MDS PREP
What is the role of camphorquinone in photocuring of resin composites?
1) It emits blue light for curing.
2) It absorbs blue light and initiates polymerization.
3) It enhances the color stability of the composite.
4) It is a filler material for increasing strength.
Camphorquinone is a photosensitizer that absorbs blue light and initiates the free radical polymerization of the resin when irradiated, leading to cross-linking and setting of the composite.
VLC resins are also called
1) microwave-activated resins.
2) tertiary amine-activated resins.
3) light-activated resins.
4) heat-activated resins.
Dental Materials Answer: 3
The first light-activated systems were formulated for UV light to initiate free radicals. Today the UV light-cured composites have been replaced by visible blue-light-activated systems with greatly improved depth of cure, a controllable working time, and other advantages.
Because of these advantages, visibly light-activated composites are more widely used than are chemically acti wited materials.
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 typical particle size range of the fillers in conventional, microfilled, and hybrid composites?
1) Conventional: 8-12 µm, Microfilled: 0.04-0.4 µm, Hybrid: 0.1-0.01 µm
2) Conventional: 1-5 µm, Microfilled: 0.04-0.4 µm, Hybrid: 0.01-0.1 µm
3) Conventional: 8-12 µm, Microfilled: 0.01-0.05 µm, Hybrid: 0.5-1 µm
4) Conventional: 0.01-0.1 µm, Microfilled: 0.1-0.5 µm, Hybrid: 0.5-1 µm
The particle size of the fillers in composite materials affects their physical and handling properties. Conventional composites have larger filler particles, while microfilled and hybrid composites have smaller ones. The text provides the typical ranges for each type of composite.
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.
What is the significance of the direction of the applied force during condensation?
1) It is not important for the success of the restoration.
2) It affects the marginal integrity of the restoration.
3) It influences the adaptation of the material to the cavity walls.
4) It does not affect the physical properties of the restoration.
The significance of the direction of the applied force during condensation is that it affects the marginal integrity and adaptation of the material to the cavity walls. It is important to direct the force at an appropriate angle to ensure proper condensation and seating of the material.
What is the purity requirement for mercury in dental amalgams according to ANSI/ADA Specification No. 6?
1) It must be at least 99.9% pure.
2) It must be at least 99.0% pure.
3) It must be at least 95.0% pure.
4) It must be at least 90.0% pure.
Mercury that complies with the requirements of the United States Pharmacopoeia also meets requirements for purity in ANSI/ADA Specification No. 6, which is typically 99.9% pure.
What is the typical wavelength absorbed by camphorquinone during photopolymerization?
1) 300-400 nm
2) 400-500 nm
3) 500-600 nm
4) 600-700 nm
Camphorquinone primarily absorbs blue light, which falls within the 400-500 nm wavelength range, triggering the polymerization process.