JVD 2018 #1 A Review of Dental Cements

Question 1

How is flexural strength determined?

Answer 1

• A 3-point bending or flexural test is performed. The flexural test defines the strength and amount of distortion expected
• Flexural strength is determined by forming the material into a simple beam.
• The beam is supported, not fixed, at each end and a load is then applied to the middle.
• The flexural strength is calculated by the maximum stress applied to materia

Question 2

What is the elastic modulus of a material?

Answer 2

• a number that measures an object or substance’s resistance to being deformed elastically (ie, nonpermanently) when a force is applied to it.
• higher values indicate a ‘stiffer’ material

Question 3

How is the hardness of a material determined?

Answer 3

The hardness of a material is determined by making a symmetrical-shaped indentation with an indenter that has a standardized force or weight.

Question 4

What is the mode of bond (non-adhesive, molecular, micromechanical) to the tooth for the following cements:

Zinc Phosphate

Polycaroxylate

Glass Ionomer

Compomer

Resin based

Answer 4

Zinc Phosphate - non adhesive

Polycaroxylate - Molercular

Gladss Ionomer - Molecular

Compomer - Molecular AND micromechanical

Resin based - Micromechanical

Question 5

Rank the following cements from most to least soluble:

Glass Ionomer, Resin based, Zinc oxide eugenol

Answer 5

ZOE, GI, Resin based:

Water based: Zinc phosphate, polycarboxylate, glass ionomer, zinc oxide eugenol (ZOE), and ethoxybenzoic acid (EBA)-reinforced ZOE cement

Question 6

Rank the following cements in their bond strength to tooth material from strongest to weakest:

Zinc Phosphate, Glass ionomer, Resin modified glass ionomer (RMGI), Resin-based cement

Answer 6

Resin based; RMGI; GI; zinc phosphate

Resin-based cements are the strongest, least soluble, best bonding cements of any of the other choices. They are also more technique sensitive and more expensive.

Question 7

What are the components of a glass ionomer cement?

Answer 7

• finely ground glass filler and fluoroaluminosilicate (FAS),
• polycarboxylic acid,
• water,
• tartaric acid
  (acts as an accelerator, aids in the extraction of ions from aluminosilicate glass and facilitates their binding to polyanion chains. Post-setting hardening is significantly increased)

Question 8

Rank the following cements on strength, durability and cost (same order for all properties):

Resin Based

ZOE

RMGI

GI

Zinc Phosphate

Self-adhesive resin based