Dentosphere : World of Dentistry

  Share # All of the following statements about the differences between self-polymerizing acrylic resins and heat-cured resins are true EXCEPT: A. The former have a lower molecular weight B. The former have higher residual monomer content C. The former are more porous D. The former have greater transverse strength # In heat cure denture base acrylic resins the monomer is: A. Methacrylate B. Ethylmethacrylate C. Methyl ethyl methacrylate D. Polymethylmethacrylate # If curing occurs at temperature more than 100°C porosity results in which area of denture? A. Hard thick central area B. Thin Palatal area C. Thin area of flanges D. Porosity is uniformly distributed # Which of the following is an example of a composite material? A. A filled resin B. Colloidal silica C. Gold alloy D. Wax # Use of dimethyl-P-toluidine is indicated for: A. Thermal polymerization of acrylic B. Chemical p...

Share # Model plaster (white) used to cast study models before mixing with water, is largely composed of: A. CaO B. CaCO3 C. (CaSO4)2. 1/2H2O D. CaSO4.2H2O # The product, which is obtained by calcining under steam pressure at 120-130°C or by dehydrating gypsum in the presence of sodium succinate is: A. Alpha - hemihydrates B. Beta - hemihydrates C. Calcium sulphate dihydrate D. Orthorhombic anhydrate # Water powder ratio of dental stone and plaster is respectively: A. 0.28 and 0.6 B. 0.6 and 0. 28 C. 0.6 and 3.2 D. 0.28 and 0.98 # Type III Dental gypsum is: A. Class II stone B. Densite C. Class I stone or hydrocal D. Model or lab plaster # Green strength with reference to plaster means: A. Dry strength B. Compressive strength C. Strength of dental stone due to green colour D. The wet strength # Beta hemihydrate particles absorb: A. more water...

 # Procedures undertaken in preventive orthodontics are all EXCEPT: A. Parents education B. Checkup for oral habits C. Extraction of supernumerary teeth D. Space regaining The correct answer is D. Space regaining.  Procedures of preventive orthodontics:  1. Parent education  2. Caries control  3. Care of deciduous dentition  4. Management of ankylosed tooth  5. Maintenance of quadrant wise tooth shedding timetable.  6. Checkup for oral habits and habit-breaking appliances if necessary.  7. Occlusal equilibration if there are any occlusal pre-maturities.  8. Prevention of damage to occlusion, e.g. Milwaukee braces  9. Extraction of supernumerary teeth  10. Space maintenance  11. Management of deeply locked first permanent molar  12. Management of abnormal frenal attachments 

 # Simple retraction of maxillary incisors using maxillary molars as anchorage is an example of: A. Simple anchorage B. Reciprocal anchorage C. Stationary anchorage D. Intermaxillary anchorage The correct answer is C. Stationary anchorage.  An anchor tooth or source, which does not move against the forces of teeth to be pulled is stationary anchorage. In a real sense, only the extraoral source of anchorage derived from headgear would be a stationary anchorage. The anchor tooth being housed in a bioactive environment would show some degree of movement and hence cannot be classified as a stationary anchorage in a real sense.

 # Bone can be induced to grow at surgically created sites by the method called: A. Osteogenesis B. Distraction osteogenesis C. Bone wax D. Green stick fracture The correct answer is B. Distraction osteogenesis. • Distraction osteogenesis is the method of inducing bone to grow at surgically created sites.  • Russian Surgeon Ilizarov discovered in 1950's that if cuts were made through the cortex of a long bone of the limbs, the arm or leg then could be lengthened by tension to separate bony segments.  • Currently it is believed that best results are obtained if this type of distraction starts after a few days of initial healing and callus formation and if the segments are separated at a rate of 0.5 - 1.5 mm/day.  • Also this technique is employed for lengthening of mandible and inducing maxillary growth by separating cranial and facial bone at their sutures. 

 # A 58-year-old woman underwent left superficial parotidectomy for a pleomorphic adenoma 2 years ago. She presents with complaints of occasional perspiration and redness of the left cheek and ear after eating. Which of the following nerves is the most likely source of these complaints?  A. Great auricular B. Frontal branch of the facial nerve C. Auriculotemporal D. Lingual The correct answer is C. Auriculotemporal. The auriculotemporal syndrome is an unusual phenomenon, which arises as a result of damage to the auriculotemporal nerve and subsequent reinnervation of sweat glands by parasympathetic salivary fibers. The patient typically exhibits flushing and sweating of the involved side of the face, chiefly in the temporal area, during eating. The severity of this sweating may often be increased by tart foods. Of further interest is the fact that profuse sweating may be evoked by the parenteral administration of pilocarpine or eliminated by the administration of atropine or by...

 # The diameter of the tip of a periodontal probe is: A. 0.25 mm B. 0.5 mm C. 0.75 mm D. 1 mm The correct answer is B. 0.5 mm. Periodontal probes are used to measure the depth of pockets and to determine their configuration. The typical probe is a tapered, rodlike instrument calibrated in millimeters, with a blunt, rounded tip. There are several other designs with various millimeter calibrations. The World Health Organization (WHO) probe has millimeter markings and a small, round ball at the tip. Ideally, these probes are thin, and the shank is angled to allow easy insertion into the pocket. Furcation areas can best be evaluated with the curved, blunt Nabers probe. When measuring a pocket, the probe is inserted with a firm, gentle pressure to the bottom of the pocket. The shank should be aligned with the long axis of the tooth surface to be probed. Several measurements are made to determine the level of attachment along the surface of the tooth. Reference: Carranza's Clinical Perio...