• Restorative Dentistry and Endodontics
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• v.7 no.1
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• pp.59-63
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• 1981

Ninety four human mandibular third molars were chosen to study the anatomy of the root canal. The experimental teeth were injected with china ink, decalcified, cleared and used in study, in vitro, to determine the number of root, the number of root canals, canals per root, frequency and location of transverse anastomoses, frequency and location of lateral canals and frequency of the apical deltas. The results were as follows: 1. Most of the teeth showed two canals, but 17.0% of the teeth were found to have one canal, 17.0% of them three canals, 3.2% of them four canals and l.1% of them five canals. 2. In so far as observing one canal per root, 17.0% of the teeth were found to have one canal in single-rooted tooth, 48.9% of them in mesial root and 58.5% of them in distal root. 3. In roots with two or three canals, the separated apical foramen appeared in 55.6% in single-rooted tooth, 64.3% in mesial side and 80.0% in distal side, and the common apical foramen appeared in 44.4% in single-rooted tooth, 35.7% in mesial side and 20.0% in distal side. 4. Of the two root canals in one root, 19.1% of the canals were found to have transverse anastomoses and were usually located in the apical third of the root. 5. 63.8% of 94 teeth were found to have lateral canals, and ramifications were mainly located in the apical third of the root.

• Restorative Dentistry and Endodontics
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• v.41 no.1
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• pp.68-73
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• 2016

This case report describes a unique C-shaped mandibular second premolar with four canals and three apical foramina and its endodontic management with the aid of cone-beam computer tomography (CBCT). C-shaped root canal morphology with four canals was identified under a dental operating microscope. A CBCT scan was taken to evaluate the aberrant root canal anatomy and devise a better instrumentation strategy based on the anatomy. All canals were instrumented to have a 0.05 taper using 1.0 mm step-back filing with appropriate apical sizes determined from the CBCT scan images and filled using a warm vertical compaction technique. A C-shaped mandibular second premolar with multiple canals is an anatomically rare case for clinicians, yet its endodontic treatment may require a careful instrumentation strategy due to the difficulty in disinfecting the canals in the thin root area without compromising the root structure.

• Restorative Dentistry and Endodontics
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• v.4 no.1
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• pp.23-27
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• 1978

Fifty two mandibular permanent canines were chosen to study the anatomy of the root canal. The experimental teeth were injected with China ink, decalcified, cleared and observed to investigate the number of root canals, frequency and location of lateral canals, the location of apical foramens, the frequency of apical deltas, and the curvature of root canals. The results were as follows: 1) all of the experimental teeth demonstrated single canal. 2) of the 52 canals, 9.6% of the canals were found to have lateral canals and the locations of the lateral canals were in the apical third of the roots 3) Thirty three apical foramens were located laterally on the root apices and nineteen foramens were located on the centers of the root apices. 4) 37 canals showed straight curvature, 12 canals distal curvature. 3 canals labial curvature.

• ALGAE
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• v.20 no.3
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• pp.217-224
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• 2005

The species composition and biomass of marine algae at the discharge canals of three (Gori, Wolseong and Uljin) nuclear power plants on the east coast of Korea were investigated seasonally from February 1992 to October 2000. As a result, 103-107 species of marine algae were found at the discharge canals during the past nine years. In general, algal communities established at the discharge canals were less diverse than those at the intake canals and control sites. 43 species (6 blue-green, 9 green, 10 brown and 18 red algae) of marine algae occurred more than 1/6 frequency and thus can be categorized as warm tolerant species. Among these, two green (Urospora penicilliformis, Cladophora albida), four brown (Sphacelaria divaricata, S. rigidula, Sargassum coreanum, S. fulvellum) and four red algae (Stylonema alsidii, Bangia atropurpurea, Hypnea charoides, Chondria crassicaulis) are recorded as warm tolerant marine algae for the first time in Korea during this study. Enteromorpha compressa, Padina arborescens, Amphiroa zonata and Ahnfeltiopsis flabelliformis were common species found more than 50% frequency at the discharge canals of all three nuclear power plants investigated. Dominant species in biomass were Padina arborescens and Amphiroa zonata. Results showed that, as a whole, the red algae appeared as predominant algal group at the discharge canals of all three nuclear power plants on the east coast of Korea. However, the biomass proportion of dominant algae at the discharge canals of each nuclear power plant varied over the year during the past nine years.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.75-78
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• 2015

Presented here is a case where 8 canals were located in a mandibular first molar. A patient with continuing pain in mandibular left first molar even after completion of biomechanical preparation was referred by a dentist. Following basic laws of the pulp chamber floor anatomy, 8 canals were located in three steps with 4 canals in each root. In both of the roots, 4 separate canals commenced which joined into two canals and exited as two separate foramina. At 6 mon follow-up visit, the tooth was found to be asymptomatic and revealed normal radiographic periapical area. The case stresses on the fact that understanding the laws of pulp chamber anatomy and complying with them while attempting to locate additional canals can prevent missing canals.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.193-198
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• 1984

