• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.89-99
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• 2003

The purpose of this study was to investigate the bonding of resin- based root canal sealer, AH26 when the sealer was applied as a thin layer between dentine and gutta-percha surface. In this study forty non-caries extracted human molars and resin-based root canal sealer(AH 26, DeTrey/Dentsply, Germany) were used. Disks of gutta-percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for thermoplastic obturation were used and dentin surfaces were treated with 2% NaOCl(Group 1) or 2%NaOCl+17% EDTA(Group 3). Disks of gutta-Percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for conventional obturation were used and dentin surface were treated with 2% NaOCl(Group 2) or 2%NaOCl+17% EDTA(Group 4). Enamel was removed by a horizontal section 1mm below the deepest portion of the central occlusal groove by using a watercooled low speed diamond saw. A second horizontal section was done around cementoenamel junction. Exposed dentin surface was cut to approximately $8{\times}8{\;}mm$ rectangular shape and was ground against 320, 400, 600 grade silicon carbide abrasive paper serially. After grinding, the dentine surface were soaked in a solution of 2% NaOCl for 30 minutes and twenty of specimens were treated with 17% EDTA solution for 1 minute. The treated specimens were washed and dried, Root canal sealer, AH26 was prepared according to the manufacture's instructions The Gutta-percha and dentin surface were coated with a thin layer of the freshly mixed seal or. The specimens were left overnight at room temperature. After their initial set, they were transferred to an incubator at $37$^{\circ}C$ for 72 h. After 72 hours, resin blocks were made. The resin block was serially sectioned vertically into stick of $1{\cdot}1mm$. Twenty sticks were prepared from each group. After that, tensile bond strength f3r each stick was measured with Microtensile Tester Failure patterns of the specimens at the interface between gutta-percha and dentin were observed under the SEM(x1000) and Stereomicroscope (LEICA M42O, Meyer Inst., TX U.S.A) at 1.25 x25 magnification. The results were statistically analysed by using a One-way ANOVA and Tukey's test. The results were as follows; 1. Tensile bond strengths($mean{\pm}SD$) were expressed with ascending order as follows: Group 1, $3.09{\pm}$ 1.05Mpa : Group 2, $6.23{\pm}1.16MPa$ : Group 3, $7.12{\pm}1.07MPa$ : Group 4, $10.32{\pm}2.06MPa$. 2. Tensile bond strengths of the group 2 and 4 used disks of gutta-percha for conventional obturation were significantly higher than that of the group 1 and 3 used fir thermoplastic obturation. (p < 0.05). 3. Tensile bond strengths of the group 3 and 4 treated with 2% NaOC1+17% EDTA were significantly higher than that of the group 1 and 2 treated with 2% NaOCl. (p < 0.05). 4. In analysis of failure patterns at the interface between sealer and gutta-percha, there were observed 49 (61%)cases of adhesive failure patterns and 31 (39%) cases of mixed failures patterns.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.537-549
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• 1998

The purpose of this study was to evaluate the influence of root resection and retrograde cavity preparation methods on the apical leakage in endodontic surgery. To investigate the effect of various root resection and retrograde cavity preparation methods on the apical leakage, 71 roots of extracted human maxillary anterior teeth and 44 mesiobuccal roots of extracted human maxillary first molars were used. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. Three millimeters of each root was resected at a 45 degree angle or perpendicular to the long axis of the tooth according to the groups. Retrograde cavities were prepared with ultrasonic instruments or a slow-speed round bur, and occlusal access cavities were filled with zinc oxide eugenol cement. Three coats of clear nail polish were placed on the lateral and coronal surfaces of the specimens except the apical cut one millimeter. All the specimens were immerged in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using two-way ANOVA and Duncans Multiple Range Test. The results were as follows: 1. No statistically significant difference was observed between ultrasonic retrograde cavity preparation method and slow-speed round bur technique, without apical bevel (p>0.05). 2. Ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, with bevel (p<0.0001). 3. No statistically significant difference was found between beveled resected root surface and non-beveled resected root surface, with ultrasonic technique (p>0.05). 4. Non-beveled resected root surface showed significantly less apical leakage than beveled resected root surface, with slow-speed round bur technique (p<0.0001). 5. No statistically significant difference in apical leakage was found between the group of retrograde cavity prepared parallel to the long axis of the tooth and the group of one prepared perpendicular to the long axis of the tooth (p>0.05). 6. Regarding isthmus preparation, ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, in the mesiobuccal root of maxillary molar, without bevel (p<0.0001).

