MDS PREP
What is the typical composition of Resin-Modified Glass Ionomer Cement (RMGI)?
1) Glass ionomer and polyacrylic acid
2) Glass ionomer, HEMA, and tartaric acid
3) Glass ionomer and polycarboxylate acid
4) Glass ionomer and zinc oxide
RMGI contains glass ionomer along with 2-hydroxyethylmethacrylate (HEMA) and tartaric acid to improve its properties.
How many grams of high-density noble metal alloy is required for casting of a molar?
1) 3 gms
2) 6 gms
3) 9 gms
4) 12 gms
Dental Materials Answer: 3
With high-density noble metal alloy 6 grams is adequate for premolar and anterior castings, 9 grams is adequate for molar casting and 12 grams is adequate for pontics.
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 timeframe for the initiation of dimensional change measurement in an amalgam?
1) At the beginning of trituration.
2) Between 5 minutes and 24 hours after the beginning of trituration.
3) At the end of trituration.
4) 40 days after the restoration.
Dimensional change measurement is typically initiated between 5 minutes and 24 hours after the beginning of trituration.
What type of cement is zinc polycarboxylate?
1) Water-based cement
2) Resin-based cement
3) Oil-based cement
4) Silicate-based cement
Zinc polycarboxylate cement is a water-based cement.
What is the purpose of using temporary cementing materials in dentistry?
1) To permanently fix the prosthesis
2) To allow for temporary fixation of a prosthesis for patient approval
3) To provide a long-term seal against microleakage
4) To strengthen the tooth structure
Temporary cementing materials are used for trial of the temporary appliance for a few days to get patient approval and to ensure it has suitable consistency and can be easily dislodged during permanent cementation.
Before restoring a tooth with composite, the area is etched. Accidental contamination occurs with saliva, Therefore
1) the area is re-etched before restoration
2) the area is air-dried using an air spray and continue with restoring
3) wipe the saliva with cotton and continue to restore.
4) add excess composie material and cure it
Dental Materials Answer: 1
Etching of tooth surface with 37% phosphoric acid creates microporosities in the enamel and dentin. This is the main method of adhesion of composite resin to tooth surface.
After etching the surface energy of the enamel will increase. This will make it very sticky to any kind of contaminants. If salivary contamination will occur, the salivary proteins will precipitate in the microporosities. This will prevent the adequate penetration of the bonding agent, therby reducing the micotag formation. Hence, complete isolation is essential.
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.