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Microshear bond strength of adhesives according to the direction of enamel rods.

Journal of Korean Academy of Conservative Dentistry.2005;30(4):344-351. doi:10.5395/JKACD.2005.30.4.344

This study compared the microshear bond strength (microSBS) to end and side of enamel rod bonded by four adhesives including two total etch adhesives and two self-etch adhesives. Crown segments of extracted human molars were cut mesiodistally. The outer buccal or lingual surface was used as specimens cutting the ends of enamel rods, and inner slabs used as specimens cutting the sides of enamel rods. They were assigned to four groups by used adhesives: Group 1 (All-Bond 2), Group 2 (Single Bond), Group 3 (Tyrian SPE/One-Step Plus), Group 4 (Adper Prompt L-Pop). After each adhesive was applied to enamel surface, three composite cylinders were adhered to it of each specimen using Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to microSBS testing with a crosshead speed of 1 mm/minute. The results of this study were as follows; 1. The microSBS of Group 2 (16.50 +/- 2.31 MPa) and Group 4 (15.83 +/- 2.33 MPa) to the end of enamel prism was significantly higher than that of Group 1 (11.93 +/- 2.25 MPa) and Group 3 (11.97 +/- 2.05 MPa) (p < 0.05). 2. The microSBS of Group 2 (13.43 +/- 2.93 MPa) to the side of enamel prism was significantly higher than that of Group 1 (8.64 +/- 1.53 MPa), Group 3 (9.69 +/- 1.80 MPa), and Group 4 (10.56 +/- 1.75 MPa) (p < 0.05). 3. The mean microSBS to the end of enamel rod was significantly higher than that to the side of enamel rod in all group (p < 0.05).
Adhesives* ; Crowns ; Dental Enamel* ; Humans ; Molar ; Water

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A study on the hemolytic properties of Prevotella nigrescens.

Ju Seok KWAK ; Hoon Sang JANG ; Seok Woo JANG ; Su Jong LEE ; Yong Wook YU ; Kyung San MIN

Journal of Korean Academy of Conservative Dentistry.2005;30(4):335-343. doi:10.5395/JKACD.2005.30.4.335

Hemolytic property is a specific feature of bacteria to obtain iron which is essential for its survival in host tissues. Therefore, it is thought to be one of several factors of virulence. The purpose of this study was to investigate the hemolytic properties of Prevotella nigrescens isolated from the teeth diagnosed as pulp necrosis and apical periodontitis under the presence of hemolysin inhibitors such as NaN3 and dithiothreitol, heat, various pH and cultural conditions. The results were as follows; 1. Clinically isolated P. nigrescens strains and standard P. nigrscens ATCC 33563 showed hemolytic activity. 2. P. nigrescens showed higher hemolytic activity against human erythrocytes than sheep or horse erythrocytes. 3. NaN3 and dithiothreitol (DTT) reduced the hemolytic activity of P. nigrescens in a dose dependent manner (p < 0.05). 4. Optimal pH for the maximum hemolytic activity of P. nigrescens was 4.0 and the hemolysin was stable under the 50degrees C, but the hemolytic activity was significantly decreased at 95degrees C. 5. P. nigrescens cultured in 10% CO2 condition showed higher hemolytic activity than the bacteria cultured in the anaerobic condition.
Bacteria ; Dental Pulp Necrosis ; Dithiothreitol ; Erythrocytes ; Horses ; Hot Temperature ; Humans ; Hydrogen-Ion Concentration ; Iron ; Periapical Periodontitis ; Prevotella nigrescens* ; Prevotella* ; Sheep ; Sodium Azide ; Tooth ; Virulence

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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):327-334. doi:10.5395/JKACD.2005.30.4.327

