Thermoplastic whitening trays, often called boil-and-bite trays, offer a convenient and cost-effective method for at-home tooth whitening. These devices are made from a heat-sensitive polymer that softens when exposed to hot water, allowing them to be shaped precisely to the contours of your teeth and gums. Achieving an accurate, custom fit is important because the tray holds the whitening gel directly against the enamel surfaces. A poorly molded tray allows the gel to leak out, reducing efficacy and potentially irritating the surrounding gum tissue. Following instructions ensures maximum contact between the gel and the tooth surface, leading to a uniform and safer whitening experience.
Necessary Supplies and Preparation
Before beginning the molding process, gather all necessary items and prepare your workspace. You will need the thermoplastic tray, a timer for precise measurement, a pot or kettle to heat the water, and tongs or a slotted spoon for safely handling the plastic. A mirror is helpful to guide tray placement, and a large bowl of cold water must be ready to set the final shape.
Preparing your mouth is also important. Begin by thoroughly brushing your teeth to remove any debris or plaque, ensuring the tray molds against a clean tooth structure for the most accurate fit. Wash your hands and set the cold water bath next to your heating source. This quick transition prevents the tray from cooling and hardening prematurely before the fit is perfected.
Step-by-Step Guide to Molding the Trays
The molding process begins with heating the water to a temperature just below a rolling boil. Water that is too hot can cause the thermoplastic material to degrade, while water that is not hot enough will prevent the polymer from softening sufficiently. Once the water is heated, carefully submerge the tray using the tongs or spoon, ensuring it is fully immersed and the sides do not fold over. The polymer will transition from rigid to pliable, typically requiring only five to fifteen seconds.
Precision timing during this softening phase is important, as leaving the tray in the hot water for too long can cause the material to collapse or become too thin. Once the tray appears visibly pliable, remove it from the hot water and shake off the excess moisture before placing it over your teeth. Center the tray over the arch you are molding, ensuring the plastic extends up to the gum line without overlapping onto the soft tissue.
Immediately after placement, use your fingers to gently press the warm plastic against the outer (facial) surfaces of your teeth, starting from the back and moving toward the front. Simultaneously, use your tongue to apply light pressure to the inner (lingual) surfaces, helping the thermoplastic conform tightly around the tooth contours. To capture the biting surfaces, gently suck the air and moisture out of the tray while applying mild biting pressure. This pressure should be firm but not enough to cause the teeth to pierce the thin plastic.
Maintain this pressure and suction for about thirty seconds to allow the material’s temperature to drop and begin setting to the new shape. Once the tray starts to firm up, remove it from your mouth and immediately place it into the prepared bowl of cold water for at least one minute. This rapid cooling process, known as thermal setting, locks the polymer into its new, customized shape, completing the molding process.
Troubleshooting Common Molding Errors
Even with careful preparation, minor errors can occur, but the tray can often be salvaged through a re-molding attempt. One common issue is that the sides of the tray fold or collapse inward while softening, preventing the material from fitting over the arch. If this occurs, or if the initial fit is too loose, the tray can usually be reheated and reshaped one or two more times.
Another frequent problem occurs when a user bites down too hard during shaping, causing the teeth to thin or punch through the soft plastic. This excessive force compromises the integrity of the tray, creating holes that allow whitening gel to contact the gums directly. If the plastic is visibly punctured or thinned to transparency, it is safer to discard the tray and use a new one to prevent irritation.
A loose fit results from insufficient pressure or suction during the initial setting period, meaning the tray failed to capture the contours of the teeth. To correct this, reheat the tray for a slightly shorter time than the first attempt. Focus on applying firm, uniform pressure with your fingers and a strong suction with your mouth. Ensure the tray extends far enough to cover all the teeth you plan to whiten, as a short tray prevents consistent gel application. Focusing on maximum surface contact during re-molding will improve retention and efficacy.
Cleaning and Storing Your New Trays
Once the tray is successfully molded, proper hygiene and storage are necessary to maintain its shape and prolong its lifespan. After each use, clean the tray immediately to remove any residual whitening gel, saliva, or debris. Always use cool or lukewarm water for cleaning, as hot water can cause the thermoplastic polymer to soften and warp the custom shape.
A soft-bristled toothbrush is the ideal tool for gently scrubbing the interior and exterior surfaces to ensure all residue is removed. Avoid using abrasive materials, such as standard toothpaste, which can scratch the plastic surface and create areas where bacteria or gel residue can accumulate. A well-maintained thermoplastic tray can last for several months of consistent use.
After cleaning, allow the tray to air dry completely before placing it into its storage case. Storing a damp tray creates a humid environment conducive to the growth of microorganisms, which could be reintroduced to the mouth during the next session. Always keep the tray in the protective case provided to shield it from dust and physical damage when not in use.