Restorative Dentistry & Endodontics

C-shaped root canals of mandibular second molars in a Korean population: a CBCT analysis: Hee-Sun Kim, Daun Jung, Ho Lee, Yoon-Sic Han, Sohee Oh, Hye-Young Sim; Restor Dent Endod 2018;43(4):e42. Published online November 1, 2018; DOI: https://doi.org/10.5395/rde.2018.43.e42

Abstract PDF PubReader ePub: Objectives
The purpose of this study was to investigate the C-shaped root canal anatomy of mandibular second molars in a Korean population.
Materials and Methods
A total of 542 teeth were evaluated using cone-beam computed tomography (CBCT). The canal shapes were classified according to a modified version of Melton's method at the level where the pulp chamber floor became discernible.
Results
Of the 542 mandibular second molars, 215 (39.8%) had C-shaped canals, 330 (53%) had 3 canals, 17 (3.3%) had 2 canals, 12 (2.2%) had 4 canals, and 8 (1.7%) had 1 canal. The prevalence of C-shaped canals was 47.8% in females and 28.4% in males. Seventy-seven percent of the C-shaped canals showed a bilateral appearance. The prevalence of C-shaped canals showed no difference according to age or tooth position. Most teeth with a C-shaped canal system presented Melton's type II (45.6%) and type III (32.1%) configurations.
Conclusions
There was a high prevalence of C-shaped canals in the mandibular second molars of the Korean population studied. CBCT is expected to be useful for endodontic diagnosis and treatment planning of mandibular second molars.

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The effect of different fluoride application methods on the remineralization of initial carious lesions: Seon Mi Byeon, Min Ho Lee, Tae Sung Bae; Restor Dent Endod 2016;41(2):121-129. Published online May 10, 2016; DOI: https://doi.org/10.5395/rde.2016.41.2.121

Abstract PDF PubReader ePub: Objectives
The purpose of this study was to assess the effect of single and combined applications of fluoride on the amount of fluoride release, and the remineralization and physical properties of enamel.
Materials and Methods
Each of four fluoride varnish and gel products (Fluor Protector, FP, Ivoclar Vivadent; Tooth Mousse Plus, TM, GC; 60 Second Gel, A, Germiphene; CavityShield, CS, 3M ESPE) and two fluoride solutions (2% sodium fluoride, N; 8% tin(ii) fluoride, S) were applied on bovine teeth using single and combined methods (10 per group), and then the amount of fluoride release was measured for 4 wk. The electron probe microanalysis and the Vickers microhardness measurements were conducted to assess the effect of fluoride application on the surface properties of bovine teeth.
Results
The amount of fluoride release was higher in combined applications than in single application (p < 0.05). Microhardness values were higher after combined applications of N with FP, TM, and CS than single application of them, and these values were also higher after combined applications of S than single application of A (p < 0.05). Ca and P values were higher in combined applications of N with TM and CS than single application of them (p < 0.05). They were also increased after combined applications of the S with A than after single application (p < 0.05).
Conclusions
Combined applications of fluoride could be used as a basis to design more effective methods of fluoride application to provide enhanced remineralization.

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Evaluation of apical canal shapes produced sequentially during instrumentation with stainless steel hand and Ni-Ti rotary instruments using Micro-computed tomography: Woo-Jin Lee, Jeong-Ho Lee, Kyung-A Chun, Min-Seock Seo, Yeon-Jee Yoo, Seung-Ho Baek; J Korean Acad Conserv Dent 2011;36(3):231-237. Published online May 31, 2011; DOI: https://doi.org/10.5395/JKACD.2011.36.3.231

