• The korean journal of orthodontics
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• v.26 no.4
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• pp.441-447
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• 1996

This study was carried out in order to find out the pattern of the root resorption following maxillary incisor retraction after maxillary 1st bicuspid extration in maxillary protrusion patients. For this study, thirty two patient who received orthodontic treatment were chosen. The results were as follows; 1. Of the total 192 teeth, 61 teeth(31.77%) showed no apical root loss, 64 teeth(33.33%) fell into the class "slight", 46 teeth(23.96%) fell into the class "moderate". Only 21 teeth(10.94%) were classified as "excessive". 2. No correlation was noted between the amount of apical root loss and the types of tooth movement of the maxillary central incisors. 3. The patients who were treated with standard brackets had more changes in tooth axis and less movement of root apexes, but the patients with straight brackets had less changes in tooth axis and more movement of root apexes. 4. Comparing the degree of root resorption between bracket types, patients who had used standard brackets showed more apical root loss than patients who had used straight brackets. 5. The most frequent degree of root resorption observed in standard bracket patients was second degree, followed by first degree and third degree. The most frequent degree of root resorption observed in straight bracket patients was zero degree, followed by first, second degree and third degree.

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.38.1-38.10
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• 2020

Objectives: This study aimed to evaluate vital pulp tissue removal from different endodontic instrumentation systems from root canal apical third in vivo. Materials and Methods: Thirty mandibular molars were selected and randomly divided into 2 test groups and one control group. Inclusion criteria were a positive response to cold sensibility test, curvature angle between 10 and 20 degrees, and curvature radius lower than 10 mm. Root canals prepared with Hero 642 system (size 45/0.02) (n = 10) and Reciproc R40 (size 40/0.06) (n = 10) and control (n = 10) without instrumentation. Canals were irrigated only with saline solution during root canal preparation. The apical third was evaluated considering the touched/untouched perimeter and area to evaluate the efficacy of root canal wall debridement. Statistical analysis used t-test for comparisons. Results: Untouched root canal at cross-section perimeter, the Hero 642 system showed 41.44% ± 5.62% and Reciproc R40 58.67% ± 12.39% without contact with instruments. Regarding the untouched area, Hero 642 system showed 22.78% ± 6.42% and Reciproc R40 34.35% ± 8.52%. Neither instrument achieved complete cross-sectional root canal debridement. Hero 642 system rotary taper 0.02 instruments achieved significant greater wall contact perimeter and area compared to reciprocate the Reciproc R40 taper 0.06 instrument. Conclusions: Hero 642 achieved higher wall contact perimeter and area but, regardless of instrument size and taper, vital pulp during in vivo instrumentation is not entirely removed.

• Journal of Korean Dental Science
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• v.9 no.1
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• pp.42-48
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• 2016

Prophylactic removal of impacted third molars is a common procedure in dentistry, but the necessity of routine extraction is still controversial. When impacted third molars caused severe apical root resorption of the second molars, orthodontic traction of the third molars after extraction of the damaged second molars could minimize alveolar bone defect and preserve the patient's natural teeth. By well-planned orthodontic treatment, functional occlusion was established avoiding extraction of the impacted teeth and eliminating the possibility of a large bone defect after extraction.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.413-420
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• 1992

The purpose of this study was to compare the effectiveness of hand instrumentation with K - file and ultrasonic instrumentation and irrigation system in removing pulpal debris and canal wall planing. 20 mandibular molar teeth were instrumented to size 30 K - file and 20 teeth were instrumented with ultrasonic Suprasson. And Normal Saline and 2.5% NaOCl were used as irrigation solution. All specimens were viewed at the coronal, middle, and apical third of the root canals for the evaluation of the cleaning effect under the multiview microscope. The result were as follows : 1. All of the technique and irrigation solution was effecient in the debris removal and canal wall planing at the cervical and middle thirds of the root canal. 2. All of the techniques and irrigation solutions was less efficient in the debris removal and canal planing at the apical third of the root canal. 3. The debris removal and canal wall planing was depended more on the anatomical variations of the root canal than on the techniques and irrigation solutions.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.97-105
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• 1994

The purpose of this study was to evaluate the smear layer removing efficiency of two root canal preparation techniques. Twelve single-rooted teeth were used in two groups of six each. Group 1 was biomechanically prepared by hand using a K-file with a high volume of normal saline irrigation. Group 2 was. prepared by using ultrasonically activated K-file with a constant high volume of normal saline irrigation. After the experimental procedures, each root was split saggitally. The removing efficiency of the preparation methods were assessed in terms of surface condition of the canal walls at three levels, those coronal, middle, and apical thirds. On the basis of remaining debris, presence of smear layer, and patency of dentinal tubules, each canal was evaluated according to a scale form 0 to 2. A statistical analysis was used to indicated any significant differences in surface condition between the two methods. There was no statistical significance between hand instrumentation and ultrasonic instrumentation at the cervical third but removing efficiency of ultrasonic instrumentation was superior. No statistically significant differences were obhserved for middle or apical third.

