• Restorative Dentistry and Endodontics
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• 제16권1호
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• pp.106-120
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• 1991

The main purpose of this study was to investigate the possibility of obstruction of dentinal tubules through irradiation of the $CO_2$ laser on the dentin surface. For this study, 104 extracted caries - free premolars and molars were grinded their mesial or distal surface to expose dentin completly. And these specimens were divided into three Groups. Group I : those with their smear layer not removed and Group IT : those with their smear layer removed, were irradiated by the $CO_2$ laser(SPACE LASER - $CO_2$ VEGA 25) at five different energy levels ranging 4 - 20J/$cm^2$, and all specimens were observed with scanning eletron microscope (Hitachi S - 450). Group m was divided into 2 sub - groups: one with smear layer, another one without and those were irradiated with $CO_2$ laser of the same condition as Group I & II. All specimens were immersed in, $37^{\circ}C$, 0.5% methylene blue solution for 48 hours after 100 times of thermocycling at $4^{\circ}C$ and $60^{\circ}C$, and were observed with stereo -light microscope (Olympus SZH - ILLD) to evaluate dye penetration. The following results were obtained; 1. The dentinal tubules were obstructed through laser irradiation. 2. The dentinal tubules were still obstructed after treatment of 10% HCl/2sec., then it was proved that acid resistance of detin surface was also increased. 3. The Group of laser irradiation showed less dye penetration than control Group. 4. The smear layer hardly affected obstruction of the dentinal tubules through laser irradiation.

• Restorative Dentistry and Endodontics
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• 제46권1호
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• pp.11.1-11.11
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• 2021

Objectives: The aim of this study was to compare smear layer removal by conventional application (CA), passive ultrasonic irrigation (PUI), EasyClean (EC), and XP-Endo Finisher (XPF), using 17% ethylenediaminetetraacetic acid (EDTA) after chemomechanical preparation, as evaluated with scanning electron microscopy (SEM). Materials and Methods: Forty-five single-rooted human mandibular premolars were selected for this study. After chemomechanical preparation, the teeth were randomly divided into 5 groups according to the protocol for smear layer removal, as follows: G1 (control): CA of distilled water; G2 (CA): CA of 17% EDTA; G3 (PUI): 17% EDTA activated by PUI; G4 (EC): 17% EDTA activated by EC; and G5 (XPF): 17% EDTA activated by XPF. SEM images (×1,000) were obtained from each root third and scored by 3 examiners. Data were evaluated using the Kruskal-Wallis and Dunn tests (p < 0.05). Results: In the apical third, there were no statistically significant differences among the groups (p > 0.05). In the cervical and middle thirds, the experimental groups performed better than the control group (p < 0.05); however, G2 presented better results than G3, G4, and G5 (p < 0.05), which showed no differences among one another (p > 0.05). Conclusions: No irrigation method was able to completely remove the smear layer, especially in the apical third. Using CA for the chelating solution performed better than any form of activation.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.97-105
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• 1994

The purpose of this study was to evaluate the smear layer removing efficiency of two root canal preparation techniques. Twelve single-rooted teeth were used in two groups of six each. Group 1 was biomechanically prepared by hand using a K-file with a high volume of normal saline irrigation. Group 2 was. prepared by using ultrasonically activated K-file with a constant high volume of normal saline irrigation. After the experimental procedures, each root was split saggitally. The removing efficiency of the preparation methods were assessed in terms of surface condition of the canal walls at three levels, those coronal, middle, and apical thirds. On the basis of remaining debris, presence of smear layer, and patency of dentinal tubules, each canal was evaluated according to a scale form 0 to 2. A statistical analysis was used to indicated any significant differences in surface condition between the two methods. There was no statistical significance between hand instrumentation and ultrasonic instrumentation at the cervical third but removing efficiency of ultrasonic instrumentation was superior. No statistically significant differences were obhserved for middle or apical third.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.111-131
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• 1997

