MDS PREP
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.
Pit and fissure caries can be best pre vented by
1. the use of adhesive sealants
2. topical fluoride application
3. diet control
4. effective plaque control
Conservative Dentistry Answer: 1
1. The use of adhesive sealants: Adhesive sealants are thin, plastic coatings
applied to the chewing surfaces of the back teeth. They fill in the grooves and
depressions, creating a smooth surface that is easier to clean. Sealants act as
a barrier, preventing food and bacteria from lodging in these areas and thus
reducing the risk of tooth decay. This is considered the best preventive measure
because it directly addresses the anatomical vulnerability of the teeth and can
be applied quickly and painlessly.
2. Topical fluoride application: While topical fluoride is beneficial in
preventing dental cavities, it is not as effective as sealants in preventing pit
and fissure caries. Fluoride helps to strengthen the enamel and makes it more
resistant to acid attacks from plaque bacteria. However, because the pits and
fissures are already deep and narrow, fluoride may not always reach these areas
effectively. Sealants, on the other hand, provide a physical barrier that
fluoride cannot always penetrate.
Amount of force needed to condense direct filling gold depends on
1. Angle of compaction
2. Surface area of the condenser
3. Amount of the remaining dentin
4. Type of direct filling gold
Conservative Dentistry Answer: 2
Amount of force needed to condense direct filling gold depends on the surface
area of the condenser. The larger the surface area, the less pressure is
required to achieve proper condensation. The force applied affects the
compaction of the gold, but it is the size and shape of the condenser point that
dictate the actual pressure exerted on the material.
Outline form of a class V amalgam cavity preparation is related to (or) External shape of the class V amalgam restoration is related to
1. Contour of marginal gingiva
2. Axial line angles
3. Direction of the enamel rods
4. None of the above
Conservative Dentistry
Answer: 1
Explanation: The external shape of a Class V amalgam
restoration is closely related to the contour of the marginal gingiva. This is
important for aesthetic and functional reasons, as the restoration must blend
seamlessly with the surrounding gingival tissue. The outline form should respect
the natural contours to minimize plaque accumulation and promote periodontal
health. While axial line angles and the direction of enamel rods are relevant to
the preparation, they do not primarily dictate the external shape of the
restoration.
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 modified class III cavity restoration, retention is obtained mainly by
1. Acid etching
2. Retentive groove/slot
3. Retentive point
4. Retentive pin
Conservative Dentistry
Answer: 1
Explanation: In modified Class III cavity restorations,
particularly those involving composite materials, retention is often achieved
through acid etching. This process creates micro-retentive features on the
enamel and dentin surfaces, allowing the bonding agent to penetrate and create a
strong bond with the tooth structure. While retentive grooves, points, and pins
can also be used, acid etching is a fundamental technique that enhances
retention in adhesive dentistry.
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.
OVERTRITURATION of silver alloy and mercury:
1) reduces contraction
2) increases strength of lathe cut alloy but reduces strength of spherical
3) decreases creep
4) gives a dull crumby mix
overtrituration (i.e., triturating for longer than the recommended time) results in a mix that is warm and has a dull surface; often the mix sticks to the capsule; it shortens setting time (because the amalgam mass becomes heated), increases contraction, and increases creep; also increases tensile and compressive strength values (for lathe-cut alloys), decreases tensile and compressive strengths (for spherical alloys); overtrituration by 10% is acceptable