Flexible vs. Metal Dentures — When to Choose Which?

Why does material matter for the patient and the lab?

Denture material is not a matter of 'preference'. It's an engineering decision. The wrong material for a given clinical scenario = frequent repairs, unhappy patient, loss for the lab.

Metal Dentures — The Standard

Metal dentures are a proven standard. The metal framework (usually chrome-cobalt) is highly durable, rigid, and precise. If there is no specific reason otherwise — we choose metal.

Advantages of Metal

1. Rigidity — metal does not bend under load, the saddle performs reliably
2. Accuracy — the lab can achieve tolerances of up to 0.1 mm
3. Thermal stability — hot foods (60°C) do not deform the saddle
4. Longevity — with good cleaning, 10–15 years without problems
5. Lingual aesthetics — metal does not change color, does not "yellow"
6. Fracture resistance — metal saddles practically do not break
7. Hygiene — easy to clean, matte surface does not accumulate deposits

Disadvantages of Metal

1. Cost — 30–50% more expensive than acrylic (printing, engraving, polishing)
2. Time — 10–14 days for production (vs. 5–7 for acrylic)
3. Buccal aesthetics — if the saddle is in the smile zone, metal may be visible (instead of natural pink/tooth color)

When to recommend metal

• The patient has naturally pigmented (dark) oral mucosa — metal will stand out less
• The saddle is outside the smile zone (posterior saddles, mandibular)
• The patient has high chewing forces (bruxism, manual workers)
• The patient returns for a new denture after 5+ years — prefers to know it will last

Flexible Dentures (nylon, TPE)

Flexible dentures are a newer trend. Materials (nylon, TPE — thermoplastic elastomer) have properties similar to natural tissues.

Advantages of Flexible

1. Aesthetics — colors can be toned, "vein DNA" stained — more natural than metal
2. Flexibility — the material bends, absorbing some of the load
3. Patient comfort — patients often say "I feel more natural"
4. Missing teeth — if the patient has little residual bone (nowhere to place an abutment) — flexible material "adheres" more strongly to the mucosa
5. Allergy reduction — some patients are allergic to acrylic, flexible materials are better tolerated

Disadvantages of Flexible

1. Imprecision — tolerances of up to 0.2–0.3 mm (vs. 0.1 mm for metal)
2. Material fatigue — after 3–5 years it may start to deform, especially on saddles
3. Harder to repair — needs to be sent to the lab, cannot be quickly repaired in the clinic like acrylic
4. Stain absorption — nylon absorbs dyes from drinks, food (coffee, tea)
5. Cleaning — requires a more delicate approach (not hot water above 60°C)
6. Deterioration over time — flexible dentures require replacement every 5 years (vs. 10–15 years for metal)

When to recommend flexible

• The patient has little residual bone (little room for saddles)
• The patient has an acrylic allergy or psychological aversion to metal
• The patient wants maximum aesthetics and has the budget
• The patient has bruxism — flexibility absorbs some of the forces

Comparison of Material Properties

Costs — from clinician to patient

Laboratory (deltalabs.) margin:

• Metal: +50% vs. acrylic (more expensive material, more precise engraving)
• Flexible: +30% vs. acrylic (material, but easier processing)

Patient:

• Acrylic denture: 3,000–4,000 PLN
• Metal denture: 4,500–6,000 PLN
• Flexible denture: 4,000–5,500 PLN

If the patient considers a long-term investment, metal pays off (10+ years of use).