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.1-33
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• 1997

The objective of this study was to analyze the in vitro and in vivo corrosion products of low and high copper amalgams. The four different types of amalgam alloy used in this study were Fine cut, Caulk spherical, Dispersalloy, and Tytin. After each amalgam alloy and Hg were triturated according to the directions of the manufacturer by means of the mechanical amalgamator(Amalgam mixer. Shinhung Co. Korea), the triturated mass was inserted into a cylindrical metal mold which was 12mm in diameter and 10mm in height. The mass was condensed by 150Kg/cm compressive force. The specimen was removed from the mold and aged at room temperature for about seven days. The standard surface preparation was routinely carried out by emery paper polishing under running water. In vitro amalgam specimens were potentiostatically polarized ten times in a normal saline solution at $37^{\circ}C$(potentiostat : HA-301. Hukuto Denko Corp. Japan). Each specimen was subjected to anodic polarization scan within the potential range -1700mV to+400mV(SCE). After corrosion tests, anodic polarization curves and corrosion potentials were obtained. The amount of component elements dissolved from amalgams into solution was measured three times by ICP AES(Inductive Coupled Plasma Atomic Emission Spectrometry: Plasma 40. Perkim Elmer Co. U.S.A.). The four different types of amalgam were filled in occlusal and buccal class I cavities of four human 3rd molars. After about five years the restorations were carefully removed after tooth extraction to preserve the structural details including the deteriorated margins. The occlusal surface, amalgam-tooth interface and the fractured surface of in vivo amalgam corrosion products were analyzed. In vivo and in vitro amalgam specimens were examined and analyzed metallographically by SEM(Scanning Electron Microscope: JSM 840. Jeol Co. Japan) and EDAX(Energy Dispersive Micro X-ray Analyser: JSM 840. Jeol Co. Japan). 1. The following results are obtained from in vitro corrosion tests. 1) Corrosion potentials of all amalgams became more noble after ten times passing through the in vitro corrosion test compared to first time. 2) After times through the test, released Cu concentration in saline solution was almost equal but highest in Fine cut. Ag and Hg ion concentration was highest in Caulk spherical and Sn was highest in Dispersalloy. 3) Analyses of surface corrosion products in vitro reveal the following results. a)The corroded surface of Caulk spherical has Na-Sn-Cl containing clusters of $5{\mu}m$ needle-like crystals and oval shapes of Sn-Cl phase, polyhedral Sn oxide phase. b)In Fine cut, there appeared to be a large Sn containing phase, surrounded by many Cu-Sn phases of $1{\mu}m$ granular shapes. c)Dispersalloy was covered by a thick reticular layer which contained Zn-Cl phase. d)In Tytin, a very thin, corroded layer had formed with irregularly growing Sn-Cl phases that looked like a stack of plates. 2. The following results are obtained by an analysis of in vivo amalgam corrosion products. 1) Occlusal surfaces of all amalgams were covered by thick amorphous layers containing Ca-P elements which were abraded by occlusal force. 2) In tooth-amalgam interface, Ca-P containing products were examined in all amalgams but were most clearly seen in low copper amalgams. 3) Sn oxide appeared as a polyhedral shape in internal space in Caulk spherical and Fine cut. 4) Apical pyramidal shaped Sn oxide and curved plate-like Sn-Cl phases resulted in Dispersalloy. 5) In Tytin, Sn oxide and Sn hydroxide were not seen but polyhedral Ag-Hg phase crystal appeared in internal space which assumed a ${\beta}_l$ phase.

• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.51-60
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• 2009

The purpose of this study was to perform quantitative comparisons of water permeable zones in both the adhesive and the hybrid layer before and after thermo cycling in order to assess the integrity of the bonding interface. Twenty eight flat dentin surfaces were bonded with a light-cured composite resin using one of four commercial adhesives [OptiBond FL (OP), AdheSE (AD), Clearfil SE Bond (CL). and Xeno III (XE)]. These were sectioned into halves and subsequently cut to yield 2-mm thick specimens; one specimen for control and the other subjected to thermocycling for 10,000 cycles. After specimens were immersed in ammoniacal silver nitrate for 24 h and exposed to a photo developing solution for 8 h, the bonded interface was analyzed by scanning electron microscopy (SEM) and wavelength dispersive spectrometry (WDS) at five locations per specimen. Immediately after bonding. the adhesive layer of OP showed the lowest silver uptake, followed by CL, AD. and XE in ascending order (p < 0.0001); the hybrid layer of CL had the lowest silver content among the groups (p = 0.0039). After thermocycling, none of the adhesives manifested a significant increase of silver in either the adhesive or the hybrid layer. SEM demonstrated the characteristic silver penetrated patterns within the interface. It was observed that integrity of bonding was well maintained in OP and CL throughout the thermocycling process. Adhesive-tooth interfaces are vulnerable to hydrolytic degradation and its permeability varies in different adhesive systems, which may be clinically related to the restoration longevity.

