• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.190-199
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• 1991

The purpose of this study was to evaluate the antimicrobial effect of root canal cements such as AH-26, Sealapex, Canals and Apatite root sealers(Type I, II, III) and to determine the efficacy of their activities. S.mutans(AHT), S.sanguis(NCTC 9811) and B.gingivalis(381) were streaked on blood agar and the PVC tybes filled with root canal cements were applied on. Then the microorganisms were cultured for 48 hours, anaerobically. B.cereus(KCTC 1012) was streaked on nutrient agar, PVC tubes were applied on and were cultured for 48 hours, aerobically. The inhibition zones of root canal cements were measured with vernier caliper. The data statistically analyzed, and the results were as followed. 1. Apatite root sealers(Type I, II, III) showed no inhibition zones. 2. AH-26, Sealapex and Canals had inhibition zones with varying degrees. The inhibition zone of AH-26 was greatest and followed by Canals and Sealapex(P<0.01). 3. As time goes by after mixing the root canal cements, AH-26, Canals and Sealapex showed significantly reducing inhibition zones(P<0.01). 4. There were the least inhibition zones of all the root canal cements on S.mutans and followed in such order as; B.gingivalis, S.sanguis and B.cereus(P<0.01).

• Restorative Dentistry and Endodontics
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• v.38 no.3
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• pp.172-177
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• 2013

The mesiobuccal root of the maxillary molars is well known to pose a hindrance during endodontic therapy. Presented here is a case of a maxillary left second molar where three canals were located in its mesiobuccal root with the use of visual and diagnostic aids. Difficulties encountered during the process of unveiling the tooth's internal anatomy were discussed. The dilemmas encountered pertained to the root canal configuration, the nomenclature of the extra canals, and the justification for the presence of a third canal. The root canal configuration of 3-2-1 was confirmed for the mesiobuccal root using information gained from clinical, radiographic, and multidetector computed tomography (MDCT) scan findings. This case demonstrates the need for efforts to locate extra canals in the mesiobuccal root of the maxillary molars as their internal anatomy remains a mystery.

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.34.1-34.7
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• 2020

Objectives: This study evaluated by using micro-computed tomography (micro-CT) the filling ability and sealer apical extrusion promoted by a new Sealer Injection System (SIS; Angelus) with side openings needle, in comparison with the conventional injection system, associated with a new ready-to-use calcium silicate-based sealer (Bio-C Sealer). Materials and Methods: Acrylic resin models containing a main curved artificial canal and 3 simulated lateral canals in apical, middle and cervical thirds were used. The main root canals were prepared using a rotary system up to size 35.05. The canals were filled with Bio-C sealer by using a single cone technique and the conventional delivery system or SIS. Samples were scanned in micro-CT. The percentage of voids throughout the entire extension of the main root canal and in each third of the lateral canals, besides the apical extrusion of the sealer was calculated. Data were submitted to t-test (p < 0.05). Results: There was no difference between both systems in the main root canals filling. Although the volume percentage of voids was similar in the apical and middle thirds of lateral canals, SIS had the greatest filling ability of the cervical third lateral canal. Moreover, the conventional system showed the highest apical extrusion of the sealer. Conclusions: The conventional and SIS obturation systems had an appropriate filling ability of the main root canal. SIS had the best filling of the cervical third of the lateral canals, besides lower sealer apical extrusion, suggesting its clinical indication.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.241-248
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• 2015

Variation in root canal morphology, especially in maxillary first molar presents a constant challenge for a clinician in their detection and management. This case report describes the successful root canal treatment of a three rooted right maxillary first molar presenting with three canals each in the mesiobuccal and distobuccal roots and one canal in the palatal root. The clinical detection of this morphologic aberration was made using a dental operating microscope, and the canal configuration was established after correlating and computing the clinical, radiographic and cone-beam computed tomography (CBCT) scan findings. CBCT images confirmed the configuration of the canals in the mesiobuccal and distobuccal roots to be Al-Qudah and Awawdeh type (3-2) and type (3-2-1), respectively, whereas the palatal root had a Vertucci type I canal pattern. This report reaffirms the importance of careful examination of the floor of the pulp chamber with a dental operating microscope and the use of multiangled preoperative radiographs along with advanced diagnostic aids such as CBCT in identification and successful management of aberrant canal morphologies.