Eighty two of extracted bovine mandibular incisors were sectioned transversely through the cementoenamel junction(CEJ) and instrumented to a size minimum-# 110 file at the working length by 5.25 % NaOCl irrigation. The roots in group 1 were received a final irrigation with 10ml of 17% EDTA followed by 10ml of 5.25% NaOCl, group 2, 10ml of 40% citric acid followed by 10ml of 5.25% NaOCl, group 3, 20ml of 5.25% NaOCl, and control group, 20ml distilled water. Canal walls of four roots in each group and control group were examined by SEM(x3000). Calcium hydroxide was placed into all experimental roots except control group. Each root was placed in nalgen bottle containing unbuffered distilled water. The pH level of the medium surrounding tooth was recorded at 0, one hour, and daily for 1week, then 14days, 21days, and 28days using pH electrode. At 1, 3, 7, 14, 21days, and 28days, four roots from each group were split longitudinally and the ratio change was recorded using spectroiluorometer. The results were followings : 1. The smear layer was totally removed from canal walls in group 1 and 2, but was observed in group 3 and control group. 2. The hydroxyl ion diffused more rapidly through radicular dentin when smear layer was removed from canal walls. 3. The hydroxyl ion derived from calcium hydroxide began to diffuse from the root canal to the exterior surface of the root at 1day, and continued to 1-2weeks. 4. The pH level of dentin near the CEJ was not different in all experimental group regardless of presence of smear layer. It is clinically advisable to place calcium hydroxide into root canal for 1-2weeks for the purpose of expectation of diffusion of hydroxyl ion. But, after the placement of calcium hydroxide into root canal, the consequent pH level of external root surface will be futher studied with respect to it's effect on the root and periodontium.

• Restorative Dentistry and Endodontics
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• 제47권1호
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• pp.4.1-4.13
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• 2022

Objectives: This study evaluated the effects of different smear layer preparations on the dentin permeability and microtensile bond strength (µTBS) of 2 self-etching adhesives (Clearfil SE Bond [CSE] and Clearfil Tri-S Bond Universal [CTS]) under dynamic pulpal pressure. Materials and Methods: Human third molars were cut into crown segments. The dentin surfaces were prepared using 4 armamentaria: 600-grit SiC paper, coarse diamond burs, superfine diamond burs, and carbide burs. The pulp chamber of each crown segment was connected to a dynamic intra-pulpal pressure simulation apparatus, and the permeability test was done under a pressure of 15 cmH₂O. The relative permeability (%P) was evaluated on the smear layer-covered and bonded dentin surfaces. The teeth were bonded to either of the adhesives under pulpal pressure simulation, and cut into sticks after 24 hours water storage for the µTBS test. The resin-dentin interface and nanoleakage observations were performed using a scanning electron microscope. Statistical comparisons were done using analysis of variance and post hoc tests. Results: Only the method of surface preparation had a significant effect on permeability (p < 0.05). The smear layers created by the carbide and superfine diamond burs yielded the lowest permeability. CSE demonstrated a higher µTBS, with these values in the superfine diamond and carbide bur groups being the highest. Microscopic evaluation of the resin-dentin interface revealed nanoleakage in the coarse diamond bur and SiC paper groups for both adhesives. Conclusions: Superfine diamond and carbide burs can be recommended for dentin preparation with the use of 2-step CSE.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.45-63
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• 1994

128 freshly extracted human molars were used to study the interaction between dentinal smear layer removal with various agents, and the shear bond strength of a light cured glass ionomer cement to dentin. It was proposed that the removal of smear layers using acidic cleaners followed by incorporation of Fe mordant with dentin could enhanced the infiltration of monomer component in light curing glass ionomer cement and resulted in a high bond strength. For the first treatment process for removal of smear layers on the surfaces of dentin, 50 % citric acid, 10% maleic acid and 10 % phosphoric acid were used, and for the second treatment process, 15% ferric chloride, 6.8% ferric oxalate or 30% potassium oxalate were used. Distilled water was used as a control. After double sequential treatment on dentin, a light curing glass ionomer cement was bonded to dentin. After being immersed in water at 31'C for 24 hours, shear bond strengths were measured Instron testing machine(Model No.4202, USA). Surface changes were also observed using SEM (Hitachi, S-2300, Japan) after treatment process with each agents. The following conclusions were drawn : 1. Dentin surface cleaned with maleic acid and treated with ferric oxalate showed the highest bond strength with light curing glass ionomer cement. 2. Bond strengths of glass ionomer cement to dentin treated with maleic acid or citric acid were the highest, and that treated with phosphoric acid showed the lowest. 3. The effect of ferric oxalate on shear bond strength to dentin was always higher than that of ferric chloride. 4. The smear layers were clearly removed and the orifices of dentinal tubules were opened widely by the citric acid, maleic acid and phosphoric acid. 5. The orifices of dentinal tubules opened after using the first solution were closed with the treatment of ferric chloride. 6. The precipitate like crystals were formed on dentin surfaces and tubules, but a significant decrease in bond strength of glass ionomer cement to dentin surface treated with potassium oxalate.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.173-186
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• 1993

