MDS PREP
What is the role of MDPB in dental composites?
1) It provides improved mechanical properties.
2) It acts as an initiator for the polymerization reaction.
3) It enhances the antibacterial activity of the composite material.
4) It reduces the viscosity of the resin.
MDPB (methacryloxy decyl pyridinium bromide) is a quaternary ammonium salt that has been shown to be effective against various streptococci in dental composites. Its inclusion enhances the antibacterial properties of the material.
Ability of an orthodontic wire to spring back to Its original shape is evaluated by
1) Brittleness
2) Resilience
3) Tensile strength
4) Toughness
Dental Materials Answer: 2
Resilience is the amount of energy absorbed by a structure when it is stressed to proportional Limit.
The elastic area of the stress-strain graph gives resilience; entire area up to breaking point is a measure of toughness.
The slope of straight Line gives Young’s modulus.
What is the primary concern with using zinc oxide-eugenol cement in large restorations?
1) Low compressive strength
2) Potential for pulpal toxicity
3) High thermal conductivity
4) High solubility
The primary concern is the potential for pulpal toxicity due to the diffusion of eugenol.
How does the concentration of mercury in urine relate to neurological changes?
1) Neurological changes are detected at urine mercury levels of 1 µg/L.
2) Neurological changes are detected at urine mercury levels of 10 µg/L.
3) Neurological changes are detected at urine mercury levels of 500 µg/L.
4) There is no established link between mercury concentration in urine and neurological changes.
Neurological changes are not detected until urine mercury levels exceed 500 µg/L, which is significantly higher than the levels associated with amalgam placement.
What is the primary wavelength emitted by an argon laser used in dentistry?
1) 400-500 nm.
2) 500-600 nm.
3) 800-900 nm.
4) 1000-1100 nm.
Argon lasers emit light in the green-blue spectrum, with wavelengths between 488 and 514.5 nm, which are absorbed well by pigmented tissues like hemoglobin and melanin, making them useful for soft tissue procedures.
What is the primary component of zinc polycarboxylate cement?
1) Zinc oxide
2) Polyacrylic acid
3) Titanium dioxide
4) Calcium hydroxide
Zinc polycarboxylate cement primarily consists of zinc oxide and polyacrylic acid.
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 primary function of a luting agent in the context of dental restorations?
1) To bond the restoration to the tooth
2) To provide a protective barrier against bacteria
3) To insulate the tooth from thermal changes
4) To fill in gaps caused by tooth decay
A luting agent's primary function is to bond the restoration to the tooth and enhance its retention.