Laser interferometric method for measuring linear polymerization shrinkage in light cured dental restoratives

Area of Science:

• Biomaterials Science
• Optical Metrology
• Dental Materials

Background:

• Dental restorative materials undergo polymerization shrinkage, which can lead to marginal gaps and secondary caries.
• Accurate monitoring of this shrinkage is crucial for developing improved dental materials.

Purpose of the Study:

• To demonstrate a novel laser interferometric method for monitoring linear polymerization shrinkage in dental restoratives.
• To evaluate the feasibility of using interferometry to measure contraction in light-cured dental materials.

Main Methods:

• Utilized a Helium-Neon laser and a custom Michelson interferometer setup.
• Employed amplified photodiode detectors and a computer data acquisition system.
• Measured percent linear contraction in five commercial light-cured restorative systems.

Main Results:

• Collected 5-minute interferometric curing profiles for each restorative material.
• Converted interferograms into percent linear contraction profiles, revealing shrinkage kinetics.
• Observed overall percent linear contraction that favorably compares with existing literature data.

Conclusions:

• Interferometry provides a sensitive, accurate, and self-calibrating method for measuring polymerization contraction.
• High acquisition rates allow real-time characterization of rapid photopolymerization reactions.
• The apparatus is low-cost, easy to use, and advantageous over conventional methods.