The object of this study was to compare the microleakage between various composite resin systems of multistep, one-bottle, and self-etching systems using electrical conductivity.

After making class V cavities (4×3×1.5 mm around CEJ), they were bulk filled with three kinds of resins of A3. Teeth were storaged in a saline solution for one day, after then, they were finished and polished using Sof-Lex system. Another stress of thermocycling was made for 500 times from 5° to 55℃ with each dwelling time of 10 seconds. Electrical conductivity (microamphere, µA) was checked four times: before and after cavity preparation, after filling, after thermocycling.

One-way ANOVA and 95% Scheffe Post Hoc test was used for checking any statistical difference among groups. Another 95% Paired Samples T-test was also used for estimating any significant difference within group after cavity filling or thermocycling.

The results were as follows:

Every specimen showed various range of microleakage after filling.

There was, however, no difference between composite resin systems.

Within the limits of this study, it was concluded that much more consideration should be needed when using thermally unstable one-bottle and self-etching systems that have multi-advantages from simplified step. More studies will be needed to solve these kinds of problems.

Citations

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• Effect of a new resin monomer on the microleakage of composite resin restorations
  JH Bae, YK Kim, PY Yoon, MA Lee, BH Cho
  Journal of Korean Academy of Conservative Dentistry.2007; 32(5): 469.     CrossRef
• Microhardness and microleakage of composite resin cured by visible light with various band of wavelength
  Soo-Man Park, Jae-Yong Lee, Seung-Ryul Han, Sang-Yoon Ha, Dong-Hoon Shin
  Journal of Korean Academy of Conservative Dentistry.2002; 27(4): 403.     CrossRef

Mechanical properties and microleakage of two composites [conventional hybrid type DenFil (VERICOM Co., Anyang, Korea) / micro matrix hybrid type Esthet X (Dentsply Caulk, Milford, DE, U.S.A.)] were evaluated to assess whether variable light intensity curing is better than conventional curing technique.

Curing was done for 40 seconds in two ways of 2 step soft-start technique and 5 step ramping technique. Three kinds of light intensities of 50, 100, 200 mW/cm² were initially used for 10, 20, 30 seconds each and the maximum intensity of 600 mW/cm² was used for the rest of curing time in a soft-start curing technique. In a ramping technique, curing was done with the same initial intensities and the light intensity was increased 5 times with the same rate to the maximum intensity of 600 mW/cm².

After determining conditions that showed no different mechanical properties with conventional technique, Esthet X composite was filled in a class V cavity, which dimension was 4×3×1.5 mm and cured under those conditions.

Microleakage was evaluated in two ways of dye penetration and maximum gap estimation through SEM observation. ANOVA and Spearman's rho test were used to confirm any statistical significance among groups.

The results were as follows:

Several curing conditions of variable light intensities resulted in the similar mechanical properties with a conventional continuous curing technique, except conditions that start curing with an initial light intensity of 50 mW/cm²,

From the results of this study, it was revealed that ramping technique would be better than conventional technique in mechanical properties, however, soft-start technique might be better than conventional one in microleakage.

It was concluded that much endeavor should be made to find out the curing conditions, which have advantages of both aspects or to solve these kinds of problems through a novel idea of polymerization.

Citations

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• Stress distribution of three NiTi rotary files under bending and torsional conditions using a mathematic analysis
  T. O. Kim, G. S. P. Cheung, J. M. Lee, B. M. Kim, B. Hur, H. C. Kim
  International Endodontic Journal.2009; 42(1): 14.     CrossRef
• Stress distribution of three NiTi rotary files under bending and torsional conditions using 3-dimensional finite element analysis
  Tae-Oh Kim, Chan-Joo Lee, Byung-Min Kim, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
  Journal of Korean Academy of Conservative Dentistry.2008; 33(4): 323.     CrossRef
• Comparison of shaping ability using various Nickel-Titanium rotary files and hybrid technique
  Jung-Won Kim, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
  Journal of Korean Academy of Conservative Dentistry.2007; 32(6): 530.     CrossRef
• Comparison of shaping ability between various hybrid instrumentation methods with ProTaper
  Eun-Sook Hong, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
  Journal of Korean Academy of Conservative Dentistry.2006; 31(1): 11.     CrossRef
• Comparison of shaping ability of rotary Ni-Ti file systems used by undergraduates
  Mun-Seong Kang, Hyeon-Cheol Kim, Bock Hur, Jeong-Kil Park
  Journal of Korean Academy of Conservative Dentistry.2006; 31(1): 1.     CrossRef
• Effect of anticurvature filing method on preparation of the curved root canal using ProFile
  Hyun-Ji Song, Juhea Chang, Kyung-Mo Cho, Jin-Woo Kim
  Journal of Korean Academy of Conservative Dentistry.2005; 30(4): 327.     CrossRef

The purpose of this study is to evaluate the polymerization ability of three different light sources by microhardness test. Stainless steel molds of 1, 2, 3, 4 and 5 mm in thickness of 7 mm in diameter were prepared. The hybrid composite Z100 was packed into the hole of the mold and curing light was activated for designated time. Three different light sources, conventional halogen, light emitting diode, and plasma arc, were used for curing of composite. Two different curing times applied; one is to follow the manufacturer's recommendation and the other is to extend the curing time of LED and plasma arc for balancing the light energy with halogen. Immediately after curing, the Vickers hardness was measured at the bottom of specimen.

