Cytokine expression in response to root canal infection in gnotobiotic mice.
Int Endod J. 2012 Jan 10;
Authors: Maciel KF, Neves de Brito LC, Tavares WL, Moreira G, Nicoli JR, Vieira LQ, Ribeiro Sobrinho AP
Abstract
Maciel KF, Neves de Brito LC, Tavares WLF, Moreira G, Nicoli JR, Vieira LQ, Ribeiro Sobrinho AP. Cytokine expression in response to root canal infection in gnotobiotic mice. International Endodontic Journal. ABSTRACT: Aim To examine cytokine expression profiles during periapical lesion development in response to synergetic human pathogens in a gnotobiotic mouse model. Methodology Human strains of Fusobacterium nucleatum and Peptostreptococcus prevotii were inoculated into the root canals of germ-free mice in either mono- or bi-association. Animals were killed 7 and 14 days after infection, and periapical tissues were collected. mRNA expression of the cytokines IFN-γ, TNF-α, Receptor activator of nuclear factor kappa-B ligand (RANKL), IL-10, IL-4 and transforming growth factor β (TGF-β) was assessed using real-time PCR. Levene’s test was used to assess the equality of variance of the data, whereas a t-test for independent samples was used to evaluate the significance of the differences between groups (P < 0.05). Results The mRNA expression of IFN-γ and TNF-α was up-regulated by F. nucleatum during the acute (day 7) and chronic phase (day 14) of periapical lesion development. However, in bi-infection the expression of IFN-γ and TNF-α were effectively absent at both time-points. RANKL mRNA expression was down-regulated during dual infection at the chronic phase. As IL-4 expression was similar at both time-points, IL-4 does not appear to be involved in the periapical response to these bacterial strains. IL-10 was up-regulated during the chronic phase by mono-infection with either F. nucleatum or P. prevotii. Dual infection increased TGF-β mRNA expression on day 7, which paralleled the decrease in IFN-γ and TNF-α mRNA levels at the same time-point. F. nucleatum increased TGF-β mRNA expression during the chronic phase. Conclusion Cytokine profiles depend on the nature of the bacterial challenge. Both TGF-β and IL-10 appeared to be regulating the proinflammatory cytokine responses at both time-points of the periapical immune response.
PMID: 22233143 [PubMed - as supplied by publisher]
The role of DNA damage and caspase activation in cytotoxicity and genotoxicity of macrophages induced by bisphenol-A-glycidyldimethacrylate.
Int Endod J. 2012 Jan 14;
Authors: Li YC, Kuan YH, Huang FM, Chang YC
Abstract
Li Y-C, Kuan Y-H, Huang F-M, Chang Y-C. The role of DNA damage and caspase activation in cytotoxicity and genotoxicity of macrophages induced by bisphenol-A-glycidyldimethacrylate. International Endodontic Journal. ABSTRACT: Aim To evaluate the potential toxicological implications of BisGMA on murine macrophage cell line RAW264.7. Methodology Lactate dehydrogenase release, flow cytometry, Western blot and fluorometric assays were used to detect cell viability, mode of cell death and caspase activities, respectively. In addition, alkaline single-cell gel electrophoresis and cytokinesis-block micronucleus assays were applied to detect genotoxicity. Statistical analyses were performed using anova followed by the Bonferroni’s t-test for multi-group comparisons test. Results BisGMA demonstrated a cytotoxic effect on RAW264.7 cells in a dose-dependent and a time-dependent manner (P < 0.05). BisGMA was found to induce two modes of cell death. The mode of cell death changed from apoptosis to necrosis as the concentrations of BisGMA elevated. Caspase-3, caspase-8 and caspase-9 activities were significantly induced by BisGMA in a dose-dependent manner (P < 0.05). Moreover, BisGMA exhibited genotoxicity via a dose-related increase in the numbers of micronucleus and DNA strand breaks (P < 0.05). Conclusions Cytotoxicity and genotoxicity induced by BisGMA are mediated by DNA damage and caspase activation.
PMID: 22242562 [PubMed - as supplied by publisher]
Fracture resistance of root filled premolar teeth restored with direct composite resin with or without cusp coverage.
