Dentosphere : World of Dentistry

# 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

# In the mandibular arch where the canines often erupt before the premolars, ________ technique of serial extraction is followed. A. Dewel’s B. Modified Dewel’s C. Tweed’s D. Nance’s The correct answer is: B. Modified Dewel's. Tweed defines it as “the planned and sequential removal of the primary and permanent teeth to intercept and reduce dental crowding problems”. The term “serial extraction” was coined by Kjellgren in 1929 and popularized by Nance (1940) who has been called the ‘father of serial extraction'. Indications of serial extraction: Indications 1. Class I malocclusions with anterior crowding space discrepancy of 10 mm more. 2. Lingual eruption of lateral incisors. 3. Midline shift of mandibular incisors due to displaced lateral incisors. 4. Premature loss of deciduous canine. 5. Abnormal canine root resorption. 6. Severe proclination of mandibular and maxillary interiors with associated crowding. 7. Ectopic eruption. 8....

# Undetectable death of embryo occurs during first few days of conception when exposure range is: A. 0.1 – 0.3 Gy B. 0.4 – 0.7 Gy C. 0.8 - 1 Gy D. 1 – 3 Gy The correct answer is: D. 1-3 Gy. Exposures of 1 to 3 Gy during the first few days after conception are thought to cause undetectable death of the embryo because many of these embryos fail to implant in the uterine wall. The period of organogenesis, when the major organ systems form, is 3 to 8 weeks after conception. The most common abnormalities among the Japanese children exposed early in gestation were reduced growth that persisted through life and reduced head circumference (microcephaly), often associated with mental retardation. Ref: Oral Radiology, Principles and Interpretation, 7th E Page No. 25 CLICK HERE FOR MORE MCQs

# The plasma coating of a Titanium Dental implant (TPS) is done to: A. To increase its acceptance in bone B. To make the Implant Biocompatible C. To avoid contamination of the implant D. To improve implant anchorage power in bone The correct answer is: D. To improve implant anchorage power in bone. Applying calcium phosphate (CaP) coating on implants improves the osteoconductive (osseointegration) properties. Different methods have been developed to coat metal implants with CaP layer such as plasma spraying, biomimetic and electrophoretic deposition. By means of plasma polymerization, positively charged, nanometric thin coating can be applied to implant surfaces. Titanium plasma sprayed (TPS) surface results in increased surface area and it has been proposed that TPS improves implant anchorage power in bone (Osseo integration). CLICK HERE FOR MORE MCQs

# The first bone formed in response to orthodontic loading is: a) Bundle bone b) Composite bone c) Lamellar bone d) Woven bone The correct answer is D. Woven bone. When a force is applied, there is stretching of the periodontal fibres on the tension side with raised vascualarity. This raised vascularity causes mobilization of fibroblasts and osteoblasts into that area, which form osteoid. This lightly calcified bone in due course of time matures to form woven bone. CLICK HERE FOR MORE MCQs