Development of a ‘Smart’ Fluorapatite Containing Dental Composite

Objectives: The objectives of this study were to develop model dental composites incorporating fluorapatite (FA) as a secondary filler and to characterise their physical and chemical proprieties.
Methods: Experimental composites were formulated containing BisGMA/TEGMA/BisEMA and barium aluminium silicate glass as the primary filler. Synthesized fluorapatite (FA) rod-like particles were incorporated at 0 (FA0), 20 (FA20), 30 (FA30) and 40% (FA40) by mass, replacing the glass to maintain a filler content of 80wt%. A contemporary dental composite, TetricEvoCeram (TC) was used for comparison. Two-body wear, Knoop Microhardness (HK), Degree of Conversion (DC) using an ATR-FTIR spectrometer and fluoride release using the ion selective electrode method under neutral and acidic conditions were also measured. Kruskal-Wallis Test and Post Hoc Bonferroni were carried out on the data. Qualitative analysis was carried out using a 3D noncontact profilometer, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy.
Results: All experimental composites showed similar wear resistance (p>0.05) and enhanced microhardness compared to TC (p<0.05). DC for all composites ranged between 56-60% at 20s polymerisation. Under neutral condition, all FA containing groups showed similar fluoride release compared to the controls (p>0.05). Under acidic condition, FA containing groups showed higher fluoride release compared to the controls (p<0.05). Groups containing 20, 30 and 40% FA showed significantly higher fluoride release compare to 10% FA containing samples (p< 0.05).
Conclusions: Experimental dental composites were successfully produced incorporating FA as secondary filler. The addition of FA as secondary filler did not affect the wear resistance, microhardness and the degree of conversion. FA incorporation showed a promising effect for a potential “smart” fluoride releasing dental composite.