Int Endod J. 2012 Jan 14;
Authors: Xie KX, Wang XY, Gao XJ, Yuan CY, Li JX, Chu CH
Abstract
Xie KX, Wang XY, Gao XJ, Yuan CY, Li JX, Chu CH. Fracture resistance of root filled premolar teeth restored with direct composite resin with or without cusp coverage. International Endodontic Journal. ABSTRACT: Aim To evaluate the fracture resistance and fracture patterns of root filled maxillary first premolar teeth (with mesio-occlusal cavity preparation) restored with several composite restoration designs. Methodology One hundred extracted sound human maxillary first premolars were randomly divided into five groups. Group 1 remained untreated (negative control). Conventional root canal treatment with additional mesial-occlusal cavity preparation was carried out on teeth in groups 2-5. In group 2, the teeth were restored intra-coronally with direct composite resin (positive control). In group 3, the palatal cusps of the teeth were reduced, and the cavities were restored with composite resin covering the palatal cusp (partial coverage). In group 4, the buccal and palatal cusps along with the distal marginal ridges were reduced; the cavities and cusps were restored with composite resin (conventional full coverage). In group 5, the buccal and palatal cusps were reduced but the distal marginal ridges were conserved. The cavities and the cusps were restored with composite resin (modified full coverage). All teeth were subjected to a progressive compressive loading parallel to their longitudinal axis until fracture. Fracture resistance was analysed using the one-way ANOVA and Fisher’s LSD test. Fracture patterns were analyzed with chi-square test. The significance level was set at 0.05. Results The fracture resistance (mean ± SD) of groups 1-5 was 1131 ± 207N, 904 ± 184N, 927 ± 224N, 1095 ± 289N and 1085 ± 243N, respectively (groups 1, 4, 5 > groups 2, 3; P = 0.004). Cusp fractures were recorded as the fracture pattern in 20 (100%), 19 (95%), 16 (80%), 8 (40%) and 12 (60%) premolars in groups 1-5, respectively (groups 1, 2 > groups 4, 5; group 3 > group 4; P < 0.001). Conclusions When direct composite resin was used to restore root filled maxillary first premolar teeth involving a proximal surface, those restored with full-coverage designs had greater fracture resistance.
PMID: 22242600 [PubMed - as supplied by publisher]
Evaluation of Nd:YAG and Er:YAG irradiation, antibacterial photodynamic therapy and sodium hypochlorite treatment on Enterococcus faecalis biofilms.
Int Endod J. 2012 Jan 14;
Authors: Meire MA, Coenye T, Nelis HJ, De Moor RJ
Abstract
Meire MA, Coenye T, Nelis HJ, De Moor RJG. Evaluation of Nd:YAG and Er:YAG irradiation, antibacterial photodynamic therapy and sodium hypochlorite treatment on Enterococcus faecalis biofilms. International Endodontic Journal. ABSTRACT: Aim To compare the antimicrobial efficacy of two-high power lasers (Nd:YAG and Er:YAG) and two commercial antimicrobial photodynamic therapy (aPDT) systems with that of sodium hypochlorite (NaOCl) action on Enterococcus faecalis biofilms grown on dentine discs. Methodology Enterococcus faecalis biofilms were grown on dentine discs in a microtiter plate, incubated for 24 h and subjected to the following treatments: aPDT (Denfotex and Helbo system), Er:YAG laser irradiation (2940 nm, 50 mJ or 100 mJ, 15 Hz, 40 s), Nd:YAG laser irradiation (1064 nm, 2 W, 15 Hz, 40 s) and immersion in 2.5% (w/v) NaOCl for 1, 5, 10 and 30 min. Surviving bacteria were harvested, and the number of CFU per disc was determined by plate counting. Results Significant reductions (anova, P ≤ 0.05) in viable counts were observed for aPDT (Helbo) (2 log(10) reduction), Er:YAG irradiation using 100 mJ pulses (4.3 log(10) reduction) and all NaOCl treatments (>6 log(10) reduction). NaOCl (2.5%) for 5 min effectively eliminated all bacteria. aPDT (Denfotex), Er:YAG irradiation using 50 mJ pulses and Nd:YAG treatment caused a reduction in the viable counts of <1 log(10) unit; these results were not significantly different from the untreated controls. Conclusion Within the limitations of this particular laboratory set-up, NaOCl was the most effective in E. faecalis biofilm elimination, while Er:YAG laser treatment (100 mJ pulses) also resulted in high reductions in viable counts. The use of both commercial aPDT systems resulted in a weak reduction in the number of E. faecalis cells. Nd:YAG irradiation was the least effective.
