ORE Part 1 Dental Materials Science 3

Question 1

Which property of commercially pure titanium (grade 4) makes it most suitable as a dental implant material?

Accepted Answer

Exceptional biocompatibility enabling osseointegration

Answer

Titanium's native TiO2 surface oxide layer confers exceptional biocompatibility, enabling osseointegration — direct structural and functional contact between living bone and the implant surface without a fibrous tissue layer.

Question 2

The fluoride release profile of conventional glass ionomer cement (GIC) is best described as:

Accepted Answer

Initial high burst release followed by sustained lower-level long-term release

Answer

GIC shows an initial high burst of fluoride release in the first 24–48 hours, followed by sustained lower-level release; it also acts as a fluoride reservoir that can be recharged by topical fluoride application.

Question 3

At the molecular level, polymerisation shrinkage in composite resins occurs because:

Accepted Answer

Van der Waals intermolecular distances are replaced by shorter covalent bond lengths as monomers link

Answer

As free monomers (separated by Van der Waals gaps of ~3.5 Å) polymerise into a chain, covalent C-C bonds (~1.54 Å) replace the larger intermolecular distances, causing 1–5% volumetric shrinkage.

Question 4

Galvanic corrosion in the oral cavity most commonly occurs when:

Accepted Answer

A newly placed amalgam restoration contacts an existing gold crown in the opposing or adjacent arch

Answer

Galvanic corrosion requires two dissimilar metals in electrical contact within an electrolyte; amalgam (base metal) touching gold (noble metal) in saliva creates an electrochemical cell causing accelerated corrosion of the less noble metal.

Question 5

Which mechanical test is most appropriate for measuring the wear resistance of dental restorative materials?

Accepted Answer

Pin-on-disk tribology test

Answer

The pin-on-disk tribology test simulates clinical wear by sliding a material specimen against an antagonist under defined load and velocity, measuring volume or mass loss to quantify wear resistance.

ORE Part 1 Practice Test

ORE Part 1 Practice Test

ORE Part 1 Dental Materials Science 3