The purpose of denture adhesive is to enhance the stability and retention of a dental appliance that should already fit well. This sticky material creates a thin, flexible layer that seals the gap between the denture base and the gum tissue. This seal helps prevent food particles from intruding and provides security during speaking and eating. When the bond fails prematurely, causing the appliance to shift or loosen, the cause is usually related to the physical state of the mouth, the denture fit, or application errors.
When the Denture No Longer Fits
Denture adhesive is designed to supplement the natural suction and fit of a well-made dental plate, not compensate for a poor fit. The most frequent reason for ongoing adhesive failure is a change in the underlying oral anatomy. After natural teeth are lost, the jawbone (alveolar ridge) is no longer stimulated by the tooth roots, initiating bone resorption.
This natural, gradual shrinking of the jawbone and gum tissue alters the contours of the mouth, making the denture ill-fitting over time. A snug denture will begin to feel loose, creating larger gaps that the adhesive must fill. This increased space stresses the adhesive layer, causing it to break down faster and leading to rocking or clicking.
Signs that the appliance fit is the problem include needing to apply more adhesive with each use or emptying a tube much faster than recommended. A tube used on a properly-fitting appliance should last several weeks. If you frequently reapply the paste throughout the day, the denture likely requires professional intervention, such as a reline.
Common Mistakes in Adhesive Application
Even with a well-fitting denture, the bond can be compromised by errors in the application process. One common mistake is using an excessive amount of product, often to secure a loose denture. Too much adhesive oozes out when seated, which reduces the effectiveness of the seal and can cause discomfort.
The adhesive’s chemical bond relies on moisture, but too much water is detrimental. Applying adhesive to a denture that is still wet from cleaning interferes with the chemical reaction, weakening the initial bond. The denture should be clean and slightly moist—not soaking—to allow the adhesive to form a secure seal.
Another issue is improper cleaning, which leaves a film of old adhesive residue on the denture or gums. This old layer prevents the new application from bonding directly to the denture base, resulting in a weak hold. Furthermore, failing to allow adequate setting time—biting down immediately after insertion—disrupts the initial formation of the adhesive layer, leading to early failure.
Environmental Factors That Degrade the Bond
Once a secure bond is achieved, external factors in the mouth can act as solvents to break down the adhesive polymers. Hot liquids, such as coffee, tea, or soup, degrade the hold. The heat softens and melts the adhesive material, causing the denture to slip and requiring reapplication.
Oils and fats in food also act as a solvent to many denture adhesives. These adhesives are often composed of a zinc salt polymer susceptible to lipid breakdown. Consuming greasy foods like nuts, fatty sauces, or fried items can quickly dissolve the adhesive bond, causing the denture to loosen rapidly after a high-fat meal.
The natural environment of the mouth, regulated by saliva, is also a factor. Denture adhesives are activated by moisture, but both excessive and insufficient saliva can cause problems. While excessive saliva flow can wash away adhesive, a lack of saliva (xerostomia or dry mouth) is also detrimental. Without the necessary thin layer of moisture, the adhesive cannot properly hydrate and form the initial seal, leading to a weak hold.