The Process of Making Removable Dentures with PMMA

Step-by-Step Process for Fabricating Removable Dentures Using PMMA

Creating removable partial or complete dentures with polymethyl methacrylate (PMMA) involves a sequence of clinical and laboratory procedures. Each stage requires precision to ensure biocompatibility, functionality, and aesthetic appeal. Below is a detailed breakdown of the workflow.

Initial Patient Assessment and Impression Taking

The process begins with a thorough examination of the patient’s oral cavity. This includes evaluating the residual ridge anatomy, undercuts, and adjacent teeth to determine the denture’s design. Digital radiographs or scans may be used to assess bone density and identify potential complications.

Next, a primary impression is made using alginate or silicone-based materials. The impression tray must be selected carefully to avoid over- or under-extension, which could lead to an ill-fitting denture. After setting, the impression is removed gently to prevent distortion. A secondary impression with a custom tray may follow to refine the details, ensuring the final denture base conforms accurately to the oral tissues.

Articulation and Denture Base Design

Once the master cast is poured from the final impression, it is mounted on an articulator using facebow records or interocclusal registration. This step replicates the patient’s jaw movements and occlusion, guiding the placement of artificial teeth and the denture base.

The denture base outline is marked on the cast, considering factors like tissue support, esthetics, and phonetics. Retentive elements, such as clasps or precision attachments, are incorporated into the design if needed. For partial dentures, undercut areas are analyzed to ensure proper retention without compromising tissue health. The design is then transferred to a refractory cast or digital software for milling or 3D printing of the framework.

PMMA Processing and Base Fabrication

The denture base framework, often made of cobalt-chromium or resin, is positioned on the master cast. A separating medium is applied to prevent adhesion between the framework and the PMMA during processing. The PMMA resin is mixed according to the manufacturer’s guidelines, ensuring a homogeneous consistency to avoid porosity.

The resin is packed into a flask containing the framework and master cast, applying controlled pressure to eliminate air bubbles. Curing is performed in a heat-activated water bath or under specific conditions recommended by the resin supplier. Overheating or rapid cooling must be avoided to prevent warping or internal stresses. Once cured, the denture is deflasked, and excess material is trimmed using rotary instruments or hand tools.

Artificial Teeth Arrangement and Occlusal Adjustment

Artificial teeth are selected based on the patient’s age, gender, and esthetic preferences. They are positioned on the denture base using wax or digital software, aligning with the occlusal scheme determined during articulation. The teeth must be evenly spaced and harmonize with the natural dentition if present.

The wax try-in is evaluated intraorally for fit, stability, and esthetics. Adjustments are made to the tooth position or base extension as needed. After approval, the denture undergoes a second curing process to bond the teeth permanently to the PMMA base. This step ensures durability and prevents tooth dislodgement during function.

Finishing, Polishing, and Final Delivery

The denture surface is smoothed using abrasive discs or stones to remove sharp edges and rough areas. Polishing compounds are applied in stages, starting with coarse grit and progressing to fine grit, to achieve a glossy finish. This reduces plaque accumulation and enhances patient comfort.

The denture is disinfected and inspected for defects, such as cracks or voids, before delivery. During the insertion appointment, the fit is verified, and occlusal adjustments are made using articulating paper. The patient is instructed on proper cleaning techniques and scheduled for follow-up visits to address any sore spots or stability issues.

By adhering to these structured steps, dental professionals can fabricate PMMA-based removable dentures that meet functional and esthetic demands. Attention to detail at each phase minimizes errors and ensures long-term patient satisfaction.