Abstract: A lingual dental matrix tensioner comprising two posts maintained parallel by two parallel rods through the posts at a right angle to the post axes One rod is threaded and has an end knob for adjusting the spacing between the posts, the other rod is a guide rod. Both ends of a matrix band are clamped to one post and the doubled matrix is guided through one of several slots in the other to form a retainer loop at any location. Rotating the threaded rod to separate the posts reduces the size of the loop.