Dentosphere : World of Dentistry

# The forces acting through a fixed partial denture on the abutment tooth should be directed: a) As far as possible at right angles to the long axis of the teeth b) Parallel to the long axis of the teeth c) By decreasing the mesio-distal dimension d) None of the above The correct answer is B. Parallel to the long axis of the teeth/ Ideally, the forces acting on the abutment tooth should be parallel to long axis of the tooth and should be within the confines of the root. By this, the stress is directed vertically which is well tolerated by the periodontium. Narrowing the buccolingual width of occlusal surfaces of the constructed crowns help to achieve these desirable forces. CLICK HERE FOR MORE MCQs

# Ultrasonic instruments are indicated for each of the following types of patients EXCEPT one. Which is the EXCEPTION? A. Active infectious disease B. Deep periodontal pockets C. Controlled diabetic D. Edematous tissue E.Mildly uncontrolled diabetic Ultrasonic instruments should NOT be used for patients with active infectious disease because the aerosol created by the instruments serves to spread the infection around the operatory. Diabetes and deep periodontal pockets are indications that ultrasonic instrumentation. CLICK HERE FOR MORE MCQs

# Each of the following is associated with full-thickness flaps EXCEPT one. Which is the EXCEPTION? A. Periosteum stays on the bone B. Apical repositioning C. Osseous recontouring D. Dissection of the tissue with a blunt instrument The correct answer is A. Periosteum stays on the bone.  A full thickness flap includes stripping all of the soft tissue (epithelium, connective tissue, periostuem) from the bone. Following placement of the incisions, the flap is dissected using blunt instruments like a # 9 molt to separate the soft tissue from the bone. Full thickness flaps are used when recontouring the osseus structures below or when the gingiva are repositioned apically. CLICK HERE FOR MORE MCQs

# When sharpening instruments, the ______ of the blade should be placed at an angle ________ to the sharpening stone. A. Bevel, 90 B. Bevel, 45 C. Working end, 45 D. Working end, 90° The correct answer is B. Bevel, 45 When sharpening an instrument, the bevel of the blade is placed at an angle of 45° to the sharpening stone. This ensures maximum efficiency of the blade to sharpen the instrument. Instrument sharpening is an important aspect of operative dentistry. Dull instrument are not recommended for carrying out procedures in the oral cavity. Dull instruments are prone to produce more heat, are less efficient and can damage tooth structure. It is recommended to  discard those instruments which cannot be sharpened. CLICK HERE FOR MORE MCQs

# When utilizing four-handed dentistry, the assistant should be positioned... A. Higher than the dentist to facilitate visibility B. Different positions depending on where the dentist is working C. Lower than the dentist for ergonomic posturing D. At the same height because they are a team The correct answer is A. Higher than the dentist to facilitate visibility. In four handed dentistry, the assistant should sit close to the back of patient's chair higher than the dentist to facilitate visibility. This position is suitable for better view of the site, instruments and materials from the mobile cart or instrument tray. It also allows you access to these materials without leaning or overextending your arms. Assistant stools should be placed in a position so that their eye level is 4 to 6 inches higher than the dentist's. CLICK HERE FOR MORE MCQs

# Each of the following dental anomalies is likely to affect anterior teeth EXCEPT one. Which is the EXCEPTION? A. Concrescence B. False microdontia C. False macrodontia D. Gemination E. Dens-in-dente The correct answer is A. Concresence. Concrescence characteristics: Involves the union of two or more teeth through CEMENTUM ONLY. Most common in the permanent molars. It is different from fusion, because it occurs following eruption and never involves enamel and dentin. CLICK HERE FOR MORE MCQs

# In the life cycle of an ameloblast, there are cells that contain Tomes' processes. The cells described are in which of following stages? A. Morphogenic B. Maturative C. Organizing D. Secretory E. Protective The correct answer is D. Secretory. Tomes' process are projections or extensions of ameloblasts formed as the ameloblast moves away from the developing enamel matrix. The ameloblasts secrete secretory granules needed for the production enamel matrix during this phase. Ameloblasts are actively contributing to the enamel matrix formation by combining the secretory granules with the glycoprotein to lay down enamel during the secretory phase. Presence of Tomes' processes is a histological indicator of the secretory phase. CLICK HERE FOR MORE MCQs