Mouthpieces are made of a variety of materials, including metal, plastic, and rubber. Dishwashers use hot water, detergent, and high pressure, which can damage the material of the mouthpiece and/or its components.
Additionally, the residue left behind from detergent can alter the sound of the mouthpiece. To clean a saxophone mouthpiece, it is recommended to use a mild soap and water, and a soft cloth. Some mouthpiece manufacturers also provide specific instructions for cleaning their mouthpieces.