study guide specific terms

Barr body

Condensed chromatin of the inactivated X chromosome, which is found at the periphery of the nucleus of cells in women.

DNA

a substance composed of a double chain of polynucleotides, with both chains coiled around a central axis to form a double helix; it is the basic genetic code or template for amino acid formation.

Expressivity

The degree of clinical manifestation of a trait or characteristic.

Recessive

A trait or characteristic that shows clinically when a double-gene dose (homozygosity) exists in autosomal chromosomes or a single-gene dose exists in males if the trait is X-linked.

Trisomy

A pair of chromosomes with an identical extra chromosome.

Oligogenic

refers to characteristics or traits that are inherited by the participation of several genes

Prophase

First and longest stage

-the chromosomes are lining up toward metaphase-moving to opposite polls

Metaphase

chromosomes are symmetrical at both sides of the center of the cell

Anaphase

sister chromosome separate into individual and are pulled apart

Telophase

Chromosome gather at opposite ends, chromatids are in the process of splitting

Lyon Hypothesis

a theory that states that one of the X chromosomes of a female embryo is canceled and forms a Barr body which can be microscopically detected. This is significant for the detection of those diseases which are transmitted by female carriers on the X chromosome.

• Barr bodies are seen at the nuclear periphery in female cells

Klinefelter's Syndrome

due to nondisjunction

• XX+Y and variations

• Low intelligence levels

• Male; at puberty noted 50% breast development

• Cannot be detected until after puberty

• laurodontic teeth

Cri - du - chat

• Cat cry at birth

• Deletion of chromosomes # 5

• Mentally retarded, microcephaly, hypertelorism, prominent epicanthal folds, and low set ears

PAPILLON - LEFEVRE SYNDROME

• Autosomal - recessive

• Perio of both dentitions (permanent lost < 14 years)

• Hyperkeratosis of soles of feet and palms of hands

CHONDROECTODERMAL DYSPLASIA (ELLIS-VAN-CREVEID SYNDROME)

• Autosomal - recessive

• Dwarfs, due to shortening of distal extremities

• 1/3 mentally retarded (mildly)

• Extra digits

• 50% heart defects

• Maxillary gingival fused to upper lip; no vestibule and V-shaped notch in upper lip

• Centrals missing; conical shaped teeth with enamel hypoplasia

• 50 % have natal teeth

CLEIDOCRANIAL DYSPLASIA

• Autosomal - dominant

• Cranial -mushroom shape

• Fontantelles open (face small)

• Long neck; hypoplasia of clavicles; shoulder at midline

• Premaxilla underdeveloped

• Supernumerary teeth causing delayed eruption and cyst

• 1% cleft lip and/or palate

• Retained primary teeth

MANDIBULOFACIAL DYSOSTOSIS

• Autosomal - dominant

• Hypoplasia of malar check bones, zygomatic process and mandibular

• Abnormal growth in first and second brachial arches

• Abnormal ears with tags and deafness and receding chin

• Fish-like mouth with tags at commissure

• Cleft in lower eye lids - Coloboma

• Open bite, malocclusion and malposed teeth

• High or cleft palate

• Gingival disease common

Etiology of clefts

Inheritance pattern of syndrome that it is a part of

PEUTZ-JEGHERS SYNDROME

• Multiple melanotic macular pigmentations of skin and mucosa

• Occurs: around eyes, nose, and mouth (lips and buccal mucosa); diminish with age

• Gastrointestinal polyposis (hamartomas- abnormal growth of normal tissue)

WHITE SPONGE NEVUS

• Autosomal dominant

• Present at birth (or develop around puberty)

• Buccal mucosa always affected; most bilateral - palate, gingival, tongue, and inner lip

