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The canal system in the mesiobuccal root of the maxillary first molar.

Dong Hyun CHO ; Ho Young CHOI ; Sang Hyuk PARK ; Gi Woon CHOI

Journal of Korean Academy of Conservative Dentistry.2003;28(3):232-240. doi:10.5395/JKACD.2003.28.3.232

This study is to investigate the canal system in the mesiobuccal root of the maxillry first molar. 61 maxillary first molars were randomly selected. Serial transverse sections were made perpendicular to the long axis of the mesiobuccal root. Each section was placed in 3% sodium hypochlorite for 24 hours and rinsed in water and dried. The resected surface was stained with 2% methylene blue dye and examined with stereomicroscope. 1. Canal configuration analysis showed that 36.1% of the specimen classified as type I, 16.4% as type II, 37.7% as type III and 9.8% as type IV. 2. Type II canal was merged in one canal within 1 to 4mm of the apex. 40% of type II canal converged at 2mm of the apex. 3. Type IV canal was divided into two canal within 2 to 4mm of the apex. 66.6% of type IV canal branched off at 2mm of the apex. 4. None of the sections had more than two main root canal. 5. 48.4% of the sections in 3mm with two canals contained an isthmusand more than 70% with two canals has isthmus at 4 to 5mm sections. 63.9% of the mesiobuccal root of maxillary first molar had two canaland 76.5% of sections with two canals in 5 MM had an isthmus. Because of this complexity the clinician should always search for extra canal carefullyand root canal system, including an isthmus, should be cleaned and shaped completelyand obturated three dimensionally for successful endodontic treatment.
Axis, Cervical Vertebra ; Dental Pulp Cavity ; Methylene Blue ; Molar* ; Sodium Hypochlorite ; Water

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Shear bond strength of self-etching adhesives to dentin and sem analysis.

Young Gon CHO ; Kee Sun ROH ; Soo Mee KIM ; Young Gon LEE ; Jin Ho JEONG ; Young Jae KI

Journal of Korean Academy of Conservative Dentistry.2003;28(3):222-231. doi:10.5395/JKACD.2003.28.3.222

The purpose of this study was to compare shear bond strength and interfacial pattern of composite bonded to dentin using self-etching adhesive systems. Sixty extracted human molars with exposed occlusal dentin were divided into four groups and bonded with four adhesives and composites: Single Bond/Filtek Z 250(SB), Tyrian SPE-One-Step Plus/Aelitefil(TY), Prompt L-Pop/Filtek Z 250(LP), and One-Up Bond F/Palfique Toughwell(OU). The results of this study were as follows; 1. Shear bond strength for OU was significantly lower than that of other groups(p<0.05). No significant difference was founded among SB, TY, and LP. 2. Failure modes to dentin showed adhesive and mixed for SB, TY, and LP, but them for OU showed adhesive in all spceimens. 3. Dentin-resin interface showed close adaptation for SB, TY, and LP, but it showed gap for OU. 4. The hybrid layers for TY, LP, OU were thinner than that of SB. Adhesive layers were observed between composite and hybrid layer, which were 5 microm thick for TY and 10 microm thick for OU.
Adhesives* ; Dentin* ; Humans ; Molar

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Self-adhesion of low-viscosity composites to dentin surface.

Tae Hee CHO ; Kyoung Kyu CHOI ; Sang Hyuk PARK ; Sang Jin PARK

Journal of Korean Academy of Conservative Dentistry.2003;28(3):209-221. doi:10.5395/JKACD.2003.28.3.209

The objectiveness of this study was to evaluate whether low-viscosity composite can bond effectively to dentin surface without bonding resin. The low-viscosity composites being 50wt% filler content were made by the inclusion of bonding resin of two self-etching systems(Clearfil SE Bond, Unifil Bond) varied with contents as 0, 10, 20, 30, 40, 50wt%. Exposed dentin surfaces of extracted 3rd molars are used. Dentin bond strengths were measured. The tests were carried out with a micro-shear device placed testing machine at a CHS of 1mm/min after a low-viscosity composite was filled into an iris cut from micro tygon tubing with internal diameter approximately 0.8mm and height of 1.0mm. 1. Flexural strength and modulus was increased with the addition of bonding resin. 2. Micro-shear bond strength to dentin was improved according to content of bonding resin irrespective of applying or not bonding resin in bonding procedure, and that of Clearfil SE Bond groups was higher than Unifil Bond. 3. There were no significant difference whether use of each bonding resin in bonding procedure for S-40, S-50, U-50(p>0.05). 4. In SEM examination, resin was well infiltrated into dentin after primed with self-etching primer only for S-50 and U-50 in spite of the formation of thinner hybrid layer. Low viscosity composite including some functional monomer may be used as dentin bonding resin without an intermediary bonding agent. It makes a simplified bonding procedure and foresees the possibility of self-adhesive restorative material.
Dentin* ; Iris ; Molar ; Viscosity

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Effect of salivary contamination of teeth on microtensile bond strength of various dentin bonding systems.