This study investigated the effect of anticurvature filing method on preparation of the curved root canal using ProFile. Thirty six resin blocks were divided equally into three groups by instrumentation motions: anticurvature filing motion, circumferential filing motion and straight up-and-down motion. Each resin block was sectioned at 8 mm level from the apex and at the greatest curvature of the canal and reassembled in metal mold by a modified Bramante technique. All groups were instrumented with the ProFile system. At each levels, image of sectioned surface were taken using CCD camera under a stereomicroscope at x40 magnification and stored. Distances of transportation at the inner and outer area of curvature and the centering ratio were determined and compared by statistical analysis, along with the assessment of the increase of root canal cross-sectional area. The results were as follows; 1. In all groups, there was no statistical difference in the mean increase of root canal cross-sectional area, the centering ratio, and the mean distances of transportation at the inner area of curvature at each level. 2. At 8 mm level from the apex, the mean distances of transportation at the outer area of curvature decreases in following order anticurvature filing motion, circumferential filing motion, straight up-and-down motion but, no significant difference at the greatest curvature of the canal among three groups. Effect of anticurvature filing motion using ProFile does not seem to be different from other instrumentation motions at the inner area of curvature in curved root canal.
Dental Pulp Cavity* ; Fungi ; Transportation

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Comparative bond strength of single step adhesives to different dentinal depths.

Young Gon CHO ; Cheol Hee JIN ; Jung Bum MIN

Journal of Korean Academy of Conservative Dentistry.2005;30(4):319-326. doi:10.5395/JKACD.2005.30.4.319

This study compared the microtensile bond strength (microTBS) of single step adhesives to different dentin depths. Superficial or deep dentin was exposed in 30 molar teeth by sectioning immediately under the DEJ or 1.5 mm area from central pit, respectively. After polishing with 600-grit SiC paper, the dentin surfaces were assigned to three groups: AQ group-AQ Bond, L-Pop group-Adper Prompt L-Pop, Xeno group-Xeno III. The bonded specimens were sectioned into sticks and subjected to microTBS testing with a crosshead speed of 1 mm/minute. The results of this study were as follows; The microTBS to superficial dentin was higher than that to deep dentin in all group. The microTBS of Xeno group was significantly higher than that of L-Pop group and AQ group in both superficial and deep dentin (p < 0.05).
Adhesives* ; Dentin* ; Molar ; Tooth

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Microtensile bond strength of single step adhesives to dentin.

Young Gon CHO ; Young Jae KEE

Journal of Korean Academy of Conservative Dentistry.2005;30(4):312-318. doi:10.5395/JKACD.2005.30.4.312

This study compared the microtensile bond strength (microTBS) of three single step adhesives to dentin. Occlusal superficial dentin was exposed in fifteen human molars. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Prompt group (Adper Prompt L-Pop), AQ group (AQ Bond). Each adhesive was applied to dentin surface, and composite of same manufacturer was constructed. The bonded specimens were sectioned into sticks with an interface area approximately 1 mm2, and subjected to microTBS testing with a crosshead speed of 1 mm/minute. The results of this study were as follows; 1. The microTBS to dentin was 48.78 +/- 9.83 MPa for Xeno III, 30.22 +/- 4.52 MPa for Adper Prompt L-Pop, and 26.31 +/- 7.07 MPa for AQ Bond. 2. The mean microTBS of Xeno group was significantly higher than that of Prompt group and AQ group (p < 0.05). 3. There was no significant difference between the microTBS of Prompt group and AQ group.
Adhesives* ; Dentin* ; Humans ; Molar

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The change of canal configuration after instrumentation by several nickel-titanium files in the simulated canal with abrupt curvature.

Jung Jang LIM ; Dong Jun KIM ; Yun Chan HWANG ; In Nam HWANG ; Won Mann OH

Journal of Korean Academy of Conservative Dentistry.2005;30(4):303-311. doi:10.5395/JKACD.2005.30.4.303

The purpose of this study was to evaluate which type of Ni-Ti files are able to maintain canal configuration better in the simulated canal with abrupt curvature near it's apex. Ninety six simulated root canals were made in epoxy resin and #15 finger spreader was used as root canal templates. The simulated root canals were made with radius of curvature of 1.5 mm, 3.0 mm, 4.0 mm, 6.0 mm respectively and the angle of curvature of all simulated canals were adjusted to 90 degree. The simulated canals were instrumented by ProFile, ProTaper, Hero 642, and K3 at a 300 rpm using crown-down pressureless technique. Pre-instrumented and post-instrumented images were taken by digital camera and were superimposed with Adobe Photoshop 6.0 program. Images were compared by image analysis program. The changes of canal width at the inner and outer side of the canal curvature, canal transportation were measured at 9 measuring point with 1 mm interval. Statistical analysis among the types of Ni-Ti files was performed using Kruskal-Wallis test and Mann-Whitney U-test. The result was that ProFile maintain original canal configuration better than other engine driven Ni-Ti files in the canals above 3.0 mm radius of curvature, and in the 1.5 mm radius of curvature, most of Ni-Ti flies were deformed or separated during instrumentation.
Dental Pulp Cavity ; Diptera ; Fingers ; Radius ; Transportation

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A comparative study on the canal configuration after shaping by ProFile, ProTaper(TM) and K-Flexofile in simulated canals with different angles of curvature.

