This abbreviation stands for Titanium Molybden Alloy which is a Beta-Titanium alloy made from titanium and molybden and is manufactured by Ormco. This alloy is often used to manufacture orthodontic wires because it has about half the stiffness of steel yet retrains the same strength. As the patent on this product ran out a short time ago, virtually every manufacturer of orthodontic products is now offering Beta-Titanium wires. They are usually a little more expensive than steel wires and are a bit more difficult to work with so they are not used as much as the steel version. However, for many special tasks, Beta-Titanium offers orthodontists a useful addition to the materials that they use on an everyday basis.