• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.147-155
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• 1999

The purpose of this study was to investigate the effect of phosphoric acid concentration on the movement of 2-hydroxyethylmethacrylate(HEMA) from bonding resin - resin composite combination through dentin in vitro. Freshly extracted human third molar teeth were divided into four groups each of 10 teeth. A closed chamber with 1 ml distilled water was attached to the CEJ of each tooth. An occlusal cavity of 4mm diameter & remaining dentin thickness of 1.0-1.5mm was prepared in each tooth. Dentin was treated with 10% phosphoric acid gel for 15 seconds. 32% phosphoric acid gel for 15 seconds, or with 35% phosphoric acid gel for 15 seconds. A control group not treated with acid gel was also prepared. The cavities were rinsed, dried and then treated with the HEMA-containing All-Bond 2 primer & bonding resin which was light-cured for 10 seconds. The cavities were then restored with Z100 composite resin(shade:A3.5:3M Dent. Prod. USA) & light cured for 30 seconds. Water samples were retrieved from the chambers over a time course (4.32, 14.4, 43.2, 144 & 432 minutes ; 1, 3 & 10 days) and analyzed by high performance liquid chromatography. The results were as follows. 1. HEMA was detected in the pulp chambers of all teeth from 4.32 minutes after resin placement The highest rate of release was in the first sample period (0-4.32 min) & rate of release declined exponentially thereafter. 2. No significant differences were found for mean release rate for HEMA over a time course among the four groups (p>0.05). 3. The diffusion rate was significantly (p<0.05) less for 10% phosphoric acid gel than 32% phosphoric acid gel at the second sample period(4.32-14.4 min). 4. No significant differences were found for cumulative HEMA diffusion among the four groups at 10 days(p>0.05) and mean total(cumulative) release at 10 days for all groups was in the 9 - 16 nmol range. 5. The cumulative release was significantly (p<0.05) less for 10% phosphoric acid gel than 32% phophoric acid gel at the third(14.4-43.2 min) & fourth(43.2-144 min) sample period.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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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.

• Journal of Periodontal and Implant Science
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• v.40 no.6
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• pp.257-264
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• 2010

Purpose: Connective tissue reattachment to periodontally damaged root surfaces is one of the most important goals of periodontal therapy. The aim of this study was to develop a root conditioning agent that can demineralize and detoxify the infected root surface. Methods: Dentin slices obtained from human teeth were treated with a novel root planing agent for 2 minutes and then washed with phosphate-buffered saline. Smear layer removal and type I collagen exposure were observed by scanning electron microscopy (SEM) and type I collagen immunostaining, respectively. Cell attachment and lipopolysaccharides (LPS) removal demonstrated the efficiency of the root conditioning agent. Results: SEM revealed that the smear layer was entirely removed and the dentinal tubules were opened by the experimental gel. Type I collagen was exposed on the surfaces of the dentin slices treated by the experimental gel, which were compared with dentin treated with other root planing agents. Dentin slices treated with the experimental gel showed the highest number of attached fibroblasts and flattened cell morphology. The agar diffusion assay demonstrated that the experimental gel also has effective antimicrobial activity. Escherichia coli LPS were effectively removed from well plates by the experimental gel. Conclusions: These results demonstrated that this experimental gel is a useful tool for root conditioning of infected root surfaces and can also be applied for detoxification of ailing implant surface threads.

• Journal of dental hygiene science
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• v.15 no.2
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• pp.238-245
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• 2015

Dentinal hypersensitivity is a type of dental pain that occurs when various stimuli are applied to exposed dentin lesions. If the symptoms of dentinal hypersensitivity continue, the dentin is exposed and the hypersensitivity may become a periodontal disease or root caries due to bacterial infection. Therefore, the clinical goal of the present study is to reduce the pain of the patient suffering from dentinal hypersensitivity by developing antimicrobial hypersensitivity treatments and to improve oral hygiene. We prepared chlorhexidine, tetracycline, cetylpyridinium chloride, gallic acid loaded desensitizer by adding 0.1%, 0.5%, 1.0%, and 2.0% chlorhexidine, tetracycline, cetylpyridinium chloride, gallic acid to desensitizer (Micro Prime; Denville and Hurri Seal; Beutlich), and antibacterial effect, and cytotoxicity. The antibacterial test by using Staphylococcus aureus (SA. ATCC 6538, FDA 209) showed that the antibacterial effect of all experimental groups was significantly higher than that of control group (p<0.05). Cytotoxicity test by using agar diffusion assay indicated that Micro Prime showed mild toxicity, Hurri Seal showed severe toxicity and this cytotoxicity is supposed to be caused by one of desensitizer components showing weak antibacterial effect.

