in one of several collagen producing genes, COL1A1 and COL1A2, creating a loss in the production of collagen. The teeth are discolored and show bulbous crowns and small pulp chambers.

55

What is Pierre Robin syndrome?

Is present at birth, infant has smaller than normal lower jaw, tongue falls back in throat, difficulty breathing. Can be caused by intrauterine folding or by changes in the DNA near the SOX9 gene. Usually not inherited. Also includes cleft soft palate, receding chin, small jaw, natal teeth. These babies frequently experience breathing difficulties, choking, congestive heart failure, low blood oxygen and brain damage, pulmonary hypertension.

56

Which two organs does PTH mainly act on?

Bone and Kidney

57

Normally, is most of the calcium that enters glomerular filtrate reabsorbed back into the blood, or excreted?

Reabsorbed back into blood to preserve blood calcium.

58

What 14 teratogens can cause craniofacial malformations?

1. Alcohol - central midface deficiency 2. Hydantoin (anticonvulsant drugs) 3. Accutane - treacher collins 4. Toluene 5. Cigarette smoking - cleft lip and palate 6. Ionizing radiation - microcephaly 7. Aminopterin (chemotherapy) - anencephaly 8. Aspirin - cleft lip and palate 9. Cytomegalovirus - microcephaly, hydrocephaly 10. Dilantin - cleft lip and palate 11. Rubella virus - microphthalmia, cataracts, deafness 12. Thalidomide - treacher collins 13. Valium - treacher collins 14. Vitamin D excess - premature suture closure

59

What are some treatment options for amelogenesis imperfecta?

Crown, over-dentures, implants.

60

What is the central shaft of a long bone called?

Diaphysis

61

What nerve innervates all of the small salivary glands in the insides of the cheeks, tongue, lips, floor of mouth, sublingual gland, and submandibular gland, which are all below the level of the oral fissure?

Chorda tympani branch of the Facial nerve - CN VII

62

What are the two main drugs that can cause cleft lip?

1. Phenytoin - anticonvulsant 2. Vitamin A (Accutane)

63

Which cells in bone does PTH stimulate?

The osteoclasts to cause bone resorption and increase blood calcium.

64

What are the two most common types of facial clefts?

Cleft lip and cleft palate

65

What do the neural crest cells that migrate to lower regions of the facial area help form?

Aorta, pulmonary artery, aortic arch, etc. This is why many syndromic patients have heart defects.

66

What is DiGeorge syndrome?

It is caused by a deletion in the long (q) arm of chromosome 22. 22q11.2 deletion. And this deletion leads to hypoplasia of 3rd and 4th pouch derivatives.

67

Phosphorus has no direct stimulatory effect on the parathryoid glands. True or False?

False. It has been shown recently to have an effect.

68

What happens during maturation stage of amelogenesis?

Ameloblasts transport substances used in the formation of enamel.These cells become striated and have a ruffled border. The ruffled border on the distal aspect helps increase the surface area of the ameloblast to help deliver matrix proteins. The prisms in the enamel grow in thickness, but not in length here.

69

Does ossification progress from posterior to anterior or anterior to posterior with the chondrocranium?

From posterior to anterior

70

What nerve supplies sensory to the parotid gland?

The auriculotemporal nerve of the mandibular branch of the trigemincal nerve - CN V.

71

What is the structure that divides the sensory and taste into two components of the tongue (posterior 1/3 and anterior 2/3)?

Terminal sulcus

72

Bone is always formed as a primary tissue. True or False?

False. It always replaces a preexisting support tissue, it is never formed as a primary tissue.

73

What is the process of remodeling?

The balance of apposition and resorption, with new bone being formed while old bone being removed. It is seen at the surfaces of bones that are growing by endochondral replacement as well as bones that are formed directly within a connective tissue membrane.

74

What nerve innervates all of the small salivary glands in the insides of the cheeks, lips, and hard palate, above the level of the oral fissure?

Greater petrosal branch of the Facial nerve - CN VII

75

During what weeks is the basic morphology of the face created by?

During weeks 4 through 10

76

When do craniosynostosis syndromes typically occur or form?

After 8 weeks, during fetal period rather than embryological period. They result form early closure of the sutures between the cranial and facial bones.

77

At what pH can damage start happening to fluoroapatite structures?

4.5

78

What does the intermaxillary process give rise to?

