Dentosphere : World of Dentistry

Hardness –– Hardness is defined as the ability of a material to resist scratching. –– Can be divided into microhardness and macrohardness. Tests for Microhardness: - Knoop Hardness Test - Vickers Hardness Test Tests for Macrohardness: - Brinell hardness - Rockwell hardness 1. Brinell Hardness Test Oldest test employed for determining the hardness of metals A hardened steel ball is pressed under a specified load into the polished surface of a material. The load is divided by the area of the projected surface of the indentation, and the quotient is referred to as the Brinell hardness number, usually abbreviated as BHN. For a given load, the smaller the indentation, the larger is the number and the harder is the material. Used extensively for determining the hardness of metals and metallic materials used in dentistry It is related to the proportional limit and ultimate tensile strength of dental gold alloys. 2. Rockwell Hardness Number  Is somewhat similar t...

# Among the natural radiation, the one that contributes to more radiation exposure of general population: A. Cosmic B. Terrestrial C. Radon D. Consumer products # X rays cause radiation damage primarily by their property of: A. Penetration B. Radioactivity C. Electromagnetic induction D. Ionisation

# The most radiosensitive cells in the body are: A. Endothelial cells B. Epithelial cells C. Red blood cells D. White blood cells The correct answer is D. White blood cells.

# Identical twins are produced by fertilization of: A. 1 ovum by 1 sperm B. 2 ova by 1 sperm C. 1 ovum by 2 sperms D. 2 ova by 2 sperms The correct answer is: A. 1 ovum by 1 sperm Twins can be either  monozygotic  ('identical'), meaning that they develop from one  zygote , which splits and forms two  embryos , or  dizygotic  ('non-identical' or 'fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell.

# The leading cause of childhood gingivostomatitis in children aged 1 to 3 is: A. Herpes Simplex B. Chicken pox C. Influenza D. Rubella The correct answer is A. Herpes simplex The primary infection (primary herpetic gingivostomatitis) usually occurs in a chlld  under ten years of age who has had no contact with the Type I herpes simplex virus  and who therefore has no neutralizing antibodies. It may also affect young adults (15-25).  Nearly all primary infections are of the subclinical type (they may only have flu-  like symptoms) and one or two mild sores in the mouth which go unnoticed by the  parents. In other children, the primary infection may be manifested by acute symptoms (acute  herpetic gingivostomatitis). These include fever; irritability; cervical lymph adenopathy; fiery red gingival tissues; and small, yellowish vesicles that rupture  and result in painful ulcers on the free and attached mucosa. The most serious  potentia...

21st MAR 2014 B.P. Koirala Institute of Health Sciences, Dharan, Nepal 1st year BDS Internal Assessment Examination, March 2014 Paper - II A (GENETICS, GROWTH AND DEVELOPMENT, IMMUNOLOGY & BLOOD) Time - 2 Hours  Total Marks: 125 SHORT ANSWER QUESTIONS SECTION - 'A' ANATOMY   1. Classify chromosomal disorders with examples of each.                        5 2. Draw a labeled histological diagram of lymph node.                              5 3. Write the criteria and examples of X-linked recessive disorder.             5                                                                     SECTION - 'B' PHYSIO...