Odontogenic keratocyst (OKC) is derived from:

# The odontogenic keratocyst (OKC) is derived from:
A. Hertwig's epithelial root sheath
B. The reduced enamel epithelium
C. Remnants of the dental lamina
D. A pre-existing osteoma

The correct answer is: B. Reduced enamel epithelium.

Keratocysts differ from other odontogenic cysts in their microscopic appearance and clinical behavior.

They may resemble periodontal, primordial, or follicular cysts. Usually, they cannot be distinguished

radiographically. 

Clinical features:

• Wide age range. peak occurrence in 2nd and 3rd decades

• Lesions found in children are often reflective of multiple odontogenic keratocysts as a component

of the nevoid basal cell carcinoma syndrome

• More common in males than females

• The chief site of involvement is the mandible, in approximately a 2 to 1 ratio

• In the mandible. most occur within the posterior portion of the body and ramus region

• Typically asymptomatic

Radiographic features:

• Well-demarcated area of radiolucency with a scalloped, radiopaque margin

• Unilocular or multilocular

Microscopicall y:

• The lining epithelium is thin and parakeratinized.

• The basal layer is palisaded with prominent, polarized, and intensely staining nuclei of uniform

diameter

• The lumen may contain large amounts of keratin debris or clear fluid similar to serum transudate

• The parakeratotic type fonns 85 to 95% of all odontogenic keratocysts; the balance is made

up of the orthokeratinized variant.

Most common cause of xerostomia is:

# The most common cause of xerostomia is:
A. Hereditary
B. Medications
C. Tooth decay
D. Mouth breathing

The correct answer is B. Medications.

Xerostomia (dry mouth) is not a disease, however, it can be a symptom of certain diseases. Many times xerostomia is caused by failure of the salivary glands to function normally, but the sensation can also occur in people with normal salivary g lands. Xerostomia can cause health problems by a ffecting nutrition, as well as psychological heal th. At its most extreme, it can lead to rampant tooth decay and periodontal disease.

Perhaps the most prevalent cause of xerostomia is medica tion. The main culprits are antihistamines, antidepressants, anticholinergics (e.g .. atropine and scopolamine) , anorexiants, antihypertensive, antipsychotics {e.g. , chlorpromazine and prochlorperazine), anti-Parkinson agents, diuretics and sedatives.

The most common disease causing xerostomia is Sjogren's syndrome (SS), a chronic inflammatory autoimmune disease that occurs predominantly in postmenopausal women.

Sarcoidosis and amyloidosis are other chronic inflammatory diseases that cause xerostomia.

Other systemic diseases that can cause xerostomia include rheumatoid arthritis, systemic lupus erythema tosus, and scleroderma. 

Remember: Xerostomia is the most common toxicity associated with radiation therapy to the head and neck.

 

Ludwig's angina involves infection of:

# Ludwig's angina is a severe and spreading infection that involves the:
A. Submental and sublingual spaces only
B. Submandibular, submental, and sublingual spaces unilaterally
C. Submandibular and sublingual spaces only
D. Submandibular, submental, and sublingual spaces bilaterally

The correct answer is: D. Submandibular, submental, and sublingual spaces bilaterally

Ludwig's angina often results from an odontogenic infection. As a result, the bacteriology of theses infections generally involves oral flora, particularly anaerobes. Other recognized etiologies of Ludwig's angina include poor oral hygiene, IV drug abuse, trauma, and tonsillitis.

It is characterized by:

• Rapid onset

• The three facial spaces are involved bilaterally

• Board-like swelling of floor of the mouth and no fluctuance is present

• Typical "open-mouthed" appearance

• Elevation of the tongue

• Drooling. trismus, and fever

• Difficulty eating, swallowing, breathing

• Tachycardia, increased respiration rate

• Can lead to glottal edema; asphyxiation

Airway management, massive antibiotic coverage (IV), and surgical incision and drainage are the mainstays of treatment.

Very important: The most serious complication of Ludwig's angina is edema of the glottis (which is a slit-like opening between the true vocal cords).

Epithelioid cells and giant cells are derived from

# Epithelioid cells and giant cells are derived from macrophages and are important in the development of:
A. Initial inflammation
B. Granulomatous inflammation
C. Acute inflammation
D. Subacute inflammation

The correct answer is B. Granulomatous inflammation.

Granulomatous inflammation is a subtype of chronic inflammation and is characterized by granulomas, which are nodular collections of specialized macrophages referred to as epithelioid cells. A rim of lymphocytes usually surrounds granulomas. Granulomas are produced by multinucleated giant cells (Langerhans giant cells and foreign body giant cells). All the other cell types characteristic of chronic inflammation, including plasma cells, eosinophils, and fibroblasts, may also be associated with granulomas.

Note: Granulomatous inflammation is characteristically associated with areas of caseous necrosis produced by infectious agents, particularly Mycobacterium tuberculosis.

• Tuberculosis: caused by the inhalation of Mycobacte1ium tuberculosis. Oral non-healing chronic ulcers follow lung infection. Important: Characterized by caseating granulomas with multinucleated giant cells (Langerhans giant cells and foreign body giant cells).

