Antifungal effects of synthetic human β-defensin 3-C15 peptide

OBJECTIVES: The purpose of this ex vivo study was to compare the antifungal activity of a synthetic peptide consisting of 15 amino acids at the C-terminus of human β-defensin 3 (HBD3-C15) with calcium hydroxide (CH) and Nystatin (Nys) against Candida albicans (C. albicans) biofilm. MATERIALS AND METHODS: C. albicans were grown on cover glass bottom dishes or human dentin disks for 48 hr, and then treated with HBD3-C15 (0, 12.5, 25, 50, 100, 150, 200, and 300 µg/mL), CH (100 µg/mL), and Nys (20 µg/mL) for 7 days at 37℃. On cover glass, live and dead cells in the biomass were measured by the FilmTracer Biofilm viability assay, and observed by confocal laser scanning microscopy (CLSM). On dentin, normal, diminished and ruptured cells were observed by field-emission scanning electron microscopy (FE-SEM). The results were subjected to a two-tailed t-test, a one way analysis variance and a post hoc test at a significance level of p = 0.05. RESULTS: C. albicans survival on dentin was inhibited by HBD3-C15 in a dose-dependent manner. There were fewer aggregations of C. albicans in the groups of Nys and HBD3-C15 (≥ 100 µg/mL). CLSM showed C. albicans survival was reduced by HBD3-C15 in a dose dependent manner. Nys and HBD3-C15 (≥ 100 µg/mL) showed significant fungicidal activity compared to CH group (p < 0.05). CONCLUSIONS: Synthetic HBD3-C15 peptide (≥ 100 µg/mL) and Nys exhibited significantly higher antifungal activity than CH against C. albicans by inhibiting cell survival and biofilm.

Effect of acidic solutions on the microhardness of dentin and set OrthoMTA and their cytotoxicity on murine macrophage

OBJECTIVES: To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage. MATERIALS AND METHODS: OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage. RESULTS: Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%). CONCLUSIONS: Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA.

Effect of acidic solutions on the microhardness of dentin and set OrthoMTA and their cytotoxicity on murine macrophage

OBJECTIVES: To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage. MATERIALS AND METHODS: OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage. RESULTS: Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%). CONCLUSIONS: Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA.

Buckling resistance, bending stiffness, and torsional resistance of various instruments for canal exploration and glide path preparation

OBJECTIVES: This study compared the mechanical properties of various instruments for canal exploration and glide-path preparations. MATERIALS AND METHODS: The buckling resistance, bending stiffness, ultimate torsional strength, and fracture angle under torsional load were compared for C+ file (CP, Dentsply Maillefer), M access K-file (MA, Dentsply Maillefer), Mani K-file (MN, Mani), and NiTiFlex K-file (NT, Dentsply Maillefer). The files of ISO size #15 and a shaft length of 25 mm were selected. For measuring buckling resistance (n = 10), the files were loaded in the axial direction of the shaft, and the maximum load was measured during the files' deflection. The files (n = 10) were fixed at 3-mm from the tip and then bent 45degrees with respect to their long axis, while the bending force was recorded by a load cell. For measuring the torsional properties, the files (n = 10) were also fixed at 3-mm, and clockwise rotations (2-rpm) were applied to the files in a straight state. The torsional load and the distortion angle were recorded until the files succumbed to the torque. RESULTS: The CP was shown to require the highest load to buckle and bend the files, and the NT showed the least. While MA and MN showed similar buckling resistances, MN showed higher bending stiffness than MA. The NT had the lowest bending stiffness and ultimate torsional strength (p < 0.05). CONCLUSIONS: The tested instruments showed different mechanical properties depending on the evaluated parameters. CP and NT files were revealed to be the stiffest and the most flexible instruments, respectively.