This study was conducted to compare the chip removal capability of root canal enlarging instruments. Fifty five buccal or mesial canals from upper and lower molar teeth were randomly selected and divided into three groups; Reamer, K-type file and K-flex file. Fifteen canals in each group were individually enlarged with one of three tested instruments and irrigated with 5cc of normal saline solution. After instrumentation, each canal was dried with paper point and the canal was splited longitudinally and the cleanness of root canal surface was evaluated under stereoscope by three observers. The results were as follows; 1. Most of the canals experimented showed varying degree of the presence of debris. 2. The canals prepared with reamers showed the most clean canal surface. 3. There was no significant difference in debridement effect between k-type file and k-flexfile.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.161-171
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• 1988

The purpose of this study was to examine the morphological changes of different simulated canals according to the preparation procedures. With the use of clear casting resin, simulated straight and curved canals were created so that canal preparation procedures could be directly visualized and compared. Thirty clear polyester casting resin blocks which contained four simulated canals divided into three groups; Group A($0^{\circ}$), Group B($15^{\circ}$), and Group C($30^{\circ}$). In each block, 3 canals were prepared different preparation techniques, which were conventional method, step-back method, and giromatic filing. But, one canal was not prepared as a control group. The results were as follows: 1. There was no difference on canal shape among three canal preparation methods in straight canals (Group A). 2. When conventional method and Giromatic filing were used in curved canals (Group B, C), elbow, zip and hour-glass shape were formed in apical third. 3. When conventional method and Giromatic filing were used in curved canals (Group B, C), tear-drop appearance developed at the site of the canal exit in curved canals. 4. In curved canals (Group B, C), file tend to straighten within the canal. 5. There was no difference on canal shape according to curved angle in step-back method (p > 0.1). But there was significant difference on canal shape according to curved angle in conventional method and Giromatic filing (p < 0.001). 6. Step-back method was significantly more effective than conventional method and Giromatic preparation in morphologic aspects of apical third of original canals.

• Restorative Dentistry and Endodontics
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• v.3 no.1
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• pp.7-11
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• 1977

One hundred and thirteen human mandibular first molars were injected with china ink, decalcified, cleared and used in study, in vitro, to determine the number of root, the number of root canals, canals per root, frequency and location of transverse anastomoses, frequency and location of lateral canals and frequency of the apical deltas. The results were as follows; 1. Most of the teeth showed three canals, but 21. 25% of the teeth were found to have two canals and 21. 25% of them four canals. 2. In so far as observing two canals per root, 77.0% of teeth were found to have two canals in mesial root and 25.7% of them in distal root. 3. In roots with two canals, the separated apical foramen appeared 59.8% in mesial side and 40.0% in distal side, and the common apical foramen 40.2% in mesial side and 60.0% in distal side. 4. Of the two root canals in one root, 37.3% of the canals were found to have transverse anastomoses and were usually located in the apical third of the root. 5. 25.7% of 113 teeth were found to have lateral canals, and ramifications were mainly located in the apical third of the root.

• Restorative Dentistry and Endodontics
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• v.5 no.1
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• pp.47-51
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• 1979

Fifty two human mandibular second molars were chosen to study the anatomy of the root canal. The experimental teeth were injected with china ink, decalcified, cleared and used in study, in vitro, to determine the number of root, the number of root canals, canals per root, frequency and location of transverse anastomoses, frequency and location of lateral canals and frequency of the apical deltas. The results were as follows; 1. Most of the teeth showed three canals, but 19.2% of the teeth were found to have two canals and 9.6% of them four canals. 2. In so far as observing two canals per root, 80.8% of the teeth were found to have two canals in mesial root and 9.6% of them in distal canal. 3. In roots with, two canals, the seperated apical foramen appeared in 59.5% in mesial side and 40.0% in distal side, and the common apical foramen appeared in 40.5% in mesial side and 60.0% in distal side. 4. Of the two root canals in one root, 36.2% of the canals were found to have transverse anastomoses and were usually located in the apical third of the root. 5. 23.1% of 52 teeth were found to have lateral canals, and ramifications were mainly located in the apical third of the root.

• The Journal of the Korean dental association
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• v.41 no.5 s.408
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• pp.359-361
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• 2003

A cases report is presented describing treatment : of a mandibular first molar in which three canals were located, prepared, and obtained in the mesial root. The incidence of middle mesial canals in mandibular molars is reviewed 물 treatment considerations are described.