• Restorative Dentistry and Endodontics
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• v.41 no.1
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• pp.6-11
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• 2016

Objectives: The purpose of this in vitro study was to evaluate the accuracy of working length (WL) determination of four electronic apex locators (EALs), namely, Root ZX (RZX), Elements diagnostic unit and apex locator (ELE), SybronEndo Mini Apex locator (MINI) and Propex pixi (PIXI) using Stainless steel (SS) and nickel-titanium (NiTi) hand files. The null hypothesis was that there was no difference between canal length determination by SS and NiTi files of 4 EALs. Materials and Methods: Sixty extracted, single rooted human teeth were decoronated and the canal orifice flared. The actual length (AL) was assessed visually, and the teeth were embedded in an alginate model. The electronic length (EL) measurements were recorded with all four EALs using SS and NiTi files at '0.5' reading on display. The differences between the AL and EL were compared. Results: The results obtained with each EAL with SS and NiTi files were compared with AL. A paired sample t test showed that there was a statistical significant difference between EAL readings with SS and NiTi files for RZX and MINI (p < 0.05). The accuracy of RZX, ELE, MINI and PIXI within ${\pm}0.5 mm$ of AL with SS/NiTi files were 93.3%/70%, 90%/91.7%, 95%/68.3%, and 83.3%/83.3%, respectively. Conclusions: The results of this study indicate that Root ZX was statistically more accurate with NiTi files compared to SS files, while MINI was statistically more accurate with SS files compared to NiTi files. ELE and PIXI were not affected by the alloy type of the file used to determine WL.

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.29.1-29.9
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• 2020

This study describes the clinical steps taken in the treatment of a patient who had an avulsed right upper central incisor that presented with incomplete root development and chronic apical periodontitis. A 7-year-old boy was referred from a private dentist to a dental office specializing in endodontics. The tooth had remained in a dry environment for 20 minutes, and tooth replantation was performed at an emergency appointment. After clinical and radiographic examinations, root canal decontamination was performed, followed by several changes in intracanal calcium hydroxide medication. Blood clot formation was attempted, but bleeding within the root canal was insufficient; therefore, we opted for an intracanal medication change to stimulate mineralized tissue formation in the apical region. Root obturation was performed 45 days after the last change of intracanal medication, and clinical, radiographic, and tomographic follow-up examinations were performed at 3, 6, 18, and 40 months after the endodontic intervention. The increase in thickness and length of the root structure and the absence of root resorption were verified through follow-up examinations. Therefore, it was concluded that the procedures used were successful for tooth replantation.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.88-95
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• 2010

The purpose of this study was to compare the root canal shaping ability of 4 rotary NiTi instruments in simulated root canals. For the preparation of thirty two curved root canals, Mtwo instruments using "single length"technique, and Profile, ProTaper Universal, and K3 using crown-down technique (N = 8) were used. All canal samples were prepared by reaching an apical canal size of #30. Pre- and post-instrumentation digital images were recorded and an assessment of canal shape was determined using a computer image analysis program SigmaScan Pro (Systat Software Inc., San Jose, CA, USA). The changes of the dimension of inner walls of canals, (2) the changes of the dimension of outer walls of canals, and (3) the centering ratio were measured at 7 measuring points, and then data were statistically analyzed using one-way ANOVA and Duncan's test. The results were as below; 1. The root canal shaping ability of Profile was significantly faster than that of other rotary NiTi instruments (p < 0.05). 2. The deformation and fracture of all instruments used for this study were not experienced. 3. In the degree of changes of the dimension of inner walls of canals, Profile demonstrated the lowest changes of the dimension of inner walls of canals except at the measuring points of the 1 and 2 mm (p < 0.05). However, the ProTaper Universal showed the highest changes of the dimension of inner walls of canals at all measuring points (p < 0.05). 4. In the degree of changes of the dimension of outer walls of canals, Mtwo demonstrated the lowest changse of the dimension of outer walls of canals except at the measuring point of the 1 mm (p < 0.05). However, Profile exhibited the highest changes of the dimension of outer walls of canals at the measuring points of 3 and 4 mm and ProTaper Universal and K3 showed the largest changes of the dimension of outer walls of canals at the measuring points of 1, 2, 6, and 7 mm (p < 0.05). 5. In degree of centering ratio, Profile demonstrated the least centering ratio comparing with the centering ratio shown by other NiTi instruments at the measuring points of 1, 4, 5, and 6 mm. Results suggest that in the coronal part of canal preparation, active cutting files such as ProTaper Universal may efficiently flare the canal orifice and form a better taper, and in the apical part of the canal, files which have a better centering ability such as Profile may maintain the original canal curvature and reduce the shaping time.

• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.361-370
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• 2002

The aim of this study was to analyze various data of 120 non-submerged ITI implants placed in 64 korean adults. The data were retrieved from patients' charts and registered in the computer and coded for a statistical analysis. The results revealed that the most common type of edentulism was a distal extension case, and the largest number of implants were placed in the mandibular first molar position. Implants were placed more frequently in mandibular, posterior position than maxillary, anterior position, respectively. With respect to the implant diameter and length, an implant with 4.1mm in diameter and more than 10mm in length was the most common. Since a molar position was the most prevalent position for implant placement in korean patients, clinicians should be careful about implant diameter which can resist a strong occlusal force expected in the molar position. In addition, the distance to the mandibular canal and the floor of maxillary sinus should be considered to avoid possible damages, such as nerve injury and sinus perforation in selecting a proper implant length.

• Restorative Dentistry and Endodontics
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• v.35 no.6
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• pp.429-435
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• 2010

Objectives: The aim of this study was to investigate average working lengths of Korean posterior teeth and evaluate validity of endodontic file length. Materials and Methods: The endodontic working length of the posterior teeth of 670 Korean patients were measured than each mean value and standard deviation were investigated than the frequency deviation and standard deviation per each length were calculated. Results: Among the canals of premolar, 66.5% of canal length was marked under 20 mm by endodontic working length and 95.4% could be measured under 22 mm and Among the canals of molars, 95.5% of canal length was marked under 20 mm endodontic working length. Conclusions: With the result of measurement of endodontic working length of premolars of Korean, it suggested that 23 mm endodontic file is more proper than the 21 mm and 25 mm file on the market.

• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.180-187
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• 2011

Introduction: Eliminating the residual debris and bacteria in the root canal system is one of the main purposes of the endodontic treatment. However, the complexity on the anatomy of the root canal system makes it difficult to eliminate the bacterial biofilm existing along the root canal surface and necrotic pulp tissue by mechanical instrumentation and chemical irrigation. Recently, more effective irrigant delivery systems for root canal irrigation have been developed. The purpose of this review was to present an overview of root canal irrigant delivery techniques and devices available in endodontics. Review: The contents of this paper include as follows; - syringe-needle irrigation, manual dynamic irrigation, brushes - sonic and ultrasonic irrigation, passive ultrasonic irrigation, rotary brush, RinsEndo, EndoVac, Laser Conclusion: Though technological advances during the last decade have brought to fruition new agitation devices that rely on various mechanisms, there are few evidence based study to correlate the clinical efficacy of these devices with improved outcomes except syringe irrigation with needle and ultrasonic irrigation. The clinicians should try their best efforts to deliver antimicrobial and tissue solvent solutions in predictable volumes safely to working length.

• Restorative Dentistry and Endodontics
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• v.27 no.5
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• pp.521-529
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• 2002

The purpose of this study was to compare the shaping time of two shaping methods and the leakage of three different obturation techniques. Ninty three canaled human molar teeth were used, which were randomly divided into two groups of forty teeth each and ten control teeth. After working length determination, the one group was prepared crown-down technique using rotary root canal instruments of GT rotary files .12/20, .10/20, .08/20 and .06/20 taper(Maillefer Instrument SA. Switzerland). The other group was instrumented with Gates Glidden burs(#1, #2, and #3) to coronal preparation and GT rotary files .08/20 and .06/30 taper to apical preparation. Shaping time was measured. After root canals were instrumented, they were divided to three subgroups and obturated as follows : Subgroup 1, obturated with single cone method Subgroup 2, obturated with lateral condensation : Subgroup 3, obturated with continuous wave technique. Three subgroups were obturated using non-standardized gutta-percha cone(Diadent, Korea, .06 or .08 taper) and AH-26(Dentsply DeTrey, Germany) as a root canal cement. Ten unobturated teeth served as positive and negative controls. After immersion in 2% methylene blue solution for 1 month, the teeth were washed during 24h. The teeth were demineralized in 10% nitric acid and dehydrated by immersion in 80, 90 and 100% ethyl alcohol. The teeth were finally cleared and stored in 100% methylsalicylate, and apical dye penetration was evaluated under stereomicroscope(Leica M420, LC, U.S.A)at $\times$8.75 magnification. Liner measurement of dye penetration was assessed with the use of digitalized image analysing system (analySIS, GmbH, Germany) The data were analysed statistically using independent T-test and Two-way ANOVA and Tukey test. The result were as follows 1. In canal prepared with GT$^{TM}$ rotary file, shaphing time taked more than the group of using Gates Glidden drill to coronal preparation without statistical significance (p>0.05) 2. The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files showed significantly more apical leakage than those of lateral condensation and continuous wave technique regardless of shaping method (p<0.05). 3 The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files and Gates Glidden drill showed significantly more apical leakage than those of continuous wave technique regardless of shaping method (p<0.05). 4. Regardless of shaping method, The group of continuous wave obturation showed less apical leakage than those of lateral condensation without statistical significance (p>0.05). 5. The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files and Gates Glidden drill showed more apical leakage than the group of lateral condensation using same shaping method with-out statistical significance (p＞0.05).

