Disclosed herein is a dental apparatus having a flexible arm for a dental apparatus. A benefit of the inventive flexible arm is the ability to make fine adjustments in orientation of one end of the arm relative to the other. More specifically, the ability to adjust or optimize the horizontal attitude of a movable end of the arm quickly and easily without resorting to expensive and time consuming remanufacture of the arm components. Adjustment of the end of the arm is accomplished via an adjusting mechanism with a rotatable shaft having an offset pin, where rotation of the shaft caused the pin to translate as defined by the offset of the pin center relative to the shaft center.