The results were as follows.

The composite cured with LED showed equal to higher microhardnesss than halogen.

In conclusion, this study suggested that plasma arc needs properly extended curing time.

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• Power density of light curing units through resin inlays fabricated with direct and indirect composites
  Hoon-Sang Chang, Young-Jun Lim, Jeong-Mi Kim, Sung-Ok Hong
  Journal of Korean Academy of Conservative Dentistry.2010; 35(5): 353.     CrossRef

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  Azam haddadikohsar, Mohammad shokrzade, Marjan Fallah, Fatemeh Shakeri
  journal of research in dental sciences.2024; 21(1): 46.     CrossRef
• Effect of Different Sealers on the Cytocompatibility and Osteogenic Potential of Human Periodontal Ligament Stem Cells: An In Vitro Study
  Shehabeldin Saber, Shereen Raafat, Mohamed Elashiry, Ahmed El-Banna, Edgar Schäfer
  Journal of Clinical Medicine.2023; 12(6): 2344.     CrossRef
• In Vitro Comparison of Biocompatibility of Calcium Silicate-Based Root Canal Sealers
  Ju Kyung Lee, Sunil Kim, Sukjoon Lee, Hyeon-Cheol Kim, Euiseong Kim
  Materials.2019; 12(15): 2411.     CrossRef
• A comparative evaluation of cytotoxicity of root canal sealers: anin vitrostudy
  Gautam Pyarelal Badole, Manjusha Madhukar Warhadpande, Ganesh Kothiramji Meshram, Rakesh Namdeoraoji Bahadure, Shubha Gopal Tawani, Gopal Tawani, Shital Gautam Badole
  Restorative Dentistry & Endodontics.2013; 38(4): 204.     CrossRef
• The effect of restorative materials on the stress distribution of class V composite resin restorations - a 3D finite element investigation
  Hyoung-Ryoul Ahn, Hyeon-Cheol Kim, Bock Huh, Jeong-Kil Park
  Journal of Korean Academy of Conservative Dentistry.2006; 31(1): 20.     CrossRef
• Effects of occlusal load on the stress distribution of four cavity configurations of noncarious cervical lesions: a three-dimensional finite element analysis study
  Sang-Je Jeon, Jeong-Kil Park, Hyeon-Cheol Kim, Sung-Gwan Woo, Kwang-Hoon Kim, Kwon Son, Bock Hur
  Journal of Korean Academy of Conservative Dentistry.2006; 31(5): 359.     CrossRef
• Cytotoxicity of resin-based root canal sealer, adseal
  Hee-Jung Kim, Seung-Ho Baek, Woo-Cheol Lee, Han-Soo Park, Kwang-Shik Bae
  Journal of Korean Academy of Conservative Dentistry.2004; 29(6): 498.     CrossRef

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• Quantitative comparison of permeability in the adhesive interface of four adhesive systems
  Juhea Chang, Keewook Yi, Hae-Young Kim, In Bog Lee, Byeong Hoon Cho, Ho-Hyun Son
  Journal of Korean Academy of Conservative Dentistry.2009; 34(1): 51.     CrossRef

The purpose of this study was to investigate the frequency of 7 putative pathogens in endodontic infections. The specimens were collected from infected pulpal tissue of patients who were referred for root canal treatment to the department of conservative dentistry, Chosun University. Samples were collected aseptically using a barbed broach and a paper point. The cut barbed broaches and paper points were transferred to an eppendorf tube containing 500 ml of 1 X PBS. DNAs were extracted from the samples by direct DNA extraction method using lysis buffer (0.5% EDTA, 1% Triton X-100). Identification of 7 putative pathogens was performed by PCR based on 16S rDNA. The target species were as follows: Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, Bacteroides forsythus, Actinobacillus actinomycetemcomitans, and Treponema denticola. Our data revealed that the prevalence of P. endodontalis was found in 88.6% (39/54), P. gingivalis 52.3% (23/44), P. nigrescens 18.2% (8/44), P. intermedia 15.9% (7/44), B. forsythus 18.2% (8/44), A. actinomycetemcomitans 2.3% (1/44), T. denticola 25% (11/44) of the samples. The high prevalence of P. endodontalis and P. gingivalis suggests that they may play an important role in the etiology of endodontic infections.