lec 1 introduction to dental materials
Post on 08-Apr-2018
236 Views
Preview:
TRANSCRIPT
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 1/24
Introduction to Dental Materials
Dr Nadeem Hafeez KhokharAssociate Professor
Head Basic Dental sciences
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 2/24
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 3/24
1. By preventing disease
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 4/24
3. Improving mastication efficiency
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 5/24
2. Relieving pain
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 6/24
Goal of dentistry
Enhancing speech
and Improving
appearance.
Disease: Caries
Ortho treatment
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 7/24
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 8/24
Materials used for tooth replacement
1. Animal teeth
2. Human teeth
3. Seashells
4. Ivory5. Bone
6. Implants1. Hydroxyapatite
2. Cobalt Chromium
3. Titanium The denture, fabricated in 1789 for George
Washington, is carved from hippopotamus tusk
and originally contained eight human teeth.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 9/24
Classification of material used in dentistry
Four possible classesof materials are usedin dentistry: i.e.
1. Metal,
2. Ceramics,3. Polymers &
4. Composites.
Despite theimprovement in
physical propertiesnone of the materialare permanent.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 10/24
Metals (characteristics)
Oldest of 4 used in dentistry as dental materials. A metal is defined with certain characteristics like1. Thermal & electrical conductivity,2. Dductility (they can bend without breaking),3. Oopacity (do not transmit light) &
4. Lustre (they have a surface that strongly reflect light &appears bright & shiny)
Another characteristic of metal is elements which tend todissolve in water or aqueous solution producing atoms withpositive charges.
80% of elements in periodic table are metals.
All metals are white actually grey except gold (yellow), copper (red).
The only metal in liquid form is mercury
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 11/24
Metals
Metal solidify with theiratoms in a very regularor crystallinearrangement often incubes.
The increasing strengthof metallic bond causesmetal to haveincreasing meltingtemperatures.
Mercury is used in
dentistry to mix withparticles of other metalssuch as silver, tin, &copper to formamalgam.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 12/24
Metal
Because of their increasingstrength, stability &transformation into different shapes. They are extensivelyused to produce/replace loss
tooth structures as crowns Inlay : When portion of teeth to
be replaced is within the cusps.This type of restoration is calledInlay.
Onlay : When portion of teeth tobe replaced involves one ormore cusp but entire crown.
Metal crown bridge
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 13/24
Metal Uses
Most instrumentsand equipment used in dentistryare made up of metals especiallysteel (nocorrosion,economical,sterilizable & canbe sharpened).
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 14/24
Ceramics
Ceramics are combination of the metallic andnon-metallic elements.
They are manufactured by fusing together
oxide powders (such as silicon, aluminum,calcium & magnesium) in oven at hightemperatures.
Glass, Concrete, fine crystals & gypsums are
all ceramics. Most coloring pigments agent used or
dentistry are ceramic oxides hence any colorcan be produced.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 15/24
Characteristics
Glass ceramics are usedextensively as fillers fordental composites. They
are also used in severaldental cements &temporary restorativematerials.
Porcelain a special typeof ceramics extensivelyused in dentistry &other industries.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 16/24
In dentistry the use of ceramics is limited due totheir low fracture resistance as compared tometals.
Recently materials with improved fractureresistance have been developed for inlays,onlays & full crown restorations.
Because of their excellent biological properties,
ceramics are also used extensively as implant materials, either alone or as a coating for metalsubstructures made from titanium placed directlyinto maxilla or mandible.
Ceramics uses
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 17/24
Implant
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 18/24
Widely used in the market as vinyl (nylon)polymers, gelatin (natural), cellulose, DNA
protein, rubber, silicon. These are giant long chain (carbon) organic
molecules.
Covalent bond within each molecule havingtremendous strength in one direction, e.g.breaking of nylon thread by pulling (elasticity).
Poor conductor of electricity & heat.
Polymers
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 19/24
Uses
Silicon polymer made fromsilicon-oxygen bonds is usedas an impression materials.
Polymers are only used tomake teeth & denture basefor edentulous patients.
Temporary restorativematerial for onlay / inlay,temporary crown.
Used as adhesive agents toenhance bonding, sealant of
pits & fissures.
Denture base polymer
Silicon rubber impression
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 20/24
Composite
Composites are mixture of two or more of first three classes in which different components remain distinct from one
another in the final structure. e.g. fiberglass, polymer reinforced with fine glassfibers.
They remains physically separate &uniformly distributed throughout thepolymer matrix.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 21/24
Historical background
Dentistry as a specialty is believed to have begunabout 3000B.C.
Phoenicians (2500 B.C) and Etruscans (after 800B.C)used gold bands and wires as partial dentures
Modern dentistry began in 1728, when Pierre
Fauchard (father of dentistry) published a treatisedescribing many types of dental restorationsincluding artificial denture with ivory
In 1756 Pfaff described a method of takingimpression in mouth with wax and making a modelwith plaster of Paris.
De Chamant in 1792 patented a process for theconstruction of porcelain teeth.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 22/24
Historical background
In 1895 G V Black (pioneer of restorativedentistry) brought dentistry to its peak.
In 1919 the National Bureau of Standards(now NIST National Institute of Standards
and Technology) set up evaluation andselection of dental amalgam for use in federalservice.
In 1928 the Dental Research Fellowship at NBS was assumed by ADA. It was the
enthusiasm of the member of this team that first course in dental material was inducted inDental schools.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 23/24
American Dental Association
Measurement of physical and chemical properties of dental material that are of clinical significance.
Developments of new material, instruments and test methods
It issues seal of approval to instruments andmaterials fit for use in dentistry.
The ASC (Accredited Standard Committee) MD156develops specifications for all dental products except X-ray films and drugs.
FDA (food and drug administration) protects thepublic from hazardous or ineffective medical anddental devices like x-rays and drugs.
8/7/2019 lec 1 Introduction to Dental Materials
http://slidepdf.com/reader/full/lec-1-introduction-to-dental-materials 24/24
International Standards
FDI (Fdration Dentaire Internationale) andISO (International Standard Organization) areworking toward standardization of dentalmaterials and devices.
ISO is composed of standard organizationsfrom more than 80 countries.
The responsibility of this organization is tostandardize terminology and test methods
and to determine specifications for dentalmaterials , instruments, appliances andequipments.
top related