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Volume 36 (5); September 2011
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Review Article
Early caries detection using optical coherence tomography: a review of the literature
Young-Seok Park, Byeong-Hoon Cho, Seung-Pyo Lee, Won-Jun Shon
J Korean Acad Conserv Dent 2011;36(5):367-376.   Published online September 14, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.367
AbstractAbstract PDFPubReaderePub
Abstract

Early detection of carious lesions increases the possibility of treatment without the need for surgical intervention. Optical coherence tomography (OCT) is an emerging three-dimensional imaging technique that has been successfully used in other medical fields, such as ophthalmology for optical biopsy, and is a prospective candidate for early caries detection. The technique is based on low coherence interferometry and is advantageous in that it is non-invasive, does not use ionizing radiation, and can render three-dimensional images. A brief history of the development of this technique and its principles are discussed in this paper. There have been numerous studies on caries detection, which were mostly in vitro or ex vivo experiments. Through these studies, the feasibility of OCT for caries detection was confirmed. However, further research should be performed, including in vivo studies of OCT applications, in order to prove the clinical usefulness of this technique. In addition, some technological problems must be resolved in the near future to allow for the use of OCT in everyday practice.

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Basic Researchs
Rheological characterization of thermoplasticized injectable gutta percha and resilon
Juhea Chang, Seung-Ho Baek, In-Bog Lee
J Korean Acad Conserv Dent 2011;36(5):377-384.   Published online September 30, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.377
AbstractAbstract PDFPubReaderePub
Objectives

The purpose of this study was to observe the change in the viscoelastic properties of thermoplasticized injectable root canal filling materials as a function of temperature and to compare the handling characteristics of these materials.

Materials and Methods

Three commercial gutta perchas and Resilon (Pentron Clinical Technologies) in a pellet form were heated in the Obtura-II system (Obtura Spartan) at 140℃ and 200℃, and the extrusion temperature of the thermoplasticized materials was measured. The viscoelastic properties of the materials as a function of temperature were evaluated using a rheometer. The elastic modulus G', viscous modulus G", loss tangent tan δ, and complex viscosity η* were determined. The phase transition temperature was determined by both the rheometer and a differential scanning calorimeter (DSC). The consistency of the materials was compared under compacting pressure at 60℃ and 40℃ by a squeeze test.

Results

The three gutta perchas had dissimilar profiles in viscoelastic properties with varying temperature. The phase transition of softened materials into solidification occurred at 40℃ to 50℃, and the onset temperatures obtained by a rheometer and a DSC were similar to each other. The onset temperature of phase transition and the consistency upon compaction pressure were different among the materials (p < 0.05). Resilon had a rheologically similar pattern to the gutta perchas, and was featured between high and low-flow gutta perchas.

Conclusions

The rheological characteristics of the thermoplasticized root canal filling materials changed under a cooling process. The dissimilar viscoelastic properties among the materials require different handling characteristics during an injecting and compacting procedure.

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The effects of total-etch, wet-bonding, and light-curing of adhesive on the apical seal of a resin-based root canal filling system
Won-Il Ryu, Won-Jun Shon, Seung-Ho Baek, In-Han Lee, Byeong-Hoon Cho
J Korean Acad Conserv Dent 2011;36(5):385-396.   Published online September 30, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.385
AbstractAbstract PDFPubReaderePub
Objectives

This study evaluated the effects of adhesion variables such as the priming concepts of canal wall and the curing modes of adhesives on the sealing ability of a resin-based root canal filling system.

Materials and Methods

Apical microleakage of the Resilon-RealSeal systems filled with 3 different combinations of adhesion variables was compared with the conventional gutta-percha filling using a dye penetration method. Experimental groups were SEDC, Resilon (Resilon Research LLC) filling with self-etch RealSeal (SybronEndo) primer and dual-cure RealSeal sealer; NELC, Resilon filling with no etching, Scotchbond Multi-Purpose (3M ESPE) primer application and light-curing adhesive; and TELC, Resilon filling with Scotchbond Multi-Purpose primer and adhesive used under total etch / wet bonding and light-cure protocols. GPCS, gutta-percha filling with conventional AH26 plus sealer, was the control group.

Results

The median longitudinal dye penetration length of TELC was significantly shorter than those of GPCS and SEDC (Kruskal-Wallis test, p < 0.05). In the cross-sectional microleakage scores, TELC showed significant differences from other groups at 2 to 5 mm from the apical foramen (Kruskal-Wallis test, p < 0.05).

