Effect of Storage Duration on Wettability of Resin Composites

Objectives: To determine the time-dependent wettability of selected resin composites after storage in water at oral temperature (37°C) for 2 days, 4 days and 7 days.  Methods: Six specimens (d=6.0mm, h=3.6mm) each of resin composites Estelite-Σ (ES; Tokuyama), Esthet-X HD (EX; Dentsply/Caulk), Gradia Direct (GR; GC), Point 4 (PF; Kerr), and TPH³ (TP; Dentsply/Caulk) were fabricated in a stainless steel mold. The specimens (n=30 total) were polymerized against a glass slab. A 3μL drop of deionized, filtered water was dispensed onto the unpolished surfaces of the specimens within 90 min after polymerization (Day 0) in a contact angle goniometer (OCA15-Plus, Future Digital Scientific Corp.). High-resolution digital images of the axisymmetric sessile drop were recorded @ 1 frame/second for 10 min at 37±1ºC. Profiles of the drops were analyzed using the goniometer’s software to determine contact angle (θ) values using the Laplace-Young equation. After testing, the specimens were stored in ultrapure water in a bath at 37±1°C and were retested after 2-, 4- and 7-days. Contact angle values at drop placement (θ _Initial) and at time=450s (θ _Final) for each storage duration were compared using General Linear Models and Student-Newman-Keuls (SNK) tests (α=0.05).  Results: Mean ± StdDev values for θ_initial (degrees) were as follows:

 

Day	ES	EX	GR	PF	TP
0	73.47±7.10A	69.77±3.87A	70.18±8.30A	67.17±6.05A	70.48±7.19A
2	68.98±3.68A	60.62±1.65B	64.25±4.57A	65.77±5.28A	68.92±5.78A,B
4	68.50±6.02A	60.33±6.96B	61.76±2.49A	62.08±2.71A	67.32±4.53A,B
7	66.72±5.04A	59.47±2.05B	61.72±3.83A	61.46±4.27A	60.62±4.99A,B

Superscript letters in each column denote mean values that are statistically different from each other (p<0.05).

Conclusions: Mean initial contact angles of products EX and TP decreased significantly after storage in water at oral temperature for up to seven days, whereas the mean initial contact angle values remained the same for the remaining resin composites tested.  Funding: J. Dean Robertson Society, University of Oklahoma.