PMID: 22243483 [PubMed - as supplied by publisher]
Özok AR, Persoon IF, Huse SM, Keijser BJF, Wesselink PR, Crielaard W, Zaura E. Ecology of the microbiome of the infected root canal system: a comparison between apical and coronal root segments. International Endodontic Journal. ABSTRACT: Aim To evaluate the microbial ecology of the coronal and apical segments of infected root canal systems using a complete sampling technique and next-generation sequencing. Methodology The roots of 23 extracted teeth with apical periodontitis were sectioned in half, horizontally, and cryo-pulverized. Bacterial communities were profiled using tagged 454 pyrosequencing of the 16S rDNA hypervariable V5-V6 region. Results The sequences were classified into 606 taxa (species or higher taxon), representing 24 bacterial phyla or candidate divisions and one archaeal phylum. Proteobacteria were more abundant in the apical samples (P < 0.05), whilst Actinobacteria were in significantly higher proportions in the coronal samples. The apical samples harboured statistically significantly more taxa than the coronal samples (P = 0.01) and showed a higher microbial diversity. Several taxa belonging to fastidious obligate anaerobes were significantly more abundant in the apical segments of the roots compared with their coronal counterparts. Conclusions Endodontic infections are more complex than reported previously. The apical part of the root canal system drives the selection of a more diverse and more anaerobic community than the coronal part. The presence of a distinct ecological niche in the apical region explains the difficulty of eradication of the infection and emphasizes the need for new treatment approaches to be developed.
PMID: 22251411 [PubMed - as supplied by publisher]
In vivo accuracy of three electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II.
Int Endod J. 2012 Jan 19;
Authors: Somma F, Castagnola R, Lajolo C, Paternò Holtzman L, Marigo L
Abstract
Somma F, Castagnola R, Lajolo C, Paternò Holtzman L, Marigo L. In vivo accuracy of three electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II. International Endodontic Journal. ABSTRACT: Aim To compare in vivo three different electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II. Methodology Thirty single-rooted permanent teeth scheduled for extraction because of periodontal disease were selected from 10 adult patients (ranging from 45 to 67 years) and divided into three groups of 10 teeth. Before the extraction, an access cavity was prepared and the crown was adjusted to establish a stable reference point for all measurements. The working length in Group 1 was determined using the Dentaport ZX apex locator. A K-file with the largest diameter that could reach the last green bar on the screen was stabilized in the canal using a dual-curable flow resin composite. The same procedure was used for the Raypex 5 (the file reached the last yellow bar) and Propex II (0.0 orange bar) apex locators. The teeth were then extracted and cleared. The distance between the tip of the file and the major foramen was then calculated for each tooth using digital photography according to Axiovision AC software (Carl Zeiss). Positive values were assigned when the file tip passed beyond the major foramen, negative values when the tip was short of the foramen and zero value when the file tip and the foramen coincided. Statistical analysis was performed using the chi-squared test or Fisher’s exact test (P ≤ 0.05). Results Dentaport ZX, Raypex 5 and ProPex ΙΙ produced, respectively, 6, 2 and 4 out of 10 correct measurements, 0, 6 and 5 long measurements and 4, 2, and 1 short measurements. The differences between the three electronic root canal length measurement devices were not significant (P = 0.507). Conclusions Under the in vivo conditions of this study, the three electronic root canal length measurement devices were not significantly different in terms of locating the major foramen.
PMID: 22257341 [PubMed - as supplied by publisher]
Centring ability and apical transportation after overinstrumentation with ProTaper Universal and ProFile Vortex instruments.
