Question 1

During denture fabrication,a custom impression tray is typically used to obtain a final impression during the _____ appointment.

Accepted Answer

The custom impression tray is typically used during the second appointment for denture fabrication, as the first appointment is usually focused on taking preliminary impressions and measurements. The third appointment is often reserved for trying in the wax setup of the dentures, and the fourth and fifth appointments involve final adjustments and delivery of the completed dentures.

Question 2

Which of the following statements is true concerning denture acrylic polymers and water sorption?

Accepted Answer

Water sorption in denture acrylic polymers can lead to slight expansion, which helps to offset the shrinkage that occurs during polymerization.

Question 3

Orthodontic appliances use _____-linked poly(methyl methacrylate)homopolymer.

Accepted Answer

A

Question 4

Short-term lining materials consist of:

Accepted Answer

Short-term lining materials typically consist of polyethylene methacrylate powder and liquid plasticizers, which provide the necessary properties for temporary use.

Question 5

High degrees of polymerization lead to _____ rigid,_____ soluble polymer networks.

Accepted Answer

High degrees of polymerization lead to more rigid, less soluble polymer networks. This is because longer polymer chains result in increased intermolecular forces, leading to a more ordered and less flexible structure. Additionally, longer chains also lead to an increased entanglement density, making it more difficult for solvent molecules to penetrate the network and dissolve the polymer.

Question 6

The extent to which all monomer is polymerized in a polymer is referred to as:

Accepted Answer

The extent to which all monomer is polymerized in a polymer is referred to as the degree of conversion. This describes how well the monomers have reacted to form the polymer and is usually expressed as a percentage of the monomer that has reacted with others to form the polymer. The higher the degree of conversion, the more complete the polymerization reaction, which can impact the properties and characteristics of the polymer.

Question 7

The denture base resin mixture should be _____ when it is used to pack the denture flask.

Accepted Answer

The denture base resin mixture should be doughy when it is used to pack the denture flask. This ensures that it can be easily manipulated and molded to fit the shape of the denture flask. A grainy mixture would lack cohesiveness and may not set properly, while a sticky or rubbery mixture would be difficult to handle and shape.

Question 8

Which of the following statements is true of the process of polymerization?

Accepted Answer

Polymers that form by simple addition (chain-growth polymerization) do not release any byproducts such as water or alcohol, so they tend to shrink less than those that form by condensation (step-growth polymerization).

Question 9

Cross-linked acrylic polymers are _____ than their non-cross-linked counterparts.

Accepted Answer

Cross-linked acrylic polymers are more temperature resistant due to the network structure that restricts molecular movement, enhancing thermal stability.

Question 10

When contrasting chemical-cured and heat-cured polymers:

Accepted Answer

Residual monomer levels are higher in chemical-cured acrylic polymers, both heat- and chemical-cured acrylic polymers have residual stresses that result from polymerization shrinkage.

Question 11

Removable partial dentures use _____-linked poly(methyl methacrylate)homopolymer.

Accepted Answer

Removable partial dentures use unfilled, non-cross-linked poly(methyl methacrylate) homopolymer, which allows for easier processing and adjustment.

Question 12

Increased salivary viscosity does not allow good wetting of the denture polymer.Increased salivary viscosity leads to impaired retention of the denture.

Accepted Answer

Increased salivary viscosity can hinder the ability of saliva to spread and wet the denture surface, which is necessary for proper adhesion and retention of the denture.

Question 13

The polymerization reaction shrinkage of acrylics approaches _____ vol %.

Accepted Answer

The polymerization reaction shrinkage of acrylics is around 6 vol %.

Question 14

When removed from the mouth,dentures:

Accepted Answer

Dentures should be stored in water when removed from the mouth to prevent them from drying out and warping. Boiling and rubbing alcohol may damage the dentures and should not be used. Acetone can also damage dentures and is not necessary for storage.

Question 15

Which of the following is the most common type of chemical reaction used to form polymers used for dental restorations?

Accepted Answer

Free-radical addition reactions are the most common type of chemical reaction used to form acrylic polymers that are commonly used for dental restorations.

Question 16

During fabrication of removable partial dentures,the acrylic bonds _____ to the denture teeth and _____ to the alloy framework.

Accepted Answer

Acrylic material in removable partial dentures bonds chemically to the denture teeth and mechanically to the alloy framework.

Question 17

Which of the following is the most common monomer found in acrylic polymers used in dentistry?

Accepted Answer

Methyl methacrylate is the most common monomer found in acrylic polymers used in dentistry, as it polymerizes quickly, allowing for easy manipulation during the fabrication process. It also has good mechanical and physical properties, making it suitable for use in dental restorations.

Question 18

Acrylic polymers used for most dentures:

Accepted Answer

Acrylic polymers used for most dentures have a low modulus of elasticity, which means that they can deform easily under stress, making them more comfortable for the wearer. However, they are also low in strength, which can lead to fracture or breakage if subjected to excessive force or wear over time.

Question 19

Which of the following statements is(are)true of denture soft liners?

Accepted Answer

Soft liners can be used for patients with severe undercuts, long-term acrylic materials harden over time due to plasticizer leaching, and silicone liners do not harden as they lack plasticizers.

Question 20

Chemicals such as dibutyl phthalate will cause a poly(methyl methacrylate)to become:

Accepted Answer

Dibutyl phthalate is a plasticizer that softens polymers and makes them more flexible. When added to poly(methyl methacrylate), it can cause it to become rubbery. Therefore, the best choice is C, rubbery.

Quiz 13: Polymers in Prosthodontics