• Restorative Dentistry and Endodontics
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• v.47 no.4
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• pp.37.1-37.9
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• 2022

Objectives: This study aimed to evaluate the prevalence of apical periodontitis (AP) in the mesiobuccal roots of root canal-treated maxillary molars. Materials and Methods: One thousand cone-beam computed tomography images of the teeth were examined by 2 dental specialists in oral radiology and endodontics. The internal anatomy of the roots, Vertucci's classification, quality of root canal treatment, and presence of missed canals were evaluated; additionally, the correlation between these variables and AP was ascertained. Results: A total of 1,000 roots (692 first molars and 308 second molars) encompassing 1,549 canals were assessed, and the quality of the root canal filling in the majority (56.9%) of the canals was satisfactory. AP was observed in 54.4% of the teeth. A mesiolingual canal in the mesiobuccal root (MB2 canal) was observed in 54.9% of the images, and the majority (83.5%) of these canals were not filled. Significant associations were observed between the presence of an MB2 canal and the quality of the root canal filling and the presence of AP. Conclusions: AP was detected in more than half of the images. The MB2 canals were frequently missed or poorly filled.

• Restorative Dentistry and Endodontics
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• v.41 no.1
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• pp.55-62
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• 2016

Objectives: The purpose of this study was to investigate the incidence of root fusion and C-shaped root canals in maxillary molars, and to classify the types of C-shaped canal by analyzing cone-beam computed tomography (CBCT) in a Korean population. Materials and Methods: Digitized CBCT images from 911 subjects were obtained in Chosun University Dental Hospital between February 2010 and July 2012 for orthodontic treatment. Among them, a total of selected 3,553 data of maxillary molars were analyzed retrospectively. Tomography sections in the axial, coronal, and sagittal planes were displayed by PiViewstar and Rapidia MPR software (Infinitt Co.). The incidence and types of root fusion and C-shaped root canals were evaluated and the incidence between the first and the second molar was compared using Chi-square test. Results: Root fusion was present in 3.2% of the first molars and 19.5% of the second molars, and fusion of mesiobuccal and palatal root was dominant. C-shaped root canals were present in 0.8% of the first molars and 2.7% of the second molars. The frequency of root fusion and C-shaped canal was significantly higher in the second molar than the first molar (p < 0.001). Conclusions: In a Korean population, maxillary molars showed total 11.3% of root fusion and 1.8% of C-shaped root canals. Furthermore, root fusion and C-shaped root canals were seen more frequently in the maxillary second molars.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.608-608
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• 2003

The main objectives of root canal therapy are cleaning and shaping and then obturating the root canal system in 3 dimensions to prevent reinfection. Many instrumentation techniques and devices, supported by an irrigation system capable of removing pulp tissue remnants and dentin debris, have been proposed to shape root canals. But current regimens in chemomechanical debridement using instrumentation and irrigation with NaOCl are not predictably effective in root canal disinfection. These findings are not surprising because the root canal system is complex and contains numerous ramifications and anatomical irregularities. The microorganisms in root canals not only invade the anatomic irregularities of the root canal system but also are present in the dentinal tubules. Therefore further disinfection with an effective antimicrobial agent may be necessary and it well1mown that use of intracanal medication will lower bacterial count in infected root canals. Calcium hydroxide has a long history of use in endodontics, and more attention has been given to the use of calcium hydroxide as intracanal dressing for the treatment of infected pulp. However, when treatment is completed in one visit, no intracanal medications other than intracanal irrigants are used. Recently, a mixture of a tetracycline isomer, an acid, and a detergent(MTAD), has been introduced as a final rinse for disinfuction of the root canal system. It has been shown that MTAD is able to remove the smear layer with minimal erosive changes on the surface of dentin, and is effective against Enterococcus faecalis, a microorganism resistant to the action of other antimicrobial medications. In another study, the ability of MTAD was investigated to disinfect contaminated root canals with whole saliva and compared its efficacy to that of NaOCl Based on the results, it seems that MTAD is significantly more effective than 5.25% NaOCl in eradicating bacteria from infected root canals. In the cytotoxicity evaluation, MTAD is less cytotoxic than engenol, 3% $H20_2,\;Ca(OH)_2$ paste, 5.25% NaGCl, Peridex, and EDTA and more cytotoxic than 2.63%,1.31% and 0.66% NaOCl. Is it promising or transient?

