• Restorative Dentistry and Endodontics
• /
• 제46권1호
• /
• pp.14.1-14.7
• /
• 2021

Objectives: The aim of this study was to evaluate the apical pressure generated by 2 endodontic irrigation needles and the GentleWave system in mandibular molars. Materials and Methods: The mesial and distal root canals of 12 mandibular molars were irrigated with a 30-gauge close-end needle or with a 30-gauge open-end needle. Procedures were performed in the mesial and distal canals. The GentleWave procedure and irrigation at 1 mm from the apex in the distal roots using an open-end needle were used, respectively, as negative and positive controls. The apical pressure was measured using a data acquisition pressure setup. Apical pressure exerted by the different needles in the 2 different canal types was statistically compared using 2-way analysis of variance. Results: Significant differences were found in the apical pressure for both needles and the canal type. The lowest values were obtained with close-end needles and in mesial canals. Negative apical pressure values were obtained using GentleWave. Conclusions: The needle and the canal type influenced the apical pressure. The GentleWave procedure produced negative apical pressure.

• Restorative Dentistry and Endodontics
• /
• 제43권1호
• /
• pp.2.1-2.10
• /
• 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.

• Korean Journal of Dental Materials
• /
• 제45권4호
• /
• pp.275-286
• /
• 2018

The purpose of this study was to evaluate the effect of needle tip design and position, and irrigant flow rate on apical pressure (AP) during root canal irrigation. Five human mandibular premolars were instrumented up to #35 (0.06 taper) using nickel-titanium rotary instruments. Three different needles according to change of needle tip design (notched, side-vented, and flat) were positioned at the point of 1, 3, and 5 mm from the apical constriction (needle tip position). For each needle tip design and position, APs were measured with varying flow rates of 0.05, 0.1, 0.2, and 0.3 ml/s. When the other conditions were controlled, AP increased with decreasing needle tip position or increasing irrigant flow rate (p<0.05). The AP of flat needle was the highest, followed by notched, side-vented needle for the same needle tip position and irrigant flow rate. The APs at needle tip position of 1 mm or with more than 0.1 ml/s flow rate were higher than central venous pressure (5.88 mmHg) for all conditions. Flat needle was not recommended for clinical use due to sharp increase of AP with changing needle tip position and irrigant flow rate. For safe and effective root canal irrigation, irrigant should be applied with the needle tip position of 3 mm and flow rate of less than 0.05 ml/s.

• Journal of Korean Society of Forest Science
• /
• 제88권1호
• /
• pp.31-37
• /
• 1999

The frequency of gall formation by pine needle gall midges ranged from 35% to 40% in both P. densiflora and P. thunbergii species. However, there was no indication of gall development from larva on both P. virgiana and P. rigida species suggesting that some specific compounds might play role in preventing gall formation of larva. The susceptible species to pine needle gall midges including P. densiflora and P. thunbergii contained a little salicylic acid under the free phenolic compound conditions while the resistant species against such insects including P. virginiana and P. rigida species contained about 37ppm to 50ppm of salicylic acid. Thus, this compound might have important roles in insect resistance. The contents of internal salicylic acid in the needles of susceptible pines increased from 9.5ppm to 20.6ppm after direct external irrigation of salicylic acid solution and flour treatment on roots. As a result, the frequency of gall formation decreased dramatically 17~19 times lower when compared with that of control. According to our results, the application of salicylic acid for effective prevention against insect damages should be performed before hatching eggs. The frequency of gall formation in the hybrid pines of P. thunbergii(susceptible) and P. virginiana(resistant) showed approximately 24% as average value of those in both species. In the case of specific individuals, it ranged from 2.8% to 11.5% in hybrids of both species. Therefore, effective production of insect resistant pines can be obtained through hybrids by crossing between susceptible and resistant species including P. thunbergii and P. virginiana by increasing internal salicylic acid contents of the needles.

• The Korean Journal of Pesticide Science
• /
• 제20권1호
• /
• pp.35-40
• /
• 2016

Recently, bacterial angular leaf spot disease, caused by Xanthomonas fragariae, causes severe damage in strawberry production and its' export to other countries, since the pathogen has been classified as an A2 quarantine pathogen. Typical the Angular Leaf Spot (ALS) disease represent that water-soaked angular spots symptoms, bacteria ooze exudate under relatively high humidity condition and later the spot become reddish brown on the leaf surface. The pathogen disseminated by irrigation water, infected mother plant and farmer's hand. In this study, we reported that rubbing inoculation method showed more effective in the pathogen dissemination than infiltration with needles, regardless the strawberry cultivars. Additionally, Dichloroisocyanurate (NaDCC) treatment in commercial strawberry fields provided reliable efficiency to reduce the bacterial angular leaf spot disease incidency and severity.