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Pressure and temperature changes in heat-cured acrylic resin during processing.
W F E Yau1, Y Y Cheng, R K F Clark
14F, Oral Rehabilitation, Faculty of Dentistry, The University of Hong Kong, The Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong, People's Republic of China.
Summary
Adequate clamp pressure in denture flask processing prevents acrylic resin porosity. Even with fast curing, the monomer's elevated boiling point under pressure remains higher than the processing temperature, ensuring bubble-free denture bases.
Area of Science:
- Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Dental prosthetics rely on acrylic resins for denture bases.
- Processing parameters like temperature and pressure are critical for material integrity.
- Porosity in acrylic resins can compromise denture strength and fit.
Purpose of the Study:
- To measure pressure and temperature changes during acrylic resin processing.
- To record peak temperatures during fast curing in boiling water.
- To determine the monomer's elevated boiling point under high pressure within a clamped denture flask.
Main Methods:
- A subminiature pressure transducer and thermocouple monitored resin in a standardized denture base.
- Heat-cured acrylic resin (Trevalon C) underwent long and fast curing cycles.
- Pressure and temperature data were recorded throughout polymerization.
Main Results:
- Pressure within the clamped flask peaked at 22.0 atm.
- The monomer's calculated boiling point ranged from 193°C to 228°C at measured pressures.
- Maximum resin temperature during fast curing was 131°C, below the elevated boiling point, with no observed porosity.
Conclusions:
- Acrylic resin processing temperatures remain below the monomer's elevated boiling point under sufficient clamp pressure.
- Monomer does not boil in clamped denture flasks, preventing gaseous porosity.
- Adequate clamp pressure is key to achieving bubble-free denture bases, regardless of the curing cycle used.