Transcript Stainless steel

Dental Biomaterials
from the past to the present
by: Albert Mikko Hizon & Chai C. Santiago
Brief History
Brief History
• The French and the English dominated the earliest
contributions to the field of Orthodontics.
• In 1723 Fauchard invented the expansion arch and
gave the first comprehensive discussion of
appliances.
• In 1819 Delabarre introduces the wire crib, and this
marked the birth of contemporary orthodontics.
Brief History
• In 1865 Kingsley advocates plates as
retaining devices.
Early Developments
Dental bands
Dental clasps
Ligature
Dental wire
Early developments
• Gold, platinum, silver, steel, gum rubber,
vulcanite and, occasionally, wood, ivory, zinc,
copper, brass were used to form loops, hooks,
spurs, and ligatures.
• 14- to 18-karat Gold was usually used for wires,
bands, clasps, ligatures, and spurs.
Period of stagnation
Period of stagnation
• Dental practitioners learned that gold alloys have
deficiencies too.
• Gold was too expensive already.
• Stainless steel became available.
• In 1933, Archie Brusse gave a table clinic on the first
complete stainless steel system at the American
Society of Orthodontists (ASO) .
Period of stagnation
• In 1937 Acrylic’s were discovered and replaced
gold wires.
• In the 1940’s acrylic materials were being
polymerized into plates by reacting dough made
from methyl methacrylate monomer (MMA) and
acrylic powder under heat and pressure.
• By 1946, 98% of all denture bases were constructed
with the use of acrylics.
Period of stagnation
• Stainless steel gained prominence as the soft
brass ligature wire is now replaced by an 0.2544mm
(0.01in) soft stainless steel wire.
• To close this age, a man named Michael G.
Buonocore proposed the use of a 30-second, 85%
phosphoric acid etch to enhance bonding of acrylic
materials to enamel surfaces.
The rise of the dental industry
The rise of the dental industry
• By the 1960’s, gold was universally abandoned in
favor of stainless steel.
• Advantages of using stainless steel:
a.
b.
c.
The force per unit activation of stainless steel is greater than that of
gold.
By being smaller in size, stainless steel material were regarded as
being more esthetic than gold materials.
Stainless steels possess an excellent corrosion resistance, workhardening, and a very low frictional magnitude.
The rise of the dental industry
• In the1960’s:
– Bracket bands are disappearing as the bonded miniature
bracket appears – thereby disrupting the beginning of
esthetic orthodontics.
– Cobalt-chromium alloys were introduced.
• These alloys contained not only cobalt, chromium, and molybdenum
but also large amounts of nickel and iron.
• These alloys are available in four different tempers and are heat
treatable.
– Nitinol was discovered.
• This product has the lowest modulus for any cross section and has
the most extensive deactivation (range) capabilities.
The rise of the dental industry
• In the 1970’s elastics of all sorts find their niches in
the orthodontic professions. Independent of whether
elastomerics are made from ester- or ether-based
polyurethanes, they possess real limitations with
respect to the force retention, color fastness, and
odor prevention. Coatings of polytetrafluoroethylene
or Teflon are made to reduce friction.
• By 1986, two “superelastic” alloys are offered – a
Japanese NiTi and a Chinese NiTi. These are active
austenitic alloys that form stress-induced
martensite.
The rise of the dental industry
• In 1977 the beta phase of titanium was stabilized at
room temperature thus producing the titaniummolybdenum alloy.
•
This beta-titanium alloy has a modulus closest to that of traditional
gold along with good springback, formability, and weldability.
• During this point, dental practitioners had to decide
how to compare all the different types of materials.
With the use of equations, tables and other
mathematical based figures, the practitioners could
already compare one wire with the other in terms of
its three properties: stiffness, strength, and range.
Reported Properties of alloys during the 20th Century
Young’s
modulus
Yield Strength
(Mpa)
Tensile
Strength (Mpa)
100-120
70-460
260-900
85-110
170-570
320-1120
120
140-540
390-640
Stainless Steel
180-220
790-2450
930-2860
Cobalt chromium
180-230
960-2140
1210-2540
CP-Titanium
100-110
170-1000
240-1100
(α+β)Ti
100-120
740-1130
860-1220
NiTi-M
28-44
70-1240
900-1930
NiTi-A
80-110
180-690
800-1670
β-Titanium
65-70
520-1380
690-1500
Titanium-niobium
65-93
760-930
900-1030
Material
Brass
14- to 18-karat gold
Nickel Silver
Current trends in the dental
industry
Did you know that..
69% of adults ages 35 to 44 have lost at least one
permanent tooth to an accident, gum disease, a failed
root canal, or tooth decay. By age 74, 26% of adults
have lost all of their permanent teeth.
Current trends in the dental industry
• As we enter the 20th century we learn that what’s
more important is not making things smaller but
making them look, feel and function like a real teeth.
• Nowadays, the most common dental operation is
the Tooth replacement.
Current trends in the dental industry
•Attractive appearance
•Cuts down healthy teeth
•Bone loss under bridge
•Attractive appearance
•Full chewing function
•Prevents bone loss
Current trends in the dental industry
• The most common type of a dental implant is a
titanium screw that is anchored into the jawbone
where it serves as post for a custom-made tooth
crown. Once the crown is in place, you may not be
able to tell it apart from your natural teeth.
• Titanium dental implants have been placed
extensively since the 1970s. Titanium offers the
benefit of being lightweight and strong, and is not
rejected by the body (biocompatible). It is the most
widely used metal in orthopedic joint replacement
and dental implants.
Current trends in the dental industry
The implant is placed in the bone below the gum
tissue. A temporary abutment may be placed on the
implant until the healing phase is complete. A
cosmetic temporary crown can often be made to fill
the missing space.
After healing, the abutment is attached to the implant.
It will hold a custom-made crown that the dental
laboratory will mold and match to your existing teeth.
In the final step, the custom crown is cemented onto
the abutment. The tooth has been replaced without
disturbing the healthy teeth next to it and bone loss
has been eliminated.
We've sure come a long way from the wraparound "metal mouth" -- and that's something
we can all smile about!
Sources
1. R. Kusy, PhD. Orthodontic Biomaterials: From the past to the present, pg. 501-509
2. http://www.biomaterials.org
3. http://www.angle.org