Conclusions

When a resin-based root canal filling material was used, compared to the self-etching primer and the dual-cure sealer, the total etch/wet-bonding with primer and light-curing of adhesive showed improved apical sealing and was highly recommended.

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Comparison of gene expression profiles of human dental pulp cells treated with mineral trioxide aggregate and calcium hydroxide
Yong-Beom Kim, Won-Jun Shon, Woocheol Lee, Kee-Yeon Kum, Seung-Ho Baek, Kwang-Shik Bae
J Korean Acad Conserv Dent 2011;36(5):397-408.   Published online September 14, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.397
AbstractAbstract PDFPubReaderePub
Abstract Objectives:

This study investigated changes in gene expressions concerning of differentiation, proliferation, mineralization and inflammation using Human-8 expression bead arrays when white Mineral Trioxide Aggregate and calcium hydroxide-containing cement were applied in vitro to human dental pulp cells (HDPCs).

Materials and Methods:

wMTA (white ProRoot MTA, Dentsply) and Dycal (Dentsply Caulk) in a Teflon tube (inner diameter 10 mm, height 1 mm) were applied to HDPCs. Empty tube-applied HDPCs were used as negative control. Total RNA was extracted at 3, 6, 9 and 24 hr after wMTA and Dycal application. The results of microarray were confirmed by reverse transcriptase polymerase chain reaction.

Results:

Out of the 24,546 genes, 43 genes (e.g., BMP2, FOSB, THBS1, EDN1, IL11, COL10A1, TUFT1, HMOX1) were up-regulated greater than two-fold and 25 genes (e.g., SMAD6, TIMP2, DCN, SOCS2, CEBPD, KIAA1199) were down-regulated below 50% by wMTA. Two hundred thirty nine genes (e.g., BMP2, BMP6, SMAD6, IL11, FOS, VEGFA, PlGF, HMOX1, SOCS2, CEBPD, KIAA1199) were up-regulated greater than two-fold and 358 genes (e.g., EDN1, FGF) were down-regulated below 50% by Dycal.

Conclusions:

Both wMTA and Dycal induced changes in gene expressions related with differentiation and proliferation of pulp cells. wMTA induced changes in gene expressions related with mineralization, and Dycal induced those related with angiogenesis. The genes related with inflammation were more expressed by Dycal than by wMTA. It was confirmed that both wMTA and Dycal were able to induce gene expression changes concerned with the pulp repair in different ways.

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Effect of Er:YAG lasing on the dentin bonding strength of two-step adhesives
Byeong-Choon Song, Young-Gon Cho, Myung-Seon Lee
J Korean Acad Conserv Dent 2011;36(5):409-418.   Published online September 30, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.409
AbstractAbstract PDFPubReaderePub
Objectives

The purpose of this study was to compare the microshear bond strength (µSBS) and bonding interfaces of two-step total-etching and self-etching adhesive systems to three etch types of dentin either the acid etched, laser etched or laser and acid etched.

Materials and Methods

The occlusal dentinal surfaces of thirty human molars were used. They were divided into six groups: group 1, 37% H3PO4 + Single Bond 2 (3M ESPE); group 2, Er:YAG laser (KEY Laser 3, KaVo) + Single Bond 2; group 3, Er:YAG laser + 37% H3PO4 + Single Bond 2; group 4, Clearfil SE Primer + Bond (Kuraray); group 5, Er:YAG laser + Clearfil SE Bond; group 6, Er:YAG laser + Clearfil SE Primer + Bond. The samples were subjected to µSBS testing 24 hr after bonding. Also scanning microscopic evaluations were made on the resin-dentin interfaces of six specimens.

Results

The µSBS of group 2 was significantly lower than that of groups 1 and 3 in Single Bond 2 (p < 0.05). There were significant differences among the uSBS of groups 4, 5, and 6 in Clearfil SE Bond (p < 0.05). Very short and slender resin tags were observed in groups 2 and 5. Long and slender resin tags and lateral branches of tags were observed in groups 3 and 6.

Conclusions

Treatment of dentin surface using phosphoric acid or self-etching primer improved the adhesion of Er:YAG lased dentin.