Bo Kum LEE ; Dong Jun KIM ; Yun Chan HWANG ; In Nam HWANG ; Won Mann OH

Journal of Korean Academy of Conservative Dentistry.2005;30(4):294-302. doi:10.5395/JKACD.2005.30.4.294

The purpose of this study was to evaluate the canal configuration after shaping by ProFile, ProTaper and K-Flexofile in simulated resin canals with different angles of curvature. Three types of instruments were used : ProFile, ProTaper, K-Flexofile. Simulated root canals, which were made of epoxy resin, were prepared by ProFile, ProTaper with rotary instrument using a crown-down pressureless technique, and hand instrumentation was performed by K-Flexofile using a step-back technique. All simulated canals were prepared up to size 25 file at end-point of preparation. Pre and post instrumentation images were recorded with Scanner. Assessment of canal shape was completed with Image Analysis program. Measurements were made at 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA analysis of variance and the Sheffe's test. The result was that ProFile and ProTaper maintain original canal shape regardless of the increase of angle of curvature than K-Flexofile. ProFile show significantly less canal transportation and maintained original canal shape better than ProTaper.
Axis, Cervical Vertebra ; Dental Instruments ; Dental Pulp Cavity ; Transportation

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Comparative evaluation of micro-shear bond strength between two different luting methods of resin cement to dentin.

Yoon Jeong LEE ; Sang Jin PARK ; Kyoung Kyu CHOI

Journal of Korean Academy of Conservative Dentistry.2005;30(4):283-293. doi:10.5395/JKACD.2005.30.4.283

The purpose of this study was to evaluate the effect of dual bonding technique by comparing microshear bond strength between two different luting methods of resin cement to tooth dentin. Three dentin bonding systems(All-Bond 2, One-Step, Clearfil SE Bond), two temporary cements (Propac, Freegenol) were used in this study. In groups used conventional luting procedure, dentin surfaces were left untreated. In groups used dual bonding technique, three dentin bonding systems were applied to each dentin surface. All specimens were covered with each temporary cement. The temporary cements were removed and each group was treated using one of three different dentin bonding system. A resin cement was applied to the glass cylinder surface and the cylinder was bonded to the dentin surface. Then, micro-shear bond strength test was performed. For the evaluation of the morphology at the resin/dentin interface, SEM examination was also performed. 1. Conventional luting procedure showed higher micro-shear bond strengths than dual boning technique. However, there were no significant differences. 2. Freegenol showed higher micro-shear bond strengths than Propac, but there were no significant differences. 3. In groups used dual bonding technique, SE Bond showed significantly higher micro-shear bond strengths in One-Step and All-Bond 2 (p < 0.05), but there was no significant difference between One-Step and All-Bond 2. 4. In SEM observation, with the use of All-Bond 2 and One-Step, very long and numerous resin tags were observed. This study suggests that there were no findings that the dual bonding technique would be better than the conventional luting procedure.
Dentin* ; Glass ; Prospective Payment Assessment Commission ; Resin Cements* ; Tooth

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Surface roughness of composite resin according to finishing methods.

Jeong Bum MIN ; Kong Chul CHO ; Young Gon CHO

Journal of Korean Academy of Conservative Dentistry.2007;32(2):138-150. doi:10.5395/JKACD.2007.32.2.138