The philtrum of the upper lip.

79

What are the main differences between Aperts and Carpenter syndromes?

They both have acrocephaly, mental retardation, syndactyly of hands and feet, but Carpenter's is passed by autosomal recessive, has mild obesity, and mutation is RAB23 gene, whereas Apert is autosomal dominant and passed on FGFR2 gene.

80

What nerve supplies sympathetic innervation to the parotid gland?

The superior cervical sympathetic ganglion, and the function is mainly vasoconstriction. It travels around the external carotid artery.

81

What do the mesenchymal cells that appear under and around each of the 20 dental lamina growths consist of and where are they migrating from?

They consist of neural crest derived cells and are migrating from the caudal region of the mesencephalon and the cranial region of the metencephalon.

82

What regulates parathyroid hormone and what does PTH help control?

It is regulated by the four parathyroid glands, and PTH helps control calcium, phosphorus, and vitamin D levels in the blood and bone. PTH increases the amount of calcium in the blood, and helps us avoid hypoparathyroidism, which is a huge symptom of DiGeorge Syndrome. So we get low calcium levels and high phosphorus levels in the blood.

83

What two things is a tooth bud composed of?

Dental lamina and mesenchymal concentration below.

84

What is though to be the most common cause of congenital mental retardation in the western world?

Alcohol

85

What helps guarantee ionic exchanges directed towards the tooth surfaces that begin with tooth eruption resulting in post-eruptive maturation?

High concentrations of calcium and phosphate in saliva.

86

What is the concept of pattern?

The change of proportional relationships over time

87

What will be the blood calcium, phosphorus and renal calcium and phosphorus levels in Hyperparathyroidism (high PTH)?

High calcium, low phosphorus, and high urinary calcium and phosphorus.

88

How does fusion of the secondary palate take place?

First ventrally and then proceeds dorsally along the midline.

89

What are the three possibilities for growth that occur in skeletal growth?

1. Hypertrophy 2. Hyperplasia (a more prominent feature in all forms of growth) 3. Cells secrete extracellular material (which can later mineralize to form bone)

90

What helps form the nasal sac?

The deepening nasal pits fuse to form a single, enlarged ectodermal nasal sac.

91

What is Craniofacial Microsomia?

Caused by lack of neural crest cells, those that migrate to lateral and lowest parts of face have defects. They also usually have deformed external ear.

92

What is the skeleton of the head and pharynx made up of in vertebrates?

Chondrocranium

93

What are the main errors that cause cleft palate?

Inadequate growth of the palatine shelves, failure of shelves to elevate at correct time, excessively wide head, failure of shelves to fuse, secondary rupture after fusion.

94

When does the development of the tongue begin, and how?

At the end of the 4th week, it begins when the 1st pharyngeal arch forms a median swelling called the median tongue bud, then later the 1st pharyngeal arch develops an additional pair of lateral swellings called the distal tongue buds, which rapidly expand to overgrow the median tongue bud. These swellings (distal tongue buds) continue to grow throughout embryonic and fetal life and form the anterior two thirds of the tongue.

95

What is cleidocranial dysplasia?

It is a skeletal dysplasia with delayed closure of the cranial sutures, hypoplastic clavicles, and multiple dental problems. Supernumerary teeth, short stature, extra set of adult teeth, wide-open fontanelles, narrow sloping shoulders, brachydactyly, wide-open metopic suture in front.

96

What kind of learning/behavioral disorders/autoimmune disorders do people with DiGeorge syndrome have?

ADHD, autism, depression, anxiety, rheumatoid arthritis, Grave's disease, poor vision, poor kidney function, short stature.

97

How many amino acids does PTH consist of?

84 amino acids, and is secreted in response to hypocalcemia and hyperphosphatemia.

98

What is the most important trimester for normal embryological development?

First, 12 weeks.

99

What nerve supplies parasympathetic innervation to the parotid gland?

Glossopharyngeal nerve - CN IX

100

What happens during secretory stage of amelogenesis?

Ameloblast cells are columnar now and they release enamel proteins and contribue to enamel matrix, which is then mineralized by the enzyme alkaline phosphatase. The tome's process develops here when the ameloblasts move away from the dentin, and the process is in contact with the DEJ, and is lays down the crystals of the enamel matrix. The tome's processes are angled as well.

