MDS PREP
When dental bur is sterlized by autoclaving, which of the following chemicals is used for protection of the bur
1) Sodium nitrate
2) Sodium nitrite
3) Silver nitrate
4) Silver nitrite
Conservative Dentistry
Answer: 2
Explanation:Sodium nitrite is often used as a protective agent during the autoclaving process to prevent corrosion of dental instruments, including burs. It helps to maintain the integrity of the metal during the sterilization process.
Main feature of class V amalgam restoration
1) Occlusal wall is greater than gingival wall
2) Retention undercuts placed in the mesial and distal walls
3) Axial wall is flat and does not follow the contours of the tooth
4) Mesial and distal walls converge
Conservative Dentistry
Answer: 1
In Class V restorations, which are located at the gingival third of the facial or lingual surfaces of teeth, the occlusal wall is typically wider than the gingival wall. This design helps in providing retention and resistance to the restoration, as the occlusal wall is more subject to occlusal forces.
The main disadvantages of composites of not being recommended for class II posterior restorations
1. Colour matching is not good
2. Lacks sufficient strength
3. Occlusal wear
4. Frequent fractures at the isthmus
Conservative Dentistry
Answer: 3
One of the main disadvantages of composite materials in Class II posterior restorations is their susceptibility to occlusal wear, which can compromise the longevity of the restoration.
In conventional class III amalgam cavity preparation the axial wall in inciso gingival direction should be
1. Straight and parallel to the long axis of the crown, deeper incisally than gingivally
2. Convex and parallel to the long axis of the tooth
3. Concave and parallel to the incisogingival contour of the tooth
4. None of the above
Conservative Dentistry
Answer: 1
Explanation: In a conventional Class III amalgam cavity
preparation, the axial wall should be straight and parallel to the long axis of
the tooth. This design ensures that the restoration has adequate resistance form
and is less likely to dislodge under occlusal forces. The wall being deeper
incisally than gingivally helps to maintain the integrity of the tooth structure
and provides a stable base for the amalgam restoration.
The product that is formed on the surface of the amalgam restoration and frequently results in discolouration is
1) Sulphide
2) Gamma I phase
3) Gamma II phase
4) Oxide
Conservative Dentistry
Answer: 1
The discoloration of amalgam restorations is often due to the formation of silver sulfide on the surface, which can occur due to the reaction of silver with sulfur compounds in the oral environment. The gamma I phase is a strong component of amalgam, while the gamma II phase is weaker and less stable. Oxides can form as well, but sulfides are more directly associated with the discoloration observed in clinical settings.
In class V preparation the wall which is not present at all
1. Pulpal
2. Distal
3. Mesial
4. Axial
Conservative Dentistry
Answer: 1
In class V preparation, the pulpal wall is not present at all, as the cavity is
confined to the cervical third of the tooth. It does not extend into the pulp
chamber.
Annealing of gold foil is the process by which
1. Contaminants are removed from the surface
2. Rigidity decreases and ductility increases
3. Both ductility and propotional limit decrease
4. None of the above
Conservative Dentistry
Answer: 1
Annealing gold foil is the process of heating gold to remove impurities and restore its cohesion properties. Annealing of gold foil is a heat treatment process used to alter the physical and sometimes chemical properties of the material. The primary purpose of annealing gold foil is to remove any contaminants and stresses that may be present on the surface of the material. This is achieved by heating the gold foil to a specific temperature, typically around 400°C (750°F), and then allowing it to cool slowly. The process can also help in improving the foil's ductility, making it more malleable and easier to work with. However, the direct effect of annealing on the rigidity, ductility, and proportional limit is not explicitly stated in the question, and thus the correct answer is that annealing of gold foil primarily serves to remove contaminants from the surface.
The polishing agent which can be used to polish amalgam restoration is
1) Garnet
2) Emery
3) Silex
4) Alumina
Conservative Dentistry
Answer: 2
Emery is a polishing agent that can be used to polish amalgam restorations. It is a natural abrasive material that is relatively safe for metal surfaces and does not cause significant wear on the amalgam. Garnet, silex, and alumina are also abrasive materials, but they are less commonly used for polishing amalgam due to potential issues with scratching or wearing down the restoration.