Cutting efficiency of apical preparation using ultrasonic tips with microprojections: confocal laser scanning microscopy study

OBJECTIVES: The purpose of this study was to compare the cutting efficiency of a newly developed microprojection tip and a diamond-coated tip under two different engine powers. MATERIALS AND METHODS: The apical 3-mm of each root was resected, and root-end preparation was performed with upward and downward pressure using one of the ultrasonic tips, KIS-1D (Obtura Spartan) or JT-5B (B&L Biotech Ltd.). The ultrasonic engine was set to power-1 or -4. Forty teeth were randomly divided into four groups: K1 (KIS-1D / Power-1), J1 (JT-5B / Power-1), K4 (KIS-1D / Power-4), and J4 (JT-5B / Power-4). The total time required for root-end preparation was recorded. All teeth were resected and the apical parts were evaluated for the number and length of cracks using a confocal scanning micrscope. The size of the root-end cavity and the width of the remaining dentin were recorded. The data were statistically analyzed using two-way analysis of variance and a Mann-Whitney test. RESULTS: There was no significant difference in the time required between the instrument groups, but the power-4 groups showed reduced preparation time for both instrument groups (p < 0.05). The K4 and J4 groups with a power-4 showed a significantly higher crack formation and a longer crack irrespective of the instruments. There was no significant difference in the remaining dentin thickness or any of the parameters after preparation. CONCLUSIONS: Ultrasonic tips with microprojections would be an option to substitute for the conventional ultrasonic tips with a diamond coating with the same clinical efficiency.

Long-term observation of the mineral trioxide aggregate extrusion into the periapical lesion: a case series / 国际口腔科学杂志·英文版

One-step apexification using mineral trioxide aggregate (MTA) has been reported as an alternative treatment modality with more benefits than the use of long-term calcium hydroxide for teeth with open apex. However, orthograde placement of MTA is a challenging procedure in terms of length control. This case series describes the sequence of events following apical extrusion of MTA into the periapical area during a one-step apexification procedure for maxillary central incisor with an infected immature apex. Detailed long-term observation revealed complete resolution of the periapical radiolucent lesion around the extruded MTA. These cases revealed that direct contact with MTA had no negative effects on healing of the periapical tissues. However, intentional MTA overfilling into the periapical lesion is not to be recommended.

Multivariate analysis of the cleaning efficacy of different final irrigation techniques in the canal and isthmus of mandibular posterior teeth

OBJECTIVES: The aim of this study was to compare the cleaning efficacy of different final irrigation regimens in canal and isthmus of mandibular molars, and to evaluate the influence of related variables on cleaning efficacy of the irrigation systems. MATERIALS AND METHODS: Mesial root canals from 60 mandibular molars were prepared and divided into 4 experimental groups according to the final irrigation technique: Group C, syringe irrigation; Group U, ultrasonics activation; Group SC, VPro StreamClean irrigation; Group EV, EndoVac irrigation. Cross-sections at 1, 3 and 5 mm levels from the apex were examined to calculate remaining debris area in the canal and isthmus spaces. Statistical analysis was completed by using Kruskal-Wallis test and Mann-Whitney U test for comparison among groups, and multivariate linear analysis to identify the significant variables (regular replenishment of irrigant, vapor lock management, and ultrasonic activation of irrigant) affecting the cleaning efficacy of the experimental groups. RESULTS: Group SC and EV showed significantly higher canal cleanliness values than group C and U at 1 mm level (p < 0.05), and higher isthmus cleanliness values than group U at 3 mm and all levels of group C (p < 0.05). Multivariate linear regression analysis demonstrated that all variables had independent positive correlation at 1 mm level of canal and at all levels of isthmus with statistical significances. CONCLUSIONS: Both VPro StreamClean and EndoVac system showed favorable result as final irrigation regimens for cleaning debris in the complicated root canal system having curved canal and/or isthmus. The debridement of the isthmi significantly depends on the variables rather than the canals.

A survey of experience-based preference of Nickel-Titanium rotary files and incidence of fracture among general dentists

OBJECTIVES: The purpose was to investigate the preference and usage technique of NiTi rotary instruments and to retrieve data on the frequency of re-use and the estimated incidence of file separation in the clinical practice among general dentists. MATERIALS AND METHODS: A survey was disseminated via e-mail and on-site to 673 general dentists. The correlation between the operator's experience or preferred technique and frequency of re-use or incidence of file fracture was assessed. RESULTS: A total of 348 dentists (51.7%) responded. The most frequently used NiTi instruments was ProFile (39.8%) followed by ProTaper. The most preferred preparation technique was crown-down (44.6%). 54.3% of the respondents re-used NiTi files more than 10 times. There was a significant correlation between experience with NiTi files and the number of reuses (p = 0.0025). 54.6% of the respondents estimated experiencing file separation less than 5 times per year. The frequency of separation was significantly correlated with the instrumentation technique (p = 0.0003). CONCLUSIONS: A large number of general dentists in Korea prefer to re-use NiTi rotary files. As their experience with NiTi files increased, the number of re-uses increased, while the frequency of breakage decreased. Operators who adopt the hybrid technique showed less tendency of separation even with the increased number of re-use.

