Cleft Palate occurs during which week of gestation?

# Cleft palate occurs in the ___________ of embryonic life.
A. First to third week
B. Fourth to sixth week
C. Eighth to tenth week
D. Twelfth to fourteenth week

The correct answer is C. 8th to 10th week.

Cleft palate occurs in the eighth to tenth week of embryonic life. Isolated clefts of the palate are more common in females. It is characterized by a fissure in the midline of the palate, resulting from the failure of the two sides to fuse during embryonic development.

The most severe handicap imposed by cleft palate is an impaired mechanism preventing normal speech and swallowing. 

Note: It affects approximately 1 in 2000 births.

Cleft lip results when the medial nasal process fails to fuse with the lateral portions of the maxillary process of the first branchial arch. Fusion normally occurs during the sixth and seventh weeks of embryonic development. The maxillary lip is most commonly affected.

It may be bilateral (20%) or unilateral (80%). Clefts of the lip are more frequent in males. Lip cleft involvement is more frequent on the left side than the right.

Note: It affects approximately 1 in 1000 births, but varies with race.

Leukemia most common in children

# Leukemias are evenly split between the acute and chronic forms, but among children one form accounts for about two-thirds of cases. This one form is:
A. Acute lymphocytic leukemia (ALL)
B. Acute myeloid leukemia (AML)
C. Chronic lymphocytic leukemia (CLL)
D. Acute monoblastic

The correct answer is A. Acute lymphocytic leukemia (ALL).

The peak age for ALL is around four years old, and it is the form of acute leukemia that is the most responsive to therapy. Current therapies for ALL include chemotherapy with follow-up radiation and possible bone-marrow transplant after particularly high dose chemotherapy treatment or in cases of recurrence or if it is non-responsive to other treatments.

*** Acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL) are the most common types in adults.

Although the exact cause of most leukemias remains unknown, increasing evidence suggests a combination of contributing factors. These factors include: familial tendency, congenital disorders (Down syndrome, or the presence of Philadelpltia chromosome -chronic myeloid leukemia), viruses (e.g., HTLVI, herpes-like viral particles have been cultured from patients and leukemic patients have high antibody titer to the Epstein-Barr virus), ionizing radiation and the exposure to the chemical benzene and cytotoxins such as alkylating agents.

Important: Oral lesions are most likely to be observed in myelogenous leukemia. These oral lesions may be the initial manifestation of the disease. The oral lesions include gingivitis, gingival hemorrhage, generalized gingival hyperplasia. petechiae, ecchymoses, and ulcerations.

Pernicious anemia symptoms

# A patient with pernicious anemia often consults the dentist for relief of:
A. Edematous buccal mucosa
B. Severe gingivitis
C. Glossitis
D. Denuded gingiva

The correct answer is: C. Glossitis

Pernicious anemia is a relatively common, chronic, progressive, megaloblastic anemia. It is caused by the lack of secretion of the intrinsic factor in normal gastric juice. This factor is necessary for adequate absorption of vitamin B12, which is necessary for the maturation of erythrocytes. As a result, they produce fewer erythrocytes than normal.

The onset of pernicious anemia usually is insidious and vague. As the condition progresses, there will be a sore, painful tongue (atrophic glossitis), angular cheilitis, a tingling numbness of the extremities, difficulty swallowing (dysphagia), painful swallowing (odynophagia). 

A Schilling 24-hour urine test is done to evaluate whether vitamin B 12 is being absorbed by the body and is most commonly used to evaluate patients for pernicious anemia.

Bremsstrahlung / Braking radiation

# Which of the following interactions is responsible for the creating of Bremsstrahlung / Braking radiation?
A. Electrons falling from the K shell to the J shell
B. Interaction of electrons with electrons
C. Conversion of photons into electrons
D. Interaction of electrons with nuclei

The correct answer is D. Interaction of electrons with nuclei.

Bremsstrahlung radiation is created when

high-speed electrons interact with the

Tungsten nuclei at the target.

The fast-moving electron loses kinetic

energy when it interacts with the nuclei,

converting the lost kinetic energy into a

photon.

Radiographic density of which varies most

# The radiographic density of which of the
following materials varies the MOST?
A. Amalgam
B. Soft tissue
C. Composite
D. Acrylic
E. Gold

The correct answer is C. Composite.

The radiographic density of composites
varies the most because the manufacturers
may place a different amount of barium
salts or other opaque filling materials.

Metals like amalgam and gold appear with
a standard amount of radiopacity.

Acrylic typically does not possess any
opaquers, and therefore is usually totally
radiolucent.

Soft tissue is fairly radiolucent.

Use of intensifying screens

# Which of the following is the reason
intensifying screens are used with extraoral
radiographic films?
A. Improve the image quality
B. Increase the exposure time
C. Increase the kVp
D. Decrease the radiation dose of the patient

The correct answer is D. Decrease the radiation dose of the patient.

Intensifying films MUST be used with
extraoral radiographic films in order to
decrease the dose of radiation to the
patient.

Radiation is harmful, even in small doses, toi ndividual cells in the body.

Radiation can cause abnormal changes that
leads to cancer.

Intensifying screens when used with x ray
films using emulsions, make them more
sensitive to blue or green light.

The X-ray photons are converted to visible
light photons when they strike the screen.

Lead aprons and thyroid collars are
mandatory preventive armamentarium in dental radiograhy.

A longer gray scale of contrast can be accomplished through

# In radiography, a longer gray scale of contrast can be accomplished through:
A. Increasing the focal spot-skin distance
B. Increasing the kilovoltage
C. Decreasing the filtration
D. Increasing the milliamperage

The correct answer is B. Increasing the kilovoltage.

Longer gray scales of contrast can be
achieved by increasing the kilovoltage peak.

Increasing the kilovoltage causes the
radiographic image to have low contrast
and longer gray scales.

Low kilovoltage creates low energy x-rays
responsible for producing high contrast and
shorter gray scale.