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Exam 1: DHHD 5001 > Genetic Tooth Disorders (Gonzales 2) > Flashcards

Genetic Tooth Disorders (Gonzales 2) Flashcards

1
Q

Tooth development results from _______, which are reciprocal epithelial mesenchymal interactions.

A

Reciprocal Induction

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2
Q

Tooth morphogenesis and growth are controlled by ______.

A

Genes

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3
Q

_______, also known as oligodontia, is having fewer than the regular number of teeth. Missing _____ and _____ is relatively common, and is a result of _____ and ____ mutations.

A
  • Hypodontia
  • Third molars and upper lateral incisors
  • Pax9 and MSX1
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4
Q

_______: congenitally missing all primary or permanent teeth, associated with ______.

A
  • Anodontia

- Ectodermal Dysplasia

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5
Q

The ______ gene belongs to the PAX gene family, which encodes a group of transcription factors. It is expressed in the ______ of the tooth bud and plays a role in ______. Mutations result in _______.

A
  • PAX 9
  • Mesenchyme
  • Early tooth development
  • Molar hypodontia
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6
Q

______ are homeobox genes and constitute a large family of transcription factors. They induce cell-cell interactions during early development and initiate the cascades of co-regulated genes required to produce tissues are organs.

A

MSX genes

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7
Q

______ is a transcriptional repressor, and haploinsufficiency affects development of all teeth. Phenotypes depend upon where the mutation is and the effect on the protein structure and function.

A

MSX1

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8
Q

The Ser105Stop mutation is a complete absence of ________. The most severe phenotype is _____ and ______.

A
  • MSX1 homeodomain
  • Orofacial clefts
  • Tooth agenesis
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9
Q

_______ is the general term that describes a group of inherited disorders characterized by ______________ (skin, hair, nails, teeth, sweat glands, nerves, and constituent parts of the ear and eye). There are over 150 types and the condition is divided into hidrotic and anhidrotic forms.

A
  • Ectodermal dysplasia

- Aplasia or dysplasia of tissues of ectodermal origin

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10
Q
  • Sparse fine or coarse curly hair
  • Abnormally developed nails
  • Frontal bossing
  • Prominent lips
  • Depressed midface and nasal bridge
  • Soft, thin, and dry skin that’s prone to eczema
  • Hypodontia occurs in 80% of cases
A

Extra-Oral Signs of Ectodermal Dysplasia

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11
Q
  • Reduced number of sweat glands
  • X-linked recessive
  • Deletions within the EDA gene on chromosome X
  • Triad of hypodontia, hypohidrosis, and hypotrichosis (sparse hair)
  • Characteristic facial features: prominent forehead, wide eyebrows, saddle-shaped nose, thick everted lips, dry skin, and fine sparse hair
A

Anhidrotic Ectodermal Dysplasia (EDA)

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12
Q

EDA Assosciated Hypodontia: Reduced _____ growth and lack of development of the _____ that appear extremely narrow and concave lingually. Teeth are ______ in shape, malformed and widely spread. Reduced ______ facial height.

A
  • Alveolar bone
  • Alveolar ridges
  • Conical
  • Vertical
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13
Q

Management of ED Hypodontia: ________ is the treatment of choice for ED patients. The jaws are positioned correctly in relation to each other and to the cranium. The maxilla of totally edentulous patients often require bone grafting procedures of ________ combined with bone grafting. Also, _____ for denture retention.

A
  • Orthognathic surgical procedures
  • Le Fort I
  • Implant placement
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14
Q

_______ are teeth that are additional to the normal complement. Both dentitions are affected, although prevalence is lower in primary dentitions. The M:F is 2:1 (caucasians_ and 5.5-6.5:1 (Japanese).

A

Supernumerary Teeth

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15
Q

Sequelae of Supernumerary Teeth:

  • _____ eruption of dentition
  • ______ of eruption
  • Displacement or rotation
  • Crowding: abnormal ______ or premature space closing, ______, delayed or abnormal root development of permanent teeth, _____ formation, and eruption into ______.
A
  • Normal
  • Failure
  • Diastema
  • Dilaceration
  • Cystic
  • Nasal cavity
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16
Q

Classification of Supernumerary Teeth:

  • Morphology (4)
  • Location: (3)
A
  • Conical, Tuberculate (Barrel Shaped), Supplemental, Odontoma
  • Mesiodens, Paramolar, Distomolar
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17
Q

Etiology of _______ supernumerary teeth is linked to genetic mutations of specific genes (Runx2, APC).

A

Syndromic

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18
Q

Etiology of all ______ supernumerary teeth unknown; however, there is a clear hereditary component.