101

What is a LeFort II fracture?

It is a pyramidal fracture that passes through the nasal bridge medially extending laterally through the frontal process of the maxilla, lacrimal bones, orbital floor, anterior wall of maxillary sinus, passing below the zygoma, and transecting the pterygomaxillary junction to interrupt the pterygoid plates. It results in a pyramid-shaped mobile bone fragment that includes nasal complex and entire maxilla, including the hard palate.

102

What innervates both the sensory and taste coponents of the posterior 1/3 of the tongue? What are the exceptions?

CN IX, glossopharyngeal nerve. Two two exceptions are that the sensory branch of CN IX-glossopharyngeal nerve supplies the circumvallate papillae, and sensory fibers of the superior laryngeal branch of CN X-Vagus nerve innervates a small mucosa region on the dorsal side of the posterior tongue.

103

What is ACP?

It is amorphous calcium phosphate, and is given ti help release calcium and phosphate ions to convert to apatite for patients with impaired salivary flow to help with tooth remineralization.

104

Chronologic age is often not a good indicator of the individuals growth status. True or False?

True

105

What is the nasolacrimal groove or furrow?

It is a groove between the lateral nasal process and the adjacent maxillary swelling.

106

What do all cleft lip and palate patients receive before undergoing surgical repair?

Pre-surgical orthopedic treatment.

107

What is Apert's syndrome?

Caused by nucleotide alterations resulting in amin-acid substitutions, leading to mutation in FDFR2 gene located on chromosome 10. Craniosynostosis and symmetric syndactyly of the extremities are hallmarks. Wide-set eyes, mid-face hypoplasia, class III occlusion.

108

What is found at the outer end of each epiphyseal plate?

A zone of actively dividing cartilage cells. As long as the rate at which cartilage cells proliferate is equal to or greater than the rate at which they mature, growth will continue.

109

What three main things is bone made up of?

1. Collagen 2. Calcium-phosphate mineral complexes 3. Bone cells (osteoclasts, osteoblasts, osteocytes)

110

What are sharpey's fibers?

They are also called extrinsic fibers and form when collagen fibers formed by fibroblasts of the PDL form and incorporate into the cementum.

111

When does the dental lamina form?

During the sixth week, a U shaped ridge of epidermis called the dental lamina appears on the upper and lower jaws, and in the seventh week, 10 centers of epidermal cell proliferations (primary teeth) develop at intervals on each dental lamina and grow down into underlying mesenchyme.

112

What is Crouzon's syndrome?

Premature fusion of certain skull bones (craniosynostosis), and this leads to wide-set bulging eyes from underdevelopment of midface, vision problems, eyes that do not point in same direction (strabismus), beaked nose, underdeveloped jaw. This is the most frequent occurring member of Craniosynostosis syndromes. It arises because of prenatal fusion of superior and posterior sutures of the maxilla along wall of orbit, which produces distortions. Also caused by mutation in FGFR2 gene, which provides instruction for making a protein called fibroblast growth factor receptor 2.

113

What does the chondrocranium form?

The skull base and supports the brain, olfactory organs, eyes, and inner ears.

114

What is the rod sheath?

It is a space that contains an increased amount of residual matrix proteins.

115

Where do the buds of the permanent molars come from?

They arise during postnatal life from a pencil-like extension of the dental lamina that burrows back into the posterior jaw from the primary second molar tooth bud.

116

What is the Latham device?

It is indicated for babies with complete clefts of the lip and palate, which are widely space, and is considered pre-surgical orthopedics. It is designed to bring the two pieces of the cleft palate closer together, it is worn for about 6-8 weeks, and does require surgery to install it. It has a screw that you turn every day. And then closure of the lip is performed when the baby weighs as least 10 pounds, 3-6 months of age, at same time Latham is removed.

117

What forms the cementoblasts?

The inner cels of the dental sac/follicle differentiate into the cementoblasts.

118

What roles does calcium have?

Blood clotting, conduction of nerve impulses, salivary function, contraction and relaxation of muscles and blood vessels, regulation of body fluids, including hormones and enzymes.

119

How common is cleft lip and cleft palate?

They can occur in about 1 or 2 of every 1,000 in the US. More common in Asian, Latino, or Native American descent.

120

What needs to happen for amelogenesis and dentinogenesis to occur?

