Indirect retainers of partial denture:

 # Indirect retainers of partial denture:

A. Engages undercut areas

B. Most effective when close to direct retainer

C. Must be constructed with flexible materials like plastics

D. Should resist rotatory forces about fulcrum

The correct answer is D. Should resist rotatory forces about fulcrum.

Indirect retainers of a partial denture are designed to prevent rotational movement of the denture around the fulcrum line. They help stabilize the denture and distribute occlusal forces more evenly. The correct function of indirect retainers is to resist these rotatory forces about the fulcrum.

Therefore, the correct answer is:

D. Should resist rotatory forces about fulcrum.

When the distal extension denture base is dislodged from its basal seat, it tends to rotate around the fulcrum lines. Theoretically, this movement away from the tissues can be resisted by activation of the direct retainer, the stabilizing components of the clasp assembly, and the rigid components of the partial denture framework, which are located on definite rests on the opposite side of the fulcrum line away from the distal extension base. These components are referred to as indirect retainers. Indirect retainer

components should be placed as far as possible from the distal extension base, which provides the best leverage advantage against dislodgment. 

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The midline fracture of the maxillary denture are mainly due to:

 # The midline fracture of the maxillary denture are mainly due to:

A. Teeth set too buccally

B. No midline relief

C. Ridge resorption

D. All of the above

Midline fractures of the maxillary denture are primarily due to multiple factors that can contribute to the weakening of the denture structure. These factors include:

Teeth set too buccally: This can cause an uneven distribution of occlusal forces, leading to increased stress on the midline of the denture.

No midline relief: Lack of relief in the midline area can result in stress concentration, particularly during functional movements.

Ridge resorption: Loss of alveolar ridge height and support can lead to increased flexure and eventual fracture of the denture.

Given that all these factors can contribute to the midline fracture of the maxillary denture, the correct answer is:

D. All of the above.

Several factors have been attributed to be the cause of midline fracture i.e. flexural fatigue resulting from cyclic deformation and factors that exacerbate the deformation of the base or alter its stress distribution may predispose the denture to fracture. Other factors which form areas of stress concentration such as a large frenal notch, dentures with thin or underextended flanges, poorly fitting dentures or a lack of adequate relief, dentures with a wedged or locked occlusion have been implicated. Poor clinical design, dentures which have been previously repaired, poor laboratory technique, use of porcelain teeth, increase in stress concentration at the tooth/denture base interface, heavy or uneven masticatory forces, unbalanced occlusion, patient related habits, diastema and maxillary tori are other common causes for midline fractures of upper dentures.

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Cavosurface margin angulation in chamfer finish line is:

 # Cavosurface margin angulation in chamfer finish line is:

A. Always 90 degree

B. 90 degree or less than 90 degree

C. 90 degree or more than 90 degree

D. 120 degree

The correct answer is C. 90 degree or more than 90 degree.

Chamfer is an obtuse-angled finish line. Indicated where metal forms the margin of a restoration, e.g. complete metal crown. Should not be given for porcelain restorations as the obtuse angle produces shearing forces which is not well tolerated by porcelain. It is prepared using a round-end tapering diamond. This is produced by sinking in half the diamond into the tooth. The tip produces the chamfer while the sides give the necessary taper to the axial surface. 

Cavosurface angle of less than 90 degree produces a lip of unsupported enamel which fractures easily.

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MCQs on Pathology of Blood Cells - General Pathology MCQs

# Which of the following is a nutritional deficiency anemia?
A. Aplastic anemia
B. Sickle cell anemia
C. Spherocytosis
D. Megaloblastic anemia

# Megaloblastic anemia is related to:
A. Folic acid and Vit. 12 deficiency
B. Iron deficiency
C. Vit. C deficiency
D. Vit. K deficiency

A prepared cavity is best protected from moisture by:

 # A prepared cavity is best protected from moisture by:

A. Cotton rolls 

B. Saliva ejector

C. Rubber dam 

D. Paper napkin

The correct answer is C. Rubber dam.

It is not possible to properly accomplish operative dentistry without control of mouth moisture. Moisture control refers to the exclusion of saliva, gingival sulcular fluid, and gingival bleeding from the operating field. It also involves preventing or limiting the spray from the handpiece and restorative debris from being swallowed or aspirated by the patient. he rubber dam, suction devices, and absorbents are variously effective in controlling moisture. Use of the rubber dam as an optimum means of gaining moisture control is recommended.

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The finish line used in complete metal cast crown is:

  # The finish line used in complete metal cast crown is:

 A. Chamfer

 B. Chamfer with bevel

 C. Feather Edge

 D. Shoulder

The correct answer is A. Chamfer.

Indications of Chamfer Finish Line

- Cast metal restorations

- Lingual aspect of metal ceramics

 Advantages of Chamfer finish line:

- Conservative 

- Good marginal adaptation

- Provides bulk

Disadvantages of Chamfer finish line:

- Improper fabrication may result in an unsupported tip

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The best surface for a macrofilled composite resin is achieved by:

 # The best surface for a macrofilled composite resin is achieved by:

A. Allowing polymerization to occur against a mylar matrix

B. Use of a green stone

C. Use of an extra fine silicone carbide disc

D. Use of a white stone

The correct answer is A. Allowing polymerization to occur against a mylar matrix.

Finishing of composite resins is best done after 24 hours during which time the polymerization is complete. However, if a subsequent appointment is not desired finishing procedures can be started 15 minutes after curing. The initial contouring can be done with a knife or diamond stone. The final finishing is done with rubber impregnated abrasives or rubber cup with polishing pastes or aluminium oxide disks. The best finish is obtained when the composite is allowed to set against a matrix or mylar strip.

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