Substitution of glutamic acid by valine

# What disorder is a result of a genetic mutation causing the substitution of glutamic acid by a valine and results in dental radiographs with enlarged marrow spaces?
A. Cystic fibrosis
B. Muscular dystrophy
C. Polio
D. Sickle-cell anemia

The correct answer is: D. Sickle cell anemia.

Sickle-cell anemia is an inherited disease in which the red blood cells, normally disc-shaped, become crescent-shaped. As a result, they function abnormally and cause small blood clots. These clots give rise to recurrent painful episodes called "sickle cell pain crises." Sickle-cell anemia (also called sickle-cell disease) is the result of the production of abnormal hemoglobin (Hemoglobin S) due to a genetic defect. lt is carried as a trait by  10% of African Americans and 0.2% have sickle-cell anemia. It is more common in females and usually clinically manifests itself before the age of 30. The typical signs of anemia are present. The patient is weak, short of breath, and easily fatigued. Muscle and joint pains are common.

Dental radiographs are often of diagnostic value: marrow spaces are markedly enlarged because of the loss of many trabeculae; the trabeculae, which are present, are often abnormally prominent. Occasionally, osteosclerotic areas are noted in the midst of large radiolucent marrow spaces. However, the lamina dura and the teeth are unaffected.

Note: The gene defect is a known mutation of a single nucleotide (thymine for an adenine) of the beta-globin gene, which results in glutamic acid to be substituted by valine. Sickle cell anemia occurs when a person inherits two abnormal genes (one from each parent). If a person inherits one abnormal gene for the disease, they have what is called sickle cell trait. The life span of red blood cells is reduced from 120 to 20 days.

Mandibular Second Molar - Curved root Extraction

The mandibular second molar has many similarities with the mandibular first molar anatomically. The roots of the second molar may be straighter with less divergence from the furcation than in the first molar. The roots may be shorter, but there is no assurance that any of these differences will be manifested in any one tooth.

Mandibular Second Molar  has two well-developed roots, one mesial and one distal. These roots are broad buccolingually, but they are not as broad as those of the first molar, nor are they as widely separated.

Curvatures in the roots of molars pose difficulty during their root canal treatment, may cause failure of RCTs, and may be problematic even during extraction. Let's see how textbook specimens of mandibular second molar and a real life case of mandibular second molar differ and what you can expect during your clinical practice.

It took me nearly One hour and fifteen minutes to extract one particular mandibular second molar. I thought that may be due to the fatigue from the last procedure which had lasted nearly 2 hours. I even started thinking today is not a good day for extraction, after the mesial root started moving a little bit. I was taken aback when it came out in whole with its ghastly appearance as in the figure below. Few more minutes were required for the removal of distal root after this stubborn mesial root was removed.

Ten typical specimens of Mandibular Second Molar. Source: Wheeler's Dental Anatomy, Physiology and Occlusion 10th Edition

Also, ten atypical specimens.

Ten atypical specimens of mandibular Second molar. Ref: Wheeler's Dental Anatomy, Physiology and Occlusion, 10th Edition

Elimination of penicillin VK from the body

# Penicillin VK is eliminated in the body..
A. Secreted unchanged into fecal flow
B. Metabolized in liver and secreted into fecal flow
C. Excreted unchanged in urine
D. Metabolized by liver and excreted in urine

The correct answer is D. Metabolized by liver and excreted in urine.

Penicillin VK is an antibiotic metabolized in
the liver to be excreted by the kidneys into
urine.

Chemically augmented form of penicillin
that combines acid stability with an
immediate solubility and faster rate of
absorption.

Highly effective against pneumococci,
staphylococci except for strains producing
penicillinase and streptococci (groups A, C,
G, H, L and M).

Half-life is approximately 30-60 min and
takes about 5 hr to clear the body entirely.

Teeth mostly involved in Hypercementosis

# Hypercementosis is the excessive deposition of secondary cementum on the roots. Any tooth may be involved, however, which teeth are most frequently involved?
A. Molars
B. Incisors
C. Premolars
D. Canines

The correct answer is C. Premolars.

Hypercementosis is often confined to the apical half of the root but, in some instances, may involve the entire root. In a large majority of instances, it affects vital teeth, is not associated with any one particular systemic disease, and may be regarded as a dental anomaly.

lt may be seen when a tooth has lost its antagonist or when there is a chronic inflammation of the tooth. The premolars are most frequently involved. Next in frequency are the first and second molars.

Hypercementosis produces no significant clinical signs or symptoms indicative of its

presence. It is seen radiographically as a bulbous enlargement that has surrounding it a

continuous and unbroken periodontal membrane space and a normal lamina dura.

Death in Ludwig's angina occurs due to

# Death in Ludwig's angina occurs due to: (MAN -2K)
A. Sepsis
B. Respiratory obstruction
C. Cavernous sinus thrombosis
D. Carotid blow-out

The correct answer is B. Respiratory obstruction.

In Ludwig's angina there is progressive
dyspnoea due to backward spread of infection.

If not treated, it results in edema of glottis and causes complete respiratory obstruction.

What is herd immunity?

# At what point is herd immunity to a given disease observed?
A. After 100% of a population has developed a primary immune response
B. After antibiotics have treated all known cases of disease in a population
C. After 100% of a population has developed a secondary immune response
D. Immediately after 100% of a population has been Immunized
E. After enough people in a population have developed a primary immune response so that spread of an infectious agent is curtailed

The correct answer is E. After enough people in a population have developed a primary immune response so that spread of an infectious agent is curtailed. 

Herd immunity does not require that 100%

of a population be immune. Herd immunity

requires that enough people in the population have elicited memory cells.

Should the pathogen enter the population,

the number of people infected will be small

because the immunized population will not

be able to contract or spread the infection

to the non-immunized population. This

keeps the number of pathogens to a

minimum, for the protection of all.

Extend the life of a Tungsten Carbide bur

# To extend the life of a tungsten carbide bur, the bur should...
A. Be moving slow before contacting tooth structure
B. Be sterilized with heat sterilization
C. Contact tooth structure before rotating
D. Be moving fast before contacting tooth structure

The correct answer is D. Be moving fast before contacting tooth structure.

The lifespan of a tungsten carbide bur can
be extended by bringing the bur up to speed  before contacting tooth structure, because it decreases the friction between the bur and the tooth structure thereby decreasing damage to the bur and the pulp.

Sufficient rotating speed makes the cutting
edge of the bur more efficient even with
using light pressure.

Heat sterilization corrodes the carbon steel
and anneals the cutting edge of the bur.