A message is sent from the newly differentiated odontoblasts to the IEE, causing the epithelial cells to turn into active secretory ameloblasts, and dentinogenesis is in turn dependent on signals from the differentiating IEE in order for the dentinogenesis process to continue.

121

All tissue systems of the body grow at the same rate. True or False?

False

122

By the end of what week do all five facial swellings appear by?

End of the fourth week

123

At what plaque pH can remineralization start to occur?

Above 5.5. Above this pH, interbacterial plaque fluid and saliva return to being saturated and then supersaturated, with respect to hydroxyapatite.

124

During what stage does amelogenesis occur?

During the bell stage

125

What is intramembranous ossification?

It is the embryonic development of flat bones from the embryonic tissue called the mesenchyme.

126

What are facial features typical of people with DiGeorge syndrome?

Small low-set ears, wide-set eyes, hooded eyes, long face, small mandible, bowing up upper lip.

127

What forms the ossification center in intramembranous ossification?

Centrally located stem cells within the mesenchyme differentiate into osteoblasts, forming the ossification center.

128

By what two methods can bone shape be changed with intramembranous ossification?

1. Resorption 2. Apposition

129

What nerve supplies the motor component of the tongue? What is the exception?

CN XII-Hypoglossal nerve, except for the palatoglossus muscle, which is supplied by the pharyngeal branch of the CN X-Vagus nerve.

130

What is the difference between the primitive and definitive choana?

Once the nasal septum forms, the nasal passages open into the pharynx behind the secondary palate through the primitive choana, but is now called the definitive choana.

131

What is the chondrocarnium?

It is the cartilaginous portion of the cranium that represents a continuous plate of cartilage. Cartilage is nearly avascular tissue that is thin.

132

What is a LeFort I fracture?

A horizontal fracture through the maxilla that passes through the septum medially, and these result in a mobile hard palate.

133

What two structures is enamel mostly made up of?

Hydroxyapatite and fluoroapatite

134

What is Treacher Collins Syndrome?

A generalized lack of mesenchymal tissue in the lateral part of the face, a genetic disorder, about 1 in 50,000. Usually have very small cheek bones and micrognathia, cleft palate, eyes that slant downward, coloboma, normal intelligence. Patients are referred to specialist between 4 and 7 for surgery.

135

Where is the primary palate situated in patients with cleft lip?

Too far forward beyond the tip of the nasal septum.

136

What does the oval nasal pit from the nasal placode help form?

It helps divide the nasal placode into a lateral nasal process and a medial nasal process, and happens during week 6.

137

What do the outer cells of the dental sac/follicle form?

Alveolar bone formation and the PDL. Fibroblasts from the dental sac secrete collagen, which interacts with fibers on bone and cementum, and occlusion continues to shape these, to form the always changing PDL fibers.

138

What type of bone forms the roof of the skull and the viscerocranium, which supports the pharyngeal arches and their derivatives?

Membranous bone

139

What is the nasolacrimal duct?

When ectoderm at the floor of the nasolacrimal groove groove invaginates into the underlying mesenchyme, it forms a tube called the nasolacrimal duct.

140

What is the name of the midline swelling that the second pharyngeal arch develops in developing the tongue?

Copula

141

What type of symptoms can present in early children that should be checked for craniosynostosis?

Hydrocephalus, bulging anterior fontanelle, irritability, lethargy, rapidly increasing head size, vomiting, vision impairment, difficulty breathing through nose.

142

Why is Vitamin D essential and what can it's deficiency lead to?

It is essential for the body to absorb calcium, for bone development, immune functioning, and alleviation of inflammation. It's deficiency can lead to rickets, weakened immune system, osteomalacia, etc. Too much of it though can lead to increased risk of heart disease and kidney stones because of body absorbing too much calcium.

143

What does the bell stage consist of?

This is when the dental papilla has deeply invaginated the dental lamina, and it looks like a bell. Happens during 10th week.

144

What becomes the permanent teeth?

The dental lamina superficial to each primary tooth bud produces a small diverticulum, that migrates and becomes the bud of the permanent tooth.

145

Which state reports to have among the highest rates of orofacial clefts in the US and internationally?

Utah, also has the highest recorded incidence of cleft lip and palate in the US. The average lifetime medical cost is $100,000.

