OBJECTIVETo compare torsional fracture of three different types of nickel-titanium rotary instruments ProTaper, Hero642 and Mtwo by making a stimulate models in vitro.

METHODSThrough the establishment of model in vitro, compared the different time with 3 kinds of nickel titanium file in cutting-edge bound occurs, and to observe the section of fractured instruments by scanning electron microscope.

RESULTSThe resistence to torque was different from three types of nickel titanium instruments. The time to fracture of Mtwo was significantly longer than ProTaper's and Hero642's, but ProTaper's and Hero642's had no significant difference. Three kinds cross-sectional design were different, a lot of toughness nests were seen in broken surface. Most of them were ductile fracture. Time to fracture was influenced by the quality disfigurement.

CONCLUSIONThe resistance to torque of Mtwo was better than ProTaper and Hero642. The lifespan was influenced by the design of cross-section. The quality disfigurement of the files reduced the resistance to flexual fatigue.

Cross-Sectional Studies ; Dental Alloys ; Equipment Design ; Equipment Failure ; Materials Testing ; Nickel ; Root Canal Preparation ; Stress, Mechanical ; Surface Properties ; Titanium ; Torque

Instruments broken in root canal is one of the frequent complications of endodontic therapy and fortunately, as the rapid development of microscope using in the root canal treatment, most of the broken instruments can be removed with the assistance of ultrasonic appliances. In the present study, we talked about the causes, the removing methods of broken instruments and troubles during the procedures. We put much emphasis on the creation of a straight pathway along the canal as well as some concerns in using the ultrasonic appliances, such as the water spray, the rotating actions and the assistance of microscope, all of which are supposed to offer great benefits for clinically avoiding as well as dealing with broken instruments.
Dental Pulp Cavity ; Equipment Failure ; Humans ; Microscopy ; Root Canal Preparation ; Root Canal Therapy ; Ultrasonics

Root canal therapy is currently the most effective treatment for pulpal and periapical diseases. With the innovation of endodontic theory and techniques, the concept of contemporary root canal therapy has been established and promoted gradually. Advances in endodontic technology, instruments, and materials have increased the safety and clinical success rate of root canal therapy. This article reviews the recent theoretical research and clinical practices of contemporary root canal therapy.
Dental Pulp Diseases ; therapy ; Humans ; Periapical Diseases ; therapy ; Root Canal Therapy ; methods

OBJECTIVETo evaluate effect of root canal curvature and location of the fragment on the removal of broken file from root canal.

METHODSSixty extracted mandibular premolars were divided equally into six groups according to location of fragment (2 mm or 8 mm below root canal orifice) and root canal curvature (20 degrees, 30 degrees or 40 degrees). Broken files were removed using ultrasonic tips combined with dental operating microscope. Number of successfully removed case and operating time were recorded. Pre- and post-operative digital radiographs were input into image analyzing software to calculate diameter variance of root canal at the level of tip of broken file.

RESULTSAll the 6 groups of broken files were successfully removed with out perforation. Among same fragment location groups, diameter variance was increased in greater curvature groups and the difference was significant (P < 0.05), while operation time was not significantly different (P > 0.05). Among same root canal curvature groups, the deeper the fragment, the longer operation time, difference being significant (P < 0.05), while difference of diameter variance was not significant (P > 0.05).

CONCLUSIONThe more curvature of root canal, the more dentine removal amount at the level of broken file tip. Location of fragment has no effect on dentine removal amount. Safe straight-line access and adequate thickness of dentine are essential to removal of broken file from root canal.

Bicuspid ; Dental Pulp Cavity ; Dentin ; Humans ; Root Canal Preparation ; Root Canal Therapy

OBJECTIVETo observe the clinical effect of iatrogenic perforation repaired by mineral trioxide aggregate (MTA).

METHODSTwenty-one iatrogenic perforation cases were included. The root canals were shaped and cleaned and then obturated after MTA was used to repair the perforation with microscopes. Preoperative, immediate postoperative, and follow-up radiographs were evaluated to determine the pathologic changes adjacent to the perforation site.

