Difference in water accumulation patterns between solid and closed hollow obturators under a thermal cycle

Area of Science:

• Materials Science
• Biomaterials Engineering
• Prosthodontics

Background:

• Water accumulation within hollow maxillary obturators is a persistent clinical challenge.
• The role of acrylic resin porosity in this water accumulation mechanism remains unclear.
• Understanding this phenomenon is crucial for improving obturator design and patient outcomes.

Purpose of the Study:

• To investigate the influence of hollow spaces in acrylic resin obturators on water sorption under thermal cycling.
• To identify factors contributing to water accumulation within these devices.
• To differentiate between water absorption and other mechanisms of water ingress.

Main Methods:

• Fabrication of solid and hollow heat-polymerized acrylic resin spheres and hemispheres.
• Immersion of specimens in distilled water and storage at 100% relative humidity.
• Application of a 180-day thermal cycling regimen (5°C-37°C) with periodic weight measurements.

Main Results:

• 16 out of 20 closed hollow specimens exhibited no significant water accumulation.
• Specimen weight stabilized by day 90, showing increases of 1.41% (5°C) and 1.36% (37°C) for hollow specimens.
• Solid specimens showed lower weight increases (0.96% at 5°C, 0.94% at 37°C) by day 180.
• Weight fluctuations correlated with temperature changes were observed in all specimen types and conditions.

Conclusions:

• Water accumulation in closed hollow obturators is primarily linked to thermal damage, not the inherent water absorption properties of the acrylic resin.
• The porosity of the acrylic resin does not appear to be the main factor driving water accumulation.
• Findings suggest that thermal cycling can compromise the integrity of hollow obturators, leading to water ingress.