146

With Pierre Robin syndrome, does the relationship between the upper and lower teeth improve or get worse as the child grows?

It improves.

147

What are the three layers of the enamel organ?

1. IEE 2. Middle enamel reticulum 3. OEE

148

Cleft palate and cleft lip are not common in DiGeorge. True or False?

False

149

What is cleft lip?

Failure of maxillary swelling to fuse with the intermaxillary process.

150

Where do the odontoblasts come from, and during what stage?

During the bell stage, the outermost cells of the dental papilla become organized into a layer just adjacent to the inner enamel epithelium, and these cells become the odontoblasts.

151

Is there more growth of the lower limbs or the upper limbs during postnatal life?

Lower limbs

152

What are the four main drugs that cause cleft lip?

1. Phenytoin 2. Vitamin A (Accutane) 3. Prednisone 4. Cigarette smoking (hypoxia)

153

What four things is Tetralogy of Fallot composed of?

1. Pulmonary stenosis 2. Right ventricular hypertrophy 3. Overriding aorta (is huge and arises from both left and right instead of just left ventricle. 4. Ventricular septal defect (VSD)

154

What is the name of the cells in the parathyroid glands that sense the low blood levels and help make more PTH?

Chief cells

155

What does the cap stage consist of?

Dental lamina with a mesenchymal invasion below called the dental papilla.

156

What is the process of dentinogenesis?

It begins with the odontoblasts beginning to secrete the nonmineralized matrix of dentin, predentin, which later calcifies to form dentin.

157

What is intrauterine molding?

It is an arm pressed against the fetal face which can cause midface deficiency, a fetus head flexed tightly against the chest prevents the mandible from growing forward normally, whatever it is, it is caused by pressure against the developing face prenatally.

158

What does bilateral coronal synostosis result in?

Prominent frontal bone and flattened occipital.

159

During what month is there an in-growth of blood vascular elements into various points of the chondocranium?

Fourth month. These areas become centers of ossification, at which cartilage is transformed into bone (endochondral ossification) and islands of bone appear in the sea of surrounding cartilage.

160

What are the palatine shelves?

During weeks 8 and 9, the medial walls of the maxillary processes produce a pair of thin medial extensions called the palatine shelves. They grow downward parallel to the lateral surface of the tongue at first and then they rotate rapidly upward into a horizontal position and fuse with each other and the primary palate, forming the secondary palate.

161

What is holoprosencephaly?

HPE is a birth defect of the brain, which effects the development of midline facial features, including closely space eyes, microcephaly, cleft lip, cleft palate. It is caused by failure of the prosencephalon (forebrain) to divide into the doubles lobes of the cerebral hemisphere. It ranges from mild to severe. Sever cases only have one nostril, one joined eye, triangular skull. Mutations in the gene encoding the sonic hedgehog protein, which is involved in the development of the CNS, can cause holoprosencephaly. Also, toxins such as alcohol can cause it.

162

What is the NAM device?

It is a NasoAlveolar Molding device, and can be elaborate or passive. it consists of an intraoral acrylic plate held in place with extraoral elastics and tape. And in later phases, wire outriggers are added that apply protracting forces to the vestibule of the nares.

163

What does metopic synostosis result in?

A trigone-shaped skull with protrusion of the parieto-occipital region.

164

During what stage does the enamel organ form?

Bell stage, and it forms from the dental lamina.

165

What is a LeFort III Osteotomy?

It is a surgery that moves the middle portion of the face forward and aligns the upper and lower jaw to create a larger airway, and is often done in childhood with kids who have craniosynostosis.

166

Which way do the enamel rods face?

Their heads face the cusp tip and the tails face the cervical margin. Each rod is about 1 to 3 mm in length.

167

What are the main factors controlling the stability of enamel?

Active concentrations of free calcium, phosphate, and fluoride in salivary solution.

168

What are the disproven and most widely held current theory of tooth eruption?

Tooth is pushed upward by growth of root, by bone around the tooth, by vascular pressure. But probably a combination of root, PDL, dental follicle.

169

What are the three basic components of innervation of the tongue?

Motor, sensory, taste

170

What forms the periosteum?

The blood vessels on the outside of the spongy bone condense to form the periosteum.

171

What are the epithelial cell rests of Malassez?

When HERS disintegrates with the formation of the PDL, these are their remnants, and can cause future periodontal problems if cystic.

