Allergies to Prosthetic Materials — When a Patient Cannot Tolerate the Material

Why do allergies to dentures occur?

Allergies can arise in two scenarios:

1. Residual Monomers — During acrylic production, monomers (unbound molecules) are formed. If the denture is not sufficiently heated/cured, monomers remain in the matrix and irritate the mucosa.
2. Individual Sensitivity — Rarely, a patient may have a natural sensitivity to a given material (even without monomers).

Symptoms of Denture Allergies

• Gingivitis — Gums are red, swollen, edematous.
• Burning Sensation of Mucosa — Patient reports, "I feel a burning sensation where the denture rests."
• Rash — Sometimes a small rash on the palate where the denture rests.
• Angular Cheilitis — (Mainly if the denture is too loose and moves).
• Feeling of Pressure — Swollen mucosa makes the denture feel "too foreign."

Important: These symptoms can also result from poor hygiene (fungus) — differentiation is necessary.

Prosthetic Materials and Allergy Risk

Acrylic (PMMA) — a common cause

Acrylic is the most common material for dentures. The issue with monomers (residual acrylic particles) arises when:

• The denture has not been adequately cured (time, temperature).
• The lab used cheap resin (lower quality).
• The patient has a natural sensitivity to methyl methacrylate.

What to do: Send the denture back to the lab for "finishing" — re-curing at a higher temperature (sometimes just 24 hours will solve the problem).

Metal (chrome-cobalt, titanium) — rare

Metal rarely causes allergies (unless the patient has a nickel allergy, which should not be present in good chrome-cobalt). If resistance occurs — it's more likely a hygiene problem than an allergy.

Flexible (nylon) — medium risk

Nylon/TPE occasionally cause sensitivity, but less frequently than acrylic. If a patient reacts to nylon — the only solution is to change the material.

Diagnosis — Is it really an allergy?

Before changing dentures, check:

1. Hygiene — Does the patient clean the denture daily in water/enzymatic cleaner? If not — it might be fungus/inflammation due to lack of hygiene (not an allergy).
2. Denture Age — If the denture is new (< 1 week) — there might be residual monomers (which will resolve after a week of wear + curing).
3. Denture Fit — If the denture is too loose and moves, it can irritate (not an allergy, but mechanical irritation).
4. Allergy History — Does the patient have other allergies? (If so, sensitivity is more likely).

Solutions

Material Change

If it is indeed an acrylic allergy:

• Switch to metal (chrome-cobalt) — best choice.
• Switch to nylon/flexible — sometimes works.
• Definitely avoid another acrylic denture from the same lab.

Cost: A new denture in a different material = almost the same cost as the previous one.

Denture Cleaning

The patient should:

• Clean daily with water + brush.
• 2-3 times a week with enzymatic cleaner (dissolves monomers and deposits).
• Never place in hot water (>60°C) — high temperatures can release monomers from acrylic.

Temporary Denture Removal

If symptoms are mild — sometimes removing the denture for 8 hours daily (e.g., at night, during sleep) helps. The mucosa regenerates, and symptoms may subside.