STATEMENT OF PROBLEM: Concerns of laser welding for titanium dental prostheses are the limited depth of laser beam penetration and extensive surface damage. PURPOSE: This study used numerical heat transfer simulation to explain this behavior and offers an alternate multiple-pulsed method. MATERIAL AND METHODS: A one-dimensional finite difference analysis was used to simulate heat transfer in pure titanium and gold during laser welding with a custom-constructed software program. RESULTS: The thermal gradient profiles revealed the problem to be inherent in titanium's low thermal conductivity; gold did not have this problem. Time-elapsed multiple pulses on titanium relieved this problem by giving the energy time to diffuse into the depth of the material. CONCLUSIONS: With single-pulse laser irradiation on titanium, an increase in power could not greatly increase melting depth. The excess energy only vaporized the material surface.
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