Transcript INTRODUCTION TO DENTAL BIOMATERIALS SCIENCE

By
Dr.Reham Mohammed Abdallah
Science of dental materials

Is defined as;
“The Study of composition and properties of
dental materials and the manner in which they
interact with the environment in which they
are placed”.

It represents a marriage between the basic and
clinical sciences.
Goals of Studying Dental Materials

The main goal of studying course of dental
materials is to let the student:
1. Familiar with all materials used in dentistry.
2. Know all the properties of dental materials.
3. Know how to manipulate dental materials.
4. Know and understand causes of failure of
restorations.
5. Improve dental materials.
Oral environment

An
understanding
of
the
physical,
electrical and mechanical properties of
materials
used
in
dentistry
is
of
tremendous importance. This is because
these materials are exposed to the oral
environment and subjected to biting
forces.
Oral environment is characterized by

Wet (saliva, food and drinks). This may have an
effect on solubility, water sorption and staining of
the restorations.

Temperature Fluctuation (Ice cream, 5o C to coffee
or tea, 55o C).

The pH variation (pH of saliva is neutral (7.0) and
on intake of acidic fruit juices or alkaline
medicaments, pH may vary from 2.0 to 11.0 ).

Masticatory forces variation.
Characteristics of ideal dental materials
1. Biocompatibility (nontoxic, non-irritating, non
allergic).
2. Mechanically stable and durable (strong and
fracture resistant).
3. Dimensionally stable (minimally affected by
temperature or solvents).
4. Esthetics (oral tissue-like appearance)
5. Easy manipulation (easy use with no specific
equipment).
6.
Tasteless
and
odorless
(non-irritating
or
unpleasant).
7. Cost effective (within the patient's budget).
8. Cleanable (can be maintained).
9. Resistance to corrosion or chemicals (does not
deteriorate over time.
10. Low thermal conductivity (insulators) as in filling
and
cement
materials.
However,
thermal
conductivity is needed as for denture bases.
Quality Assurance Programs

Many
programs
or
agencies
were
developed to establish guidelines for
some minimal level of evaluation that
has been deemed sufficient to ensure the
safe use of the particular device or
material and maintaining quality of
dental materials.
These agencies include
1. American Dental Association (ADA) Specifications.
2. Federal Drug Administration (FDA).
3. Federation Dentaire Internationale (FDI).
4. International Standard Organization (ISO).
5. Occupational Safety and Health Agency (OSHA).
6. National Institute for standard and Technology
(NIST).
Classification of Materials Used in Dentistry

Based on the chemical composition; There are
four classes of materials used in dentistry:
a. Polymers
b. Metals
c. Ceramics
d.Composites (mixture of two or more of the first
three classes).
Polymers

Chemical
compound
consisting
of
large
organic molecules formed by the union of
many
smaller
monomer
units
is
called
a “POLYMER”

Chemical reaction in which low molecular
weight monomers are converted into high
molecular
weight
“POLYMERIZATION”
polymer
chains
Metals

“An opaque lustrous chemical substance that is
a good conductor of heat and electricity, and
when polished is a good reflector of light”.
Ceramics

“An inorganic compound with non metallic
properties, typically composed of metallic
(or semi-metallic) and non metallic elements.”
Composites

“A material formed from two distinct phases is
called a composite material”

Two distinct phases can be easily separated on
microscopic scale.

Final
properties
are
either
superior
intermediate to the individual constituents.
or
Based on the use of materials
1.Preventive dental materials
2.Restorative dental materials
3.Auxiliary dental materials

Pit and Fissure Sealants

Sealing agents that prevent leakage

Materials used primarily for their antibacterial effects.

Liners, bases, cements and restorative materials that
are used primarily because they release fluoride.

Synthetic components that can be used to
repair or replace tooth structure, including
amalgams, resin-based composites, cast metals,
metal-ceramics,
polymers.
ceramics,
and
denture
Direct restorative materials
Used intraorally to fabricate restoration or prosthetic
devices directly on the teeth.
Indirect restorative materials
Made extraorally in which the materials are formed
indirectly on the teeth or tissues.
Temporary restorative materials
Intended to be used to restore the tooth temporarily.
1.
Orthodontic wires.
2.
Cements used as temporary liners.
3.
Cements used as temporary filling materials.

Substances used in the process of fabricating
dental prostheses and appliances but do not
become part of these devices.

Acid – etch solutions, impression materials,
casting investments, gypsum cast, and model
materials and dental waxes.
Properties of Matter

Properties
of
materials
include
microscopic and macroscopic properties.

Microscopic properties are responsible
about
the
behavior
properties of a material;
or
macroscopic
Microscopic properties

Atomic structure

Crystal structure
Macroscopic properties

Physical properties

Mechanical properties

Surface properties

Time-dependent properties
Failure of Materials in the Oral Cavity

There are four modes of failure of restorations/
materials in the oral cavity:
Corrosion (occurs only in metals)
Wear
Fracture
Craze (occurs only in polymers)