MDS PREP
What is the role of a primer in the bonding process of resin cements?
1) To clean the tooth surface
2) To increase the surface energy of the tooth structure
3) To reduce the surface tension of the bonding agent
4) To accelerate the setting of the cement
A primer increases the surface energy of the tooth structure, enhancing the ability of the bonding agent to wet and infiltrate the surface.
What is the typical refractive index range of bis-GMA and TEGDMA, and what happens when they are mixed in equal proportions?
1) 1.50 to 1.60 and increases.
2) 1.40 to 1.60 and decreases.
3) 1.55 for bis-GMA and 1.46 for TEGDMA, and a mixture yields approximately 1.50.
4) 1.50 for bis-GMA and 1.60 for TEGDMA, and a mixture yields approximately 1.55.
The refractive indices of bis-GMA and TEGDMA are approximately 1.55 and 1.46, respectively, and when mixed in equal proportions, they provide a refractive index of around 1.50.
Which of the following is not a type of temporary cementing material?
1) Zinc oxide-eugenol (type III)
2) Calcium hydroxide
3) Glass ionomer cement (type 1)
4) Resin-modified glass ionomer cement
Resin-modified glass ionomer cement is not listed as a type of temporary cementing material in the text.
What is the effect of increasing the concentration of the amine initiator in a light-cured composite?
1) It decreases the depth of cure.
2) It increases the depth of cure.
3) It has no effect on the depth of cure.
4) It can lead to premature polymerization.
An excessive amount of amine initiator can lead to a faster reaction rate and a decrease in the depth of cure, as the light may not be able to penetrate deep enough into the material to activate the entire polymerization process.
The constituent used in porcelain that fuses at high temperature to form matrix
1) Soda ash
2) Feldspar
3) Quartz
4) Koalin
Dental Materials Answer: 3
What is the typical range of pH for acidic dental cements?
1) pH > 7
2) pH 7-10
3) pH 4-7
4) pH < 4
Acidic dental cements typically have a pH less than 7.
What is the primary difference between the setting mechanism of light-cured and chemically cured composite resins?
1) Light-cured resins shrink towards the external surface, while chemically cured resins shrink towards the center.
2) Chemically cured resins require light activation.
3) Light-cured resins require a chemical catalyst.
4) There is no significant difference in the setting mechanism.
The setting mechanism of light-cured resins involves free radical polymerization initiated by light, which causes the material to contract away from the light source (typically the external surface).
How is platinized gold foil formed?
1) By mixing gold and platinum powders and then beating them
2) By rolling gold and platinum sheets together to form a laminated foil
3) By plating gold onto a platinum substrate
4) By fusing a platinum rod with a gold ingot
Platinized gold foil is a combination of gold and platinum where 15% of the content is platinum. It is produced by rolling layers of gold and platinum together to achieve the desired thickness and distribution of the platinum within the gold foil. This process creates a homogeneous mixture that enhances the hardness and wear resistance of the restoration, making it suitable for high-stress areas like incisal edges and cusp tips.