The purpose of this study was to evaluate the difference of surface roughness of composite resin according to composite resin type, polishing methods, and use of resin sealant. Two hundred rectangular specimens, sized 8 x 3 x 2 mm, were made of Micro-new (Bisco, Inc., Schaumburg, IL, U.S.A) and Filtek Supreme (3M ESPE Dental Products, St. Paul, MN, U.S.A.), and divided into two groups; Micronew-M group, Filtek Supreme-S group. Specimens for each composite group were subdivided into five groups by finishing and polishing instruments used; M1 & S1 (polyester strip), M2 & S2 (Sof-Lex disc), M3 & S3 (Enhance disc and polishing paste), M4 & S4 (Astropol), and M5 & S5 (finishing bur). Polished groups were added letter B after the application of resin surface sealant (Biscover), eg, M1B and S1B. After specimens were stored with distilled water for 24 hr, average surface roughness (Ra) was taken using a surface roughness tester. Representative specimens of each group were examined by FE-SEM (S-4700: Hitachi High Technologies Co., Tokyo, Japan). The data were analysed using paired t-test, ANOVA and Duncan's tests at the 0.05 probability level. The results of this study were as follows; 1. The lowest Ra was achieved in all groups using polyester strip and the highest Ra was achieved in M5, S5 and M5B groups using finishing bur. On FE-SEM, M1 and S1 groups provided the smoothest surfaces, M5 and S5 groups were presented the roughest surfaces and voids by debonding of filler on the polished specimens. 2. There was no significant difference in Ra between Micronew and Filtek Supreme before the application of resin sealant, but Micronew was smoother than Filek Supreme after the application of resin sealant. 3. There was significant corelation between Ra of type of composite resin and polishing methods before the application of resin sealant (p = 0.000), but no significant interaction between them after the application of resin sealant. On FE-SEM, most of composite resin surfaces were smooth after the application of resin sealant on the polished specimens. 4. Compared with before and after the application of resin sealant in group treated in the same composite and polishing methods, Ra of M4B and M5B was statistically lower than that of M4 and M5, and S5B was lower than that of S5, respectively (p < 0.05). In conclusion, surface roughness by polishing instruments was different according to type of composite resin. Overall, polyester strip produced the smoothest surface, but finishing bur produced the roughest surface. Application of resin sealant provided the smooth surfaces in specimens polished with Enhance, Astropol and finishing bur, but not provided them in specimens polished with Sof-Lex disc.
Polyesters ; Water

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The Effect of Surface Defects on the Cyclic Fatigue Fracture of HEROShaper Ni-Ti rotary files in a Dynamic Model: A Fractographic Analysis.

Jung Kyu LEE ; Eui Sung KIM ; Myoung Whai KANG ; Kee Yeon KUM

Journal of Korean Academy of Conservative Dentistry.2007;32(2):130-137. doi:10.5395/JKACD.2007.32.2.130

This in vitro study examined the effect of surface defects on cutting blades on the extent of the cyclic fatigue fracture of HEROShaper Ni-Ti rotary files using fractographic analysis of the fractured surfaces. A total of 45 HEROShaper (MicroMega) Ni-Ti rotary files with a #30/.04 taper were divided into three groups of 15 each. Group 1 contained new HEROShapers without any surface defects. Group 2 contained HEROShapers with manufacturing defects such as metal rollover and machining marks. Group 3 contained HEROShapers that had been clinically used for the canal preparation of 4-6 molars. A fatigue-testing device was designed to allow cyclic tension and compressive stress on the tip of the instrument whilst maintaining similar conditions to those experienced in a clinic. The level of fatigue fracture time was measured using a computer connected the system. Statistical analysis was performed using a Tukey's test. Scanning electron microscopy (SEM) was used for fractographic analysis of the fractured surfaces. The fatigue fracture time between groups 1 and 2, and between groups 1 and 3 was significantly different (p < 0.05) but there was no significant difference between groups 2 and 3 (p > 0.05). A low magnification SEM views show brittle fracture as the main initial failure mode. At higher magnification, the brittle fracture region showed clusters of fatigue striations and a large number of secondary cracks. These fractures typically led to a central region of catastrophic ductile failure. Qualitatively, the ductile fracture region was characterized by the formation of microvoids and dimpling. The fractured surfaces of the HEROShapers in groups 2 and 3 were always associated with pre-existing surface defects. Typically, the fractured surface in the brittle fracture region showed evidence of cleavage (transgranular) facets across the grains, as well as intergranular facets along the grain boundaries. These results show that surface defects on cutting blades of Ni-Ti rotary files might be the preferred sites for the origin of fatigue fracture under experimental conditions. Furthermore, this work demonstrates the utility of fractography in evaluating the failure of Ni-Ti rotary files.
Edible Grain ; Fatigue* ; Fractures, Stress* ; Microscopy, Electron, Scanning ; Molar

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