Bonding of Composite resin to tooth

# Bonding of composite resins to tooth structure is by: (KAR-01)
a) Covalent bond
b) Ionic bond
c) Mechanical
d) Vander waal forces

The correct answer is C. Mechanical

Bonding of composites to tooth structure occurs by micromechanical retention. Acid etching creates micro porosities into which the resin penetrates resulting in resin tag formation. These tags penetrate to a depth of 5 - 10 µm but their lengths are dependent on the enamel etching time.

Advantages of Dental Composite Resins:

# The main advantage of composites over unfilled direct filling resin is their: (KAR-97)
a) Higher solubility in saliva
b) Lower modulus of elasticity
c) Esthetic excellence
d) Lower thermal co-efficient of expansion

The correct answer is D. Lower coefficient of thermal expansion.

Advantages of composites over unfilled resins:

• Lower coefficient of thermal expansion
• Low polymerization shrinkage
• Low water absorption
• High abrasive resistance

Disadvantages of composites:

• Less color stability
• Less smooth finish than unfilled resins

Hyperplastic Tissue Management in Complete Dentures

# The most common reason why hyperplastic tissue is removed during the construction of a complete denture is that:
a) It interferes with the arrangement of the teeth
b) It is unaesthetic to construct a denture on a hyperplastic tissue
c) It interferes with the stability of the denture
d) All of the above

The correct answer is C. It interferes with the stability of the denture.

The most important reason for the treatment of hyperplastic tissue before the construction of complete or removable partial dentures is to provide a firm, stable base for the denture. 

Functional cusp reduction

# The amount of functional cusp reduction required for metal-ceramic crown is -
a) 1.0 - 2.5 mm
b) 1.5 - 2.0 mm
c) 2.0 - 2.25 mm
d) 1.85 - 2.10 mm

The correct answer is B. 1.5 -2.0 mm. 

Metal ceramic restorations require a 1.5 - 2 mm reduction in the functional cusp and 1.0 - 1.5mm reduction in the non-functional cusp.