Your retainer is an important part of completing your orthodontic work, so take care of it and it will take care of you. Regardless of whether it's made of acrylic and wire or thermoplastic, the process for cleaning your device should be pretty much the same.
Long before bacteria and plaque build up to the point of affecting the fit, they'll cause your retainer to develop a bad odor. The best way to prevent this is to brush your retainer whenever you brush your teeth. If you don't regularly use a soft toothbrush, purchase an extra toothbrush with soft bristles to use when cleaning your retainer, so as not to scratch or damage it. Brush the device gently, and then rinse it off.
You can use toothpaste when brushing the retainer, but use a type that's considered gentle -- a harsh toothpaste may damage the appliance. Look, for example, for a toothpaste that's formulated for people who are prone to canker sores; these gentle toothpastes should be free of sodium lauryl sulfate and other strong cleansing agents that could damage the retainer [source: Bergh].
In addition to brushing your retainer, you will need to disinfect it by soaking it in a denture cleanse or a cleanser made specifically for retainers (your orthodontist can recommend the best option for you). These may contain peracetic acid or other antifungal/antibacterial agents, and you'll probably need to mix them with warm -- but never hot -- water. Thoroughly rinse the retainer with plain water before placing it back in your mouth. Do this daily if possible or once a week at the very least.
Don't ever put your retainer in the dishwasher, boiling water, the washing machine or in direct sunlight -- the heat from these sources can damage the device. If your retainer becomes cracked, or if any wires become loose, contact your orthodontist immediately.
Failing to properly care for your retainer could lengthen the period of your orthodontic treatment, so keep up with it, clean it and -- most importantly -- wear it as directed. For lots more information on oral care, check out the links on the next page.