Disadvantages of NMCD

There are also a few disadvantages associated with NMCDs, they include:¹¹

1. Staining and degradation: The thermoplastic resin surface loses luster and becomes rough with use making it susceptible to staining and discoloration (Figure 4).^21,22

   Figure 4 - Discolored and stained NMCD

   

   Figure 4 - Discolored and stained NMCD

2. Special materials/techniques to finish and polish: NMCDs are challenging to finish and polish chairside.²⁰ They require special techniques and materials for accomplishing these procedures. Overheating of the thermoplastic resin during finishing and polishing procedures may result in material deterioration and loss of elasticity.

3. Difficult to repair/reline: Some of the thermoplastic materials (Polyamides) do not adhere to self-curing resins and are difficult to repair and reline.

4. Periodontal disease: The thermoplastic resin clasp of NMCDs covers the cervical third of the abutment tooth, the marginal gingiva, and a portion of the attached gingiva. If the area between the clasp and the dental tissues is not regularly and optimally cleaned it may lead to the development/exacerbation of caries and periodontal diseases.

5. Teeth displacement and ridge resorption: Selecting a non-rigid NMCD in situations where it is not indicated may lead to the displacement of the abutment teeth and resorption of the alveolar ridge.