Management of Separated Instruments Extruded into the Maxillary Sinus and Soft Tissue: a Case Series.

Extrusion of separated endodontic instruments is a frustrating complication that can occur during root canal treatment and is difficult to handle. This report aimed to introduce different methods to retrieve such separated instruments through three cases with different locations of fragments. Fragments extruded completely into the maxillary sinus, partially into the maxillary sinus and lying in the soft tissue were retrieved using a lateral window approach, ultrasonic method and minimally invasive surgery, respectively. These methods can be recommended for retrieving fragments in certain cases.

Evaluation of Silk Fibroin-RGD-Stem Cell Factor Scaffold Effect on Adhesion, Migration, and Proliferation of Stem Cells of Apical Papilla.

This study explored the effects of a silk fibroin-RGD-stem cell factor (SF-RGD-SCF) scaffold on the migration, proliferation, and attachment of stem cells of apical papilla (SCAPs). SF, SF-RGD, SF-SCF, and SF-RGD-SCF scaffolds were prepared, and laser confocal microscopy was used to observe the adhesion and growth status of SCAPs on the scaffolds. Furthermore, the numbers of SCAPs on the scaffolds were counted by a digestion counting method to evaluate their proliferation. Cells on the SF-RGD-SCF scaffold proliferated more than those on the other scaffolds and showed a more obvious tendency to migrate to the scaffold's deep porous structure after 7 d seeding. Live/dead cell staining results showed that almost all the adhered cells were alive after 7 d. Furthermore, cell counting showed that the number of cells on the SF-RGD-SCF scaffold was highest after both 1 and 7 d (P < 0.05). Thus, the SF-RGD-SCF composite is biocompatible and promotes the migration, adhesion, and proliferation of SCAPs, making it of potential use as a scaffold for cell-homing pulp regeneration.

Morphological Changes of the Root Apex in Permanent Teeth with Failed Endodontic Treatment.

OBJECTIVE: To determine the number, shape and diameter of apical foramina as well as changes in root apex morphology of permanent teeth with failed endodontic treatment. METHODS: Clinical records were collected for teeth diagnosed with posttreatment periapical periodontitis that subsequently underwent endodontic microsurgery. Resected root apices were examined with stereomicroscopy. The number, shape and diameter of apical foramina were recorded. Scanning electron microscopy (SEM) was used to investigate the presence and extent of apical external root resorption and evaluate how it was influenced by sex, age, tooth position, periapical radiolucency size and periapical lesion biopsy results. External root resorption was classified according to site (periforaminal or foraminal), and the extent of resorption was graded as 0, 1, 2 or 3. RESULTS: A total of 112 teeth with 112 apices were examined. The mean diameter of the main apical foramina was 420.78 µm. The apical foramen was most commonly irregularly shaped (68.39%). The incidence of multiple foramina was 48.21%. SEM revealed that 96.43% of apices had periforaminal resorption (PR) and 94.64% had foraminal resorption (FR). The existence and extent of external root resorption were not correlated with sex, age, tooth position, periapical radiolucency size or periapical lesion biopsy results (P > 0.05). CONCLUSION: Apical foramina of permanent teeth with failed endodontic treatment were commonly irregularly shaped, with a mean diameter of approximately 420 µm. Nearly half of the samples had multiple foramina. There was a high prevalence of apical external root resorption. A relationship may exist between morphological changes in the root apex and treatment failure.

A screening method for gastric cancer by oral microbiome detection.

Gastric cancer is the second most common malig-nancy and one of the principal causes of cancer­related mortality worldwide. Early diagnostic and screening methods for gastric cancer are limited at present, most of them involving invasive procedures. We aimed to investigate the characteristics of the oral microbiome in gastric cancer individuals and to conduct a screening method for gastric cancer by oral microbiome detection. We used high­throughput sequencing to examine the total bacterial profile of saliva and plaque samples of 50 subjects, including 37 individuals with gastric cancer and 13 controls. The Venn diagram and species abundance clusters were generated from the data. The results indicated that the oral bacteria were more complex in patients with gastric cancer. Based on the characteristics of the oral microbiome in individuals with gastric cancer, a scoring system was designed to screen gastric cancer. In the present study, 36 out of 37 individuals in the gastric cancer group were identified as a high­risk population, giving a sensitivity rate of 97%. One out of 13 individuals in the control group was identified as a high­risk population, providing a false-positive rate of 7.7%. The scoring system we designed may be a potential method for screening suspected gastric cancer patients by oral microbiome detection. Further calibration of this scoring system is needed by recruiting a larger study population.

