• Restorative Dentistry and Endodontics
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• v.43 no.1
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• pp.2.1-2.10
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• 2018

Objectives: To determine the effect of size and insertion depth of irrigation needle on the amount of apical extruded debris and the amount of penetration depth of sealer using a confocal laser scanning microscope (CLSM). Materials and Methods: Twenty maxillary premolars were assigned to 2 groups (n = 10), according to the size of needle tip, 28 G or 30 G. Buccal roots of samples were irrigated with respective needle type inserted 1 mm short of the working length (WL), while palatal roots were irrigated with respective needle type inserted 3 mm short of the WL. Prepared teeth were removed from the pre-weighed Eppendorf tubes. Canals were filled with F3 gutta-percha cone and rhodamine B dye-labeled AH 26 sealer. Teeth were transversally sectioned at 1 and 3 mm levels from the apex and observed under a CLSM. Eppendorf tubes were incubated to evaporate the irrigant and were weighed again. The difference between pre- and post-weights was calculated, and statistical evaluation was performed. Results: Inserting needles closer to the apex and using needles with wider diameters were associated with significantly more debris extrusion (p < 0.05). The position of needles and level of sections had statistically significant effects on sealer penetration depth (p < 0.05 for both). Conclusions: Following preparation, inserting narrower needles compatible with the final apical diameter of the prepared root canal at 3 mm short of WL during final irrigation might prevent debris extrusion and improve sealer penetration in the apical third.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.4
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• pp.372-377
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• 2019

Recently, as the global problem of marine debris and marine plastics is getting serious, various ways to solve them have been proposed, and the use of the biodegradable fishing gear is proposed as an alternative. Currently, 13 types of biodegradable fishing gears are available, but their penetration rate is only 8.7%. However, the need for the use of the biodegradable fishing gear is growing as awareness of protecting marine ecosystems is growing. Therefore, in this study, the economic effects of the expansion of biodegradable fishing gear distribution in Korea's coastal areas were analyzed through the conservation of marine ecosystems, augmentation of fisheries resources, and augmentation of fishing efficiency. According to the analysis, the economic effects of 52,795 million won, 105,590 million won, and 158,385 million won was generated as the distribution of biodegradable fishing gear were expanded to 10%, 20% and 30% across all gill net and trap.