The adjustment of the interproximal contact points (N) is important to avoid caries, periodontal problems, and halitosis. When this pressure is evaluated, a correct restoration can be made with composite or prosthesis in those points. A metal strip (6 mm wide and 0.03 mm thick) is placed interproximal between adjacent teeth and attached to a dynamometer through a Tofflemire matrix holder. The formula to use is N = Fd / 2μ. The dynamic force of friction (Fd) is given by the dynamometer when the strip begins to move between the teeth. A coefficient of friction (μ) for wet enamel-steel metal of 0.176, previously calculated, is used. In this way, to measure adjustments of interproximal points we use the formula N = Fd / 0.352. Electronic experimental instruments are much more complicated to use than the instrument described here. The materials used are for daily use in any dental clinic and it is easy to use. The coefficient of friction depends on the humidity of the surface, but here the natural saliva of the patient is used as a lubricant. This simple technique allows the measurement of the fits of interproximal contact points so that dental restorations can be improved at those points.