Soldering vs. Welding in Dentistry

Soldering And Welding

Soldering: Soldering is a process in which two or more metals are joined together by melting and flowing a filler metal (solder) into the joint.
Welding: Welding is the process by which two pieces of similar metals are joined together without the addition of another metal.

Laser welding is a recent advancement in the welding procedures.
In laser welding, the laser used is a pulsed neodymium laser with a very high power density.
The laser unit consists of a small box that contains the laser tip, an argon gas source, and a stereo microscope with lens crosshairs for the correct alignment of the laser beam with the components.
The maximum depth the laser can penetrate is 2.5 mm.
The heat generated is small, so the parts can be hand-held during welding and it can be done close to the ceramic or even resin facings without damaging it.

Laser welding is used mainly to join titanium components.
This is because the commercially pure titanium (cpi) used in dentistry for fixed and removable partial denture frameworks is highly reactive in the air.
Ordinary soldering procedures result in a weak joint because of the formation of a thick layer of titanium oxide (especially when heated above 850°C).
Laser welding or plasma welding can be done at lower temperatures.

Soldering vs. Welding In Dentistry

When the light beam reaches the surface of the metal, the metal absorbs its energy, converting it into heat that penetrates into the interior of the metal by conduction.
Owing to a high concentration of heat, the metal is taken to its melting point, and a series of events culminates in the formation of a keyhole or spots that will be filled with the melted metal.

Lower heat generation.
Laser welding can be executed directly in the working model.
Allows welding in regions near the resins and porcelain portions without fear of damage to these materials.
No oxide formation because of the inert argon atmosphere.
Joints made of the same pure titanium as the components, thus reducing the risk of galvanic corrosion.
Laser welding produces a keyhole that concentrates the energy absorbed in a small region resulting in high penetration and formation of a narrow heat affected zone (HAZ) that results in less distortion compared to conventional welding methods.
Less time expended.
Allows welding with the structures in close contact or with minimal space for bragging using filer metal

Residual stress introduced into welding joints is a consequence of the heating and cooling cycles of the welding process. This affects the mechanical behavior of laser—welded structures.
Argon gas can cause porosities which can lead to the failure of welded structures.
Insufficient penetration of the laser beam can cause a big defect or internal failure if the equipment is not adjusted properly.
High cost of the equipment.