Dentosphere : World of Dentistry

 # The maximum penetration among the following is seen with which ray:  a. Alpha  b. Beta  c. Gamma  d. Electron Beam  The correct answer is C. Gamma. Gamma (γ) rays originate in the nuclei of radioactive atoms. They typically have greater energy than x rays. In contrast, x rays are produced outside the nucleus and result from the interaction of electrons with large atomic nuclei in x-ray machines. The higher energy types of radiation in the electromagnetic spectrum— ultraviolet rays, x rays, and γ rays—are capable of ionizing matter. Some properties of electromagnetic radiation are best explained by quantum theory, whereas others are most successfully described by wave theory.

 # The most unwanted side effect seen with Herbst appliance is: A. Lower incisor proclination B. Frequent breakage of the appliance C. Downward rotation of palate D. Mandible rotate anticlockwise The correct answer is A. Lower incisor proclination. The most unwanted side effects seen with Herbst appliance are:  - More chance of labial tipping as well as proclination of mandibular incisors - Retrusion of maxillary incisors Reference: Pancherz H. Treatment of Class II malocclusions by jumping the bite with the Herbst appliance. A cephalometric investigation. Am J Orthod. 1979;76(4):423–442.

 # Salivary gland stone most commonly involves:  a. sublingual gland  b. Submandibular gland  c. Parotid gland  d. Lingual glands  The correct answer is B. Submandibular gland.  Sialoliths (salivary calculi or salivary stones) are calcified organic masses that form within the secretory system of the salivary glands. Although the exact mechanism of sialolith formation has not been established, it has been proposed that microcalculi are frequently formed in salivary ducts during periods of secretory inactivity.  Sialoliths occur most commonly in the submandibular glands (80–90%), followed by the parotid (5–15%) and sublingual (2–5%) glands, and only very rarely occur in the minor salivary glands. Spontaneous secretion in the minor and sublingual salivary glands may provide continuous salivary flow, thereby preventing stasis. The higher rate of sialolith formation in the submandibular glands is due to: (1) the torturous course of Wharton’s duct; (2) ...

 # A patient on warfarin sodium following myocardial infarction reports for an oral surgical procedure. Which one of the following laboratory tests should be preferred to ascertain the fitness?  a. Prothrombin time  b. Torniquet time  c. clotting time  d. bleeding time  The correct answer is A. Prothrombin time. The PT and INR tests measure the time it takes for blood to clot by forming thrombin. They evaluate the extrinsic and common coagulation pathways, screening for the presence or absence of fibrinogen (F I), prothrombin (F II), and F V, F VII, and F X. The normal range of PT is approximately 11–13 seconds. Because of individual laboratory reagent variability and the desire to be able to reliably compare the PT from one laboratory with that from another, the PT test is commonly reported with the INR. The INR, introduced by the World Health Organization in 1983, is the ratio of PT that adjusts for the sensitivity of the thromboplastin reagents, such tha...

 # Bremsstrahlung refers to:  a. the primary source of X-rays from an X-ray tube  b. Characteristic radiation emitted when an electron is displaced from the outer shell of a tungsten atom in the target  c. the electromagnetic spectrum  d. particulate radiation  The correct answer is: A. a. the primary source of X-rays from an X-ray tube.  BREMSSTRAHLUNG RADIATION: The sudden stopping or slowing of high-speed electrons by tungsten nuclei in the target produces bremsstrahlung photons, the primary source of radiation from an x-ray tube. (Bremsstrahlung means “braking radiation” in German.)

 # Multiple punched-out radiolucencies is a feature of:  a. Multiple Myeloma  b. Thalassemia  c. Fibrous Dysplasia  d. Ewing's Sarcoma  The correct answer is A. Multiple myeloma. The periphery of multiple myeloma lesions is well-defined but not corticated; it lacks any sign of bone reaction. The lesions have been described as appearing “punched out.” However, many appear ragged and even infiltrative. Some lesions have an oval or cystic shape. Untreated or aggressive areas of destruction may become confluent, giving the appearance of multilocularity.

 # Bleeding time is prolonged in: A. Hemophilia B. Von willebrand disease C. Telangiectasia D. Henoch Schonlein purpura  The correct answer is B. Von Willebrand disease. Von Willebrand disease (VWD) is the most common hereditary blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of von Willebrand factor (VWF), a multimeric protein that is required for platelet adhesion. It is known to affect several breeds of dogs as well as humans. The three forms of VWD are hereditary, acquired, and pseudo or platelet type. The three types of hereditary VWD are VWD type 1, VWD type 2, and VWD type 3. Type 2 contains various subtypes. Platelet type VWD is also an inherited condition. The various types of VWD present with varying degrees of bleeding tendency, usually in the form of easy bruising, nosebleeds, and bleeding gums. Women may experience heavy menstrual periods and blood loss d...