Etiologic agents associated with granulomatous inflammation:

• Infectious agents

- TB and leprosy, which are mycobacterial diseases

- Fungal infections (blastomycosis, histoplasmosis, and coccidioidomycosis)

- Spirochetes (Treponema pallidum, which causes syphilis)

- Cat scratch disease (caused by an unnamed gram-negative organism)

• Foreign material (e.g., suture or talc)

• Sarcoidosis (unknown etiology; it is non-necrotizing)

• Crohn's disease (it is non-caseating)

Hepatitis found only in patients with acute or chronic episodes of Hepatitis B

# Which type of Hepatitis is found only in patients with acute or chronic episodes of Hepatitis B?
A. Hepatitis C
B. Hepatitis D
C. Hepatitis E
D. Hepatitis A

The correct answer is B. Hepatitis D, this virus causes "serum" or long-incubation hepatitis

The Hepatitis B virus (HBV) is a double-stranded DNA virus with worldwide distribution, transmitted by parenteral and sexual contact. Risk factors include multiple sexual partners, intravenous drug abuse, and receipt of blood products. Its incubation period is 40 to 100 days, and it can be recovered from all body fluids, most importantly, blood, breast milk, and amniotic fluid. The signs and symptoms are similar to hepatitis A (leve1; abdominal pain, nausea, etc.) but there is a longer incubation period (6-8 weeks). The symptoms are slower in developing but are of a longer duration. Most patients recover fully, however, some develop chronic liver disease.

Previously, viral hepatitis that was not caused by the type A or type B virus was called "non-A, non-B hepatitis." Recently three more viruses have been identified that cause some of these non-A, non-B infections.

These new viruses include:

• Hepatitis C: is a serum hepatitis that is caused by a virus antigenically different from Hepatitis viruses A and B. Most cases of post-transfusion hepatitides are of this type. It is usually much milder than A or B but is otherwise clinically indistinguishable from them. There is a higher incidence of chronic disease (chronic hepatitis), cirrhosis, and hepatocellular carcinoma. Note: Hepatitis C is now the most common reason for liver transplantation in the U.S.

• Hepatitis D: is found only in patients with acute or chronic episodes of Hepatitis B, and it makes the Hepatitis B infection more severe. Drug addicts are at relatively high risk.

• Hepatitis E: is transmitted enterically, much like Hepatitis A. It causes occasional epidemics similar to those caused by Hepatitis A. So far these epidemics have occurred only in underdeveloped countries.

Disease associated with a decreased incidence of dental caries

# Which of the following diseases is associated with a decrease in caries?
A. Sjogren's syndrome
B. Cystic fibrosis
C. Cerebral palsy
D. Down syndrome

The correct answer is B. Cystic fibrosis.

** Important: There is a significantly reduced caries rate in patients with cystic fibrosis. This is probably the result of alterations in saliva and the long-term use of antibiotics. Cystic fibrosis is a congenital metabolic disorder that causes the exocrine glands (which are glands that secrete fluids into a duct) to produce abnormal secretions, resulting in several symptoms, the most important of which affect the digestive tract and the lungs. In some glands, such as the pancreas and those in the intestines, the secretions are thick or solid {an excessively viscous mucous) and may block the gland completely. The mucous producing glands in the airways of the lungs produce abnormal secretions that clog the airways and allow bacteria to multiply. The sweat glands secrete fluids that have high sodium and chloride content. Note: The staining of the teeth is most likely due to the fact

that patients with cystic fibrosis are usually subjected to large amounts of tetracyclines during childhood.

Symptoms of CF include:

• Poor growth despite a good appetite

• Malabsorption and foul, bulky stools: steatorrhea

• Chronic bronchitis (COPD) with cough

• Recurrent pneumonia: respiratory infections

• Clubbing of fingers and toes

• Barrel-chested appearance 

Severe hypothyroidism in a child

# Severe hypothyroidism in a child is called:
A. Dwarfism
B. Myxedema
C. Cretinism
D. Acromegaly

The correct answer is C. Cretinism.

Hypothyroidism refers to a condition in which the amount of thyroid hormone in the body is below normal. This is the most common form of thyroid function abnormality and is far more common than hyperthyroidism. This condition is considerably more common in women than in men. The most common cause of hypothyroidism is Hashimoto's thyroiditis.

The second most common cause is the treatment of hyperthyroidism. Hypothyroidism is characterized by the puffiness of the face and eyelids and swelling of the tongue and larynx. The skin becomes dry and rough and the hair becomes sparse. The individual has a low basal-metabolic rate and a low body temperature. The affected individuals also have poor muscle tone, low strength and get tired very easily. Mentally they are very sluggish. The treatment of hypothyroidism is straight forward and consists of administering thyroid hormone (thyroxin).

Severe hypothyroidism in a child is called cretinism. Due to a lack of thyroid hormone, there is a retardation of growth and abnormal development of bones. Mental retardation is caused by the improper development of the CNS. If this condition is recognized early, it can be markedly improved with the use of thyroid hormones. Note: Extreme hypothyroidism in adults is called myxedema.

Note: Dental findings in a child with hypothyroidism include an underdeveloped mandible with an overdeveloped maxilla, enlarged tongue which may lead to malocclusion, delayed eruption of teeth, and deciduous teeth being retained longer.