• Produced by an extra layer of keratin

• White corrugated, soft, folding oral mucosa

• Progressive childhood to adulthood

• No treatment - prognosis is good

HYPOPLASTIC AMELOGENESIS IMPERFECTA

Type I

• Tooth enamel not normal thickness

• Due to failure of ameloblasts to lay down enamel matrix

• Pitted; local; smooth; rough (pitted most common) - yellow to brown color

• Autosomal - dominant and autosomal-recessive

HYPOCALCIFIED AMELOGENESIS

IMPERFECTA

Type II

• Enamel normal thickness

• Poorly calcified enamel

• Enamel - dark yellow-brown, chalky easily breaks down

• Treatment - restorations, crowns, and veneers

• Autosomal dominant

• Autosomal recessive

• More severe; characterized by yellow to orange enamel that is rapidly lost

• Moth eaten radiographic appearance

• Associated with open bite

HYPOMATURATION AMELOGENESIS

IMPERFECT

Type III

• Enamel is mottled appearance - softer occlusal 1/3 appears "white" but normal thickness characterizes

• Large amount of enamel matrix

• Enamel softer than normal (explorer can penetrate)

• Defect in enamel rod sheath Enamel chips easily

• Snow-capped amelogenesis imperfecta

• X-linked recessive or autosomal dominant

• Hypomaturation of occlusal 1/3 Maxillary teeth (most common); whitish discoloration

HYPOPLASTIC-HYPOMATURATION AMELOGENESIS IMPERFECTA

Type IV

• Associated with taurodontic teeth

• Thin enamel, pitted, yellow to brown

• Radiographically as dense as dentin: single rooted

• Large pulp chambers

DENTINOGENESIS IMPERFECTA type I

associated with osteogenesis imperfecta other 2 types are NOT associated with osteogenesis imperfecta

DENTINOGENESIS IMPERFECTA type II

Hereditary opalescent dentin

• autosomal - dominant

• bulbous crowns

• brown; brownish-blue

• affects primary more severely than permanent

• 20% enamel hypoplasia

• Soft dentin produces enamel chipping - attrition

• Radiographically no pulp chambers or canals

• Roots short and thin with Periapical radiolucencies

• Defect with odontoblasts lay abnormal matrix

• Dentin -irregular tubules -inorganic content

• Treatment - cast metal crowns; caution with partial appliances -root fracture

Dentin Dysplasia type I

radicular dysplasia

• Autosomal dominant

•Normal crowns; abnormal roots

•Partial or lack of pulp chambers (permanent chamber not affected as much) & canals

• Occasionally Periapical cysts

• Disturbance with Hertwigs epithelial root sheath -which forms roots

• Early exfoliation

Dentin dysplasia type II

CORONAL DYSPLASIA

• Autosomal dominant

• Primary dentition: amber

•Permanent: thistle-shaped pulp chambers on radiographs

•Lack of pulp chambers and small canals

• Basic cause unknown

HYPOPHOSPHATEMIC VITAMIN D RESISTANT RICKETS

• Low absorption of inorganic phosphate

• Cracks of dentin induce fractures of enamel with micro exposure of the pulp and subsequent pulpal infections

• Affects bone; bow legs short stature

• Large pulp chambers and very long pulp horns

Bell’s Palsy

• Unilateral facial paralysis

• Uncontrollable salivation

• Treatment - corticosteroids

Leukemia

• Malignant neoplasms of blood forming stem cells

• Excessive number of white blood cells

• Symptoms similar to nonthrombocytopenic purpura

• Clinical symptoms are similar to mononucleosis

• ANUG, petechiae and ecchymosis, gingival bleeding and typical periodontal disease

• Treatment - remissions with chemotherapy, bone marrow transplant, prognosis poor

Paget’s disease

• Chronic metabolic bone disease

• Enlargement of bone causing spacing of teeth

• Bones feel warm to the touch

• Cotton-wool radiographic appearance

• Treatment - experimental

Addison's Disease

Vitamin D deficiency in young children - may delay tooth eruption

• Insufficient adrenal steroids

• Brown pigmentation of skin and mucosa

• Treatment - hormone replacement therapy

DIABETES MELLITUS

Abnormally high blood glucose levels

(hyperglycemia)

DIABETES MELLITUS type I

-insulin dependant

• Excessive thirst (polydipsia)

