The answer to whether new dentures can be made from old dentures is yes, but the process involves copying the design rather than reusing the materials. Dentures are removable replacements for missing teeth and surrounding tissues. Over time, they need replacement due to natural wear and changes in the mouth. When a denture has a comfortable fit and pleasing appearance, a dental professional may use it as a template to create a successor. This technique, known as duplication, aims to preserve the features a patient has grown accustomed to.
Duplication vs. Recycling: Clarifying the Process
The idea of making new dentures from old ones often leads to a misunderstanding about material recycling. Dentures are typically made from a strong acrylic resin, and the process does not involve melting down the old plastic to mold a new one, as the quality and structural integrity would be compromised. Instead, the existing denture serves as a blueprint for a new device, which is fabricated using fresh, high-quality materials.
The primary objective of denture duplication is to maintain the successful aspects of the original appliance, such as the arrangement of the teeth and the contours of the polished surfaces. These features are crucial for a patient’s established speech patterns, facial aesthetics, and neuromuscular control when chewing. Duplication is particularly helpful for older patients who may struggle to adapt to a completely new shape and contour, reducing the stress associated with a replacement appliance. The process allows for minor corrections to be made while keeping the overall design familiar.
Methods Used to Create a Copy Denture
The duplication process can be achieved through both traditional analog techniques and modern digital workflows. The analog method, sometimes called the copy denture technique, involves using the original denture to create a mold or impression. This is done using a rigid container, such as a duplication flask, filled with a flexible material like alginate or silicone putty.
The old denture is carefully embedded in this material to capture its exact shape. Once the material sets, the denture is removed, leaving a detailed mold of the teeth and base. New acrylic resin is then poured into this mold to create an exact replica of the original denture. This new replica often acts as a custom impression tray, allowing the dentist to capture the current shape of the patient’s gums and underlying jaw ridge, correcting for minor fit issues.
Modern digital duplication uses computer-aided design and manufacturing (CAD/CAM) technology. The existing denture is scanned using a specialized desktop scanner or an intraoral scanner to create a three-dimensional digital file (STL file). This file contains the precise measurements and contours of the old denture.
The digital file is imported into CAD software, where a dental technician can virtually design the new denture, making necessary adjustments or improvements. The final design is sent to a manufacturing unit where the new appliance is either milled from a solid block of acrylic resin or created using a 3D printer. This digital method offers advantages in speed, precision, and the ability to easily store the digital file for future replacements.
When Old Dentures Cannot Be Used as a Template
The duplication technique is only appropriate when the existing denture is fundamentally sound and the patient is satisfied with its appearance and function. If the original denture has major flaws, simply copying it will perpetuate the problems into the new appliance. One of the most common reasons duplication is impossible is severe alveolar ridge resorption, which is the progressive shrinkage of the underlying jawbone after tooth loss.
The jawbone is a dynamic tissue that continuously remodels, and the pressure from dentures can accelerate this resorption, causing the foundation to shrink over time. If the bone has resorb significantly, the tissue-fitting surface of the old denture will no longer match the current ridge shape, rendering the original shape useless as a template. Duplicating a denture with a flawed fit would result in a new appliance that is unstable and loose.
Another serious contraindication is the loss of vertical dimension due to excessive wear of the denture teeth. Over many years, the biting surfaces of the acrylic teeth wear down, which causes the patient’s jaws to close too far, a condition known as a collapsed bite. This can lead to jaw joint issues and facial pain. Copying a denture with severely worn teeth would fail to correct this functional problem. When these significant issues exist, a complete re-fabrication using traditional methods is necessary to re-establish proper fit and function.