Indications for Non-metal clasp dentures (NMCD)

NMCDs have been categorized into two types; NMCDs without a metal structure (non-rigid) and the NMCDs with a metal structure (rigid).¹¹ The NMCDs in combination with a metal framework are indicated in a wide range of partially edentulous situations including those where there is a lack of posterior occlusal support.¹¹

Indications of NMCDs without a metal structure (non-rigid) include the following:¹¹

1. Interim dentures: NMCDs are often indicated as interim prostheses.^11,12 They are routinely treatment planned following tooth extraction and implant placement. The improved patient satisfaction makes them more popular compared to conventional temporary acrylic-based RDPs. In addition, fractures commonly associated with the acrylic-based RDPs are seldom reported with NMCDs.

2. Desire for superior esthetics: NMCDs with their thermoplastic resin clasps are more esthetic and less objectionable compared to RDPs with metal clasps, hence, are recommended in patients who have a high esthetic demand (Figure 1).

   Figure 1 - Esthetic thermoplastic resin clasp of NMCD

   

   Figure 1 - Esthetic thermoplastic resin clasp of NMCD

3. Missing anterior teeth: NMCDs are recommended in patients with a few anterior teeth missing not only because of their superior esthetics but also because the occlusal forces are relatively low in these areas.

4. Missing posterior teeth: NMCDs may be indicated when a few posterior teeth are missing. However, they should not be planned as definitive restorations when there is occlusal instability due to missing occlusal stops.

5. Tilted teeth: Tilted teeth may develop an associated soft tissue undercut leading to difficulty in insertion and removal of a rigid RDP. Owing to their flexibility, NMCDs are a suitable choice in these situations.

6. Large bony exostoses: NMCDs are a preferred choice when an inoperable large bony exostoses/torus is associated with the ridge because they can engage undercuts below the bony exostoses, thereby offering enhanced retention.^13,14

7. Radiotherapy: Metal-clasp retained prostheses may cause backscatter of the radiation, hence, radiolucent NMCDs are recommended for rehabilitation in patients planned for radiotherapy following jaw resective surgeries.^12,15

8. Young children: Pediatric patients with early loss of primary teeth or anomalies such as ectodermal dysplasia may accept and adapt to flexible NMCDs more easily compared to conventional temporary acrylic partial dentures.

9. Allergy: NMCDs are routinely recommended in patients with a history of metal allergy or allergy to acrylic monomers.^13,14

10. Xerostomia: NMCDs retain more moisture and provide superior patient comfort and accommodation to the denture bearing tissues compared to rigid acrylic RDPs.¹⁶

11. Systemic diseases: NMCDs are preferred in patients suffering from microstomia, scleroderma, or any other systemic conditions that cause reduced mouth opening.¹⁷

12. Patients who refuse tooth modification: NMCDs help conserve tooth structure and may be indicated in patients who refuse tooth preparation.