Post endodontic pain following single-visit root canal preparation with rotary vs reciprocating instruments: a meta-analysis of randomized clinical trials.

BACKGROUND: In endodontic therapy, continuous rotary instrumentation reduced debris compared to reciprocal instrumentation, which might affect the incidence of post-endodontic pain (PP). The aim of our study was to assess whether PP incidence and levels were influenced by the choice of rotary or reciprocal instruments. METHODS: In this meta-analysis the Pubmed and EM databases were searched for prospective clinical randomized trials published before April 20, 2016, using combinations of the keywords: root canal preparation/instrumentation/treatment/therapy; post-operative/endodontic pain; reciprocal and rotary instruments. RESULTS: Three studies were included, involving a total of 1,317 patients, 659 treated with reciprocating instruments and 658 treated with rotary instruments. PP was reported in 139 patients in the reciprocating group and 172 in the rotary group. The PP incidence odds ratio was 1.27 with 95% confidence interval (CI) (0.25, 6.52) favoring rotary instruments. The mild, moderate and severe PP levels odds ratios were 0.31 (0.11, 0.84), 2.24 (0.66, 7.59) and 11.71 (0.63, 218.15), respectively. No evidence of publication bias was found. CONCLUSIONS: Rotary instrument choice in endodontic therapy is associated with a lower incidence of PP than reciprocating instruments, while reciprocating instruments are associated with less mild PP incidence.

The incidence of root microcracks caused by 3 different single-file systems versus the ProTaper system.

INTRODUCTION: The aim of this study was to compare the incidence of root cracks observed at the apical root surface and/or in the canal wall after canal instrumentation with 3 single-file systems and the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland). METHODS: One hundred mandibular incisors were selected. Twenty control teeth were coronally flared with Gates-Glidden drills (Dentsply Maillefer). No further preparation was made. The other 80 teeth were mounted in resin blocks with simulated periodontal ligaments, and the apex was exposed. They were divided into 4 experimental groups (n = 20); the root canals were first coronally flared with Gates-Glidden drills and then instrumented to the full working length with the ProTaper, OneShape (Micro-Mega, Besancon, France), Reciproc (VDW, Munich, Germany), or the Self-Adjusting File (ReDent-Nova, Ra'anana, Israel). The apical root surface and horizontal sections 2, 4, and 6 mm from the apex were observed under a microscope. The presence of cracks was noted. The chi-square test was performed to compare the appearance of cracked roots between the experimental groups. RESULTS: No cracks were found in the control teeth and teeth instrumented with the Self-Adjusting File. Cracks were found in 10 of 20 (50%), 7 of 20 (35%), and 1 of 20 (5%) teeth after canal instrumentation with the ProTaper, OneShape, and Reciproc files, respectively. The difference between the experimental groups was statistically significant (P < .001). CONCLUSIONS: Nickel-titanium instruments may cause cracks on the apical root surface or in the canal wall; the Self-Adjusting File and Reciproc files caused less cracks than the ProTaper and OneShape files.

Microbial diversity in failed endodontic root-filled teeth.

BACKGROUND: Persistent/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. METHODS: DNA 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. RESULTS: All 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. CONCLUSIONS: Persistent 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.

[Treatment outcome of iatrogenic perforation repair by mineral trioxide aggregate].

OBJECTIVE: To observe the clinical effect of iatrogenic perforation repaired by mineral trioxide aggregate (MTA). METHODS: Twenty-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. RESULTS: Nineteen cases healed and two cases were healing. No cases failed. CONCLUSIONS: MTA is effective in the treatment of iatrogenic perforation.

[National examinations for dentist in Japan and implications].

Questions such as the law that was accorded by National Board Examinations for Dentist in Japan, the qualification of the examinee, the organization of the committee, the implementation of the exam, testing items development and the eligibility criteria were introduced in details in this article. The evolution of the number of qualified candidates and the issues for development needed to be explored were proposed.