• Restorative Dentistry and Endodontics
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• v.44 no.1
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• pp.8.1-8.7
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• 2019

Objectives: Irrigants are imperative in endodontic therapy for the elimination of pathogens from the infected root canal. The present study compared the antimicrobial efficacy of octenidine dihydrochloride (OCT) with chlorhexidine (CHX) and sodium hypochlorite (NaOCl) against Staphylococcus epidermidis (S. epidermidis) for root canal disinfection. Materials and Methods: The minimum inhibitory concentration (MIC) was obtained using serial dilution method. The agar diffusion method was then used to determine the zones of inhibition for each irrigant. Lastly, forty 6-mm dentin blocks were prepared from human mandibular premolars and inoculated with S. epidermidis. Samples were randomly divided into 4 groups of 10 blocks and irrigated for 3 minutes with saline (control), 2% CHX, 3% NaOCl, or 0.1% OCT. Dentin samples were then collected immediately for microbial analysis, including an analysis of colony-forming units (CFUs). Results: The MICs of each tested irrigant were 0.05% for CHX, 0.25% for NaOCl, and 0.0125% for OCT. All tested irrigants showed concentration-dependent increase in zones of inhibition, and 3% NaOCl showed the largest zone of inhibition amongst all tested irrigants (p < 0.05). There were no significant differences among the CFU measurements of 2% CHX, 3% NaOCl, and 0.1% OCT showing complete elimination of S. epidermidis in all samples. Conclusions: This study showed that OCT was comparable to or even more effective than CHX and NaOCl, demonstrating antimicrobial activity at low concentrations against S. epidermidis.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.701-709
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• 1998

Many dental composites are Bis-GMA based resin which diluted with the more fluid monomer triethylenglycol dimethacrylate(TEGDMA). TEGDMA is often present in exess so that some quantity remains unreacted following photo-initiated polymerization. TEGDMA is a component of some resin composites which contributes to their cytotoxicity. The presence of dentin between resin composite and pulp space reduce the cytotoxicity in vitro. The root system from extrcted human third molar was removed and then a circular occlusal cavity 4mm in diameter was prepared, leaving a remaining dentinal thickness to the roof of the pulpal chamber within the range 1.0-1.5mm. Dentine was treated with 37% phosphoric acid prior to Z 100 placement without using bonding resin(group 1). In group 2, SMP(Scotchbond Multi Purpose) primer, bonding resin prior to Z 100 placement were applied sequently. In group 3, moulds with internal dimensions 4mm diameter by 2mm depth were used to contain the composite alone with an equvalent mass on tooth model, and then they were immersed directly into water. The purpose of this study is to evaluate the release rate and quantity of TEGDMA with or without the application of bonding resin. Both release rate and total cumulative amount of TEGDMA for the three groups were determined using reversed-phase HPLC at times up to 10 days. The results were as follows: 1. All experimental groups showed the highest rate of release was in the first sample period(0-4.32 min) and the rate of release declined exponentially thereafter. 2. The maximum release rate and total cumulative account of TEGDMA in the tooth model of group 1 and group 2 with the use of SMP bonding resin were reduced however ther were no significant differences between these groups(P>0.05). 3. In the first sample period(0-4.32 min), the rate of release of TEGDMA from composite resin in group 3 immersed directly into water was significantly higher than that in group 1 and group 2 of tooth model(P<0.05). Conclusively, TEGDMA diffusion from Z 100 resin was not effectively prevented by the presence of dentin in spite of using the SMP bonding resin.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.399-408
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• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.