Dentosphere : World of Dentistry

# Advantage of chromic gut over plain is: A. Delayed resorption B. Increased strength C. Less irritation D. Less tissue reaction The correct answer is A. Delayed resorption. Chromic gut sutures consist of the plain gut that has been treated with chromium trioxide. This results in a delay in the absorption rate. Because retention of sutures beyond a few days is not recommended in endodontic surgery, the use of chromic gut sutures offers no advantage. Also, evidence indicates that plain gut is more biocompatible with oral soft tissues than is the chromic gut. The gut suture material is marketed in sterile packets containing isopropyl alcohol. When removed from the packet, the suture is hard and non-pliable because of its dehydration. Before using gut sutures should be hydrated by placing them into sterile, distilled water for 3 to 5 minutes. After hydration, the gut suture material will be smooth and pliable with manipulative properties similar to silk. ...

# Benzodiazepine antagonist is: A. Flumazenil B. Naloxone C. Furazolidone D. Dapsone The correct answer is A. Flumazenil Benzodiazepine act by enhancing presynaptic or postsynaptic inhibition through a specific receptor which is integral part of gabba receptor Cl-channel complex. Flumazenil is a BZD analogue which has little intrinsic activity but it competes with BZDs as well as inverse agonists for BZD receptor and reverses their depressant or stimulant effects respectively. Flumazenil is the drug of choice for benzodiazepine overdose.

# To prevent sensitivity caused by acid etching and to protect pulp in deep cavities, which of the following should be used? A. Calcium hydroxide liner B. ZnO liner C. Light cure GIC liner D. Lining with varnish The correct answer is A. calcium hydroxide liner Deep caries excavation close to the pulp, which may result in either an undetected pulpal exposure or a visible pulpal exposure, should be covered with a calcium hydroxide liner that can stimulate formation of dentin bridges (reparative dentin) over the exposure. For amalgam restorations, deep excavations not encroaching on the pulp should be covered with a glass-ionomer material that will contribute to thermal protection and provide mechanical protection from amalgam condensation forces at thicknesses of I to 1.5 mm or greater.

# Bonding of composite resins to tooth structure is by: (KAR-01) a) Covalent bond b) Ionic bond c) Mechanical d) Vander waal forces The correct answer is C. Mechanical Bonding of composites to tooth structure occurs by micromechanical retention. Acid etching creates micro porosities into which the resin penetrates resulting in resin tag formation. These tags penetrate to a depth of 5 - 10 µm but their lengths are dependent on the enamel etching time.

# The main advantage of composites over unfilled direct filling resin is their: (KAR-97) a) Higher solubility in saliva b) Lower modulus of elasticity c) Esthetic excellence d) Lower thermal co-efficient of expansion The correct answer is D. Lower coefficient of thermal expansion. Advantages of composites over unfilled resins: Lower coefficient of thermal expansion Low polymerization shrinkage Low water absorption High abrasive resistance Disadvantages of composites: Less color stability Less smooth finish than unfilled resins

# The most common reason why hyperplastic tissue is removed during the construction of a complete denture is that: a) It interferes with the arrangement of the teeth b) It is unaesthetic to construct a denture on a hyperplastic tissue c) It interferes with the stability of the denture d) All of the above The correct answer is C. It interferes with the stability of the denture. The most important reason for the treatment of hyperplastic tissue before the construction of complete or removable partial dentures is to provide a firm, stable base for the denture. 

# The amount of functional cusp reduction required for metal-ceramic crown is - a) 1.0 - 2.5 mm b) 1.5 - 2.0 mm c) 2.0 - 2.25 mm d) 1.85 - 2.10 mm The correct answer is B. 1.5 -2.0 mm.  Metal ceramic restorations require a 1.5 - 2 mm reduction in the functional cusp and 1.0 - 1.5mm reduction in the non-functional cusp.