Abstract PDF PubReader ePub: Objectives
The purpose of this study was to determine the optimal master apical file size with minimal transportation and optimal efficiency in removing infected dentin. We evaluated the transportation of the canal center and the change in untouched areas after sequential preparation with a #25 to #40 file using 3 different instruments: stainless steel K-type (SS K-file) hand file, ProFile and LightSpeed using microcomputed tomography (MCT).
Materials and Methods
Thirty extracted human mandibular molars with separated orifices and apical foramens on mesial canals were used. Teeth were randomly divided into three groups: SS K-file, Profile, LightSpeed and the root canals were instrumented using corresponding instruments from #20 to #40. All teeth were scanned with MCT before and after instrumentation. Cross section images were used to evaluate canal transportation and untouched area at 1- , 2- , 3- , and 5- mm level from the apex. Data were statistically analyzed according to' repeated nested design'and Mann-Whitney test (p = 0.05).
Results
In SS K-file group, canal transportation was significantly increased over #30 instrument. In the ProFile group, canal transportation was significantly increased after preparation with the #40 instrument at the 1- and 2- mm levels. LightSpeed group showed better centering ability than ProFile group after preparation with the #40 instrument at the 1 and 2 mm levels.
Conclusions
SS K-file, Profile, and LightSpeed showed differences in the degree of apical transportation depending on the size of the master apical file.

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The effect of several root-end filling materials on MG63 osteoblast-like cells: Jeong-Ho Lee, Won-Jun Shon, WooCheol Lee, Seung-Ho Baek; J Korean Acad Conserv Dent 2010;35(3):222-228. Published online May 31, 2010; DOI: https://doi.org/10.5395/JKACD.2010.35.3.222

Abstract PDF PubReader ePub: The purpose of this study was to compare mineral trioxide aggregate (MTA; Dentsply, Tulsa Dental, Tulsa, OK, USA), which is widely used as root-end filling material, with DiaRoot BioAggregate (DB; Innovative BioCaramix Inc, Vancouver, BC, Canada), newly developed product, by using MG63 osteoblast-like cells. MTA, DB, and Intermediate Restorative Material (IRM; Dentsply Caulk, Milford, DE, USA) were used for root-end filling material while tissue culture plastic was used for control group. Each material was mixed and, the mixtures were left to set for 24 hours. MG63 cells were seeded to each group and then they were cultured for attachment for 4 hours. Following the attachment of cells to the root-end filling material, early cellular response was observed. After another 12 hours'culture, the level of attachment between cells and material was observed and in order to identify the effect of each material to bone formation, transforming growth factor beta1 (TGFβ1) and osteocalin (OC) were estimated by using enzyme-linked immunosorbent assay (ELISA), and the amount of alkaline phosphatase (ALP) was also measured. The data were analyzed using one-way ANOVA. As a result, only at OC and the number of cells which were attached to materials, there was no statistical difference between MTA and DB. At other items, there was statistically significant difference in all groups. Although DB has not shown exactly the same cellular response like that of MTA, the number of attached cells shows that biocompatibility of the material and OC indicates bone formation rate. Therefore, if DB is used for root end filling material, it is expected to lead to similar results to MTA.

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Evaluation of canal preparation with Ni-Ti rotary files by micro computed tomography: Jeong-Ho Lee, Mi-Ja Kim, Chang-In Seok, Woo-Cheol Lee, Seung-Ho Baek; J Korean Acad Conserv Dent 2004;29(4):378-385. Published online July 31, 2004; DOI: https://doi.org/10.5395/JKACD.2004.29.4.378

Abstract PDF PubReader ePub

The purpose of this study was to compare the effects of preparation with GT files and profiles .04 in shaping of root canals and reconstruct the three-dimensional root canal system using micro computed tomography.

40 canals of the extracted human mandibular molars were used, and randomly distributed into two experimental groups. In group 1, canals were prepared by GT files. In group 2, Profiles .04. were used. Apical preparation size was #30.

For each tooth pre and post operative cross-sectional images were obtained by the micro CT at 50 micron intervals. Pre and post operative cross-sectional images of 1, 2, 3, 5, and 8mm from the apex were compared. For each section, canal area and centering ratio were determined. For each tooth pre- and post-operative root canal volume from the furcation to the apex of the roots was calculated by three-dimensional image software. Following results were obtained:

1. At 8mm from the apex, area of dentin removed by GT rotary file was significantly larger than that by Profile .04. And at the other levels there was not a significant difference.

2. There was a trend for GT rotary file to remain more centered in the canals than Profile .04 at all levels. But at 3mm level, there was a statistically significant difference.

3. In root canal volume increments after instrumentation, there was no significant difference between two groups.

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