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...

 # Which of the following may create gingival deformities that require gingivoplasty to eliminate the defects? A. Erosive linchen planus  B. Desquamative gingivitis  C. Acute herpetic gingivostomatitis  D. Necrotising ulcerative gingivitis  The correct answer is D. Necrotising ulcerative gingivitis. ■ Shelf-like gingival margins after healing may result in plaque accumulation.  ■ The gingiva is reshaped with periodontal knife or with electrosurgery. This process of eliminating the defects by reshaping is called as gingivoplasty.  ■ Gingival deformities are seen in gingival disease:  (Asked in AIIMS 1999) (ANUG)   Surgical procedure for severe tissue destruction in ANUG infection is:  (Asked in COMED 2011) (Reshaping the gingiva, Gingivoplasty) 

 # Site of Antidiuretic hormone (ADH) action is: A. Proximal tubule B. Loop of Henle C. Vasa recta D. Collecting tubule The correct answer is D. Collecting tubule. Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travels down the axon terminating in the posterior pituitary, and is released from vesicles into the circulation in response to extracellular fluid hypertonicity (hyperosmolality). AVP has two primary functions. First, it increases the amount of solute-free water reabsorbed back into the circulation from the filtrate in the kidney tubules of the nephrons. Second, AVP constricts arterioles, which increases peripheral vascular resistance and raises arterial blood pressure. Acute increase of sodium absorption across the ascending loop of Henle. This adds to the countercurrent multiplication whi...

 # Pyruvate dehydrogenase complex contains all EXCEPT: A. Biotin B. NAD C. FAD D. Co-A The correct answer is A. Biotin. Pyruvate dehydrogenase complex (PDC) is a complex of three enzymes that converts pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, and this complex links the glycolysis metabolic pathway to the citric acid cycle. Pyruvate decarboxylation is also known as the "pyruvate dehydrogenase reaction" because it also involves the oxidation of pyruvate. The enzymes involved in PDC are Pyruvate dehydrogenase (E1), Dihydrolipoyl transacetylase (E2), and Dihydrolipoyl dehydrogenase (E3). The cofactors involved are:  TPP (thiamine pyrophosphate), magnesium, lipoate, coenzyme A,  FAD and  NAD+.  Reference:  https://en.wikipedia.org/wiki/Pyruvate_dehydrogenase_complex

 # The benign neoplasm of ‘brown fat’ noted in oral/pharyngeal region is: A. Lipoma B. Hibernoma C. Teratoma D. Brown tumor The correct answer is B. Hibernoma.  Hibernomas are uncommon neoplasms of brown adipose tissue. The most frequent sites of occurrence include the thigh, shoulder, and back. Less common myxoid and spindle cell hibernoma variants are likely to be located in the posterior neck and shoulder. Hibernomas are benign lipomatous neoplasms and have no potential for malignant transformation.  Hibernomas contain brown fat, and the name was coined about the presence of brown fat in hibernating animals. First described by Merkel 1906, these tumors are similar to lipomas in clinical behavior but have unique imaging and histopathologic features. Hibernomas generally present in young adults with a mean age of 38. In summary, these tumors are: Composed of brown fat Represent benign neoplasms Generally well-circumscribed masses Generally are small in size Exhibit slow ...

 # SNA angle describes the relationship of the: A. Maxilla to the cranial base B. Mandible to the cranial base C. Maxilla to mandible D. Maxilla to the upper incisors The correct answer is A. Maxilla to the cranial base.  SNA: the angle between the sella/nasion plane and the nasion/A plane (normal value at the end of growth 82 ± 2°). This angle assesses the antero-posterior position of the maxilla relative to the upper cranial structures.

 # Analysis of skull shape and size, supraorbital ridge, extension of zygomatic arch beyond external meatus, measurement of angle of mandible helps in: A. Sex determination B. Racial determination C. Age determination D. Ethnicity determination The correct answer is A. Sex determination. Skull and facial features like mastoid process, supraorbital ridges, size and architecture of skull can help in determining the sex of patient in 94% cases.  Sex differentiation (Sexing) of a specimen: It can be done using methods as below:    Using craniofacial morphology: T he following 6 traits give accurate results 94% times:  - Mastoid process  - Supraorbital ridge \ - Size and architecture of skull  - Extension of the zygomatic arch beyond the external auditory canal  - Nasal aperture and  - Gonial angle (on the mandible) (Including more features increases accuracy by 2%) 

 # Prolonged retention is usually needed in: A. Diastema B. Mild crowding C. Anterior cross bite D. Deep bite The correct answer is A. Diastema. Fixed (bonded) orthodontic retainers are normally used where intra-arch instability is anticipated and prolonged retention is planned. There are three major indications: • Maintenance of lower incisor position during late growth • Diastema maintenance • Maintenance of posterior tooth position in adults Reference: Proffit's Contemporary Orthodontics, 6th Edition.

 # Root shape before and after orthodontic treatment with radiographic evidence was first given by: A. Kaley and Phillip B. Newman and Proffit C. Ketcham AH D. Malmgren and Lavendar The correct answer is C. Ketcham AH. Albert H. Ketcham was born on August 3, 1870, and grew up in Whiting, Vermont. He graduated from the Boston Dental School in 1892, then moved to Colorado due to ill health. Inspired by the challenges of the young profession of orthodontics, he chose to enter the Angle School of Orthodontia in 1902. As a deep thinker with an inquiring mind, Ketcham explored many of the philosophical and mechanical problems, as well as the controversies of the profession of his day. He was one of the first to investigate root resorption, which continues to be a challenge today. He began to question some of Angle’s arbitrary pronouncements, causing Angle to attack him vehemently as a deviationist. He was smart enough to travel his own way from that time on. He worked hard to improve the...

 # Non caseating granuloma with bilateral Hilar lymphadenopathy is a feature of: A. Histoplasmosis B. Sarcoidosis C. Silicosis D. Tannosis The correct answer is B. Sarcoidosis. Sarcoidosis is described as a multisystem granulomatous disease of unknown origin characterized by the formation of uniform, discrete, compact, non-caseating epithelioid granulomas. It is more common in blacks than in whites. Though many investigators have regarded this disease, of unknown etiology, both infective and noninfective agents have been implicated. Currently the infectious etiology is more favored with focus on Mycobacterium and Propionibacterium. It is interesting to note that there was a belief that sarcoidosis is in some way related to tuberculosis. The factors which stood against were inability to culture the bacteria from the pathological tissues and difficulty in identifying them in stained sections. Reference: Shafer's Textbook of Oral Pathology 7th Edition.