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.7.1-7.9
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• 2020

Objectives: This study was performed to assess the anatomy of mandibular first molars. Materials and Methods: In this in vivo study, cone-beam computed tomography (CBCT) volumes of 312 bilateral intact first mandibular molars from 156 patients (79 men and 77 women; average age, 35.6 ± 11.2 years) were investigated in terms of the direction of each canal's curvature in the buccolingual and mesiodistal dimensions (direction of the position of the apex in relation to the longitudinal axis of the root), the presence of an isthmus (a narrow, ribbon-shaped communication between 2 root canals) in 3 segments (0-2, 2-4, and 4-6 mm) from the apex), and the presence and number of accessory canals (smaller canals besides the main root canals, connecting the pulp to the periodontium). Data were analyzed statistically (α = 0.05). Results: Mesiolingual canals were mostly buccally and distally inclined, while mesiobuccal and distolingual canals were mostly distally curved. Isthmuses were more common in younger patients (χ² test, p < 0.05). The average numbers of accessory canals in the apical, middle, and coronal segments were 9.9 ± 4.2, 6.9 ± 2.9, and 9.3 ± 3.0 canals per segment, respectively (analysis of variance, p < 0.001). Age and sex were not associated with the number of accessory canals (p > 0.05). Conclusions: The complex anatomy of these teeth deserves attention during non-surgical or surgical endodontic treatment. Around the apex, isthmuses might be more prevalent in younger and female individuals.

• The Journal of the Korean dental association
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• v.45 no.6 s.457
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• pp.362-369
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• 2007

The aim of this study was to investigate the effect of the hybrid instrumentation method with ProTaper and ProFile on the change of root canal area and distance from the canal to the root surface after canal shaping. The mesial canals of twenty extracted mandibular first molars having $10-20^{\circ}\Delta$ curvature were scanned using X-ray microcomputed tomography (XMCT)-scanner before root canals were instrumented. They were divided into four groups (n=10 canals ter group). In Group 1, root canals were instrumented by the step-back technique with stainless steel K-Flexofile after coronal flaring. The remainders were instrumented by the crown-down technique with, ProTaper system (Group 2), ProFile (Group 3) or ProTaper (Group 4). All canals were prepared up to size 25 at the end-point of preparation and scanned again. Pre- and post-operative cross-sectional images of 1, 3, 5, and 7 mm from the apical foramen were compared. For each level, change of cross-sectional canal are and distance to the nearest external root surface was calculated using Adobe Photoshop 6.0 and image software program. In the change of cross-sectional area, Group 4 was less than Group 2 at 3 mm and 5 mm level (p<0.05). In the difference of the distance from the canal to the root surface after canal shaping, Group 4 was least among the other groups at 7 mm level (p<0.05). According to the results, the methods using ProFile or K file only and the hybrid instrumentation technique using ProTaper and ProFile are more appropriate methods of canal preparation than ProTaper system for narrow of curved canals.

• Imaging Science in Dentistry
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• v.44 no.2
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• pp.115-119
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• 2014

Purpose: The aim of this in vitro study was to determine the sensitivity and specificity of cone-beam computed tomography (CBCT) and digital periapical radiography in the detection of mesial root perforations of mandibular molars. Materials and Methods: In this in vitro study, 48 mandibular molars were divided into 4 groups. First, the mesial canals of all the 48 teeth were endodontically prepared. In 2 groups (24 teeth each), the roots were axially perforated in the mesiolingual canal 1-3 mm below the furcation region, penetrating the root surface ("root perforation"). Then, in one of these 2 groups, the mesial canals were filled with gutta-percha and AH26 sealer. Mesial canals in one of the other 2 groups without perforation (control groups) were filled with the same materials. The CBCT and periapical radiographs with 3 different angulations were evaluated by 2 oral and maxillofacial radiologists. The specificity and sensitivity of the two methods were calculated, and P<0.05 was considered significant. Results: The sensitivity and specificity of CBCT scans in the detection of obturated root canal perforations were 79% and 96%, respectively, and in the case of three-angled periapical radiographs, they were 92% and 100%, respectively. In non-obturated root canals, the sensitivity and specificity of CBCT scans in perforation detection were 92% and 100%, respectively, and for three-angled periapical radiographs, they were 50% and 96%, respectively. Conclusion: For perforation detection in filled-root canals, periapical radiography with three different horizontal angulations would be trustworthy, but it is recommended that CBCT be used for perforation detection before obturating root canals.