Q. 1. All of the following are the uses of EDTA, except:

1. Dissolution of pulp
2. Softening of dentin
3. Removal of smear layer
4. Chelation of calcium ions

ANSWER. 1 (Dissolution of pulp)

EDTA (ethylenediaminetetraacetic acid) is a chelating agent that can bind to metal ions, and it is used in various fields such as medicine, dentistry, and laboratory research.

The uses of EDTA include:

• Chelation of calcium ions: EDTA can chelate or bind to calcium ions, which makes it useful in medical treatments for heavy metal poisoning or to prevent blood from clotting.
• Softening of dentin: In dentistry, EDTA is used to remove the smear layer, which is a layer of debris that accumulates on the surface of dentin during dental procedures.
• EDTA can soften the dentin, making it easier to remove the smear layer.
• Removal of smear layer: EDTA can effectively remove the smear layer, which can improve the adhesion of dental materials to dentin.
• Preservation of blood samples: EDTA is also used as an anticoagulant to prevent blood from clotting during the collection and storage of blood samples.
• Therefore, the correct answer to the question is option 1 - EDTA is not used for the dissolution of pulp.

Q. 2. Which of the following can be used as a base under CaOH2 when the remaining dentin thickness is less than 1 mm?

1. ZnOE
2. Resin modified GIC
3. Polycarboxylate
4. ZnPO4

ANSWER. 2 (Resin modified GIC)

When the remaining dentin thickness is less than 1 mm, it is important to provide additional support to the tooth structure before placing calcium hydroxide (CaOH2) as a base. In his situation, resin modified glass ionomer cement (GIC) can be used as a base under CaOH2.

• Resin modified GIC is a type of dental cement that contains a resin component to improve its mechanical properties and bond strength.
• It is often used as a base material because it can bond to both dentin and restorative materials, providing additional support to the tooth structure.
• Resin modified GIC also has good biocompatibility and can release fluoride, which can help prevent secondary caries.

Zinc oxide eugenol (ZnOE) is another commonly used dental cement,but it may not be the best choice for a base when the remaining dentin thickness is less than 1mm because it may not provide enough mechanical support to the tooth structure.

Polycarboxylate cement and zinc phosphate (ZnPO4) cement are also options for base materials, but they may not have the same level of bond strength and biocompatibility as resin modified GIC. Therefore, the correct answer to the question is option 2 - resin modified GIC can be used as a base under CaOH2 when the remaining dentin thickness is less than 1 mm.

Q. 3. The plaque found in heavy calculus former differs from that in non-calculus former in that it has:

1. Low calcium
2. Low potassium
3. Low phosphorus
4. Mineral content is same

ANSWER. 2 (Low potassium)

Q. 4. The dentist tries to prepare wax try-in using base plate wax in tropical area, the type of wax preferred is:

1. Type I base plate wax
2. Type II base plate wax
3. Type III base plate wax
4. Type IV base plate wax

ANSWER. 3 (Type III base plate wax)

BASE PLATE WAX

It derives its name from its use on the baseplate tray in the technique for denture construction.

Used to establish the vertical dimension, the plane of occlusion, and the initial arch form.

Pink color provides some esthetic quality in the initial stage of denture construction.

Composition

1. Ceresin 80%
2. Beeswax 12%
3. carnuaba 2.5%
4. natural or synthetic resins 3%
5. microcrystalline or synthetic wax 2.5%

ADA Sp.No-24 divides into three types

1. Type 1-Soft-building veneers
2. Type II- Medium- Pattern tried in mouth
3. Type III- Hard- Trial fitting in tropical climates

Desirable properties of baseplate wax could be defined as follows:

• High strength and rigidity at mouth temperature.
• Broad softening range above mouth temperature.
• Easily pliable in its softened state, without flaking, cracking or tearing.
• Low thermal contraction.
• Easily carved at room temperature without flaking or chipping.
• Little change in properties on melting and re-solidification.
• No residue on boiling out.

Q. 5. The 18:8 stainless steel is composed of:

1. 18 – Chromium, 8 – Nickel
2. 18 – Cobalt, 8 – Chromium
3. 18 – Cobalt, 8 – Nickel
4. 18 – Nickel, 8 – Chromium

ANSWER. 1 (18 – Chromium, 8 – Nickel )

• 18/8 stainless steel is the most widely used and flexible austenitic form of stainless steel.
• The numbers 18/8 represent the composition of this steel; it is 18% chromium and 8% nickel, making it very resistant to corrosion and oxidation.18/8 stainless steel is also highly durable and easy to fabricate. It's also simple to clean and available in various appearances and finishes. 18/8 stainless steel may also be known as austenite steel or 304 grade steel.
• Stainless steel is a low-carbon steel that contains chromium at 10% or sometimes more by weight.
• The chromium gives the steel its stainless, corrosion-resistant properties. Stainless steel's chromium content also allows the formation of a rough, corrosion-resistant chromium oxide film on the steel surface. If it is damaged in any way, this film is regenerates—as long as oxygen, even in very small amounts, is present.