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A Brief Overview of Laser Welding in Dental Technology
A lot of noise has been made lately about CAD /CAM systems in Dental Technology and with
good reason .I can remember 15 years ago people talking about machines that would mill crowns chairside. They all said "yea but it won't replace the technician". Here we are in 2002 and in some instances the technician has been replaced by these machines. Limited as they are in function only time will tell what is around the corner. I doubt if we will be replaced but I think our job description will definitely change and so will the materials we use. Let's consider Titanium.
The introduction of " the great biocompatible " Titanium to the dental world has brought about great change and challenges to the dental laboratory. Implants are big business and lets face it you would have nothing but a Titanium Implant placed in your jawbone these days. But how do we work with this stuff? Well years ago people asked the same questions about Aluminium and yet today we take it for granted.
Titanium has sparked it 's own technology within the Dental world. Titanium casting, Titanium milling (via CAD /CAM systems) and the big question is "how on earth do you join this metal?"
The answer is of course with a LASER.
LASER is an acronym for "Light Amplification by the Stimulated Emission of Radiation" which produces a sharp focused light beam that melts a very small area of metal. The benefit of this technology is that very little heat is generated at the weld point, allowing users to easily weld .2.5 to 1.0mm away from the most complicated and intricate component parts without damaging heat sensitive materials. The laser welder allows the operator hold parts in their hands while viewing the application through a stereomicroscope in the welding chamber. This is ideal for Titanium and of course other metals. No other method is available to join Titanium so easily.
Why use a Laser welder
Why laser weld? No solder, simple. Because laser welding joins parent metals together, it does not introduce solder to make a connection. The coefficient of expansion remains consistent giving absolute accuracy with no expansion or contraction at the connection this is especially important during porcelain application. However, the preparation of the join is critical.
The weld-effected area is in a limited range of only approximately 0.25 to 2 mm, depending on the material. The laser welds two metals together and thus permits safe, durable, and precise and non-warp joining of parts in the form of a spot or seam. Because of the very short time of the laser pulse the zone of heat influence is limited to the immediate vicinity of the welded spot or seam.
Benefits of laser welding:
Weld is with the parent metal without the introduction of additional metals or alloys thereby eliminating any galvanic effect
Homogeneous structure with high mechanical strength
Corrosion resistant welding technology without solder
Welding is done with little or no heat transfer providing advantages to outdated soldering techniques
Small heat affected area eliminates the risk of warping and the weld can be safely positioned close to porcelain or acrylic work
Accuracy of fit is significantly higher than with conventional soldering techniques.
Titanium can be laser welded in an argon gas environment providing a bio-compatible and corrosion free appliance
Laser beam micro-adjusts in width and power output enabling a precision weld of finer parts and precision attachments without risk of damage.
A laser welded bridge will not warp in a porcelain furnace
More precise fit due to welding directly on the master model.
Laser welding technology has become a tool of great value in the dental laboratory. It is quicker and easier than ever to repair breaks, add clasps, eliminate rocking or other alterations to fixed bridges and cast partials. Repairs are made directly on the model without causing damage to porcelain or acrylic. Orthodontic appliances are an area just being explored due to the new materials for this specialty eg TMA wire.
However,this technology comes with a high price tag. Expect to pay $50,000 plus for a welder and the operating costs are considerable. Outsourcing for the smaller laboratory would be a genuine consideration. If you are serious about laser welding expect a steep learning curve but don't be put off after all this is the future. Soldering is finished.
Terence Whitty
Director Australian Orthodontic Laboratories Pty. Ltd.
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