Comparison of gene expression profiles of human dental pulp cells treated with mineral trioxide aggregate and calcium hydroxide / 대한치과보존학회지

OBJECTIVES: This study investigated changes in gene expressions concerning of differentiation, proliferation, mineralization and inflammation using Human-8 expression bead arrays when white Mineral Trioxide Aggregate and calcium hydroxide-containing cement were applied in vitro to human dental pulp cells (HDPCs). MATERIALS AND METHODS: wMTA (white ProRoot MTA, Dentsply) and Dycal (Dentsply Caulk) in a Teflon tube (inner diameter 10 mm, height 1 mm) were applied to HDPCs. Empty tube-applied HDPCs were used as negative control. Total RNA was extracted at 3, 6, 9 and 24 hr after wMTA and Dycal application. The results of microarray were confirmed by reverse transcriptase polymerase chain reaction. RESULTS: Out of the 24,546 genes, 43 genes (e.g., BMP2, FOSB, THBS1, EDN1, IL11, COL10A1, TUFT1, HMOX1) were up-regulated greater than two-fold and 25 genes (e.g., SMAD6, TIMP2, DCN, SOCS2, CEBPD, KIAA1199) were down-regulated below 50% by wMTA. Two hundred thirty nine genes (e.g., BMP2, BMP6, SMAD6, IL11, FOS, VEGFA, PlGF, HMOX1, SOCS2, CEBPD, KIAA1199) were up-regulated greater than two-fold and 358 genes (e.g., EDN1, FGF) were down-regulated below 50% by Dycal. CONCLUSIONS: Both wMTA and Dycal induced changes in gene expressions related with differentiation and proliferation of pulp cells. wMTA induced changes in gene expressions related with mineralization, and Dycal induced those related with angiogenesis. The genes related with inflammation were more expressed by Dycal than by wMTA. It was confirmed that both wMTA and Dycal were able to induce gene expression changes concerned with the pulp repair in different ways.

Matrix metalloproteinase-8 and substance P levels in root canal exudates of nonvital teeth / 대한치과보존학회지

OBJECTIVES: The aim of this study was to investigate levels of matrix metalloproteinase-8 (MMP-8) and substance P (SP) in root canal exudates during root canal treatment (RCT) of nonvital, painful teeth. MATERIALS AND METHODS: Patients scheduled for nonsurgical RCT were prospectively selected; the study was performed after obtaining informed consent from the patients and was approved by the Institutional Review Board for Clinical Research of Gangnam Severance Hospital, Yonsei University (3-2008-0118). Canal exudates samples were collected using sterilized paper points from teeth scheduled for RCT across three different time periods. MMP-8 and SP levels were measured using enzyme-linked immunosorbent assay (ELISA). Data were analyzed using a mixed model analysis and the Pearson correlation analysis (p < 0.05). RESULTS: MMP-8 and SP levels in GCF were decreased during RCT (p < 0.0001), and they showed a weak positive correlation to each other (p < 0.05). Patients'subjective pain levels and the response from percussion test were significantly related to SP level. CONCLUSIONS: This study demonstrated that periradicular inflammation endodontic origin can elevate SP and MMP-8 levels in root canal exudates. Interestingly, SP level of canal exudates showed a possibility of being used as an indicator of pain due to periapical pathosis.

