Tooth most likely to not erupt due to overcrowding

# Which of the following teeth is most likely to NOT erupt into the arch due to overcrowding?
A. Canine
B. Central incisor
C. Lateral incisor
D. 2nd premolar
E. 1st premolar

The correct answer is A. Canine.

Canines are the anterior teeth that are most
likely to be unable to erupt within a crowded dentition because the canine erupts after the incisors and premolars have already erupted.

Tooth crowding may occur in patients with
teeth that are too wide mesiodistally or if
their dental arch is too small to
accommodate all the erupted teeth.

Tooth crowding carries a genetic predisposition because it is often a matter of tooth size vs arch size.

Facial profile change with ageing

# The facial profile of most people change as they age and mature through becoming..
A. More convex
B. The same level of convexity
C. Less concave
D. Less convex

The correct answer is D. Less convex. 

The facial profile may vary as we age due to

the loss of facial fat, muscle atrophy and

loss of skin elasticity.

The buccal fact pad is gradually lost in the

cheeks, causing the skin to adapt itself to

the underlying muscle and bone.

During the aging process, metabolism

slows down and the production of skin,

collagen, and muscle fibers is reduced.

The constant pull of gravity also contributes

to the sagging of the face.

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.