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Microtensile bond strength of resin inlay bonded to dentin treated with various temporary filling materials
Tae-Woo Kim, Bin-Na Lee, Young-Jung Choi, So-Young Yang, Hoon-Sang Chang, Yun-Chan Hwang, In-Nam Hwang, Won-Mann Oh
J Korean Acad Conserv Dent 2011;36(5):419-424.   Published online September 30, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.419
AbstractAbstract PDFPubReaderePub
Objectives

This study was aimed to determine the effects of temporary sealing materials on microtensile bond strength between resin-coated dentin and resin inlay and to compare the bonding effectiveness of delayed dentin sealing and that of immediate dentin sealing.

Materials and Methods

The teeth were divided into 4 groups: group 1, specimens were prepared using delayed dentin sealing after temporary sealing with zinc oxide eugenol (ZOE); group 2, specimens were prepared using immediate dentin sealing and ZOE sealing; group 3, specimens were prepared using immediate dentin sealing and Dycal (Dentsply) sealing; group 4, specimens were prepared using immediately sealed, and then temporarily sealed with a resin-based temporary sealing material.

After removing the temporary sealing material, we applied resin adhesive and light-cured. Then the resin inlays were applied and bonded to the cavity with a resin-based cement. The microtensile bond strength of the sectioned specimens were measured with a micro-tensile tester (Bisco Inc.). Significance between the specimen groups were tested by means of one-way ANOVA and multiple Duncan's test.

Results

Group 1 showed the lowest bond strength, and group 4 showed the highest bond strength (p < 0.01). When temporary sealing was performed with ZOE, immediate dentin sealing showed a higher bonding strength than delayed dentin sealing (p < 0.01).

Conclusions

Based on these results, immediate dentin sealing is more recommended than delayed dentin sealing in bonding a resin inlay to dentin. Also, resin-based temporary sealing materials have shown the best result.

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The effects of short-term application of calcium hydroxide on dentin fracture strength
Eun-Jung Shin, Yeong-Joon Park, Bin-Na Lee, Ji-Hyun Jang, Hoon-Sang Chang, In-Nam Hwang, Won-Mann Oh, Yun-Chan Hwang
J Korean Acad Conserv Dent 2011;36(5):425-430.   Published online September 30, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.425
AbstractAbstract PDFPubReaderePub
Objectives

This in vitro study investigated whether short-term application of calcium hydroxide in the root canal system for 1 and 4 wk affects the fracture strength of human permanent teeth.

Materials and Methods

Thirty two mature human single rooted mandibular premolars in similar size and dentin thickness without decay or restorations were hand and rotary instrumented and 16 teeth vertically packed with calcium hydroxide paste and sealed coronally with caviton to imitate the endodontic procedure and the other 16 teeth was left empty as a control group. The apicies of all the samples were sealed with resin, submerged in normal saline and put in a storage box at 37℃ to mimic the oral environment. After 1 and 4 wk, 8 samples out of 16 samples from each group were removed from the storage box and fracture strength test was performed. The maximum load required to fracture the samples was recorded and data were analysed statistically by the two way ANOVA test at 5% significance level.

Results

The mean fracture strengths of two groups after 1 wk and 4 wk were similar. The intracanal placement of calcium hydroxide weakened the fracture strength of teeth by 8.2% after 4 wk: an average of 39.23 MPa for no treatment group and 36.01 MPa for CH group. However there was no statistically significant difference between experimental groups and between time intervals.

Conclusions

These results suggest that short term calcium hydroxide application is available during endodontic treatment.

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Case Report
A maxillary canine with two separated root canals: a case report
Dong-Ryul Shin, Jin-Man Kim, Duck-Su Kim, Sun-Young Kim, Paul V Abbott, Sang-Hyuk Park
J Korean Acad Conserv Dent 2011;36(5):431-435.   Published online September 30, 2011
DOI: https://doi.org/10.5395/JKACD.2011.36.5.431
AbstractAbstract PDFPubReaderePub

Maxillary canines have less anatomical diversities than other teeth. They usually have a single root and root canal. This report describes an endodontic treatment of a maxillary canine with two separated root canals which have not been reported through the demonstration of radiography and computerized tomography (CT).

Even though appropriated endodontic treatment has been performed, the severe pain could happen due to lack of consideration of anatomical variations of the teeth. Therefore, the clinicians should be well aware of the possibility of anatomical variations in the root canal system during endodontic treatment even if the number of root canals is obvious such as in this case.

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