In Vitro Wear of Experimental Fluoride-releasing Dental Composite

Objectives: 1) to evaluate the wear resistance of an experimental fluoride-releasing composite (Expt) and compared it with a control composite and a commercial composite Venus (Heraeus Kulzer) using an in vitro three-body wear tester (Leinfelder simulator, Caulk/Dentsply); 2) to investigate the correlation between two wear measurement methods: FTSS stylus and laser scanner. Methods: The experimental and control composites were formulated using 70wt% silanized fluoroaluminosilicate filler (mean 1.3µm, Caulk/Dentsply) and 30wt% monomers (Control: BisGMA:EBPADMA:HDDMA 40:40:20, Expt: BisGMA:EBPADMA:HDDMA:F-releasing-monomer 30:30:20:20). The three composites (n=8) were placed into cylindrical cavities 4x3mm prepared in Macor cylinders (14x12mm, Ceramic Products) and light cured for 40s. The specimens were finished with 5-micron alumina slurry. The wear test was conducted using a polymer-bead slurry (15g+9ml H₂O) and 8 kg pressure for 400,000 cycles. The wear volumes and maximum wear depths were measured using a 3D profilometer (TalyScan 150, Taylor Hobson) with two scanners: FSTT stylus and laser under the same scan speed (2000 mm/s). The data were analyzed using ANOVA and Tukey's B tests. Results: (mean ± SD)

	FTSS Stylus Scanner		Laser Scanner
Materials	Max. Depth (mm)	Wear Volume (mm3)	Max. Depth (mm)	Wear Volume (mm3)
Control	0.0813 ± 0.016	0.0304 ± 0.0159	0.0873 ± 0.0091	0.0234 ± 0.0130
Expt	0.0951 ± 0.0124	0.0351 ± 0.0126	0.0901 ± 0.0050	0.0295 ± 0.0095
Venus	0.0919 ± 0.0221	0.0399 ± 0.0128	0.102 ± 0.0212	0.0358 ± 0.0126

There is no significant difference in either maximum depth or wear volume between Expt, Control, and Venus (p>>0.05). There is a significant correlation (p<0.0001) between "maximum depth" and "wear volume" using either FTSS stylus (r = 0.732) or laser scanner (r = 0.615). The FTSS stylus gives more accurate surface roughness than the laser scanner. Conclusion: the experimental fluoride-releasing composite has wear resistance similar to the control and commercial composite. Supported by the Brown Foundation.