Int Endod J. 2012 Jan 20;
Authors: González Sánchez JA, Duran-Sindreu F, de Noé S, Mercadé M, Roig M
Abstract
González Sánchez JA, Duran-Sindreu F, de Noé S, Mercadé M, Roig M. Centring ability and apical transportation after overinstrumentation with ProTaper Universal and ProFile Vortex instruments. International Endodontic Journal. ABSTRACT: Aim To evaluate morphological changes to the major foramen after overinstrumentation with ProTaper Universal and ProFile Vortex Ni-Ti rotary instruments. Methodology Twenty-eight mesiobuccal canals of maxillary and mandibular first molars were divided into two groups of 14 canals each. The root canals were prepared with ProTaper Universal or ProFile Vortex instruments. ProTaper and Vortex instruments were used until the file tip protruded 1 mm beyond the working length (0.5 mm beyond the major foramen). The major foramen was photographed before and after overinstrumentation with each file of the two systems used. The images were superimposed and evaluated using Adobe Photoshop. The parameters evaluated were canal transportation, centring ability and shape of the major foramen. Transportation and centring ability were calculated in two directions: the direction of maximum curvature (MC) and a direction vertical to the maximum curvature (VC). Measurements of canal transportation and centring ability were analysed by anova followed by post hoc least significance difference (LSD) multiple comparisons. Results No significant differences were observed amongst the different instruments with respect to centring ability in either direction (P > 0.05). The F3 ProTaper Universal instrument was associated with a higher mean values for transportation in the direction of MC (P < 0.05) than the S1, S2 and F1 ProTaper Universal instruments and the size 15, 0.06 taper, size 20, 0.06 taper, and size 25, 0.06 taper ProFile Vortex instruments. The size 30, 0.06 taper ProFile Vortex instrument had a larger mean value for transportation in the direction of MC (P < 0.05) than the S1 ProTaper Universal and size 15, 0.06 taper ProFile Vortex instruments. The S1, S2, F1, F2 and F3 ProTaper Universal files and the size 15, 0.06 taper, size 20, 0.06 taper, size 25, 0.06 taper, and size 30, 0.06 taper ProFile Vortex files produced an oval foramen in 71%, 71%, 85%, 85%, 71%, 71%, 85%, 85% and 89% of the cases, respectively. Conclusions In most samples, the ProTaper Universal and ProFile Vortex files produced transportation of the major foramen and created an oval-shaped major foramen after overinstrumentation.
PMID: 22264187 [PubMed - as supplied by publisher]
Efficacy of D-RaCe and ProTaper Universal Retreatment NiTi instruments and hand files in removing gutta-percha from curved root canals – a micro-computed tomography study.
Rödig T, Hausdörfer T, Konietschke F, Dullin C, Hahn W, Hülsmann M. Efficacy of D-RaCe and ProTaper Universal Retreatment NiTi instruments and hand files in removing gutta-percha from curved root canals – a micro-computed tomography study. International Endodontic Journal. ABSTRACT: Aim To compare the efficacy of two rotary NiTi retreatment systems and Hedström files in removing filling material from curved root canals. Methodology Curved root canals of 57 extracted teeth were prepared using FlexMaster instruments and filled with gutta-percha and AH Plus. After determination of root canal curvatures and radii in two directions, the teeth were assigned to three identical groups (n = 19). The root fillings were removed with D-RaCe instruments, ProTaper Universal Retreatment instruments or Hedström files. Pre- and postoperative micro-CT imaging was used to assess the percentage of residual filling material as well as the amount of dentine removal. Working time and procedural errors were recorded. Data were analysed using analysis of covariance and analysis of variance procedures. Results D-RaCe instruments were significantly more effective than ProTaper Universal Retreatment instruments and Hedström files (P < 0.05). Hedström files removed significantly less dentine than the rotary NiTi systems (P < 0.0001). D-RaCe instruments were significantly faster compared to both other groups (P < 0.05). No procedural errors such as instrument fracture, blockage, ledging or perforation were detected in the Hedström group. In the ProTaper group, four instrument fractures and one lateral perforation were observed. Five instrument fractures were recorded for D-RaCe. Conclusions D-RaCe instruments were associated with significantly less residual filling material than ProTaper Universal Retreatment instruments and hand files. Hedström files removed significantly less dentine than both rotary NiTi systems. Retreatment with rotary NiTi systems resulted in a high incidence of procedural errors.