Gene expression profiling in human dental pulp cells treated with mineral trioxide aggregate / 대한치과보존학회지

This study investigated the changes in gene expression when mineral trioxide aggregate (MTA) was applied in vitro to human dental pulp cells (HDPCs). MTA in a teflon tube (diameter 10 mm, height 2 mm) was applied to HDPCs. Empty tube-applied HDPCs were used as negative control. For microarray analysis, total RNA was extracted at 6, 24, and 72 hrs after MTA application. The results were confirmed selectively by performing reverse transcriptase polymerase chain reaction for genes that showed changes of more than two-fold or less than half. Of the 24,546 genes, 109 genes were up-regulated greater than two-fold (e.g., FOSB, THBS1, BHLHB2, EDN1, IL11, FN1, COL10A1, and TUFT1) and 69 genes were down-regulated below 50% (e.g., SMAD6 and DCN). These results suggest that MTA, rather than being a bio-inert material, may have potential to affect the proliferation and differentiation of pulp cells in various ways.

The effect of several root-end filling materials on MG63 osteoblast-like cells / 대한치과보존학회지

The purpose of this study was to compare mineral trioxide aggregate (MTA; Dentsply, Tulsa Dental, Tulsa, OK, USA), which is widely used as root-end filling material, with DiaRoot BioAggregate (DB; Innovative BioCaramix Inc, Vancouver, BC, Canada), newly developed product, by using MG63 osteoblast-like cells. MTA, DB, and Intermediate Restorative Material (IRM; Dentsply Caulk, Milford, DE, USA) were used for root-end filling material while tissue culture plastic was used for control group. Each material was mixed and, the mixtures were left to set for 24 hours. MG63 cells were seeded to each group and then they were cultured for attachment for 4 hours. Following the attachment of cells to the root-end filling material, early cellular response was observed. After another 12 hours'culture, the level of attachment between cells and material was observed and in order to identify the effect of each material to bone formation, transforming growth factor beta1 (TGFbeta1) and osteocalin (OC) were estimated by using enzyme-linked immunosorbent assay (ELISA), and the amount of alkaline phosphatase (ALP) was also measured. The data were analyzed using one-way ANOVA. As a result, only at OC and the number of cells which were attached to materials, there was no statistical difference between MTA and DB. At other items, there was statistically significant difference in all groups. Although DB has not shown exactly the same cellular response like that of MTA, the number of attached cells shows that biocompatibility of the material and OC indicates bone formation rate. Therefore, if DB is used for root end filling material, it is expected to lead to similar results to MTA.

In vitro evaluation of cleaning efficacy of various irrigation methods in mandibular molars / 대한치과보존학회지

The aim of this in vitro study was to evaluate the cleaning efficacy of various irrigation methods in the mandibular mesial roots. The forty five mesial root canals were shaped by Profile .06 instruments to apical size #30 and irrigated with 5 ml of 3.5% NaOCl. The teeth were divided into 3 groups and irrigated finally for 1 minute; Group 1: syringe irrigation, Group 2: ultrasonic irrigation, Group 3: RinsEndo irrigation. After histological processing, the cross sections of apical 1, 3, and 5 mm level were examined with an optical microscope. The cleanliness values of canals and isthmuses were calculated and analyzed by Mann-Whitney U test. 1. There were no significant differences in both canal and isthmus cleanliness between syringe irrigation and ultrasonic irrigation except 5 mm level of isthmus. 2. RinsEndo irrigation had significantly higher canal cleanliness values than syringe irrigation at 1 mm and 3 mm levels (p < 0.05). Also, RinsEndo irrigation had significantly higher isthmus cleanliness values than syringe irrigation at all levels evaluated (p < 0.05). 3. There were no statistical differences in both canal and isthmus cleanliness between ultrasonic irrigation and RinsEndo irrigation except 3 mm level of canal. From this study, RinsEndo irrigation can be useful as an additional irrigation procedure.