• Restorative Dentistry and Endodontics
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• v.36 no.5
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• pp.409-418
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• 2011

Objectives: The purpose of this study was to compare the microshear bond strength (${\mu}$SBS) 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% $H_3PO_4$ + Single Bond 2 (3M ESPE); group 2, Er:YAG laser (KEY Laser 3, KaVo) + Single Bond 2; group 3, Er:YAG laser + 37% $H_3PO_4$ + 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 ${\mu}$SBS testing 24 hr after bonding. Also scanning microscopic evaluations were made on the resin-dentin interfaces of six specimens. Results: The ${\mu}$SBS 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.

• Proceedings of the KACD Conference
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• 2008.05a
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• pp.246-257
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• 2008

The purpose of this study was to investigate the influence of various occlusal loading sites and directions on the stress distribution of the cervical composite resin restorations of maxillary second premolar, using 3 dimensional (3D) finite element (FE) analysis. Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). HyperMesh (Altair Engineering. Inc., Troy, USA) and ANSYS (Swanson Analysis Systems. Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid (Z100, 3M Dental Products, St. Paul, MN, USA) or flowable resin (Tetric Flow, Viva dent Ets., FL-9494-Schaan, Liechtenstein) and each restoration was simulated with adhesive layer thickness ($40{\mu}m$). A static load of 200 N was applied on the three points of the buccal incline of the palatal cusp and oriented in $20^{\circ}$ increments, from vertical (long axis of the tooth) to oblique $40^{\circ}$ direction towards the buccal. The maximum principal stresses in the occlusal and cervical cavosurface margin and vertical section of buccal surfaces of notch-shaped class V cavity were analyzed using ANSYS. As the angle of loading direction increased, tensile stress increased. Loading site had little effect on it. Under same loading condition. Tetric Flow showed relatively lower stress than Z100 overall, except both point angles. Loading direction and the elastic modulus of restorative material seem to be important factor on the cervical restoration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.185-197
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• 1992

Differences in the amount and chemical characteristics of the epicuticular waxes on rice leaves were studied for the active tillering and heading stages of rice varieties differing widely in gross leaf-surface property and genetics. The amount of waxes on surfaces of rice leaf-blades was determined by extraction with chloroform and chemical composition of the waxes was characterized by thin layer chromatography, gas liquid chromatography and infrared spectrophotometry. The amount of waxes varied by variety and significantly with growth stage. The amount at the heading stage was 1.7 to 3.6 mg/g fresh weight of leaves, which was two to three times as much as that at the tillering stage of 0.8 to 1.8 mg/g fresh weight. The waxes consisted of seven chemical classes, namely diols, fatty acids, fatty alcohols, fatty aldehydes, fatty esters, saturated and unsaturated hydrocarbons. Diols and unsaturated hydrocarbons were identified as new chemical classes of the rice epicuticular waxes. The polar constituents such as dials, fatty acids and fatty alcohols and the non-polars such as fatty aldehydes, fatty esters, and saturated and unsaturated hydrocarbons were identified at the heading stage, but at the tillering stage only the non-polar compounds were identified. In the carbon numbers (C) of the chemical classes, diols were composed entirely of C30 and acids were mainly of C30 and C31. In alcohols, primary alcohols were composed of C13 and C32, and the secondary alcohols were of C14, C16 and / or C30 regardless of the rice varieties. The acid portion of fatty esters, mainly composed of C22 and C23, showed low cabon numbers compared with the aldehydes. The alcohol portion of them showed a wide distribution in carbon numbers from C13 to C26 depending on the rice varieties. Hydrocarbons had odd carbon numbers, consisting mainly of C29 and C31.

• Journal of Animal Science and Technology
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• v.46 no.6
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• pp.947-956
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• 2004

The primary role of lipoprotein lipase(LPL) is the hydrolysis of triglycerides(TG) from the core of triglyceride-rich lipoproteins such as chylomicrons and very low density lipoproteins in plasma. Fatty acids liberated by LPL on capillary endothelial surfaces are available for tissues as energy sources especially in muscles or for storage in the form of TG in adipose tissues. Therefore, as the candidate gene related to the carcass traits of the beef cattle, we have directly sequenced the exon 5${\sim}$exon 6 region in the bovine LPL gene for discovery of single nucleotide polymorphism(SNP) with 24 unrelated Hanwoo(Korean cattle). Novel eight sequence variants were detected: three loci on exon 5, three on intron 5 and two on exon 6. All SNPs identified were strongly linked each other, and one hundred twenty eight Hanwoo samples were genotyped one SNP on intron 5 using PCR-restriction fragment length polymorphism method by digestion with Hae III restriction enzyme. The allele frequency of the polymorphism was 0.76 and 0.24. The effects of this polymorphism on the breeding values of the carcass weight, loin muscle area, back fat thickness and marbling score were analyzed using least square methods of SAS GLM. The marbling score of BB genotype was significantly higher than those of AA and AB genotypes(P<0.05). This result indicates that this polymorphism may be associated with the variation of marbling score. Further study is warranted to investigate the phenotypic association in Hanwoo.

• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.20-29
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• 1989

The purpose of the study is to evaluate the degree of the marginal leakage of class V cavities with 4 brands of esthetic filling materials by means of the dye penetration at the enamel & dentinal margins. 160 cavities of class V were prepared on the buccal & lingual surfaces of 80 extracted premolar teeth, which divided into 4 groups. The four groups of cavities were filled with Durafill$^{(R)}$-Durafill bond$^{(R)}$(KuIzer & Co GmbH), Bisfil M$^{(R)}$-Resin bond$^{(R)}$(BISCO Inc.), Silux$^{(R)}$-Scotchbond$^{(R)}$(3M Co.) and Fuji ionomer$^{(R)}$(type II, G-C Co.) each. All specimens were immersed in 2% methylene blue dye solution for 24 hours at $37^{\circ}C$ after a 30-second thermocycling at $4^{\circ}C$ and $60^{\circ}C$ and longitudinally sectioned with diamond disk into two parts. The results were as follows : 1. At enamel margins, the group filled with Durafill$^{(R)}$-Durafill bond$^{(R)}$, Bisfil M$^{(R)}$-Resin bond$^{(R)}$ and Silux$^{(R)}$-Scotchbond$^{(R)}$ show no significant difference each other(p>0.05), and the above groups show less marginal leakage comparing with the group filled with Fuji ionomer$^{(R)}$(p<0.01). 2. At dentinal margins, the group filled with Silux$^{(R)}$-Scotchbond$^{(R)}$ or Fuji ionomer$^{(R)}$ show less marginal leakage than that with Durafill$^{(R)}$-Durafill bond$^{(R)}$ or Bisfil M$^{(R)}$-Resin bond$^{(R)}$(p<0.01). 3. The enamel margins show less marginal leakage than dentinal margins in all the class V cavities(p<0.01).

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.123-131
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• 1982

The purpose of this study was to observe the responses of the remaining pulp tissue after pulpotomy upon the several kinds of $Ca(OH)_2$ products and the responses of periapical tissue upon some root canal filling materials after extirpation. For pulpotomy, the class V cavities were prepared on the premolars, molars and upper canines, and the pulp was amputated. Each drug was placed over the amputated tissue and cavity was sealed with zinc oxide eugenol cement. The drugs which were used for the study were Dycal (Caulk Co. U.S.A.), Cavitec (Kerr Co. U.S.A.), Calvital, Nobudyne and Neodyne (Neo Dental Chemical Products). For extirpation, the endodontic cavities were prepared on the lingual surfaces of anterior teeth, and the pulp tissues were extirpated as routine method. After enlarging, irrigation, and measuring of root length by taking X-ray, each root canal filling material was filled in the canal with gutta percha cone, and endodontic cavity was sealed with zinc oxide eugenol cement. Zinc oxide eugenol, $Ca(OH)_2$ (Eli Lilly Co. U.S.A.) and Vitapex (Neo Dental Chemical Products) were used as root canal filling materials. Animals were sacrificed after 1, 3 and 6 weeks following the operation. The teeth were decalcified in formic acid, sectioned and stained with hematoxylin eosin. Microscopic examination revealed as follows. 1. Dycal: The dentin bridge formation was observed at the 3rd week after pulpotomy. Inflammatory conditions which were infiltration of inflammatory cells and dilatation of blood vessels were kept in remaining pulp tissue at the 6th week. 2. Calvital: The dentin bridge was observed at the 1st week after pulpotomy. As the time clasped, the pulp tended to be the fibrous degeneration. 3. Cavitec, Nobudyne and Neodyne: In the case of Cavitec and Nobudyne, the incompleted and irregular dentin bridge was observed at the 6th week, and in Neodyne, was observed at the 3rd week. The severe inflammatory changes were seen in the remaining pulp tissue. As the time clasped, the fibrous degeneration tended to spread in the remaining pulp tissue. 4. $Ca(OH)_2$: Osteocementum was formed at the 3rd week, the matrix of cementum and dentin were resorted, and infiltration of lymphocytes was seen in periapical tissue when $Ca(OH)_2$ was used as canal-filling materials. S. ZOE and Vitapex The cementum like substance was seen in periapical portion at the 1st week, when ZOE and Vitapex were used as root canal filling materials. As the time elapsed, the matrix of cementum and dentin tended to be resorted. At the 6th week, the inflammatory condition of periapical tissue was continued in the case of ZOE, but was reduced in the case of Vitapex.