An anterior tooth bounded edentulous area which crosses the midline:

 # An anterior tooth bounded edentulous area which crosses the midline:

A. Class I

B. Class III

C. Class IV

D. Class IX

The correct answer is C. Class IV.

Class IV Kennedy classification is a single but bilateral (crossing the midline) edentulous area located anterior to the remaining natural teeth.

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Which of these muscles may affect the borders of mandibular complete denture?

 # Which of these muscles may affect the borders of mandibular complete denture?

A. Mentalis

B. Lateral pterygoid

C. Orbicularis oris

D. Levator angularis

The correct answer is A. Mentalis.

The labial vestibule extends from the labial frenum to the buccal frenum. The mucolabial fold extends from the inner aspect of the lip to the mandible. The mentalis muscle inserts very close to the crest of the ridge in this area and limits the border extension in length and width.

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The minimal occlusal thickness of amalgam restoration for appropriate resistance to fracture is:

# The minimal occlusal thickness of amalgam restoration for appropriate resistance to fracture is:

A. 0.5 mm

B. 0.8 mm

C. 1.5 mm

D. 2.5 mm

The correct answer is C. 1.5 mm.

The relatively horizontal pulpal and gingival walls, prepared perpendicular to the tooth’s long axis, help the restoration resist occlusal forces and limit the likelihood of tooth fracture from wedging effects caused by opposing cusps. It may be necessary to reduce cusps that no longer have sufficient dentin support and cover (or envelope) them with an adequate thickness of restorative material in order to provide resistance to fracture of the tooth and/or the restorative material. Preparation design must allow for adequate thickness of polycrystalline restorative materials to ensure adequate primary resistance to restoration fracture. he minimal occlusal thickness, for appropriate resistance to fracture, of amalgam is 1.5 to 2 mm and glass-ceramic is 2 mm. Polymeric restorative materials (e.g., composite resins) have no minimal thickness.

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Primer is a:

 # Primer is a:

A. Acid etching agent

B. Adhesion promoting agent

C. Coupling agent

D. Bonding agent

The correct answer is B. Adhesion promoting agent.

PRIMERS are hydrophilic monomers, which are applied over the etched/conditioned surfaces for the easy flow of bonding agents. Eg. 2-HEMA and HEMA dissolved in acetone or alcohol.

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