MDS PREP
What is the elastic limit of a wire?
1) The point at which the wire returns to its original shape.
2) The point at which the wire starts to weaken.
3) The point at which the wire yields permanently.
4) The point at which the wire breaks.
The elastic limit of a wire is the point at which it yields permanently, meaning any greater force applied will result in irreversible deformation.
What are the two primary components of the liquid phase of a denture base resin?
1) Nonpolymerized methyl methacrylate and a cross-linking agent
2) Prepolymerized beads and benzoyl peroxide
3) Hydroquinone and glycol dimethacrylate
4) Monomer and initiator
The liquid phase of a denture base resin primarily consists of nonpolymerized methyl methacrylate (monomer) and a cross-linking agent like glycol dimethacrylate.
What is the primary function of a dental sealer in restorative procedures?
1) To prevent microleakage
2) To desensitize the tooth
3) To enhance the aesthetics of the restoration
4) To reinforce the tooth structure
A dental sealer is used to fill the microscopic spaces between the restorative material and the tooth structure, primarily to prevent microleakage.
What are the main properties of Compomers?
1) High elasticity and high load deflection rate.
2) High modulus of elasticity and low shrinkage.
3) Easy to inject, shape, and polish with good aesthetics.
4) High thermal conductivity and good radiopacity.
Compomers are known for their ease of use, being non-sticky, and simple to place and shape. They are a hybrid of glass ionomer and composite resin properties, offering good aesthetics and user-friendly handling.
What is the effect of pH on the bond strength of zinc polycarboxylate cement?
1) High pH increases bond strength.
2) Low pH increases bond strength.
3) pH has no effect on bond strength.
4) High pH decreases bond strength.
The bond strength is influenced by the acidity; a lower pH can enhance the bond strength.
If a partially set material is seated, the die material obtained from such impression will be
1) Oversized
2) Undersized
3) Retains its dimension due to elasticity of the material
4) Dimensions will be un changed but may leave a rough surface
Dental Materials Answer: 2
If Impression tray comprising of elastomeric impression material is seated too late as elasticity starts to develop, raised seating pressure is applied to overcome the stiffness of impression material.
Because of recovery of excessive elastic deformation there is development of distortion
The die produced in the inaccurate impression is too narrow and too short.
What is the typical setting time for a high strength dental stone?
1) Less than 10 minutes.
2) 10-30 minutes.
3) 30-60 minutes.
4) More than 60 minutes.
High strength dental stones typically have a setting time of 30-60 minutes, which allows for sufficient working time while providing enhanced mechanical properties.
What is the typical compressive strength of hardened ZnOE impression paste?
1) 0.4-0.7 MPa
2) 7 MPa
3) 245 MPa
4) 32 MPa
The compressive strength of hardened zinc oxide eugenol (ZnOE) impression paste is generally about 7 MPa, indicating its ability to withstand compressive forces without deformation or failure.