Dentosphere : World of Dentistry

# 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.

# 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.

# 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.

# 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 nu...