172

What becomes the tooth pulp?

The inner mesenchyme of the dental papilla.

173

Which cells secrete calcitonin? And when?

Thyroid gland parafollicular cells, also called C cells. Extra calcium in blood elicits the C cells to release Calcitonin, and calcitonin reduces blood calcium by inhibiting the activity of osteoclasts, and by decreasing the re-absorption of calcium in the kidneys, which leads to lower blood calcium levels.

174

When can a neonatal mandibular distraction osteogenesis be used?

It can be used to treat Pierre Robin syndrome. It starts with an osteotomy on both sides of lower jaw, and a small metal device is placed under the skin, two days later, a callus forms, and the device is activated and slowly opens the osteotomy gap and moves the lower jaw forward and opens the baby's airway, and weeks later, the device is removed.

175

At what age do most kids born with cleft lip or palate have surgery to repair them?

Within the first 12-18 months of life

176

When do the ectodermal thickenings called the nasal placodes begin to appear on the frontonasal process?

During week 5

177

What is Carpenter syndrome?

Mutation in the RAB23 gene, located on chromosome 6, unlike most craniofacial syndromes, this is passed in an autosomal recessive fashion. You get acrocephaly with this, which is premature closure of lambdoid and coronal sutures, extra fingers and toes, short fingers and toes, mental retardation, obesity, short neck, heart disease.

178

What is a teratogen?

Chemical and other agents capable of producing embryologic defects if given at a critical time. At high levels, can cause death.

179

What are the three stages of amelogenesis?

1. Inductive 2. Secretory 3. Maturation

180

What two ions are needed to remineralize a carious lesion before cavitation occurs?

Calcium and phosphate

181

When does the migration of neural crest cells conclude?

During the fourth week

182

What needs to take place for ameloblasts to form?

As soon as mineralized dentin is formed, cells of the IEE differentiate into the ameloblasts, and begin to secrete enamel prisms.

183

What is dentinogenesis imperfecat?

It is an autosomal dominant inheritance and is caused by a mutation in the DSPP gene, which provides instructions to cleave the protein dentin sialophosphoprotein for making two proteins essential for normal tooth development. It breaks them into dentin sialoprotein and dentin phosphoprotein (for hardening of collagen).

184

What secretes the bony matrix called osteoid?

Osteoblasts

185

What innervates the sensory component of the anterior 2/3 of the tongue?

It is supplied by the lingual branch of the mandibular branch (V3), which comes off of CN V-Trigeminal nerve

186

What is a syndrome that can be caused by intrauterine folding?

Pierre Robin syndrome

187

How much of the total body does the head take up at the third month of intrauterine development?

Almost 50%

188

What is the definition of growth?

An increase in size, but it can tend to be more linked to change than anything else.

189

What forms the nasal septum?

While the secondary palate is forming, ectoderm and mesoderm of the frontonasal process proliferate to form the nasal septum that grows down from the roof of the nasal cavity to fuse with the upper surface of the primary and secondary palates, divides the nasal cavity into two nasal passages.

190

What is the dental sac?

It is the mesenchyme surrounding both the dental lamina and dental papilla.

191

When do the ameloblasts lose their ruffled borders?

As enamel maturation nears completion.

192

What is endochondral ossification?

The bones of the chondrocarnium are preformed in cartilage and ossify by the process of endochondral ossification.

193

Are older people more or less likely to meet their vitamin D requirements by sunlight alone?

Less, because their skin pigmentation deteriorates with age, so the conversion of UV light is much less efficient, and they do not spend as much time outdoors.

194

What is interstitial growth?

Growth that occurs at all points within the tissue, and this involves growth of soft tissues that occurs by a combination of hyperplasia and hypertrophy.

195

What is cleft palate?

Results from failure of the two palatine shelves to fuse with each other along the midline.

196

What does the parotid gland develop from?

A groove-like invagination of ectoderm that forms in the crease between the maxillary and mandibular swellings during week six, the groove turns into a tubular duct which sinks into the underlying mesenchyme toward the ear, then later on is transferred to the inner surface of the cheek, and the opposite end of the tube becomes the parotid gland, and the tube becomes the parotid duct. The submandibular and sublingual glands develop similarly, from invaginations of the endoderm in the floor of the oral cavity and in the paralingual sulci on either side of the tongue, respectively.