The depth and volume of calculus removed was measured using a laser profilometer. A HeNe laser at (Model LHGR-0050, PMS Electro-Optics, Boulder, Colorado) was focused to a line onto the tooth surface using an -cylindrical lens and then scanned across the irradiated region before and after laser irradiation. The line was magnified (VMZ450i, Edmund Industrial Optics, Barrington, New Jersey) by imaging onto a charge-coupled device camera (TM-1020A-15CL, JAI, San Jose, California) oriented at 45 deg, resulting in an axial resolution of . The transverse resolution was . Depth-removal maps were found by taking the difference between three-dimensional (3-D) surface images taken before and after irradiation (as described in 21). Calculus removal rates were determined by irradiating in 5-pulse increments using a remotely operated shutter in the laser cavity. Single-pulse (S.P.) removal rates are calculated from the depth/volume removed by five laser pulses and dividing by the number of pulses, whereas the average removal rates are calculated from the total depth/volume removed. The uncertainty of the average removal rate was based on the uncertainty in the 3-D surface images. The main uncertainty arose from laser speckle and the high of the observation lens.