• Excessive urination (polyuria)

• Excessive appetite (polyphagia)

• Treatment - insulin injections

DIABETES MELLITUS Type II

noninsulin dependent

• Adult onset or obesity

• Poor circulation (gangrene of feet); blindness, atherosclerosis, kidney failure, nerve damage, xerostomia, candidiasis, increased response to plaque, excessive periodontal bone loss, and decreased wound healing

• Treatment - diet, weight reduction, meds and/or insulin

HYPERTHYROIDISM

• Excess production of thyroid hormones

• Hormones are responsible for metabolic rate

• Most common caused by a goiter - enlargement of the thyroid gland

• More common to women

• Also called thyrotoxicosis

HYPOTHYROIDISM

• Insufficient thyroid hormone

• Sunken eyes

• Develop disorder auto-immune

HYPERPARATHYROIDISM

• Excessive production of parathyroid hormone

• Most commonly caused by a parathyroid adenoma

• Elevated blood levels of calcium (hypercalcemia)

• Rare

• Four parathyroid glands are located near the thyroid; regulate role of calcium and phosphorus metabolism

PRIMARY -abnormality of parathyroid gland

• SECONDARY - calcium is abnormally secreted by kidneys.

• Caused by kidney failure.

• Joint pain

• Radiolucencies of the mandible or maxilla containing multinucleated giant cells.

• Teeth become mobile

• Treatment -correct cause

- Bone lesions resolve when treated successfully

CHERUBISM

• Autosomal - dominant with marked penetrance

• Bilateral facial swelling (ages 1 ½ and 4); most common mandible

• Displacement of the eyes > cherub appearance

• Radiographically soap bubble appearance

• Radiolucency contains multinucleated giant cells

• Pseudoanodontia: teeth falsely appear to be lacking (actually delayed eruption)

• Growth stops at puberty; facial deformity remains

SICKLE CELL ANEMIA

Inherited disorder found in Afro-Americans

Experience weakness, fatigue, and joint pain

Abnormal hemoglobin decreases oxygen and causes the cell to become sickle shaped

• Treatment - oxygen and supportive; premedication is needed

Lipoma

Benign

• Fat cells (adipose tissue); yellowish mass of thin epithelium

• Surgical excision; not recur

• Most common on subcutaneous tissue

• Uncommon in oral cavity- most common locations are the buccal mucosa and vestible

• Adipose Tissue

Fibroma

a non-cancerous growth made of fibrous or connective tissue

NEUROFIBROMATOSIS OF VON RECKLINGHAUSEN

• Autosomal dominant

• Multiple neurofibromas on facial skin;

• eyelids

• Intra oral most on lateral border of tongue

• 3-15% become malignant

• Café-au-lait pigmentation of skin 90%; 1st decade (color of coffee with milk)

HYPOHIDROTIC ECTODERMAL DYSPLASIA

• X-linked recessive; autosomal recessive

• Hypodontia

• Lack of body hair and sweat & sebaceous glands

• Clinical symptoms evident by 2nd year

• Small conical shaped crowns incisors and canines

MULTIPLE ENDOCRINE NEOPLASIA (MEN 2B)

• Multiple mucosal neuromas (earliest sign) - benign neoplasm oi nerve cells

• On lips and anterior dorsal surface of the tongue

• Buccal mucosa and eyelids

• Medullary (inner portion) carcinoma of the thyroid (75%)

• Occurs in first few years of life

Pheochromocytoma - benign neoplasm around ganglia of adrenal glands

• Early diagnosis -highest malignant potential of thyroid carcınoma

• Produces night sweats; high BP; diarrhea

• Cutaneous pigmentation; skeletal abnormalities

• Predisposition to develop malignant thyroid carcinoma

• Also develop functional adrenal gland tumors

Snow capped Amelogenesis imperfecta

A type of hypomaturation amelogenesis imperfecta

• X-linked recessive or autosomal dominant

• Hypomaturation of occlusal 1/3 Maxillary teeth (most common); whitish discoloration