Effect of genistein on the sexual maturation in immature female rats / 소아과

PURPOSE: Exposure to dietary phytoestrogens such as genistein during early childhood is a growing public health concern. We examined the effect of early exposure to genistein on sexual maturation in immature rats. METHODS: Weaning (3wk-old) Sprague-Dawley female rats were assigned to three groups (n=6 for each): fed by high dose of genistein (100 mg/kg/d), low dose of genistein (10 mg/kg/d) and control group. First vaginal opening (VO) day was observed. Structural alterations in the ovary and uterus were assessed by histologically. Expression of genes of ERalpha, ERbeta, and progesterone receptor (PR) in the ovary and uterus were investigated by RT-PCR. RESULTS: High genistein group had earlier VO than control and low genistein group. Graafian follicle s and corpora lutea were observed from the ovary of genistein-treated groups, while primary, secondary follicles and small atretic follicles were observed in the control group. Hypertrophy of luminal and glandular uterine epithelia were found in the genistein-treated groups while poor development of gland and fewer myometrial cell layers were evident in control group. In ovary, the transcriptional activities of ERalpha and ERbeta were higher in high genistein group than in controls. In uterus, the transcriptional activities of ERalpha, ERbeta and PR were higher in low genistein group than in controls. CONCLUSION: Acute exposure to genistein during the prepubertal period could activate the reproductive endocrine system resulting in the early onset of puberty in female rats. Further clinical investigation on the effect of genistein on the sexual maturation in children is warranted.

Finite element analysis of maxillary central incisors restored with various post-and-core applications / 대한치과보존학회지

The purpose of this study was to investigate the effect of rigidity of post core systems on stress distribution by the theoretical technique, finite element stress-analysis method. Three-dimensional finite element models simulating an endodontically treated maxillary central incisor restored with a zirconia ceramic crown were prepared and 1.5 mm ferrule height was provided. Each model contained cortical bone, trabecular bone, periodontal ligament, 4 mm apical root canal filling, and post-and-core. Six combinations of three parallel type post (zirconia ceramic, glass fiber, and stainless steel) and two core (Paracore and Tetric ceram) materials were evaluated, respectively. A 50 N static occlusal load was applied to the palatal surface of the crown with a 60degrees angle to the long axis of the tooth. The differences in stress transfer characteristics of the models were analyzed. von Mises stresses were chosen for presentation of results and maximum displacement and hydrostatic pressure were also calculated. An increase of the elastic modulus of the post material increased the stress, but shifted the maximum stress location from the dentin surface to the post material. Buccal side of cervical region (junction of core and crown) of the glass fiber post restored tooth was subjected to the highest stress concentration. Maximum von Mises stress in the remaining radicular tooth structure for low elastic modulus resin core (29.21 MPa) was slightly higher than that for high elastic modulus resin core (29.14 MPa) in case of glass fiber post. Maximum displacement of glass fiber post restored tooth was higher than that of zirconia ceramic or stainless steel post restored tooth.

Anterior esthetic improvement through orthodontic extrusive remodeling and single-unit implantation in a fractured upper lateral incisor with alveolar bone loss: A case report / 대한치과보존학회지

The treatment of esthetic areas with single-tooth implants represents a new challenge for the clinician. In 1993, a modification of the forced eruption technique, called "orthodontic extrusive remodelling," was proposed as a way to augment both soft- and hard-tissue profiles at potential implant sites. This case report describes augmentation of the coronal soft and hard tissues around a fractured maxillary lateral incisor associated with alveolar bone loss, which was achieved by forced orthodontic extrusion before implant placement. Through these procedures we could reconstruct esthetics and function in a hopeless tooth diagnosed with subgingival root fracture by trauma.

The effect of mineral trioxide aggregate on the production of growth factors and cytokine by human periodontal ligament fibroblasts / 대한치과보존학회지

Mineral trioxide aggregate (MTA) would influence healing of periapical tissues by modulating the production of growth factors and cytokines from PDL fibroblasts, however, the studies are insufficient. Therefore, the purpose of this study was to monitor the expression of transforming growth factor-beta1 (TGF- beta1), fibroblast growth factor-2 (FGF-2), and interleukin-6 (IL-6) from PDL fibroblasts in the presence of MTA. The human PDL fibroblasts were seeded onto the set MTA or IRM at a level of 1 x 10(5) cells per unit well, and further incubated for 6, 12, 24, and 48 hours. The levels of TGF-beta1, FGF-2, and IL-6 from the supernatant were measured by enzyme-linked immunosorbent assay (ELISA). The data were analyzed using one-way ANOVA. The level of TGF-beta1 was down-regulated when the cells were grown in the presence of MTA except at 6 hours. The levels of FGF-2 release were significantly suppressed when PDL fibroblasts were grown in the presence of MTA or IRM at all time intervals (p < 0.05). The expressions of IL-6 from MTA treated cells were comparable to those of untreated control cells throughout the observation periods. We presume that this material inhibits the stimulatory function of growth factors on granulation tissue formation and in turn, it promotes the healing process modulated by other bone-remodeling cells.