• Restorative Dentistry and Endodontics
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• v.37 no.4
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• pp.220-227
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• 2012

Objectives: The study was to compare the shaping ability of Reciproc (VDW) and WaveOne (Dentsply Maillefer) instruments compared with ProTaper, Profile and hand instrument during the preparation of simulated root canals. Materials and Methods: Five groups (n = 5) were established. Reciproc, WaveOne, ProTaper, Profile and K file (K-flexo file) were used to prepare the resin simulated canals. A series of preoperative and postoperative images were taken by a microscope and superimposed in 2 different layers. The amount of resin removed from both the inner and the outer sides of the canal was measured to the level of 10 mm from the apical tip, with a 1 mm increment. Results: The mean of resin removal from the inner canal wall was not different from the outer canal wall for Reciproc and WaveOne groups at apical third (1 - 3 mm level). There was no difference in the change of working length and maintenance of canal curvature. NiTi instruments are superior to stainless-steel K file in their shaping ability. Conclusions: Within the limitation of this present study, Reciproc and WaveOne instruments maintained the original canal curvature in curved canals better than ProTaper and Profile, which tend to transport towards the outer canal wall of the curve in the apical part of the canal.

• Restorative Dentistry and Endodontics
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• v.1 no.1
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• pp.34-38
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• 1975

Artificial canals were prepared by means of engine reamer on the slab which was made of clear acrylic resin. The shape of this canal is similar to the natural canal, the size is almost same as Kerr File No. 70, and the length is about 20mm. Sealer, Zine oxide eugenol mixture was prepared as matched to spatula test. Lentulo filler was inserted as deep as middle portion and apical one-third portion of the canal and the dental engine was driven in the speed of 1,000 and 3,000 r.p.m. in 30 seconds and 60 seconds with feeding of the sealer. The author measured the excess flow of the canal sealer from Lentulo end. Following are the results obtained from this study. 1. Lentulo insertion at the middle portion 1,000 r.p.m. in 30 seconds case: 0.21mm Same as above in 60 seconds: 0.20mm 2. Lentulo insertion at apical-thirds. 1,000 r.p.m. in 30 seconds: 0.22mm. Same as above in 60 seconds: 0.20mm. 3. Lentulo insertion at middle portion. 3,000 r.p.m. in 30 seconds: 0.14mm Same as above in 60 seconds: 0.25mm. 4. Lentulo insertion at apical-thirds, 3,000 r.p.m. in 30 seconds: 0.11mm Same as above in 60 seconds: 0.27mm.

• Journal of Plant Biotechnology
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• v.48 no.1
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• pp.44-53
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• 2021

The present work aims to study the induction of somatic embryogenesis in cork oak (Quercus suber L.) from immature zygotic embryos and young apical leaves obtained from 2-month-old seedlings through acorn germination on sterilized peat. The immature zygotic embryos were grown for 1 month on the mineral solution of MS in the presence of 4.52 µM 2,4-D and 30 g/L sucrose. They were then transferred to the same mineral solution with no added growth regulators. In the third subculture, yellow somatic embryos, characterized by two voluminous cotyledons, were differentiated from the radicle of the immature zygotic embryos. The induction of somatic embryogenesis in young leaves required a series of transfers on different culture media containing 30 g/L sucrose and 100 mg/L myo-inositol. Secondary or recurrent somatic embryogenesis occurred within the immature somatic embryo radicles after 1 month of culture on growth regulator-free medium containing WPM macronutrients, MS micronutrients, and vitamins.

• Journal of Bio-Environment Control
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• v.20 no.1
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• pp.58-61
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• 2011

This study was conducted to develop an optimal pruning method for okra production. Three pruning methods were tested including apical bud removing, one-third removing from the top of plant, and no pruning as a control with 3 kinds interval for 15 days after 2 months sowing. The growth and development of okra was better at the treatment of one-third removing of plant than the others. The number of branches was 0.7 in control, 3.7~4.0 in apical bud removing, and 3.0~6.0 in one-third removing treatment. In summary, one-third pruning of plant from the top of plant at 30 days after starting of pruning treatment, which showed the highest yield by 12,910 kg/10a.

• Animal cells and systems
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• v.6 no.1
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• pp.23-33
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• 2002

A new species, Dimorphostylis namhaedoensis (Cumacea, Diastylidae) is described on the basis of the specimens collected from southern shallow coast of Korean peninsula. The new species resembles four other species, D. asiatica, D. valida, D. hisuta and D. acroplicata, in having three apical spines on the terminal margin of the male telson and three pairs of the oblique ridges on the carapace, but are obviously distinguished from them in that the pattern of the ridges on the carapace is different and the third article of the antennular peduncle is very long in female. Furthermore, the dorsal carina of the female carapace has a row of forward spines and among the three apical spines of male telson, the median spine is much smaller than the lateral ones.