An in vitro study of resistance to corrosion in brazed and laser-welded orthodontic appliances

Many orthodontic appliances comprise a number of elements soldered together. This technique is known as brazing and has now been in use for over thirty years, although today laser welding is increasingly widespread. Biocompatibility of alloys contained in orthodontic appliances has become a hotly-debated issue and previous studies have shown that it depends on the products of alloy corrosion and their effects on the oral cavity. The present study is intended to compare the corrosion resistance of stainless steel when traditionally soldered - i.e, brazed - and when laser-welded. Samples comprising stainless steel band strips and Remanium® wire were soldere d together traditionally (i.e. brazed) and laser-welded and were then left in artificial saliva for 7 days at 37±1 degrees . Corrosion was studied by: a) SEM observation of sample surface morphology before (TO) and after standardized immersion test (Tl); b) X-ray micro analysis (EDAX). SEM observat ion of the brazed samples showed surface corrosion, which was not visible in the laser-welded samples. Our study shows that laser-welded samples have superior resistance to corrosion. Copyright © by BIOLIFE, s.a.s.