Late mesial shift of permanent first molars

# The closure of which of the following spaces results in the late mesial shift of permanent 1st molars?
A. Canine
B. Interocclusal
C. Extraction
D. Leeway
E. Primate

The correct answer is D. Leeway space. 

Leeway space is closed as the 1st permanent molars move mesially after the

exfoliation of the primary 2nd molar and is

usually seen among children from 11-12

years of age.

Leeway space is created from the difference of sizes between the primary canine and molars compared to the erupting premolars and permanent canines.

The discrepancy in size of primary molars and premolars creates a free space that allows the late mesial migration of permanent 1st molar after the exfoliation of the primary 2nd molar.

Pigmented (usually purple) lesions in the skin caused by extravasation of blood from the capillaries

# The category of pigmented (usually purple) lesions in the skin caused by extravasation of blood from the capillaries is known as:
A. Petechiae
B. Purpura
C. Ecchymosis
D. Varicose veins

The correct answer is B. Purpura.

Purpura spots (pinpoint spots) are purplish discolorations in the skin produced by small bleeding vessels near the surface of the skin. Purpura may also occur in the mucous membranes (such as the lining of the mouth) and in the internal organs. Purpura by itself is only a sign of other underlying causes of bleeding. Purpura may occur with either normal platelet counts (non-thrombocytopenic purpuras) or decreased platelet counts (thrombocytopenic purpura). Platelets help maintain the of the capillary lining and are important in the clotting process. Note: Large purpura spots (> 3 mm) are called ecchymoses.

Major kinds of purpura:

- Thrombocytopenic purpura (Werlhof's disease): a bleeding disorder characterized by a deficiency in the number of platelets. This results in multiple bruises, petechiae, and hemorrhage into the tissues

- Thrombotic thrombocytopenic purpura (TTP) : a severe and frequently fatal form characterized by a low platelet count in the blood due to the consumption of platelets by thrombosis in the terminal arterioles and capillaries of many organs.

Oral manifestations of thrombocytopenic purpura:

• Severe and profuse gingival hemorrhage

• Petechiae occur commonly on the palate

Important: Tooth extractions are contraindicated due to the tendency for excessive bleeding.

Loss of tooth structure due to non-masticatory physical friction

# The abnormal loss of tooth structure due to non-masticatory physical friction is referred to as:
A. Erosion
B. Abfraction
C. Attrition
D. Abrasion

The correct answer is D. Abrasion.

Types of abrasion:

1. Toothbrush abrasion: most often results in V-shaped wedges at the cervical margin in the canine and premolar areas. It is caused by the use of a hard toothbrush and/or a horizontal brushing stroke and/or a gritty dentifrice.

2. Occlusal abrasion: results in flattened cusps on all posterior teeth and worn incisal edges. It results from the chewing or biting of hard foods or objects and chewing tobacco.

-  Attrition is the wearing away of enamel and dentin due to the normal function or most commonly, due to the excessive grinding or gritting together of teeth by the patient (referred to as bruxism). The most noticeable effects of attrition are polished facets, flat incisal edges, discolored surfaces of the teeth and exposed dentin. Facets usually develop on the linguoincisal of the maxillary central incisors, the facioincisal of the mandibular canines and the linguoincisal of the maxillary canines.

- Erosion is the loss of tooth structure from non-mechanical means. It can result from drinking acidic liquids or eating acidic foods. It is common in bulimic individuals as a result of regurgitated stomach acids. It affects smooth and occlusal surfaces.

- Abfraction lesions are cervical erosive lesions that can not be attributed to any particular cause: causing the enamel to "pop" off starting at the base of the tooth and exposing the gum line of the tooth to excessive wear.

Bald tongue and Koilonychia - Funny Fingernails

# A 48 year old female patient walks into your office. She states that she is diagnosed with some disease which she can't remember the name of. Her physician wants her to follow up with you, her dentist, regularly to watch out for cancer of the tongue and throat. She also has a bald tongue, and states that her fingernails "look funny." What disease does she have?
A. Aplastic anemia
B. Plummer-Vinson syndrome
C. Pernicious anemia
D. Cushing's syndrome

The correct answer is B. Plummer Vinson Syndrome.

Plummer-Vinson syndrome characterized by iron-deficiency anemia, atrophic changes in the buccal, glossopharyngeal, and esophageal mucous membranes, koilonychia (spoon-shaped fingernails), and dysphagia. The dysphagia is due to an esophageal stricture or web. SCC of the tongue and throat are complications. It is most common in middle-aged women, rarely in the male. The etiology is unknown. 

Because of the predisposition to the development of carcinoma of the oral mucous membranes, it is essential that the diagnosis be established early so that treatment can be given ASAP. This includes the administration of iron, vitamin B complex and a high protein diet.

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.