Titanium
Introduction:
- titanium is very good biocompatible material
- it has a exeptional resistance before corrosion
- it can be as a bioactive material, which can make adhesion to the
vital tissue
- even though it was applyed in dental practice as a last metal
material
Introduction – titanium and its alloys:
- in the nature is titanium as binary alloys, as a oxid TiO2
- it discovered in 1789 in department of Cornwallu
- at 1795 y. Mr. Klaproth detected, that it isi oxid unknown origin
and he termed as a titanium
- the rich europen deposits of titanium are in the Norway, Finland
and in Russia
- at 1822y. – was first isolated pure titanium , but in very little rate.
It was enough for laboratory research.
- at 1910y. – at first was isolated a lot of pure titanium Mr. Hunter, it
was reaction between TiO2 and natrium
Introduction – titanium and its alloys:
- at 1932y. – it was begin of industrial production of titanium (
chemical reaction between TiO2 and calcium)
- from this metal it maked wires, plates and zo získaného kovu sa
sformovali tyče, drôty a plech
- other technology used for industrial production, chemical
reaction between TiO2 and magnesium
- with this technology was made a lot of tons of pure titanium. It
was in America, Japan and in Russia.
Chemickal characteristic:
- Titanium is alotropic metal (as a solid state has in two phases with
unequal atomic lattice)
- from the temperature 882°C is as a .............. Atomic lattice , which
is not so stable , as a cubic atomic lattice
- if the temperature is less than 882°C, titanium has cubic atomic
lattice
- for practice it means, that by the temperature diverse between
cooling and melting create changes between these two internal
structure
- by the very quick cooling, the number of atoms is decreased and
it results to the depression of mechanical resistance
Chemical properties – pure titanium:
- this metal has a strong potential to release the hydrogen
- it results to the:
- volume expansion of titanium maximally about 15 %
- titanium obtained light color
- metalic brightnees
Chemical charakteristic – pure titanium:
- the atoms of oxygen and nitrogen can very quick to diffuse into
the atomic lattice and so incresed melting temperature
- it means, that by heating create:
- oxidation on surface layer
- dissolution of oxygen and nitrogen in metal
- the very hard and think layer on surface, which is
protection of titanium before oxidation. This layer must be
remove before processing
- others elements, as a niob, tantal, alluminium, tin and zircon
change the mechanical properties by the changes into the atomic
lattice
Physical properties:
- titanium is the metal steel color with high brightness
- difference from steel is in the weight. It is result from unequal
density
- the density of pure titanium is about 4,51 g/cm3 , and Ti – alloys is
4,40 – 4,80 g/cm3 .
- in equation with cobalt alloys, which have density about 8,2 g/cm3
, the weight of the metal titanium cast is less about 43% than
weight of similar cobalt cast ( according to large and shape)
- titanium has worse termic conduction than cobalt alloys titán
Mechanical properties:
- the mechanical properties is good, but titanium is more breakable
than cobalt alloys, it has narrower flexibility
- for the modification of mechanical properties is added to the
titanium others elements, as a oxygen and ferrrum
- according to content of oxygen and ferumm, can be the titanium
alloys divided at four group( T1- T4)( similar distribution as a gold
alloys) ; from soft to hard alloys
Corrosion of titanium:
- pure titanium is very resistant metal
- pure titanium can be enough stable in water and acid solution,
- it is resistant to action of sulphur compounds
- but fluoride compounds can change the surface of titanium and
so support corrosion
- similar effect have fluoride toothpaste with high content of fluoride
( more than 2000 ppm. They are the pastes for caries prevention , as
Elmex gel, fluid or others solution for tooth protect before caries)
- fluorides from solutions remove the passive layer from surface and
so enable the absorbtion hydrogen and so participate on
oxidatation and corrosion surface layer of titanium
Melting of titanium:
- the melting of titanium is by the mercury arc in vacuum
- intense cooling creates strong crust on the inside surface of
special box
- this crust can isolate melting titanium from the elements of box
- this metod names as a „skull melting“.
Melting of titanium:
- other type of melting titanium is during the induction current, the
melting titanium is absorbed by the special ceramic box, which is
indifferent according to composition of ceramic box
- the ceramic crucible is to expensive and it can be used only once
kelímok je však drahý a vhodný len na jedno použitie
- this melting is in the vacuum with special inert gas, argon
(colorless and odorless gas)
- cooling of melting titanium is in vacuum too
Soldering:
- soldering of titanium parts is by the welding
- according to very strong chemical reaction of titanium by the
temperature above than 500°C, must be soldering very quick and
with high thermal energy
- this condition satisfy the mercury arc, plasma, laser ray and
electron stream
- laser ray is the best for soldering of titanium parts
- laser is device which can generate the monochromatic ray with
high density of electrons and from it result the high thermic energy
- it can function continuously
Soldering:
-other type of soldering is by the solders
- for soldering of titanium parts can be used the solders on
argentum or palladium base
- the cooling of soldering place must be during the protect
atmosphere, in vacuum
- the soldering space is the site with reduced resistence before
corrosion
Biocompatibility:
- titanium can be good biocompatible metal and bioactive metal
- as a bioactive metal is participate the ions OH-, which can react
with macromolecules of vital tissue and so produce biofilm
- biocompatibility is compared with biocompatibility of gold alloys,
although the titanium belong to the general metal alloys
- it can make the active connection with vital tissue
- although the price of pure titanium is narrower than the price of
gold alloys, the technology of producing titanium is very expensive
Biocompatibility:
- the resistance before corrosion is very strong, according to good
passive layer
- for elimination of cytotoxic elements is enough few milliseconds
and the thickness of passive layer is only few nanometers
- titanium in dental practice was begin use at 60-y. of 20.century
- it was good reconstruction for very mechanical shirt sleeved, it
was for implants of large joints
- in equation with cobalt alloys the titanium alloys have better
resistnace before corrosion , better biocompatibility and active
bioadhesion
Conclusion:
- in dental practice is used the titanium as pure metal
- from titanium are made implants, crowns, metal construction for
fixed bridge, metal framwork for sceletal RPD, clasps system and so
on....
- in combination with ceramic, have to be use the special type of
ceramic ( it is zircon oxid ceramic, aluminium oxide ), because these
types of ceramics are indiferent to the titanium and dont make the
changes in atomic structure
- the titanium is distribute from name as a Tritan, Rematitan ( as 6g
rollers)
Pre prax:
END.