PMID: 22264204 [PubMed - as supplied by publisher]
The development of iron-free partially stabilized cement for use as dental root-end filling material.
Int Endod J. 2012 Jan 23;
Authors: Ndong F, Sadhasivam S, Lin FH, Savitha S, Wen-Hsi W, Lin CP
Abstract
Ndong F, Sadhasivam S, Lin F-H, Savitha S, Wen-Hsi W, Lin C-P. The development of iron-free partially stabilized cement for use as dental root-end filling material. International Endodontic Journal. ABSTRACT: Aim To determine the effect of increasing the proportion of zinc on partially stabilized cement (PSC) produced using a one-step sol gel process. Methodology A one-step sol-gel process of Portland cement-based PSC with Zn was synthesized by replacing iron nitrate. The crystalline phases of the PSC-Zn powder were analysed by using X-ray diffraction (XRD). The experimental groups [i.e. MTA, PSC-Fe (control), PSC with 1% Zn, PSC with 3% Zn, and PSC with 5% Zn] were immersed in simulated body fluid for 3 h, 1 and 3 days to evaluate the hydration product formation. The microstructure and surface morphology were analysed using scanning electron microscopy (SEM). Initial and final setting times of the materials were determined using an ASTM Vicat needle testing machine. To evaluate the cytotoxicity of PSC-Zn system, primary osteoblasts cell lines were used. Results The addition of increased weight percentages of Zn, resulted in a more unstable phase which favoured the formation of a monoclinic structure of C(3) S with an increased hydration reaction of PSC and reduced setting time. The cytotoxicity testing of PSC with Zn revealed that the material was not toxic. Conclusions The newly synthesized PSC-Zn material had short setting time and was biocompatible.
PMID: 22268443 [PubMed - as supplied by publisher]
Cyclic fatigue of Reciproc and WaveOne reciprocating instruments.
Int Endod J. 2012 Jan 23;
Authors: Plotino G, Grande NM, Testarelli L, Gambarini G
Abstract
Plotino G, Grande NM, Testarelli L, Gambarini G. Cyclic fatigue of Reciproc and WaveOne reciprocating instruments. International Endodontic Journal. ABSTRACT: Aim To evaluate the cyclic fatigue resistance of Reciproc(®) and WaveOne(®) instruments in simulated root canals. Methodology Two groups of 15 NiTi endodontic instruments of identical tip size of 0.25 mm were tested, group A; Reciproc(®) R25 and group B: WaveOne(®) primary. Cyclic fatigue testing was performed in a stainless steel artificial canal manufactured by reproducing the instrument’s size and taper. A simulated root canal with a 60° angle of curvature and 5-mm radius of curvature was constructed for both the instruments tested. The centre of the curvature was 5 mm from the tip of the instrument and the curved segment of the canal was approximately 5 mm in length. The Reciproc(®) instruments were activated using the preset programme specific for the Reciproc(®) instruments, whilst the WaveOne(®) instruments were activated using the preset programme specific for the WaveOne(®) instruments. All instruments were rotated until fracture occurred and the time to fracture (TtF) and the length of the fractured tip were recorded and registered. Means and standard deviations of TtF and fragment length were calculated for each system and data were subjected to Student’s t-test (P < 0.05). Results A statistically significant difference (P < 0.05) was noted between Reciproc(®) and WaveOne(®) instruments. Reciproc(®) R25 instruments were associated with a significant increase in the mean time to fracture when compared with primary WaveOne(®) instruments (130.8 ± 18.4 vs. 97.8 ± 15.9 s). There was no significant difference (P > 0.05) in the mean length of the fractured fragments between the instruments. Conclusions Reciproc(®) instruments were associated with a significantly higher cyclic fatigue resistance than WaveOne(®) instruments.
PMID: 22268461 [PubMed - as supplied by publisher]
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