Dentosphere : World of Dentistry

# The impurity that is theoretically found in nitrous oxide that is considered slightly toxic is: A. Methane B. Cyclohexane C. Ethylene oxide D. Nitric oxide The correct answer is D. Nitric oxide. Nitrous oxide is a gas that creates analgesia and dissociated anesthesia and is commonly used in dentistry. Nitrous oxide was first used by Horace Wells for his own tooth extraction by his assistant. Nitrous oxide is used in general anesthesia to enhance the effect of other drugs being administered by allowing the concentration of other drugs to be decreased without decreasing their effect. When nitrous oxide reacts with oxygen and is converted into nitric oxide, causing vasodilation.

# After processing a film, you notice that it appears too dark. What is the most likely cause of this problem? A. Inadequate development time B. Developer solution too cool C. Depleted developer solution D. Excessive developing time The correct answer is D. Excessive developing time. The causes underlying dark appearance of a radiograph are: - Excessive developing time - Developer solution too hot - Inaccurate timer or thermometer - concentrated developer solution Solutions for the dark appearance of radiograph - Chcck development time. - Check developer temperature. - Replace faulty timer or thermometer. - Replenish developer with fresh solutions as needed.

# The image of the coronoid process of the mandible often appears in periapical x-rays of: A. The incisor region of the mandible B. The molar region of the mandible C. The incisor region of the maxilla D. The molar region of the maxilla The correct answer is D. The molar region of the maxilla. As the mouth is opened, the coronoid process moves forward, and therefore it comes into  view most often when the mouth is opened to its fullest extent at the time the exposure is made. It is evidenced by a tapered or triangular radiopacity, which may be seen below, or in some instances superimposed on the molar teeth and maxilla. The coronoid process appears as a triangular-shaped radiopacity.

# Pulpotomies are CONTRAINDICATED on primary molars with which of the following? A. Radiographic evidence of deep caries approximating the pulp chamber B. Radiographic evidence of internal resorption C. Sensitivity to sweets D. Exposure of the pulp during caries excavation The correct answer is B. Radiographic evidence of internal resorption. Root canal therapy is indicated to treat cases involving internal resorption. When a carious lesion approximates or extends into the pulp chamber of a deciduous tooth, removal of coronal pulp is performed to prevent the spread of the infection into the radicular pulp. Pulpotomies are performed on deciduous teeth to prevent premature tooth loss and potential loss of space. Careful clinical and radiographic assessment along with the child's medical and dental history are necessary before performing a pulpotomy. Pulpotomy is contraindicated where there i s: - Internal resorption (root canal therapy indicated) - Per...