The purpose of this study is to observe the morphological changes of prepared dentin surfaces by 5 dentin conditioning agents. Freshly extracted 48 healthy human molars were used in this study. The teeth were stored at $4^{\circ}C$ physiologic saline solution befor experiment. The teeth were cross-sectioned to expose dentin below 3.0mm at the cusp tip and above 2.0mm at the cemento-enamel junction with Crystal Cutter (MC411 D, Maruto Co., Japan). The specimens were then divided into 12 groups. The sectioned dentin surfaces in group 1, 3, 5, 7, 9, and 11 were prepared with No. 301 diamond point under air-water spray and those in group 2, 4, 6, 8, 10, and 12 were prepared with No. 700 carbide bur. The prepared dentin surfaces were conditioned with Nitric acid, Citric acid, Poly acrylic acid, EDTA, and Phosphoric acid. All the specimens were gold-coated with Eiko ion coater (Eiko-engineering Co.) and observed in Hitachi S-2300 Scanning electron microscope at 20 KV. The following results from this study were obtained; 1. The dentinal smear layers prepared with diamond point were compacted than those prepared with the carbide bur. 2. The dentinal smear layers prepared with diamond point or carbide bur were thick but after treatment of dentin conditioning agents smear layers were removed almost. 3. Irrespective of the uses of the diamond point or the carbide bur the morphological changes of dentin surfaces treated with the same conditioning agents were similar. 4. Treatment of nitric acid and EDTA was a little effect in removing dentinal smear layer. 5. Treatment of citric acid and phosphoric acid removed the smear layer very effectively and showed dissolution of peritubular dentin and opening of dentinal tubules.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.574.2-574
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• 2001

The objective of this study was to evaluate the effect of EDTA irrigant depending on application times and temperatures. 31 human mature extracted teeth with a single canal and a closed apex were sectioned with microtome in 3mm thickness. They were distributed randomly into 6 groups of 10 specimens each and control group of 2 specimens. Each specimen was prepared with $GT^{TM}$ rotary file (Dentsply, Maillefer Co., Swiss) and irrigated with 3ml sodium hypochlorite every minute. Then smear layer wasn removed with EDTA solution ($PULPDENT^{\circledR}$, PULPDENT Co., USA.) except two control specimens. Specimens of each group were irrigated with 17％ EDTA.(omitted)

• 산업기술연구
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• 제31권A호
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• pp.59-62
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• 2011

The demineralizing effect of chelating agents(Maleic acid solution, EDTA salts solutions; disodium-, trisodium- and tetrasodium-EDTA) on hydroxyapatite(HA) for the root canal dentin treatment was investigated. Dissolution of Ca from HA was increased with increasing immersion time in chelating solutions. Among the EDTA salts solutions, tetrasodium-EDTA was least effective in dissolving Ca out from HA, and trisodium-EDTA was the most effective. Trisodium-EDTA solutionmight be more effective in removing the smear layer compared to tetrasodium-EDTA solution.

• Restorative Dentistry and Endodontics
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• 제17권2호
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• pp.365-382
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• 1992

The purpose of this study was to evaluate the adaptation of filling material to the dentinal walls of root canals with and without smear layer. Fifty extracted upper and lower anterior teeth were selected, and the root canals were instrumented with K - files 1mm short of the apical foramen by step - back method. The teeth were randomly divided into two groups of 25 each : in the group I, smear layers were not removed, and in the group II, smear layers were removed by 15% EDTA solution. Again the two groups 25 teeth were randomly divided into unfilled contol group and filling groups(lateral, ultrasonic, ULTRAFIL, McSpadden compaction group). Upon completion of root canal filling, the teeth were grooved on the both the labial and lingual surfaces and then split with mallet and chisel. Each specimens were examined with JSM - 840 Scanning Electron Microscope (JEOL., Japan). The results were as follows : 1. In the contol group, dentinal tubules of group I couldn't be distinguished in the canal wall, but those of group II appeared to be open and patent. 2. In the filling groups of group I, the tubular penetration of the sealer or gutta percha couldn't be seen, but in the filling groups of group II, it could be seen except McSpadden compaction group. 3. In the filling groups, ULTRAFIL group showed the best adaptation of filling material to root canal wall among the group I, and lateral and ultrasonic condensation group showed the best adaptation of filling material among the group II. McSpadden compaction group showed the worst adaptation in group I, II. 4. Generally, the group II showed better adapation of filling material to root canal wall than the group I.