A

Non-syndromic

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19
Q

The most accepted theory of non-syndromic supernumerary teeth is localized and independent hyperactivity of the _______ results in the development of supernumerary teeth.

A

Dental lamina

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20
Q

_______ supernumerary teeth result from local, independent, conditioned hyperactivity of the dental lamina. The _______ of an additional tooth bud leads to a supplemental tooth.

A
  • Supplemental

- Lingual extension

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21
Q

The ______ (dysmorphic) supernumerary tooth arises from proliferation of _______ of the dental lamina.

A
  • Rudimentary

- Epithelial remnants

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22
Q

Syndromes associated with supernumerary teeth

A
  • Cleft lip and palate (22%)
  • Cleidocranial Dysplasia (CCD)
  • Gardner’s Syndrome (FAP)
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23
Q
  • Short stature
  • Late closure of fontanels and sutures
  • Aplasia of clavicles
  • Hypertelorism (wide eyes)
  • Low nasal bridge
  • Supernumerary teeth
A

Cleidocrainal Dysplasia (CCD) Clinical Features

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24
Q

_______ has an autosomal dominant pattern of inheritance and heterozygous mutations of _______, a transcription factor essential for bone and tooth development.

A
  • Cleidocrainal Dysplasia (CCD)

- Runx2

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25
Q
  • Supernumerary teeth
  • Delayed eruption
  • Malformed roots
  • No cellular cementum
  • High palate
  • Submucosal cleft
A

Cleidocranial Dysplasia Oral Features

26
Q
  • Develop multiple premalignant colorectal adenomas
  • 100% chance that one or more will progress to colorectal cancer in middle aged adults (~39 yo)
  • Jaw osteomas, odontomas, and supernumerary teeth
A

Familial Adenomatous Polyposis (FAP)

27
Q

______ = FAP + extra-intestinal manifestations

  • Oral signs precede GI symptoms
  • Early diagnosis is life saving
A

Gardner’s Syndrome

28
Q

Familial Adenomatous Polyposis (FAP) is autosomal _______ and result from mutations in the _________ gene. 1/3 of cases are due to spontaneous mutations, and it is diagnosed by >100 colorectal adenomas or a deleterious mutation in APC gene.

A
  • Recessive

- Adenomatous polyposis coli

29
Q

APC Mutations

  • ___ Exons
  • ____ germline mutations described, most located in Exon 15
  • Site of mutation correlates with the clinical phenotype: mutations between codons 1444 and 1578 are associated with oral manifestations and 11-27% of patients will have supernumerary teeth
A
  • 15

- 400

30
Q

The dentist is often the first clinician to diagnose _______.

A

Gardner’s Syndrome

31
Q

Mutations in genes expressed early in tooth development result in variations in ______.

A

Number of teeth formed

32
Q

___ and ___ mutations cause arrested tooth formation and ________.

A
  • PAX9 and MSX1

- Hypodontia/Anodontia

33
Q

____ and ____ mutations cause supernumerary teeth.

A

Runx2 and APC

34
Q

Formation of enamel by ameloblasts (epithelial derived), which are not active through the life of the tooth

A

Amelogenesis

35
Q

Formation of dentin by odontoblasts (ectomesenchymal derived), which are active throughout the life of the tooth.

A

Dentinogenesis

36
Q

Proteins associated with mineralized tissues encoded on chromosome 4: Enamel ECM proteins

A

Ameloblastin & Enamelin

37
Q

Proteins associated with mineralized tissues encoded on chromosome 4: Dentin ECM proteins. These are expressed in __________. They have small regions of similarity between them (RGD) and AA sequence highly conserved across species.

A
  • SIBLING

- Bone and dentin

38
Q

Enamel Extracellular Matrix:

  • ___% mineral
  • ___% protein
  • ___% water
A
  • 95
  • 4
  • 1
39
Q

The 4% of Extracellular Matrix Proteins:

  • ___% Amelogenins
  • ___% Non-Amelogenins
A
  • 90%

- 10%

40
Q

______ (90% ECM Proteins) regulate growth of crystals in length. They are encoded by two genes on the X&Y chromosomes (Males: 2 types; Females: 1 type). Many isoforms due to alternative splicing of mRNA.

A

Amelogenins

41
Q

Non-Amelogenins (10% ECM Protein) are _______ (chromosome 4, regulates crystal elongation) and ______ (chromosome 4, cement protein that integrates enamel and dentin at the DEJ).

A
  • Enamelin

- Ameloblastin

42
Q

______ is an inherited abnormality affecting the enamel. Both primary and permanent dentition are affected and may be associated with a syndrome.

