• Restorative Dentistry and Endodontics
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• v.37 no.2
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• pp.68-73
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• 2012

Objectives: The purpose of this study was to assess the accuracy of Root ZX (J. Morita Corp.) according to the location of major foramen and open apex. Materials and Methods: 81 mandibular premolars with mature apices were selected. After access preparation, 27 teeth were instrumented to simulate open apices. 54 teeth were classified according to location of major foramen under surgical microscope (${\times}16$). The file was fixed at the location of apical constriction by Root ZX using glass ionomer cement .The apical 4 mm of the apex was exposed and photo was taken and the distance from file tip to the major foramen was measured by calibrating metal ruler on graph paper. The results were statistically analyzed using ANOVA and Scheffe test at p < 0.05 level. Results: Mean distance from file tip to major foramen was 0.308 mm in Tip foramen group (I), 0.519 mm in Lateral foramen group (II) and 0.932 mm in open apex group (III). Root ZX located apical constriction accurately within ${\pm}0.5mm$ in group I of 85.71%, in group II of 59.09%, and in group III of 33.33%. There was a statistically significant difference between group I and III (p < 0.05). Conclusion: Root ZX located apical constriction accurately regardless of location of major foramen. However, Root ZX couldn't find it in open apex. Clinicians have to use a combination of methods to determine an appropriate working length at open apex. It may be more successful than relying on just electronic apex locator.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.175-175
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• 2017

Agricultural Policy/Environmental eXtender Model(APEX)는 전 농장 또는 소규모 유역 관리에 활용하고자 개발된 모형이다. APEX는 사용자들을 고려하고 다양한 형태로 개발하였다. 사용자들이 사용하기 쉽도록 윈도우 인터페이스 형태의 WinAPEX 모듈을 개발하기도 하였으며, ArcGIS 프로그램과 연계하여 다양한 지리정보시스템을 사용할 수 있는 ArcAPEX 모듈을 개발하기도 하였다. 그러나 WinAPEX 모듈은 유역에 대한 정보를 시각적으로 확인할 수 없다는 단점을 가지고 있으며, ArcGIS 프로그램은 유료의 라이센스라는 단점을 보유하고 있다. 본 연구에서는 이러한 단점을 극복하기 위하여 APEX 모형을 GNU General Public License 기반의 Open Source Geographic Information System(GIS)인 Quantum GIS(QGIS)와 연계하여 QAPEX 모듈을 개발하고자 하였다. QAPEX 모듈은 오픈소스 기반의 QGIS 프로그램과 APEX 모형을 이용하여 무료로 사용할 수 있으며, 사용자의 편의를 위해 유역에 대한 정보를 시각적으로 확인할 수 있다. 뿐만아니라 QGIS는 사용자간의 정보 및 자료 공유에 용이한 장점을 보유하고 있어 QAPEX를 이용하는 사용자들 간의 정보 공유로 인해 원활하고 지속적인 개선이 이루어 질 것으로 기대된다.

• Journal of Bio-Environment Control
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• v.23 no.1
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• pp.56-59
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• 2014

Apex removal is a common practice in artichoke cultivation to harvest heads of lateral shoots. This experiment was carried out to investigate the effect of apex removal by different planting times on the growth and yield of Artichoke (Cynara scolymus L.) in open field. Two treatments (apex removal and no apex removal) at three different planting times ($1^{st}$: Sep. 27, 2011, $2^{nd}$: March 29, 2012, and $3^{rd}$: Sep. 21, 2012) were tested using 'Green Globe' variety. There was no difference in the head characteristics and the number of harvested head between the treatments. The head weight was heavier in no apex removal of 242.7 g than the apex removal of 170.8 g. The yield also increased in no apex removal by 25% (1,249 kg/10a) compared to the apex removal of 997 kg/10a at the first planting time. At the second planting time, there was no difference in the head weights between the treatments. But the number of the harvested head was higher in no apex removal with 10.8 than 8.2 of the apex removal. The yield of no apex removal was 2,660 kg/10a, which was higher than 1,848 kg/10a of apex removal. At the third planting time, the head weight increased in no apex removal with 253.5 g compared to the apex removal with 218.7 g. The yield of no apex removal was 1,405 kg/10a, which was higher than 1,148 kg/10a of the apex removal. All the tests at 3 different planting times showed that the artichoke yields were higher in no apex removal than in apex removal. Therefore, it is desirable to cultivate artichoke without removing the apex for the higher yield and labor saving in open-field cultivation in Jeju island.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.435-445
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• 2000