[Torque resistance of three different types of nickel-titanium rotary instruments].

OBJECTIVE: To compare torsional fracture of three different types of nickel-titanium rotary instruments ProTaper, Hero642 and Mtwo by making a stimulate models in vitro. METHODS: Through 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. RESULTS: The 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. CONCLUSION: The 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.

[Theoretical research and clinical practices of contemporary root canal therapy].

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.

Bond strength of different adhesives to normal and caries-affected dentins.

BACKGROUND: Currently, 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. METHODS: Twenty 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). RESULTS: Etch-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. CONCLUSION: The etch-and-rinse adhesive performed more effectively to caries-affected dentin than the self-etching adhesives.

[Evaluation of homogeneity and density of root canal filling with four obturation techniques].

OBJECTIVE: To evaluate the homogeneity and density of root canal filling with four obturation techniques. METHODS: Forty 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. RESULTS: The 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). CONCLUSIONS: Warm vertical condensation and thermafil produce significantly higher PGFA than guttaflow and cold lateral condensation technique.

[The effect of curvature of simulated root canal and location of fragment on removal of broken file from simulated root canal].

OBJECTIVE: To evaluate effect of root canal curvature and location of the fragment on the removal of broken file from root canal. METHODS: Sixty 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. RESULTS: All 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). CONCLUSION: The 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.

[Clinical effect of the use of dental operating microscope and ultrasonic instruments in the management of blocked canals].

OBJECTIVE: To evaluate the effect of using dental operating microscope and ultrasonic instruments in treating blocked canals. METHODS: The 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. RESULTS: 178 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. CONCLUSION: The use of dental operating microscope and ultrasonic instruments is proved to be an effective method in the management of blocked canals.

[Ultrasonic techniques for removing broken instruments from root canal].

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.

[Expression of lipopolysaccharide receptors CD14 and TLR4 in a model of rat molar apical periodontitis].

OBJECTIVE: To 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. METHODS: After 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. RESULTS: CD14 and TLR4 were not detected in healthy periapical tissue but strongly positive in inflammatory periapical tissue. Positive cells were mostly monocytes/macrophages. CONCLUSIONS: CD14 and TLR4 may play an important role in the pathogenesis of periapical periodontitis, probably via immune cells such as monocytes/macrophages and neutrophils.

[Expression of lipopolysaccharides signal receptors CD14 and TLR4 in human dental pulp tissue and fibroblasts].

OBJECTIVE: To investigate the expression of lipopolysaccharides (LPS) receptors CD14 and TLR4 in normal and inflamed human dental pulp tissue and fibroblasts and to determine the signal transduction pathway of LPS in pulpitis. METHODS: CD14 and TLR4 expression in healthy and inflammatory pulps was observed by immunohistochemistry. The rates of CD14 and TLR4 positive cells and the mean fluorescence intensity in in vitro cultured pulp fibroblasts before and after being stimulated by LPS. RESULTS: CD14 and TLR4 were not detected in healthy pulp tissues, but they were strongly positively stained in inflammatory pulps. Ratio of TLR4 positive cells and mean fluorescence intensity produced by the cells stimulated by LPS increased significantly compared with normal pulp cells. However, there were no CD14 expression in human dental pulp cells before and after LPS stimulation. CONCLUSIONS: This study revealed a significant increase in the expression of CD14 and TLR4 in inflamed human dental pulp tissue. Human dental pulp cells could be induced by LPS to express TLR4, which may play an important role in the process of pulpitis.

[Secretory expression of sCD14 in Pichia pastoris and its LPS binding activity].

AIM: To achieve secretory expression of mature sCD14 gene in Pichia pastoris and to analyze its LPS binding activity. METHODS: sCD14 gene was cloned into yeast expression vector pPIC9K. Recombinant plasmid was lineared by Sac I and transformed into Pichia pastoris GS115. Positive integrated clones were screened and expressed by methanol inducing. RESULTS: The mature sCD14 was expressed in BMMY with pH 6.5 after optimization of inducing expression condition. Western blot and ELISA data revealed recombinant products combined with specific antibody. The results from FACS showed recombinant product had biological activity of binding with LPS. CONCLUSION: The recombinant mature sCD14 molecules with favorable LPS-binding activity could be used for further study on its structure and functions.