2000 年 13 巻 3 号 p. 559-563
Synopsis
Since metal welding by a laser features a narrow heat-affected zone and accurate joining of a prosthesis, it has been used for increasingly more dental applications.
However, such metal welding can be accomplished by using a high-power laser unit for prosthetics, and as yet there are no reports on metal welding in the mouth using a dental laser unit.
In order to improve the superstructural accuracy of an implant, thermal influences on tooth metal and its strength were investigated, using an Nd:YAG laser designed to provide a high peak power value per pulse.
Twelve percent gold-silver-palladium alloy, high-carat gold alloy,and gold alloy for burning ceramics were used as metal samples. Ten samples of each alloy were prepared for tensile tests and thermal influence tests.
For tensile tests, each sample was cut at the center, welded all around under an irradiating condition of 900 mJ, 15 pps, and at a distance of 0.1 mm, and then measured by a tensile tester.
For thermal influence tests,the variation in temperature of each irradiated sample was measured using a thermograph.
The results of these tests showed that the tensile strength of each sample was about 80 MPa.
The strength of resin for picking up at the time of trying was approximately 60 MPa, and the variation in temperature of each sample subjected to the thermal influence test was less than 4℃, proving an extremely small thermal influence.
As a result of this investigation, the possible use of metal welding in the mouth was suggested.
