Dentosphere : World of Dentistry

# The radiographic density of which of the following materials varies the MOST? A. Amalgam B. Soft tissue C. Composite D. Acrylic E. Gold The correct answer is C. Composite. The radiographic density of composites varies the most because the manufacturers may place a different amount of barium salts or other opaque filling materials. Metals like amalgam and gold appear with a standard amount of radiopacity. Acrylic typically does not possess any opaquers, and therefore is usually totally radiolucent. Soft tissue is fairly radiolucent.

# Which of the following is the reason intensifying screens are used with extraoral radiographic films? A. Improve the image quality B. Increase the exposure time C. Increase the kVp D. Decrease the radiation dose of the patient The correct answer is D. Decrease the radiation dose of the patient. Intensifying films MUST be used with extraoral radiographic films in order to decrease the dose of radiation to the patient. Radiation is harmful, even in small doses, toi ndividual cells in the body. Radiation can cause abnormal changes that leads to cancer. Intensifying screens when used with x ray films using emulsions, make them more sensitive to blue or green light. The X-ray photons are converted to visible light photons when they strike the screen. Lead aprons and thyroid collars are mandatory preventive armamentarium in dental radiograhy.

# In radiography, a longer gray scale of contrast can be accomplished through: A. Increasing the focal spot-skin distance B. Increasing the kilovoltage C. Decreasing the filtration D. Increasing the milliamperage The correct answer is B. Increasing the kilovoltage. Longer gray scales of contrast can be achieved by increasing the kilovoltage peak. Increasing the kilovoltage causes the radiographic image to have low contrast and longer gray scales. Low kilovoltage creates low energy x-rays responsible for producing high contrast and shorter gray scale.

# Which of the following MOST ACCURATELY describes osseointegrated dental implants? A. They create a pseudo-periodontal ligament B. They create a junctional epithelium with the surrounding tissue C. They are attached directly to living bone as determined by analysis by radiographs and light microscopy D. They possess a direct structural and functional connection with bone only at the radiographic level of detection The correct answer is C. They are attached directly to living bone as determined by analysis by radiographs and light microscopy. Osseointegrated implants are implants that are able to create a direct interface with bone cells after they grow and interlock, without any interposing layer of soft tissue. In the process of osseointegration, the bone directly attaches to the implant material because the titanium oxide fuses with the surrounding bone. In osseoinegration, no scar, fibrous or connective tissues get in between the bone and the implant material....

# What is the most common reason for a crown not to fully seat upon delivery? A. Excessive proximal contacts B. Over extended margins C. Undercuts on the axial surfaces of the prepared tooth D. Positives on the intaglio surface The correct answer is A. Excessive proximal contacts.  Excessive proximal contacts are sometimes accidentally made by dental technicians effort to prevent open contacts on their fabricated dental crown/ bridge. The respective tooth preparations on the die casts are sawed to separate each component and provide better visualization of the prep. Dental technicians may accidentally scrape a portion of the contact area of the adjacent teeth causing a future excessive contact in the final crown restoration. Excessive contacts can also be created when wax patterns are not immediately invested, causing dimensional changes in the final restoration.

# Which of the following organisms is an intracellular parasite? A. Nocardia asteroides B. Coccidioides immitis C. Histoplasma capsulatum D. Aspergillus flavus E. Cryptococcus neoformans The correct answer is C. Histoplasma capsulatum. Histoplasma capsulatum is a type of fungi which is the main cause of histoplasmosis infection. This is an intracelular parasite of macrophages that commonly causes fungal respiratory infection in the US.

# Acute arthritis of the great (big) toe is a diagnostic sign of which of the following diseases? A. Osteoarthritis B. Osteomyelitis C. Gout D. Osteoporosis E. Rheumatoid arthritis The correct answer is C. Gout.  The acute arthritis of the big toe is a pathognomonic sign of Podagra or Gout. What distinguishes Gout from others is that, it usually occurs in one of the joints in the body, however, about 50% are said to occur in the big toe. This disease is also referred to as "disease of the kings" or "the rich man's disease".