The effect of mineral trioxide aggregate on the production of growth factors and cytokine by human periodontal ligament fibroblasts / 대한치과보존학회지

Mineral trioxide aggregate (MTA) would influence healing of periapical tissues by modulating the production of growth factors and cytokines from PDL fibroblasts, however, the studies are insufficient. Therefore, the purpose of this study was to monitor the expression of transforming growth factor-beta1 (TGF- beta1), fibroblast growth factor-2 (FGF-2), and interleukin-6 (IL-6) from PDL fibroblasts in the presence of MTA. The human PDL fibroblasts were seeded onto the set MTA or IRM at a level of 1 x 10(5) cells per unit well, and further incubated for 6, 12, 24, and 48 hours. The levels of TGF-beta1, FGF-2, and IL-6 from the supernatant were measured by enzyme-linked immunosorbent assay (ELISA). The data were analyzed using one-way ANOVA. The level of TGF-beta1 was down-regulated when the cells were grown in the presence of MTA except at 6 hours. The levels of FGF-2 release were significantly suppressed when PDL fibroblasts were grown in the presence of MTA or IRM at all time intervals (p < 0.05). The expressions of IL-6 from MTA treated cells were comparable to those of untreated control cells throughout the observation periods. We presume that this material inhibits the stimulatory function of growth factors on granulation tissue formation and in turn, it promotes the healing process modulated by other bone-remodeling cells.

MMP and TIMP production in periodontal ligament fibroblasts stimulated by Prevotella nigrescens lipopolysaccharide / 대한치과보존학회지

The purpose of this study was to monitor the secretion of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) by human periodontal ligament (PDL) fibroblasts stimulated with Prevotella nigrescens lipopolysaccharide (LPS), and to examine the effect of calcium hydroxide treatment on P. nigrescens LPS. LPS was extracted and purified from anaerobically cultured P. nigrescens. PDL fibroblasts were stimulated by the LPS (0, 0.1, 1, 10 ug/ml) or LPS (10 ug/ml) pretreated with 12.5 mg/ml of Ca(OH)2 for 3 days, for various periods of time (12, 24, 48 h). Immunoprecipitation were performed for protein level analysis of MMP-1, MMP-2 and TIMP-1. Total RNA was isolated and real-time quantitative polymerase chain reaction (PCR) was performed for quantification of MMP-1 mRNA. According to this study, the results were as follows: 1. The production of MMP-1 by stimulation with P. nigrescens LPS increased in time-dependent manner, and showed maximum value at 48 h in both protein and mRNA level. But there was no dose-dependent increase. 2. MMP-2 production time-dependently increased when stimulated with 1 and 10 ug/ml LPS, but there was no dose-dependent increase. 3. TIMP-1 production increased to 24 h, but decreased at 48 h. It increased when stimulated with 0.1 and 1 ug/ml LPS, but suppressed at 10 ug/ml. 4. P. nigrescens LPS pretreated with Ca(OH)2 markedly downregulated MMP-1 gene expression.

The effect of Treponema denticola immunoinhibitory protein on cytokine expression in T cells / 대한치과보존학회지

Immunoinhibitory protein extracted from sonicated Treponema denticola have been shown to suppress cell cycle progression of human lymphocytes. To study in detail about the effect of this microorganism on the function of lymphocytes, we investigated the levels of Interleukin-2 (IL-2) and Interleukin-4 (IL-4) production by T lymphocytes before and after the addition of 12.5 microg/ml T. denticola sonicated extracts. In this study, levels of IL-2 and IL-4 produced from T cells pretreated with sonicated extracts were evaluated by using the quantitative sandwich enzyme immunoassay technique. In response to phytohemagglutinin (PHA) stimulation, T cell produced increased levels of IL-2 and IL-4. However, the expressions of both cytokines were significantly inhibited when PHA activated-T cells were pre-exposed to sonicated T. denticola extracts (p < 0.05). These findings suggest that the T. denticola sonicated extracts induced-immunosuppression in Th1 and Th2 cell functions could be a part of the pathogenic mechanism of the endodontic failure associated with this microorganism.