Flowable composite materials are less filled than traditional composites. Their composition allows ease of manipulation but makes these materials susceptible to increased polymerization shrinkage and increased wear. Objective: To compare the wear and polymerization shrinkage of 4 highly-filled and 4 flowable materials. Methods: Six mm thick flat composite specimens (n=10) were prepared and polymerized with a curing light (560mW/cm2) in 2mm intervals. Specimens were mounted in brass holders and stored at 37°C. Specimens were loaded into an Alabama Wear Testing Device for 40,000 cycles at 72 Hz applying a 75N force. The test was performed with a ceramic antagonist and in a slurry of 50um PMMA beads. The volumetric and depth loss through wear of the specimens was determined using a non-contact light profilometer (Proscan 2000). Specimens (n=5) were placed into an ACUVOL volumetric shrinkage device and polymerized with a curing light (800mW/cm2). Values of shrinkage were recorded and averaged between 7 to 8 minutes following polymerization and reported as polymerization shrinkage (%vol). Data were analyzed with repeated ANOVA and post-hoc Tukey/Kramer test (p=.05). Results:
Material
| Wear depth (um) | Wear volume (mm3) | Polymerization shrinkage (%) |
Estelite Σ (Tokuyama Dental) | 39.1±19.5 | 0.005±0.003 | 1.9±0.1 |
Filtek Supreme (3M ESPE) | 45.2±15.1 | 0.021±0.014 | 1.9±.1 |
Esthet X Plus (Dentsply Caulk) | 40±8.8 | 0.008±0.001 | 3.1±0.1 |
Premise (Kerr) | 38.9±12.6 | 0.009±0.003 | 2.±0.1 |
Estelite Flow Quick (Tokuyama Dental) | 16.4±3.9 | 0.002±0.001 | 4.02±0.2 |
Filtek Supreme Plus Flow (3M ESPE) | 62.6±7.6 | 0.037±0.018 | 5.01±0.8 |
Esthet X Flow (Dentsply) | 72±21.2 | 0.019±0.007 | 5.08±0.9 |
Revolution 2 (Kerr) | 42.1±18.2 | 0.015±0.009 | 6.39±0.3 |
As expected, polymerization shrinkage was statistically greater for flowable materials. Flowable materials did not present statistically greater volumetric or depth wear. Conclusions: Clinically, flowable materials should be avoided in large restorations where extreme polymerization shrinkage could cause marginal gaps. Supported in part by a grant from Tokuyama Dental.