Water sorption of several bonding resins.

PURPOSES: To determine, over the period of 1 month, (a) the degree of water sorption, and (b) the change in dimension, of four bonding resins and one low viscosity resin.
MATERIALS AND METHODS: Six specimens of bonding resin (Prisma Universal Bond 3, All-Bond 2, Bondwell LC, and LB Bond from the Clearfil Liner Bond II system) and a low viscosity resin (Protect Liner F) measuring 5 mm long, 5 mm wide and 3 mm thick were made. Each specimen was weighed immediately after curing and placed in distilled water at 37 degrees C. Weights at 1, 2, 3, 7 days and 2, 3 and 4 weeks were obtained. Specimens were measured initially and at the above times. After 4 weeks, specimens were dried for 2 weeks and remeasured for size and weight. Then, the specimens were placed in a vacuum for approximately 4 hours and the weights and dimensions were remeasured. Values were converted to a mean percentage of the original dry weight and dimension and analyzed using one-way ANOVA and Fisher's PLSD test.
RESULTS: All materials absorbed most water in the first week. Prisma Universal Bond 3 stabilized within 2 days, LB Bond stabilized within the first week, whereas the remaining materials showed statistical increases in weight for 2-3 weeks (P < 0.05). After 4 weeks, LB Bond and All-Bond 2 resins demonstrated an approximate 8% weight increase, and the least increase was observed for Protect Liner F and Prisma Universal Bond 3 at about 3%. After desiccation, Protect Liner F and All-Bond 2 returned close to their original weight, and the remainder weighed less than initially. Dimensional changes were similar to changes in weight; LB Bond showed the greatest dimensional change over the 4 weeks (5%) and Protect Liner F the least change.