• Proceedings of the KACD Conference
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• 2008.05a
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• pp.204-212
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• 2008

The purpose of this study was to compare the apical microleakage in root canal filled with Resilon by methacrylate-based root canal sealer or 2 different self-adhesive resin cements. Seventy single-rooted extracted human teeth were sectioned at the CEJ perpendicular to the long axis of the roots with diamond disk. Canal preparation was performed with crown-down technique using Profile NiTi rotary instruments and GG drill. Each canal was prepared to ISO size 40, .04 taper and 1 mm short from the apex. The prepared roots were randomly divided into 4 experimental groups of 15 roots each and 5 roots each for positive and negative control group. The root canals were filled by lateral condensation as follows. Group 1: Gutta-percha with AH-26, Group 2: Resilon with RealSeal primer & sealer, Group 3: Resilon with Rely-X Unicem, Group 4: Resilon with BisCem. After stored in $37^{\circ}C$, 100% humidity chamber for 7 days, the roots were coated with 2 layers of nail varnish except apical 3 mm. The roots were then immersed in 1% methylene blue dye for 7 days. Apical microleakage was measured by a maximum length of linear dye penetration after roots were separated longitudinally. One way ANOVA and Scheffe's post-hoc test were performed for statistical analysis. Group 1 showed the least apical leakage and there was no statistical significance between Group 2, 3, 4. According to the results, the self adhesive resin cement is possible to use as sealer instead of primer & sealant when root canal filled by Resilon.

• Restorative Dentistry and Endodontics
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• v.33 no.3
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• pp.204-212
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• 2008

The purpose of this study was to compare the apical microleakage in root canal filled with Resilon by methacrylate-based root canal sealer or 2 different self-adhesive resin cements. Seventy single-rooted extracted human teeth were sectioned at the CEJ perpendicular to the long axis of the roots with diamond disk. Canal preparation was performed with crown-down technique using Profile NiTi rotary instruments and GG drill. Each canal was prepared to ISO size 40, .04 taper and 1 mm short from the apex. The prepared roots were randomly divided into 4 experimental groups of 15 roots each and 5 roots each for positive and negative control group. The root canals were filled by lateral condensation as follows. Group 1: Guttapercha with AH-26, Group 2: Resilon with RealSeal primer & sealer, Group 3: Resilon with Rely-X Unicem, Group 4: Resilon with BisCem. After stored in $37{\circ}C$, 100% humidity chamber for 7 days, the roots were coated with 2 layers of nail varnish except apical 3 mm. The roots were then immersed in 1% methylene blue dye for 7 days. Apical microleakage was measured by a maximum length of linear dye penetration after roots were separated longitudinally. One way ANOVA and Scheffe's post-hoc test were performed for statistical analysis. Group 1 showed the least apical leakage and there was no statistical significance between Group 2, 3, 4. According to the results, the self adhesive resin cement is possible to use as sealer instead of primer & sealant when root canal filled by Resilon.

• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.335-342
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• 2007

C-shaped canals are known to present a complex canal anatomy with numerous fins connecting individual canals, thus requiring supplementary effort to accomplish a successful root canal treatment. This study examined the frequency of the C-shaped mandibular second molars and interrelation between the clinical records and radiographs to recognize them treated in the Department of Conservative Dentistry of the Chosun University Dental Hospital during a six-year period (1998-2004). This study reviewed the clinical records of 227 patients who underwent root canal treatment of the mandibular second molars. After opening the chamber, those cases with C-shaped orifices in the pulpal floor were selected, ana the C-shaped root canal types were classified according to Melton's criteria. Three experienced dentists evaluated the radiographs of the C-shaped mandibular second molar on a viewer using a magnifying glass in order to determine if the root apex was fused or separated, the distal root canal was either centered or mesial shifted in the distal root, and if there was bilateral symmetry in a panorama. In conclusion, there is a high frequency of C-shaped mandibular second molars in Koreans. Simultaneous interpretation of the root shape and distal root canal using the preoperative, working length and post-treatment radiographs is important for diagnosing a C-shaped mandibular second molar.