Dentosphere : World of Dentistry

 # Which is a premalignant lesion? A. Oral submucous fibrosis B. Syphilitic glossitis C. Erythroplakia D. Lichen planus The correct answer is C. Erythroplakia. Premalignant lesion according to WHO (1978) is defined as a morphologically altered tissue in which cancer is more likely to occur than its apparently normal counterpart. Examples include leukoplakia, erythroplakia, carcinoma in situ.  Precancerous condition is a generalised state associated with a significantly increased risk of cancer. These include siderophenic dysphagia, submucous fibrosis, lichen planus, syphilitic glossitis. 

 # A patient presents with a slow growing mass on the left cheek in front of ear lobule. A sample is sent for gene analysis and cytogenic analysis reveals anomaly of chromosome 8q12. What is the diagnosis? A. Mucoepidermoid carcinoma B. Adenoid cystic carcinoma C. Acinic cell carcinoma D. Pleomorphic adenoma The correct answer is D. Pleomorphic adenoma. The cytogenetic abnormality of chromosome 8q12 is clearly indicative of Pleomorphic adenoma.  Pleiomorphic adenoma is most commonly seen in the Parotid gland.  PLEOMORPHIC ADENOMA  • Synonym: Mixed tumor.  • Histogenesis: Following are the possible origins: - Myoepithelial cell - Intercalated duct reserve cell  • It is the most common tumor of salivary gland cell. - Constitutes > 50% of all salivary gland tumors. - Constitutes 90% of all benign salivary gland tumors.  • It contains cells of pleomorphic origin (can differentiate into epithelial- ductal/ non-ductal and mesenchymal cells-chondral, myxoi...

 # Oral surgery retractor with V shaped notch is: A. Obwegeser retractor B. Langenbeck retractor C. Minnesota retractor D. Austin retractor The correct answer is A. Obwegeser retractor. Obwegeser Coronoid/ Ramus Retractor:  • The retractor is similar to the Langenbeck's retractor except that the edge of the retracting blade is forked, forming a 'V' shaped notch, so as to engage the anterior border of the ramus of the mandible and aid in good tissue retraction.  • Uses: - To retract the soft tissues along the anterior border of the ramus during sagittal split or ramus osteotomy - To retract the tissues from the anterior border of the ramus during coronoidectomy procedures.  Langenbeck's Retractor:  It has a long handle and an 'L' shaped blade. This retractor is most commonly used in oral surgery. It is available in different sizes with various blade widths. The instrument can be single or double ended. It is used to retract the soft tissues, incision edges, to al...

 # ‘Choking off’ phenomenon takes place after application of: A. APF B. NaF C. SnF2 D. Amine Fluoride The correct answer is B. NaF. Choking off phenomenon is seen with the application of sodium fluoride varnish. Neutral Sodium Fluoride  • Fluoride concentration = 9200 ppm  • Formed by dissolving 20 gms NaF in 1 Litre of water in a plastic bottle  • Knutson technique: used for NaF application - Clean and dry teeth and isolate the field - Apply 2% NaF over teeth with cotton bud/applicator. Allow the solution to dry for 3-4 minutes - Application is repeated at 2nd, 3rd and 4th week at an interval of 1 week each. These applications are not preceded by Scaling. - The four-visit procedure is recommended for age groups 3, 7, 11, 13 years coinciding with eruption of different dentitions  • Mechanism of action - NaF applied to tooth surface reacts with tooth calcium to form CaF2 - As CaF2 develops, it impedes further penetration of fluoride into hydroxyapatite. This is c...

 # Raloxifene is used in the treatment of: A. Renal osteodystrophy B. Post menopausal osteoporosis C. Chronic renal failure D. Chronic osteomyelitis The correct answer is B. Post menopausal osteoporosis.  Raloxifene is used by women to prevent and treat bone loss (osteoporosis) after menopause.  Raloxifene belongs to a group of drugs called Selective Estrogen Receptor Modulators (SERMs). It is a Second- generation agent.  The principal use of Raloxifene is in the management of Post-menopausal Osteoporosis. It is also useful in Hormone sensitive Breast cancer (both prevention and treatment).  It is important to remember that SERMs are partial Estrogen receptor antagonists. Raloxifene inhibits the estrogen receptors in breast while stimulates those in Bone marrow. Thus, it has tissue selective action which reduces the toxicity. Like Tamoxifen, it also lowers LDL cholesterol and thus has a favorable lipid profile. Side effects include hot flushes and calf pain (lik...

 # Which of the following acts as an astringent? A. Thymol B. Glycerin C. Zinc chloride D. Liquoron The correct answer is C. Zinc chloride. Zinc chloride is a commonly known astringent used in various ways as in with retraction cords, gum paints and for management of oral ulcers.  • Astringents : These are substances that act by precipitating proteins on the superficial layer of mucosa and make it mechanically stronger. Examples are alum or aluminum potassium sulfate (KAl (SO4)2), A1C13 and zinc chloride (ZnC12)  • Styptics: These are concentrated forms of astringents, which cause superficial and local coagulation. Examples are ferric chloride and ferric sulfate (Fe2 (SO4)3)  • A1C13 and ferrous sulfate are preferred astringents among dentists because of minimum tissue damage.  • Because of the caustic action of zinc chloride on the oral tissues, it is not the preferred chemical for gingival retraction although it is still used for management of oral ulcers....

 # Which of the following is an opsonin? A. C3b B. C3a C. IgG D. IgA The correct answer is A. C3b. Opsonization is the process of increasing ability for phagocytosis of foreign body. In opsonisation, opsonin antibodies attach to the bacteria and facilitate the phagocytosis of that bacterium.  Different types of opsonins:  • Antibodies- IgM and IgG  • Complement proteins- C3b, C4b  • Circulating proteins- Pentraxins, collectins, and ficolins