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 investigate the morphologic and functional characteristics of the immortalized human liver sinusoidal endothelial cell line (LSEC line).

METHODSImmunofluorescence staining and fluorescence microscopy were used to detect the classic endothelial cell markers in LSEC line, and flow cytometry was used to analyze the purity of the human LSEC line. The morphology (including W-P bodies and surface fenestrations) and phagocytotic capacity of the human LSEC line were observed by transmission and scanning electron microscope. The proliferation curve of the human LSEC line was analyzed by MTT assay. The functional differences between the human LSEC line and human primary LSEC in expression of ELAM-1 and ICAM-1, activities of fibrinolysis (PAI-1, t-PA, u-PA), releasing of IL-6 and IL-8 were compared respectively by enzyme linked immunosorbent assay. Comparison of the susceptibility to hypoxia-reoxygenation induced apoptosis between the human LSEC line and human primary LSEC were investigated by TUNEL.

RESULTSThe established human LSEC line maintained a high proliferative ability and has been passaged for more than 80 times in the absence of any growth factors. Immunofluorescence staining showed that the human LSEC line could express classic endothelial cell marks including von Willebrand Factor (vWF), and could take up acetylated low-density lipoproteins (Ac-LDL). The purity of the human LSEC line was confirmed over 95% by flow cytometric analysis. The W-P bodies and the phagocytosis of Dynabeads was demonstrated by transmission electron microscope. And fenestrations could be found cellular surface with scanning electron microscopy. When compared with human primary LSEC, the human LSEC line has an equivalent responsiveness to tumor necrosis factor in up-regulation of ELAM-1 and ICAM-1. The human LSEC line can also release PAI-1, t-PA, u-PA but can not release IL-6 and IL-8 to TNF-alpha. In contrast, human primary LSEC could release IL-6. The human LSEC line showed higher susceptibility to hypoxia-reoxygenation-induced apoptosis, and the percentage of apoptotic cells was as high as (38.4 +/- 6.7)%, while (28.6 +/- 4.5)% and (7.8 +/- 1.2)% respectively in primary LSEC and in human umbilical vein endothelial cells.

CONCLUSIONSThe established human LSEC line maintains the special phenotypes and the major functional characteristics, and especially maintains the high susceptibility to hypoxia-reoxygenation-induced apoptosis. Therefore it is feasible to use this cell line for the study of liver ischemia-reperfusion injury.

Apoptosis ; Cell Line ; Cell Proliferation ; E-Selectin ; metabolism ; Endothelial Cells ; cytology ; metabolism ; Humans ; Intercellular Adhesion Molecule-1 ; metabolism ; Interleukin-6 ; metabolism ; Interleukin-8 ; metabolism ; Liver ; cytology

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 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

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 provide data on alcohol consumption and drug use among middle-school students aged 13-15 in 4 cities of China, and to provide evidence for developing intervention strategies on adolescents alcohol and drug use.

METHODSStandardized sample selection process of two-stage cluster-sampling was used in middle-school students in Beijing, Hangzhou, Wuhan and Urumchi. A self-administered questionnaire survey was conducted in Sept. 2003 and data was analyzed by Epi Info software.

RESULTSAmong 7344 students from grade 1 to 3, 36.5% had tasted while 14.4% had drunk alcohol in the past 30 days. 9.9% had experienced drunkness, 5.1% had been in trouble because of drinking, and 1.6% had ever used illegal drugs. Significant differences had been found in all the cities. Higher graders, older students and boys had higher rates of alcohol and addictive drug use than low graders, younger students and girls. 51.9% had been taught on take alcohol safety and another 27.6% on skills of rejecting alcohol, during the past school year.

CONCLUSIONSThe current situation of alcohol and addictive drug use among Chinese middle-school students aged 13-15 seemed to be quite critical, suggesting that it is necessary to carry out relevant health education in accordance with different characteristics in area, gender and age of the students.

Adolescent ; Alcohol Drinking ; epidemiology ; China ; epidemiology ; Female ; Humans ; Male ; Students ; Substance-Related Disorders ; epidemiology

OBJECTIVETo evaluate the effect of using dental operating microscope and ultrasonic instruments in treating blocked canals.

METHODSThe etiology of canal blockage included calcification, broken instruments, posts, resinifying, etc. 236 blocked canals were treated with ultrasonic tips under dental operating microscope. The success rate was calculated.

RESULTS178 blocked canals were successfully managed with a success rate of 75.4%. The success rate of each category of the blocked canals were: 71.7% for calcified canals, 81.1% for broken instruments, 100% for canals blocked by posts, 62.5% for canals blocked by resinifying therapy, and 84.1% for canals blocked by filling materials.

CONCLUSIONThe use of dental operating microscope and ultrasonic instruments is proved to be an effective method in the management of blocked canals.

Dental Pulp Cavity ; Humans ; Microscopy ; Treatment Outcome ; Ultrasonics

OBJECTIVESTo study the effect of lead acetate on the expression of nerve growth factor (NGF) protein in rat brain and the regulation of thyroid hormone.

METHODSLead acetate was given to SD rats intraperitoneally ip. at the dosage of 25, 50 and 100 mg/kg respectively. 6-n-propyl-2-thiouracil (PTU) was used to make a hypothyroid model and then lead acetate was given at the dosage of 50 mg/kg body weight through i.p. The NGF protein expression in rat brain was observed by immunohistochemistry Triiodothyronine (T3), thyroxin (T4), TSH in serum and T3, T4 in brain tissue were determined by radio immunoassays (RIAs).

RESULTSThe average gray value of NGF protein in cerebral cortex of 50 mg, 100 mg treated groups (180.49 +/- 10.33, 169.72 +/- 19.75, respectively) were lower than the control (200.75 +/- 3.27, P<0.01). The area density of NGF protein in hippocampus of three treated groups (0.08 +/- 0.14, 0.12 +/- 0.02, 0.13 +/- 0.04, respectively) were significantly different from the control (0.025 +/- 0.015, P<0.05). The area density and the average gray value of NGF protein in lead acetate treated hypothyroid rat brain were of no significant changes. The levels of serum T3 in three treated groups [(0.68 +/- 0.02), (0.57 +/- 0.04), (0.54 +/- 0.02) microg/L respectively] and T4 [(28.30 +/- 1.83), (27.35 +/- 2.55), (24.00 +/- 3.01) microg/L] in serum were significantly lower while TSH [(6.34 +/- 1.13), (7.74 +/- 0.79), (9.16 +/- 0.77) IU] higher than those in the control [T3 (0.97 +/- 0.14) microg/L, T4 (54.50 +/- 3.70) microg/L and TSH (4.62 +/- 2.16) IU], and there was a good dose-response relationship. The levels of T3 in cerebral cortex of three treated groups [(13.26 +/- 0.81), (11.49 +/- 0.10), (10.42 +/- 1.19) pg/mg pro respectively] and T4 [(0.50 +/- 0.03), (0.49 +/- 0.13), (0.42 +/- 0.01) ng/mg pro] were significantly lower than those in control [(20.85 +/- 11.01) pg/mg pro, (0.76 +/- 0.14) ng/mg pro, P<0.05, P<0.01].

CONCLUSIONLead could increase the NGF protein expression in rat brain, which may be regulated by thyroid hormone.

Animals ; Brain Chemistry ; drug effects ; Immunohistochemistry ; Male ; Nerve Growth Factor ; analysis ; Organometallic Compounds ; toxicity ; Rats ; Rats, Sprague-Dawley ; Thyroid Hormones ; analysis ; blood ; physiology