1,720,994 research outputs found
Cyclic fatigue of Reciproc and WaveOne reciprocating instruments
No full textPlotino G, Grande NM, Testarelli L, Gambarini G. Cyclic fatigue of Reciproc and WaveOne reciprocating instruments. International Endodontic Journal, 45, 614618, 2012. Abstract Aim To evaluate the cyclic fatigue resistance of Reciproc (R) and WaveOne (R) 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 (R) R25 and group B: WaveOne (R) primary. Cyclic fatigue testing was performed in a stainless steel artificial canal manufactured by reproducing the instruments size and taper. A simulated root canal with a 60 degrees 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 (R) instruments were activated using the preset programme specific for the Reciproc (R) instruments, whilst the WaveOne (R) instruments were activated using the preset programme specific for the WaveOne (R) 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 Students t-test (P 0.05) in the mean length of the fractured fragments between the instruments. Conclusions Reciproc (R) instruments were associated with a significantly higher cyclic fatigue resistance than WaveOne (R) instruments
Adapting fiber-reinforced composite root canal posts for use in noncircular-shaped canals.
No full textPost placement in oval-shaped root canals implies the sacrifice of sound dental tissue to adapt the canal shape to fit the post, which can result in one of several significant complications. A semidirect, single-visit, chairside procedure is proposed, which permits the use of an almost anatomically shaped post, starting from a preformed fiber-reinforced composite root canal post of the largest size commercially available. The utilization of this post capitalizes on the advantages of both the fiber post and the anatomical post in oval- and ribbon-shaped canals to provide restoration of endodontically treated teeth
Ultrasonics in endodontics: A review of the literature
No full textDuring the past few decades endodontic treatment has benefited from the development of new techniques and equipment, which have improved outcome and predictability, Important attributes such as the operating microscope and ultrasonics (US) have found indispensable applications in a number of dental procedures in periodontology, to a much lesser extent in restorative dentistry, while being very prominently used in endodontics. US in endodontics has enhanced the quality of treatment and represents an important adjunct in the treatment of difficult cases. Since its introduction, US has become increasingly more useful in applications such as gaining access to canal openings, cleaning and shaping, obturation of root canals, removal of intracanal materials and obstructions, and endodontic surgery. This comprehensive review of the literature aims at presenting the numerous uses of US in clinical endodontics and emphasizes the broad applications in a modern-day endodontic practice
Influence of surface remodelling using burs on the macro and micro surface morphology of anatomically formed fibre posts
No full textAim To evaluate the effect of modifying preformed fibre-reinforced composite (FRC) endodontic posts on their surface morphology and to determine how this procedure affects the integrity of the posts. Summary Surfaces of 10 preformed glass-fibre posts (group 1) and carbon-fibre posts (group 2) were compared with those of individually formed glass-fibre posts (group 3). Ten FRC posts were modelled in order to give them a shape as close as possible to the anatomy of oval root canals. Starting from a preformed cylindrical fibre post 2.5 mm in diameter, it was modelled in such a way as to passively occupy the entire post-space length, using a cast previously created as a guide. Microscopic analyses (optical stereomicroscope and scanning electron microscope) of the post surfaces revealed similar features in all three groups. All posts had regular surfaces after cutting with a diamond bur. Smear layer mainly attributable to the cutting procedures covered the cut surface of some specimens. In conclusion, modulation of a fibre post using a diamond-coated bur did not show a loss of integrity of the post. Key learning points Because of the importance of micromechanical retention, the surface integrity of fibre posts may be important for adhesion between post and composite resin. Modification of a fibre post using a diamond-coated bur did not damage the surface integrity of the posts. Fibre posts can be ground to a different shape without losing their surface integrity, resulting in posts with a surface that is not visibly different from unmodified commercially available fibre posts
Root canal morphology of the mesiobuccal root of maxillary first molars: A micro-computed tomographic analysis
