Ag 1 10kn

Five
groups of dental composites,
including the 15% TCP- and 15% TCP-G-containing BT resins, BT resin
alone, GIC, and SF, were subjected to a three-point bending mechanical
test (span = 20 mm) using a universal testing machine (AG-I 10KN,
Shimadzu, Japan) at crosshead speed = 1.00 mm/min, and the load cell
capacity was 250 N. The FS and flexural modulus (FM) were obtained
according to the ISO 4049: 2009 standard. Prior to the mechanical
tests, 16 specimens per group were prepared using a customized 2 mm ×
2 mm × 25 mm split mold. Each photocurable sample was irradiated
under a visible light-curing unit (Elipar S10, 3M ESPE, Germany) at
an averaged irradiance of 1800 mW/cm² for 2 min (1 min
each side). While the GIC samples were fabricated by following the
manufacturer’s introduction in the same mold. The setting time
of the GIC specimen was over 48 h so that the sample was completely
cured before the mechanical tests. Eight specimens in each group were
subjected to mechanical tests under dry conditions. The other eight
specimens in each group were first immersed in 30 mL of deionized
water at 37 °C for 30 days; deionized water was replaced every
week.

Repaired tendons were moistened with wet gauze prior to testing; all were subjected to linear load-to-failure testing using a tensile test machine (AG-I 10kN; Shimadzu Corp., Kyoto, Japan) (
Fig. 3). The force transducer of the machine was connected to the upper clamp. The force was recorded with a specialized software program (TRAPEZIUM; Shimadzu Corp., Kyoto, Japan). The tendon ends were tightly gripped in the upper and lower clamps. The initial distance between the clamps was 5 cm. A preload of 1 Newton (N) was applied before loading evaluation. The overhead crossbar connected to the upper clamp was advanced at a constant speed of 25 mm/min. The preload and the tendon pull rate simulated the loading of a tendon during active finger flexion.
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The distance between the stumps was monitored by a video camera that had been vertically mounted at the level of the tendon repair site. The pulling force was continuously recorded. Any force that produced gaps evident on the monitor was recorded on the display board; each such force was considered an initial gap force. Any force separating the tendon stumps by 2 mm was recorded as a 2-mm gap formation force. An external observer recorded the initial and 2-mm gap forces. The tendons were pulled until complete pullout or rupture of the sutures occurred. The ultimate strength of the repair was the peak force recorded during the test.