Microbial-flora of root canals at the time of root filling and the outcome of treatment

published_or_final_versio

Factors affecting the chance of post-operative sensitivity in indirect porcelain onlays

published_or_final_versio

Cytotoxicity of a novel nano-silver particle endodontic irrigant

published_or_final_versio

根管治療失敗的根尖外科處理

根管外科通常是應用于根管治療失敗的病例,但是并非所有根管治療失敗的病例都是根管外科的適應癥;是否應進行根管外科治療受到許多因素影響.本視頻講座將詳細討論這些因素以及根尖外科的臨床技術.link_to_subscribed_fulltex

Outcome of endodontic therapy with thermafil and lateral condensation technique

Journal of Dental Research, 2003, v. 82 Spec. Iss. C, p. C-635, abstract no. 19published_or_final_versio

Long-term outcome of primary non-surgical root canal treatment

Aim: The aim of this study is to examine the survival distributions of primary root canal treatment using interval-censored data and to assess the factors affecting the outcome of primary root canal treatment, in terms of periapical healing and tooth survival. Materials and methods: About one tenth of primary root canal treatment performed between January 1981 and December 1994 in a dental teaching hospital were systematically sampled for inclusion in this study. Information about the patients' personal particulars, medical history, pre-operative status, treatment details, and previous review status of the treated teeth, were obtained from dental records. Patients were recalled for examination clinically and radiographically. Treatment outcomes were categorized according to the status for periapical healing and tooth survival. The event time was interval-censored and subjected to survival analysis using the Weibull accelerated failure time model. Results: A total of 889 teeth were suitable for analysis. Survival curves of both outcome measures (periapical healing and tooth survival) declined in a non-linear fashion with time. Median survival of the treated teeth was 119 months (periapical healing) and 252 months (tooth survival). Age, tooth type, pre-operative periapical status, occlusion, type of final restoration, and condition of the tooth/restoration margin were significant factors affecting both periapical healing and tooth survival. Apical extent and homogeneity of root canal fillings had a significant impact towards periapical healing (p < 0.05), but not tooth survival. Conclusion: The longevity of treated teeth based on tooth survival was considerably greater than that of periapical healing. Both outcome measures were affected by a number of socio-demographic, pre-, intra-, and post-operative factors. Clinical relevance: Root canal-treated teeth may continue to function for a considerable period of time even though there may be radiographic periapical lesion present. Decision for extraction may be due to reasons other than a failure of the periapical tissues to heal. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 28 May 201

An in vitro Evaluation on a Novel Root Canal Cleansing Method by Using Nylon Fibers

Despite traditional metal-based dental files, such as NiTi being demonstrated effective in root cleaning, the tooth structure is always damaged. Thus, to fulfill the need for a minimally invasive tool for contemporary endodontics and dentistry, the use of polymer fibers might provide a good option, as it is soft, fabricable, and disposable. In this study, two types of nylon fibers with respective average diameters of 206.9 µm (fiber W) and 156.4 µm (fiber B), respectively, were used as dental files, and mounted onto either a reciprocating or a low-speed rotary hand-piece. In vitro, simulated root canal models were colored red using nail varnish, and then cleaned by the fiber files mounted on the hand-pieces. Three parts of the simulated models, i.e., the apical third, the medium third, and the coronal third, were chosen to assess the cleaning the efficiency (CE) of each specimen by calculating the ratio of the cross-sectional area changes, before and after cleansing, using micro-Computer Tomography (CT). A NiTi file with a low-speed hand-piece was used as a control. SEM was used to observe the nylon fiber surfaces before and after the cleansing. Micro-CT results showed that for both the nylon fibers, W and B, an average CE of 82.11% ± 9.68% for the medium third could be achieved, which is statistically higher (p < 0.01) than the coronal third and apical third. The cleansing efficiency was not affected by, the types of fibers, nor the hand-pieces according to student’s t-test. Most of the nylon fibers could withstand deformation after the cleansing. To conclude, nylon fiber files have demonstrated a certain cleansing efficiency in simulated root canals, and micro-CT is a promising method to assess CE.published_or_final_versio

Mechanical behavior of ProTaper Universal F2 finishing file under various curvature conditions: A finite element analysis study

Introduction: The purpose of this study was to visualize the stresses and strain distribution patterns in ProTaper Universal F2 files (Dentsply Maillefer, Ballaigues, Switzerland) and to establish the stress- and strain-curvature relationship for this instrument under various conditions by using a dynamic, three-dimensional finite-element model. Methods: An accurate geometric model of a ProTaper Universal F2 instrument was created. Two short, straight tubes were also modeled to represent the parts of root canal apical and coronal to the curvature. Then, the file was constrained to a curve of varying degree, curve length, and position. The maximum von Mises stress and strain on the tension side of the instrument was measured at 5-degree intervals in a numerical simulation package (LS-DYNA; Livermore Software Technology, Livermore, CA). Results: The mechanical performance of the ProTaper F2 file under various conditions was simulated. A long curvature length produced lower values of stress and strain under the same angle of curvature. An increase in the curvature angle generally induces higher stress and strain. For the same degree and curve length, the stress and strain increased if the curved portion was situated further up the shaft of the instrument (ie, with a larger diameter). Conclusions: The dynamic, numerical model may be used to evaluate and compare the effect of various root canal curvatures on the behavior of different designs of root canal instrument. The magnitude of stress and strain imposed on the instrument is influenced by the abruptness and degree of curvature as well as the location of the curved portion. Copyright © 2011 American Association of Endodontists.postprin

Effect of miR-146a/bFGF/PEG-PEI Nanoparticles on Inflammation Response and Tissue Regeneration of Human Dental Pulp Cells

published_or_final_versio

The Effect of Cultured Autologous Periodontal Ligament Cells on the Healing of Delayed Autotransplanted Dog's Teeth

Introduction: The regeneration of the periodontal structure for avulsed teeth extended dry times has been a goal of dentists. The aim of this study was to investigate a new strategy of delayed replantation for avulsed teeth that were not suitable for immediate replantation. Methods: Extracted dog's premolar teeth were maintained in a dry environment for a month after isolation and proliferation of the periodontal ligament (PDL) cells. Then, tooth roots coated with 1 × 106 cultured autologous PDL cells were autotransplanted in artificial sockets created in the mandible. The dogs were sacrificed 60 days after transplantation. Histologic analyses showed that a root-PDL-bone complex was found in all cases of the PDL cell-loaded samples. Results: The new PDL-like connective tissue was located between the alveolar bone and the transplanted roots, with fibers inserting into the newborn cementum on one end and alveolar bone on the other. For the control samples, no PDL-like tissue was found, and ankylosis was commonly observed. Conclusions: The results indicated that cultured autologous PDL cells assist in the re-establishment of periodontal architecture of autotransplanted teeth that is devoid of viable periodontal cells. © 2010 American Association of Endodontists.postprin