MDS PREP
Aluminium oxide polishing powder is obtained from
1) Aluminium
2) Cryolite
3) Bauxite
4) Vulcanite
Conservative Dentistry
Answer: 3
Aluminium oxide (Al₂O₃) is primarily derived from bauxite, which is an ore that contains a high percentage of aluminium. The Bayer process is commonly used to extract aluminium oxide from bauxite.
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
Explanation: In a Class V amalgam restoration, the occlusal
wall (or the wall facing the occlusal surface) is typically wider than the
gingival wall (the wall facing the gingiva). This design feature helps to
provide adequate bulk for the restoration, ensuring strength and resistance to
fracture. The other options, such as retention undercuts and wall convergence,
are not characteristic features of Class V restorations, which are primarily
concerned with the gingival and occlusal relationships.
Retention grooves are placed in a class V cavity for non-adhesive restoration in
1. Mesioaxial and distoaxial line angles
2. Occlusoaxial and gingivoaxial line angles
3. All line angles of the cavity
4. None of the above
Conservative Dentistry
Answer: 2
Retention grooves in a class V cavity for non-adhesive restoration are placed in
the mesioaxial and distoaxial line angles. These grooves help hold the
restoration in place by providing mechanical retention and reducing the risk of
microleakage.
An old composite restoration is to be replaced. The best method is
1) To remove entire restoration, re-etch and refill
2) To roughen the old restoration, re-etch and refill
3) Composite restoration cannot be replaced or refilled
4) None of the above
Conservative Dentistry
Answer: 2
Roughening the old restoration and re-etching it allows for better bonding of the new composite material.
During cavity preparation, more incidence of exposure is in
1. Class V cavity in first premolar
2. Class II mesioocclusal cavity
3. Class II distoocclusal cavity
4. Class IV cavity
Conservative Dentistry
Answer: 1
During cavity preparation, the incidence of pulpal exposure is higher in class V
cavities on first premolars due to the proximity of the margins to the pulp
horns.
In class III composite preparation, retention points should be placed
1. In the axial wall
2. Entirely in dentin
3. At the dentinoenamel junction
4. At the expense of facial and lingual wall
Conservative Dentistry
Answer: 2
Explanation: In Class III composite preparations, retention
points should be placed entirely in dentin. This is because dentin provides a
more reliable substrate for bonding compared to enamel, especially in areas
where the enamel may be thin or compromised. By placing retention points in
dentin, the restoration can achieve better mechanical retention and bonding
strength, which is crucial for the longevity of the restoration.
Primary determinant of the outline form in class V preparation
1. Height of the gingival crest
2. Extension of the caries
3. Type of the restorative material
4. Teeth anatomy
Conservative Dentistry
Answer: 2
Explanation: The outline form of a Class V cavity preparation
is primarily determined by the extent of carious tissue. The goal is to remove
all carious dentin while preserving as much healthy tooth structure as possible.
The outline form must encompass the entire area affected by caries to ensure
that the restoration is effective and durable. Other factors, such as the height
of the gingival crest, type of restorative material, and tooth anatomy, may
influence the preparation but are secondary to the extent of caries.
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.