MDS PREP
What is the typical peak wavelength for light-activated dental composite resins?
1) 300-400 nm.
2) 400-500 nm.
3) 500-600 nm.
4) 600-700 nm.
Light-activated dental composite resins are usually cured with blue light at a peak wavelength of about 470 nm, which is absorbed by the photoinitiator, such as camphorquinone.
What is the typical range of Charpy impact strength for a heat-activated denture resin?
1) 0.48 to 0.78 joules
2) 0.98 to 1.27 joules
3) There is no typical range provided
4) The information is not relevant to heat-activated resins
Heat-activated denture resins typically have a Charpy impact strength range of 0.98 to 1.27 joules, which is higher than that of chemically activated resins.
What is the typical composition of Zinc Oxide-Eugenol Cement?
1) Zinc oxide and polyacrylic acid
2) Zinc oxide and eugenol
3) Zinc phosphate and polyacrylic acid
4) Zinc oxide and sodium silicate
Zinc Oxide-Eugenol Cement is primarily composed of zinc oxide and eugenol, with a pH of approximately 7, making it less irritating to pulpal tissues.
What is the typical setting time for zinc oxide-eugenol temporary cement?
1) Less than 5 minutes
2) 5-10 minutes
3) 10-15 minutes
4) More than 15 minutes
Zinc oxide-eugenol temporary cement typically sets in about 5-10 minutes.
During crown cementation, complete filling of crown with cement is not advisable due to :
1) Increased risk of bubble entrapment
2) Increased seating time
3) Increased pressure required for seating crown
4) All of the above
Dental Materials Answer: 4
It is not advisable to fill the crown completely with cement due to following 4 reasons:
1. the time for removal of excess cement elevates.
2. the risk for bubble entrapment increases
3. increased pressure may be needed
4. the time for seating increases
What is the purpose of adding barium sulfate to Gutta Percha?
1) To make it more radio-opaque
2) To improve thermal conductivity
3) To enhance the setting reaction
4) To act as a plasticizer
Barium sulfate is added to Gutta Percha to enhance its radiographic visibility.
How does the elastic range of a wire affect its ability to be activated in orthodontic appliances?
1) A high elastic range allows for greater activation without causing permanent deformation.
2) A low elastic range allows for more precise and controlled activation.
3) The elastic range does not affect wire activation; it is only dependent on the force applied.
4) A wire with a high elastic range is more prone to permanent deformation during activation.
The elastic range of a wire determines the extent to which it can be deflected and still return to its original shape without permanent deformation. A wire with a high elastic range can be activated to a greater extent before it reaches its plastic range, making it suitable for larger tooth movements.
What is the maximum allowable level of mercury in the blood according to the given information?
1) 1 µg/L
2) 3 µg/L
3) 5 µg/L
4) 10 µg/L
The maximum allowable level of mercury in the blood is specifically mentioned as 3 µg/L in the provided text.