A denture that no longer feels secure can be frustrating, affecting daily activities like eating and speaking. A properly fitted denture relies on a precise match with the contours of the mouth, using muscle control and natural suction to remain stable. Looseness signals that the relationship between the appliance and the underlying oral structures has changed, breaking the tight seal. This lack of retention is a common physical problem that requires professional adjustment, and understanding the specific causes is the first step toward finding a lasting solution.
Natural Changes in Jaw Structure
The primary reason a once-snug denture begins to slip is the continuous biological process known as alveolar bone resorption. Natural tooth roots provide mechanical stimulation to the jawbone whenever you bite or chew, which signals the body to maintain the bone’s density and volume. Once the teeth are removed, that stimulating force is lost, and the body interprets the bone as unnecessary material to be reabsorbed.
This jaw shrinkage, or atrophy, is a chronic and progressive event that reshapes the foundation upon which the denture rests. The most significant changes often occur rapidly, with some studies indicating a loss of up to 25% of bone height and width within the first year after extraction. Over time, the bony ridge that supports the denture becomes smaller and flatter, especially in the lower jaw, which is more susceptible to this loss.
As the underlying jaw changes shape, the rigid plastic base of the denture remains the same, leading to an increasing mismatch. This loss of fit breaks the seal necessary for suction, causing the denture to rock or shift during function. Furthermore, the pressure exerted by the denture itself on the gum tissue can accelerate the rate of bone loss, creating a cycle of worsening fit and faster structural change.
Denture Wear and External Factors
Beyond the natural changes in jaw structure, the denture appliance itself is subject to wear, and certain external factors can quickly compromise its fit. Traditional dentures are made from acrylic resin, a material that can degrade over years of constant use. The forces of biting and chewing, along with exposure to various temperatures and chemicals, cause the acrylic to weaken and wear down.
The physical structure of the denture can also be altered by improper care, such as soaking it in excessively hot water or allowing it to dry out for prolonged periods. These actions can cause the acrylic base to warp slightly, which is enough to destroy the precise fit required for stability and retention. When a denture is visibly cracked or chipped, the uneven pressure points created by the damage can lead to rapid movement and discomfort.
Another significant cause of looseness is dry mouth, or xerostomia, which is frequently a side effect of common medications or chronic health issues. Saliva is essential for denture retention because it forms a thin, adhesive film that creates the suction seal between the denture and the mouth’s moist tissues. Without enough saliva, this natural seal is lost, causing the denture to slip and rub against the gums. Rapid weight loss or gain can also affect the soft tissue and muscle contours of the face and mouth, which subtly changes the shape of the supporting structures and destabilizes the fit.
When to Seek Professional Correction
Ignoring a loose denture is strongly discouraged, as the constant friction from a moving appliance can lead to serious oral health issues. Ill-fitting dentures commonly cause painful gum irritation, chronic sores, and an increased risk of oral infections like stomatitis. The movement also accelerates the underlying bone loss by placing excessive, uneven pressure on the alveolar ridge.
When the fit is slightly off due to minor tissue changes, a procedure called relining is often the solution. This process involves adding a new layer of acrylic material to the underside of the existing denture base to precisely conform to the current shape of the gums. Relining is an efficient way to restore the seal and stability without creating an entirely new appliance.
If the denture base is structurally compromised, cracked, or has been relined multiple times, a more comprehensive procedure known as rebasing may be necessary. Rebasing involves completely replacing all the acrylic base material while keeping the artificial teeth, providing a new foundation for the existing teeth. When the teeth themselves are significantly worn down, or the jawbone loss is severe, a complete replacement of the denture is the only option to restore function and comfort. Regular check-ups allow a professional to monitor the fit and address the changes before they lead to severe complications.