Mechanical Properties and ion Release of a Fluoride-Releasing Resin Composite

Objectives: Despite the satisfactory clinical longivity, currenlty commercially available resin composites are technique-sensitive, lack of biomineralisation mechanism and experience secondary caries. Resin composites with thearaputic ion release inbihiting bacterial growth and the ability of promoting remineralisation are therefore highly desireable. This project aimed to investigate the degree of conversion, surface hardness and ion release of a newly formulated fluoride-releasing resin composite (FRC).
Methods: A newly formulated fluoride-releasing resin composite FRC and Tetric EvoCeram® Bulk Fill (Tec) were used in the present study. Real time degree of conversion (DC) upto 24h was monitored using Fourier Transform Infrared Spectroscopy. Post-irradiance hardness measured by a Vickers indenter. Ion release profile (upto 60d) was evaluated using a fluoride ion selective electrode and an inductively coupled plasma–optical emission spectroscopy.
Results: FRC can be both self- or light-cured with a DC_FRC24 approaching 71.6 % (higher than DC_Tec24). The mean DC_{2 h post-cure} of Tec and FRC are 92.8 % and 98.2 % of the mean DC_{24 h post-cure.} Self-cured FRC possesses similar DC with light-cured FRC. The mean DC_{2 h post-cure} of self-cured and light-cured FRC are 96.8 % and 98.2 % of the mean DC_FRC24. The Vickers hardness of Tec and FRC immediately and 24 hours after polymerisation at the top surface are higher than the bottom surface. Besides, the Vickers hardness of Tec and FRC at both top surface and bottom surface increased with increasing post cure time. Fluoride and calcium release were only found in FRC that increased steadily with immersion time.
Conclusions: Technical-insensitive FRC showed better DC, surface hardness compared to a market leading resin composite. FTC also offers sustainable fluoride and calcium release that may promote remineralisation of fluorapatite in an oral enviroment and inhibit plague bacterial in acid production indicating that the new FRC can be a promising restorative material.