RESULTSNineteen cases healed and two cases were healing. No cases failed.

CONCLUSIONSMTA is effective in the treatment of iatrogenic perforation.

Aluminum Compounds ; therapeutic use ; Calcium Compounds ; therapeutic use ; Dental Pulp Cavity ; diagnostic imaging ; injuries ; Drug Combinations ; Follow-Up Studies ; Humans ; Iatrogenic Disease ; Incisor ; diagnostic imaging ; injuries ; Molar ; diagnostic imaging ; injuries ; Oxides ; therapeutic use ; Radiography ; Root Canal Filling Materials ; therapeutic use ; Silicates ; therapeutic use

OBJECTIVETo evaluate the homogeneity and density of root canal filling with four obturation techniques.

METHODSForty extracted single root teeth were randomly divided into four groups with 10 teeth each. Under simulated clinical conditions, the root canals were shaped with Nickle titanium rotary files (Protaper) using crown-down technique and were filled with warm vertically condensed gutta-percha (group A), core carrier technique-thermafil (group B), guttaflow (group C) and conventional cold laterally condensed gutta-percha (group D). Roots were sectioned at four levels. The cross-sections were photographed through a microscope, the photos were analysed, and the percentage of gutta-percha filled area (PGFA) was measured.

RESULTSThe overall PGFA values were (96.5 ± 3.6)%, (95.6 ± 3.9)%, (86.5 ± 5.7)% and (81.5 ± 4.2)% for groups A, B, C and D, respectively. The differences between these groups were statistically significant (P < 0.01). Group A and B were significantly higher than group C and D (P < 0.01). The PGFA in group D was significantly lower than that in other groups (P < 0.01). The average PGFA in both group A and B was higher than that of group C and D at apical and middle level (P < 0.01).

CONCLUSIONSWarm vertical condensation and thermafil produce significantly higher PGFA than guttaflow and cold lateral condensation technique.

Dental Pulp Cavity ; Dimethylpolysiloxanes ; Drug Combinations ; Gutta-Percha ; Humans ; Incisor ; Nickel ; Root Canal Filling Materials ; Root Canal Obturation ; Temperature ; Titanium

OBJECTIVETo characterize the expression of lipopolysaccharide (LPS) receptors-CD14 and TLR4 in rat peri-radicular tissue and to investigate the signal transduction pathway of LPS and its receptors in periapical periodontitis.

METHODSAfter establishment of a model of rat molar LPS-induced apical periodontitis, CD14 and TLR4 expression in healthy and inflammatory periapical tissue were determined by immunohistochemistry.

RESULTSCD14 and TLR4 were not detected in healthy periapical tissue but strongly positive in inflammatory periapical tissue. Positive cells were mostly monocytes/macrophages.

CONCLUSIONSCD14 and TLR4 may play an important role in the pathogenesis of periapical periodontitis, probably via immune cells such as monocytes/macrophages and neutrophils.

Animals ; Disease Models, Animal ; Lipopolysaccharide Receptors ; metabolism ; Lipopolysaccharides ; toxicity ; Periapical Periodontitis ; chemically induced ; metabolism ; pathology ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Toll-Like Receptor 4 ; metabolism

BACKGROUNDPersistent/secondary infections of human root canals play an important role in the failure of endodontic treatment. This study used 16S rRNA sequencing to assess microbial diversity in root-filled teeth associated with failed endodontic treatment.

METHODSDNA was extracted from 15 teeth with persistent intraradicular infections, and the 16S rRNA of all present bacteria were amplified by PCR, followed by cloning and sequencing of the 16S rRNA amplicons.

RESULTSAll sample extracts were positive for PCR amplification using the universal 16S rRNA gene primers. Negative control reactions yielded no amplicons. Sixty-five phylotypes belonging to seven phyla were identified from 760 clones; a mean of 9.4 phylotypes were detected in each sample (range 3 - 15). Twenty-eight phylotypes were detected in more than one sample, revealing a high inter-sample variability. Parvimonas micra (60%, 9/15), Solobacterium moore (47%, 7/15), Dialister invisus (33%, 5/15), Enterococcus faecalis (33%, 5/15), Filifactor alocis (27%, 4/15), and Fusobacterium nucleatum (27%, 4/15) were the prevalent species. Nineteen as-yet-uncultivated phylotypes were identified, comprising a substantial proportion of the bacteria in many cases.