The purpose of this study was to compare the leakage of four different obturation techniques in conjunction with immediate apical barrier of ${\beta}$-tricalcium phosphate(TCP) in teeth with open apex. Eighty single-rooted human premolar teeth were prepared and sectioned horizontally, so maximum diameter in apex was 4mm. Apical defects that were similar to open apex, were created with #1/2 round bur and SF104R bur. The apical foramen were opened to a size 80 file extended 3mm beyond the apex. The teeth were placed into the oasis block soaked saline to simulate periapical tissue often associated with pulpless teeth and received apical barriers consisting of TCP followed by obturation using lateral condensation technique, vertical condensation technique, continuous wave technique and thermoplasticized gutta-percha injection technique. Two unobturated teeth served as positive and negative controls. Teeth were immersed in resorcinol-formaldehyde resin for S days at $4^{\circ}C$, and the resin was allowed to polymerize completely for 4 days at room temperature. Teeth were then sectioned horizontally at 1.5mm(level 1), 2.5mm(level 2) and 3.5mm(level 3) from the apex, and examined under a stereomicroscope at ${\times}40$ magnification. The photographs were taken at ${\times}40$ magnification of the filling in each level and scanned. The leakage length in tooth/resin interface was measured at each of the three levels. Each ratio of leakage was obtained by calculating the ratio of the leakage length of canal wall infiltrated with resin to the total length of the canal and was analyzed statistically(One-way ANOVA and Scheffe test). The result were as follows : 1. At the level 1, there was the least leakage in the thermoplasticized gutta-percha injection technique group(group 4), but there was statistically significant(p<0.05). 2. At the level 2, there was the least leakage in the thermoplasticized gutta-percha injection technique group(group 4), and the most leakage in the continuous wave technique group(group 3). There was statistically significant difference between the thermoplasticized gutta-percha injection technique group and the continuous wave technique group(p<0.05). 3. At the level 3, there was the least leakage in the thermoplasticized gutta-percha injection technique group(group 4), but there were no statistically significant differences between other groups(p>0.05). These results suggest that thermoplasticized gutta-percha injection technique which had 1mm apical gutta-percha matrix after the formation of TCP apical barrier, can demonstrate favorable apical sealing.

• Imaging Science in Dentistry
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• v.47 no.3
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• pp.157-164
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• 2017

Purpose: This study determined and compared the distances from the maxillary root apices of posterior teeth to the floor of the maxillary sinus, or maxillary sinus distances(MSDs), and the distances from the mandibular root apices of the posterior teeth to the mandibular canal, or mandibular canal distances(MCDs), in Thai subjects with skeletal open bite and skeletal normal bite. Materials and Methods: Pretreatment cone-beam computed tomography (CBCT) images were obtained from 30 Thai orthodontic patients (15 patients with skeletal normal bite and 15 with skeletal open bite) whose ages ranged from 14 to 28 years. The CBCT images of the patients were processed and measured using the Romexis Viewer program. The MSDs and MCDs from the root apices of the maxillary and mandibular second premolar, first molar, and second molar to the maxillary sinus floor or the mandibular canal were measured perpendicularly to the occlusal plane. The Student t test was used for comparisons between the 2 groups. Results: The greatest mean MSDs were from the root apex of the second premolars in both groups, whereas the least mean MSDs were from the mesiobuccal root apex of the second molars. The greatest mean MCDs were from the mesial root apex of the first molars, whereas the least mean MCDs were from the distal root apex of the second molars. Conclusion: There were no differences in the mean MSDs or the mean MCDs between the skeletal normal bite group and the skeletal open bite group.

• Proceedings of the KACD Conference
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• 2003.05a
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• pp.267-270
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• 2003

• Restorative Dentistry and Endodontics
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• v.42 no.1
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• pp.65-71
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• 2017

A revascularization procedure was shown to be the best alternative therapy for immature teeth with necrotic pulp and apical infection. A 12 year old female with a history of trauma to her upper central incisor and a sinus tract was referred for endodontic treatment. She was an active orthodontic patient and had undergone regenerative endodontic treatment for the past 2 years. Clinical examination revealed no response to sensibility, percussion, and palpation tests. The preoperative radiograph showed an open apex and apical rarefaction. The case was diagnosed as previously treated tooth with asymptomatic apical periodontitis. Regenerative endodontic retreatment was performed, and the case was followed for 3 years. Clinical, radiographic, and cone-beam computed tomography follow-up examination revealed an asymptomatic tooth, with evidence of periapical healing and root maturation.

• Proceedings of the KACD Conference
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• 2007.05a
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• pp.280-280
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• 2007

• Proceedings of the KACD Conference
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• 2006.05a
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• pp.237-237
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• 2006

• Restorative Dentistry and Endodontics
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• v.39 no.2
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• pp.120-125
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• 2014

Use of an apical plug in management of cases with open apices has gained popularity in recent years. Biodentine, a new calcium silicate-based material has recently been introduced as a dentine substitute, whenever original dentine is damaged. This case report describes single visit apexification in a maxillary central incisor with necrotic pulp and open apex using Biodentine as an apical barrier, and a synthetic collagen material as an internal matrix. Following canal cleaning and shaping, calcium hydroxide was placed as an intracanal medicament for 1 mon. This was followed by placement of small piece of absorbable collagen membrane beyond the root apex to serve as matrix. An apical plug of Biodentine of 5 mm thickness was placed against the matrix using pre-fitted hand pluggers. The remainder of canal was back-filled with thermoplasticized gutta-percha and access cavity was restored with composite resin followed by all-ceramic crown. One year follow-up revealed restored aesthetics and function, absence of clinical signs and symptoms, resolution of periapical rarefaction, and a thin layer of calcific tissue formed apical to the Biodentine barrier. The positive clinical outcome in this case is encouraging for the use of Biodentine as an apical plug in single visit apexification procedures.