No full textAim: To investigate ex vivo, the root canal morphology of the MB root of maxillary first molar teeth by means of micro-computed tomography. Methodology: Thirty extracted intact human maxillary first molar teeth were selected for micro-tomographic analysis (SkyScan 1072, Aartselaar, Belgium) with a slice thickness of 38.0 m. The following data regarding the MB root were analysed and recorded: number and type of root canals, prevalence of isthmuses, prevalence of intercanal connections, presence of accessory canals, presence of loops and number of apical foramina. Results: The MB2 canal was present in 80% of specimens and was independent in 42% of these cases. When present, the MB2 canal merged with the MB1 canal in 58% of cases. Communications between the two canals were found in all specimens, with isthmuses in 71% of the cases. These communications and isthmuses were respectively in 42% and 54% of the cases in the coronal third, in 59% and 79% of the cases in the middle third and in 24% and 50% of the cases in the apical third. A single apical foramen was found in 37% of specimens, two apical foramina were present in 23% of the cases, with three or more separate apical foramina occurring in 40% of the specimens. Conclusions: The MB root canal anatomy was complex: a high incidence of MB2 root canals, isthmuses, accessory canals, apical delta and loops was found. © 2008 International Endodontic Journal
Cyclic fatigue resistance of two reciprocating nickel-titanium instruments after immersion in sodium hypochlorite
No full textPedulla E, Grande NM, Plotino G, Palermo F, Gambarini G, Rapisarda E. Cyclic fatigue resistance of two reciprocating nickel-titanium instruments after immersion in sodium hypochlorite. International Endodontic Journal, 46, 155-159, 2013. Aim To assess resistance to cyclic fatigue of reciprocating nickel-titanium (NiTi ) files (Reciproc and WaveOne) after immersion in NaOCl solution over several time periods. Methodology A total of 90 new Reciproc R25 and WaveOne Primary were tested. The 45 files of the same brand were randomly assigned to three groups (n = 15) and submitted to the following immersion protocol in 5% NaOCl at 37 degrees C for 16 mm: no immersion (control), 1 or 5 min dynamically. The dynamic immersion and the following cyclic fatigue tests were performed using the appropriate preset reciprocation modes ('RECIPROC ALL' or 'WAVEONE ALL') in a specially designed endodontic motor. Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60 degrees angle of curvature and 5 mm radius of curvature. The artificial canal was manufactured reproducing the instrument's size and taper. Data were analysed by 2-way analyses of variance. Results Resistance to cyclic fatigue of the same NiTi file was not significantly affected by immersion in NaOCl . Reciproc R25 was associated with a higher cyclic fatigue resistance in all groups compared to WaveOne Primary (P < 0.0001). Conclusions Reciprocating dynamic immersion in NaOCl for 1 or 5 min did not reduce the cyclic fatigue resistance of NiTi files significantly. However, the type of reciprocating instrument influenced cyclic fatigue resistance with Reciproc R25 being more resistant than WaveOne Primary
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Micro-computerized tomographic analysis of radicular and canal morphology of premolars with long oval canals.
No full textThe aims of this in vitro study were to measure root and canal diameters, root and canal diameter ratios, mean taper of the root canal and of each root canal section, and radicular wall thickness at different levels in premolars with long oval root canals
Three-dimensional imaging using microcomputed tomography for studying tooth macromorphology
No full textBackground. The authors conducted a study to demonstrate potential, applications of microcomputed tomography (microCT) in the analysis of tooth morphology. Methods. The authors selected for microCT analysis five maxillary first molars with a second canal in the mesiobuccal (AM) root, five mandibular first molars with a mesial root possessing a considerable curvature and five single-canal premolars with complicated apical anatomy. The hardware device used in this, study was a desktop X-ray microfocus CT scanner (SkyScan 1072, SkyScan bvba, Aartselaar, Belgium). Results. The authors,obtained a three-dimensional image from each of the 15 teeth. In three cases, the MB canals coalesced into one canal, while in the other two molars the canals were separate. Four of the five mandibular molars exhibited A single canal in the mesial root, which had a broad, flat appearance in a mesiodistal dimension. In the premolar teeth, the canals were independent; however, the apical delta and ramifications of the root canals were obvious, yet intricate. Conclusions. MicroCT offers a reproducible technique for 3-D non-invasive assessment of root canal systems. Clinical Implications. While this technique is not suitable for clinical use, it can be applied to improve preclinical training and analysis of fundamental procedures in endodontic and restorative treatment
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