PMMA Biocompatibility and Soft-Tissue Response in Temporaries

PMMA has sat in mouths for 80 years, yet "PMMA" on a disc label tells you nothing about tissue response. The difference is in the monomer residue.

What makes a disc tissue-safe

Properly polymerised CAD/CAM PMMA keeps residual monomer under ~1%, which is why certified discs show negligible soft-tissue irritation in 4-week provisional studies. Cheap castable PMMA can leach far more, reddening the gingiva within days.

Chairside verification you can do

• Smell the milled blank edge — a sharp acrylic odour signals high residual monomer.
• Polish to a closed surface; an unpolished PMMA surface harbours plaque 3× more.
• Keep provisionals out of occlusion to limit flexural fatigue.

Our PMMA discs are medical-grade, colour-stable for up to 6-month provisionals, and mill with minimal chipping.

Why soft tissue tolerates PMMA

Well-polymerised PMMA releases negligible residual monomer; the gingival response tracks surface roughness, not the material itself. Keep Ra below 0.2 µm and you avoid the chronic redness that reads as an allergy.

Three checks before seat

• Confirm no tacky surface — tacky means unreacted monomer.
• Polish to a mirror finish at the margin.
• Flush with water 30 s to remove fines.

If the gingiva stays red after a polished PMMA seat, look at the margin, not the material.