CONCLUSIONSPersistent intraradicular infections were present in all root-filled teeth associated with failed endodontic treatment. The current observations reveal new candidate endodontic pathogens, including as-yet-uncultivated bacteria and phylotypes that may participate in the mixed infections associated with post-treatment apical periodontitis.

Adolescent ; Adult ; Aged ; Bacteria ; classification ; isolation & purification ; Female ; Humans ; Male ; Middle Aged ; RNA, Ribosomal, 16S ; genetics ; Tooth, Nonvital ; microbiology ; Treatment Failure

OBJECTIVETo investigate effect of particle size on oral absorption of silymarin-loaded solid lipid nanoparuicles.

METHODSolid lipid nanoparticles (SLN) of various sizes (150 nm, 500 nm and 1000 nm) using Compritol 888 ATO as the material and silymarin (SM) as a model drug were prepared. Silybinin concentration in plasma of rats were determined by RP-HPLC with UV detector. The main pharmacokinetic parameters were calculated by 3p97.

RESULTResults showed that the AUC of 150 nm SLN was 2.08 fold that of 500 nm SLN and 2.54 fold of 1000 nm SLN treated orally to rats (P < 0.05). The oral bioavailability of 150 nm SLN was remarkably higher than the other two size SLN.

CONCLUSIONThis has important implications in designing of SM-SLN as a new oral drug delivery system.

Administration, Oral ; Animals ; Area Under Curve ; Biological Availability ; Drug Carriers ; Drug Delivery Systems ; Excipients ; Fatty Acids ; Female ; Male ; Milk Thistle ; chemistry ; Nanostructures ; Particle Size ; Plants, Medicinal ; chemistry ; Rats ; Rats, Sprague-Dawley ; Silymarin ; administration & dosage ; isolation & purification ; pharmacokinetics

BACKGROUNDCurrently, several systems of dentin substrate-reacting adhesives are available for use in the restorative treatment against caries. However, the bond effectiveness and property of different adhesive systems to caries-affected dentin are not fully understood. The objective of this study was to evaluate the bond strength of different adhesives to both normal dentin (ND) and caries-affected dentin (CAD) and to analyze the dentin/adhesive interfacial characteristics.

METHODSTwenty eight extracted human molars with coronal medium carious lesions were randomly assigned to four groups according to adhesives used. ND and CAD were bonded with etch-and-rinse adhesive Adper Single Bond 2 (SB2) or self-etching adhesives Clearfil SE Bond (CSE), Clearfil S(3) Bond (CS3), iBond GI (IB). Rectangular sticks of resin-dentin bonded interfaces 0.9 mm(2) were obtained. The specimens were subjected to microtensile bond strength (microTBS) testing at a crosshead speed of 1 mm/min. Mean microTBS was statistically analyzed with analysis of variance (ANOVA) and Student-Newman-Keuls tests. Interfacial morphologies were analyzed by Scanning Electron Microscopy (SEM).

RESULTSEtch-and-rinse adhesive Adper(TM) Single Bond 2 yielded high bond strength when applied to both normal and caries-affected dentin. The two-step self-etching adhesive Clearfil SE Bond generated the highest bond strength to ND among all adhesives tested but a significantly reduced strength when applied to CAD. For the one-step self-etching adhesives, Clearfil S(3) Bond and iBond GI, the bond strength was relatively low regardless of the dentin type. SEM interfacial analysis revealed that hybrid layers were thicker with poorer resin tag formation and less resin-filled lateral branches in the CAD than in the ND for all the adhesives tested.

CONCLUSIONThe etch-and-rinse adhesive performed more effectively to caries-affected dentin than the self-etching adhesives.

Adhesives ; Dental Bonding ; methods ; Dentin ; Humans ; Microscopy, Electron, Scanning ; Molar ; Tensile Strength