Ultrasonic measurement of the effects of adhesive application and power density on the polymerization behavior of core build-up resins

Abstract

Objective. To use ultrasonic measurements to monitor the effects of adhesive application and power density on the polymerization behavior of dual-cured core build-up resins. Methods. Ultrasonic measurements were carried out using a pulser–receiver, transducers and an oscilloscope. The core build-up resins were mixed, inserted into a transparent mold and then placed onto a sample stage with or without self-etch adhesive. Power densities of 0 (no light irradiation), 200 and 600 mW/cm² were used for curing. The transit time through the core build-up resin disk was divided by the specimen thickness to obtain the longitudinal sound velocity (V). Results. Light irradiation of the core build-up resins at a power density of 600 mW/cm² caused V values to rise to an initial plateau of 1550–1650 m/s, then to rise rapidly to a second plateau of 2800–3200 m/s. The rate of V increase was slower when the resin cements were light-irradiated and became faster when irradiated at a higher power density. There were no significant differences between the groups with or without adhesive. Conclusions. The polymerization behavior of the core build-up resins was affected by the power density of the curing unit. The influence of adhesive application differed among the core build-up resins tested.

Key Words::

• adhesive
• core build-up resin
• polymerization
• ultrasonic sonic velocity

Acknowledgments

This work was supported, in part, by a Grant-in-Aid for Scientific Research (C) number 21592430 from the Japan Society for the Promotion of Science (JSPS). This project was also supported, in part, by the Sato Fund and by a grant from the Dental Research Centre of Nihon University School of Dentistry, Japan.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.