Kyoung Kyu CHOI ; Gil Joo RYU

Journal of Korean Academy of Conservative Dentistry.2003;28(3):203-208. doi:10.5395/JKACD.2003.28.3.203

The purpose of this study was to evaluate the effect of salivary contamination of teeth on bonding efficacy of self-priming and self-etching DBSs. The materials used were Single Bond(SB, self-priming system, 3M), Unifil Bond(UB, self-etching system, GC), and Scotchbond Multi-Purpose Plus(SM, 3M) as control. Forty five human molars randomly allocated to three groups as dentin bonding systems tested and embedded in epoxy resin. Then the specimens were wet-ground to expose flat buccal enamel surface or flat occlusal dentin surface and cut bucco-lingually to form two halves with slow speed diamond saw. One of them was used under non-contamination, other under contamination with saliva. The bonding procedure was according to the manufacturer's directions and resin composite(Z-100, 3M Dental Products, St. Paul, MN) was built-up on the bonded surface 5mm high. The specimens were ground carefully at the enamel-composite interface with fine finishing round diamond bur to create an hour-glass shape yielding bonded surface areas of 1.5+/-0.1mm2. The specimens were bonded to the modified microtensile testing apparatus with cyanoacrylate, attached to the universal testing machine and stressed in tension at a CHS of 1mm/min.. The tensile force at failure was recorded and converted to a tensile stress(MPa). Mean values and standard deviations of the bond strength are listed in table. One-way ANOVA was used to determine significant difference at the 95% level. The bond strength of SBMP and SB were not affected by salivary contamination, but that of UB was significantly affected by salivary contamination. These results indicate that DBSs with total etch technique seems less likely affected by salivary contamination in bonding procedure.
Adhesives ; Cyanoacrylates ; Dental Enamel ; Dental Instruments ; Dentin* ; Diamond ; Humans ; Molar ; Saliva ; Tooth*

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Color changes in composite resins exposed to xenon lamp.

Young Gon CHO ; Jeong Il SEO ; Soo Mee KIM ; Jin Ho JEONG ; Young Gon LEE

Journal of Korean Academy of Conservative Dentistry.2003;28(3):195-202. doi:10.5395/JKACD.2003.28.3.195

The purpose of this study was to evaluate the color changes of the composite resin resulting from xenon lamp exposure in different environments. Composite resin (Z 250 ; shade A1, A2, A3, A3.5, and A4) were applied in a cylindrical metal mold. Seventy five specimens according to environments of exposure were made as follows; Group I: aluminum foiling of the specimens in the air at 37degrees C for 1 day and 7 days. Group II: exposure of xenon lamp to the specimens in the air at 37degrees C for 1 day and 7 days. Group III: exposure of xenon lamp to the specimens in distilled water at 37degrees C for 1 day and 7 days. The color characteristics (L*,a*,b*) of the specimens before and after exposure of xenon lamp were measured by spectrophotometer and the total color differences (DeltaE*) were computed. The results obtained were as follows: 1. In all groups except A1 shade of group III, the DeltaE* values presented below 2.0, and group III showed the highest DeltaE* values followed by group II and group I in a decreasing order(p<0.05). 2. In all shades and groups, the more the exposure time of xenon lamp and the lighter the shade were, the higher the tendency for discoloration (p<0.05). 3. The composite resins which was exposed to xenon lamp in the distilled water was more discolored than those in the air (p<0.05). 4. The major changes of composite resins which were exposed to xenon lamp in the air were an increase in yellowness through a positive shift of the b* value, and those in the distilled water were an increase in darkness and yellowness through a negative shift of the L* value and a positive shift of the b* value.
Aluminum ; Composite Resins* ; Darkness ; Fungi ; Water ; Xenon*

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

Young Gon CHO ; Jong Jin KIM

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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