A

Amelogenesis Imperfecta (AI)

43
Q

3 major categories of Amelogenesis Imperfecta

A
  • Hypoplastic: defect in amount of enamel
  • Hypomaturation: defect in removal of proteins from enamel
  • Hypocalcified: defect in calcification
44
Q

There are 13 subclasses of Amelogenesis Imperfecta based upon _____, _____, and working to correlate the _____ with the ______.

A
  • Mode of inheritance (ex. autosomal dominant)
  • Enamel appearance
  • Genotype (genetic defect) with the Phenotype (clinical appearance)
45
Q
  • Rough pitted surface
  • (+) calcification
  • Enamel is hard
  • Defect in amount of enamel (very thin, cannot detect enamel on radiograph)
A

Hypoplastic Amelogenesis Imperfecta

46
Q

Genetic findings in Hypoplastic AI

A
  • Enamelin: Chromosome 4, 5 mutations have been reported

- Amelogenin: Chromosomes X & Y, 12 mutations in amelogenin

47
Q
  • Defect in mineralization of ECM
  • Enamel is softer than unaffected enamel, but stronger than hypocalcified AI
  • Mottled enamel with brown pigment
  • Snow-capped on incisal/occlusal surface
A

Hypomaturation Amelogenesis Imperfecta

48
Q

Genetic findings in Hypomaturation AI

A
  • Enamelysin (MMP20): early protease, secretory stage, chromosome 11
  • Kallikrein-4: late protease, transition-maturation, chromosome 19
49
Q
  • Matrix formation normal thickness
  • No calcification
  • Soft Enamel - “Swiss cheese”
  • Brown due to extrinsic stains
  • Not prone to caries
  • 2/2008 Gene FAM83H identified, first gene involved with AI that does not encode a secreted protein, associated with secretory vesicles
A

Hypocalcified Amelogenesis Imperfecta

50
Q

Treatment of AI:

  • Identify the problem
  • Observe and describe clinical findings
  • Note: ______
  • Ask: _______
  • Identify which type of AI it is.
  • Risk of their children also having AI
A
  • Are both primary and permanent dentitions affected?

- “Does this run in your family?”

51
Q

Dentin Extracellular Matrix:

  • Collagen Type I, III, V, and VI
  • Hydroxyapatite >67%
  • Non-collagenous proteins, including _____ and _______, which are encoded by a single gene (DSPP) and cleaved post-translationally.
A
  • Dentin Sialoprotein: DSP

- Dentin Phosphoprotein: DPP

52
Q

DSPP is cleaved post-translationally to form ____ and ____.

A

DSP and DPP

53
Q
  • Inherited abnormality affecting the dentin (primary and permanent)
  • Autosomal dominant
  • Teeth appear blue-grey or amber-brown and opalescent
  • Roots are narrow with little to no pump chamber
  • Crowns are bulbous
  • Enamel splits readily from dentin when subjected to force
A

Dentinogenesis Imperfecta (DGI)

54
Q

3 Types of DGI

A
  • Type I Osteogenesis Imperfecta: (+) bone defects
  • Type II Opalescent: (-) bone defects
  • Type III Brandywine isolate: (-) bone defects
55
Q

-Associated with Osteogenesis Imperfecta
-Mutation in Type I Collagen
(Brittle bones, Blue sclera, Bitemporal bossing, Bowing of the limbs)

A

Dentinogenesis Imperfecta Type I

56
Q
  • Enamel splits away from dentin
  • Amber translucent color is common
  • Severe attrition
A

Clinical Oral Manifestations DGI Type I

57
Q
  • Obliteration of pulp chamber
  • Small underdeveloped roots
  • Roots and fractures
A

Radiogrpahic Findings of DGI Type I

58
Q
  • Hereditary Opalescent Dentin
  • Not associated with Osteogenesis Imperfecta
  • Single mutation in DSPP gene (affects DSP region)
  • First nucelotide in Exon 3 G –> T (may interfere with secretion of the protein or affect processing of mRNA)
A

Dentinogenesis Imperfecta Type II

59
Q
  • Also called the Brandywine Isolate (triracial isolated group in Maryland)
  • Mutation in DSPP gene shortening the protein by 6 AA
  • Bell shaped crowns
  • “Shell teeth”
  • Enlarged pulps
  • Pulpal exposures
A

Dentinogenesis Imperfecta Type III

60
Q

Treatment of DGI:

  • ______ is critical: Both dentition? Run in family? Risk of children.
  • ______ can make restoration impossible
  • Complete mouth restoration
A
  • Early detection

- Excessive wear

Exam 1: DHHD 5001 (14 decks)

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