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This study aimed to characterize the chemical properties and bioactivity of an endodontic sealer (GuttaFlow Bioseal) based on polydimethylsiloxane (PDMS) and containing a calcium bioglass as a doping agent. Commercial PDMS-based cement free from calcium bioglass (GuttaFlow 2 and RoekoSeal) were characterized for comparison as well as GuttaFlow 2 doped with dicalcium phosphate dihydrate, hydroxyapatite, or a tricalcium silicate-based cement. IR and Raman analyses were performed on fresh materials as well as after aging tests in Hank's Balanced Salt Solution (28 d, 37 °C). Under these conditions, the strengthening of the 970 cm−1 Raman band and the appearance of the IR components at 1455–1414, 1015, 868, and 600–559 cm−1 revealed the deposition of B-type carbonated apatite. The Raman I970/I638 and IR A1010/A1258 ratios (markers of apatite-forming ability) showed that bioactivity decreased along with the series: GuttaFlow Bioseal > GuttaFlow 2 > RoekoSeal. The PDMS matrix played a relevant role in bioactivity; in GuttaFlow 2, the crosslinking degree was favorable for Ca2+ adsorption/complexation and the formation of a thin calcium phosphate layer. In the less crosslinked RoekoSeal, such processes did not occur. The doped cements showed bioactivity higher than GuttaFlow 2, suggesting that the particles of the mineralizing agents are spontaneously exposed on the cement surface, although the hydrophobicity of the PDMS matrix slowed down apatite deposition. Relevant properties in the endodontic practice (i.e., setting time, radiopacity, apatite-forming ability) were related to material composition and the crosslinking degree. [ABSTRACT FROM AUTHOR]

A fundamental step in non-surgical retreatment is the removal of the existing root filling material to permit radicular access. Different root filling materials require different techniques of removal. The endodontic literature is littered with studies exploring the relative merits of one technique of removal over another. In this review, the focus is on the experimental models and techniques employed to investigate the removal of root filling materials during non-surgical retreatment. The correlation and clinical relevance to everyday endodontic practice is also discussed. [ABSTRACT FROM AUTHOR]

Introduction: The aim of the present in vitro study was to evaluate the efficacy of D-RaCe, ProTaper retreatment kit and hand H-files in removal of obturating materials (OM) from the curved root canals using cone-beam computed tomography (CBCT). Materials and methods: Sixty extracted molars were prepared and obturated. The samples were divided into three groups (n=20). In each group the OM was removed using hand H-files, D-RaCe and ProTaper retreatment kit. All the samples underwent CBCT imaging. The amount of OM was evaluated in CBCT sagittal cross-sections and scored. The maximum concentration of residual OM was recorded. The duration of the procedure (including the required time for reaching working length=T1 and total working time=TT) and procedural errors were also recorded. Data were analyzed using one-way ANOVA, Tukey's post hoc test, Fisher's exact test and Kruskal-Wallis test. The level f significance was set at 0.05. Results: No significant differences were observed in the residual OM among the three groups. T1 and TT were not significantly different in all groups. There were no significant differences in concentration of OM between the groups (P<0.05). In relation to procedural errors, 4 and 5 cases of file fracture were recorded in the ProTaper and D-RaCe groups, respectively, with no significant differences. Conclusion: Rotary and hand H-files had similar efficacy in removing root canal filling materials but instrument fracture occurred more frequently in rotary files. [ABSTRACT FROM AUTHOR]

Abstract: New obturation biomaterials have been introduced over the past decade to improve the seal of the root canal system. However, it is not clear whether they have really produced a three-dimensional impervious seal that is important for reducing diseases associated with root canal treatment. A review of the literature was performed to identify models that have been employed for evaluating the seal of the root canal system. In vitro and in vivo models are not totally adept at quantifying the seal of root canals obturated with classic materials. Thus, one has to resort to clinical outcomes to examine whether there are real benefits associated with the use of recently introduced materials for obturating root canals. However, there is no simple answer because endodontic treatment outcomes are influenced by a host of other predictors that are more likely to take precedence over the influence of obturation materials. From the perspective of clinical performance, classic root filling materials have stood the test of time. Because many of the recently introduced materials are so new, there is not enough evidence yet to support their ability to improve clinical performance. This emphasizes the need to translate anecdotal information into clinically relevant research data on new biomaterials. [Copyright &y& Elsevier]

Akcay I, Ilhan B, Dundar N. Comparison of conventional and digital radiography systems with regard to radiopacity of root canal filling materials. International Endodontic Journal, 45, 730-736, 2012. Abstract Aim To compare the radiopacity of five root filling materials as measured on digitized E-speed films, storage phosphor plate and CCD sensor images. Methodology Radiopacity of Resilon cones and Epiphany, MM-Seal, EndoREZ and AH Plus sealers were investigated. Ten acrylic plates were prepared and filled with the materials. Samples were radiographed together with samples of dentine and an aluminium stepwedge. Images were obtained using E-speed films, Digora storage phosphor plates and Schick CDR CCD sensor. Conventional radiographs were digitized using a desktop scanner. Mean grey values of the materials, stepwedge and dentine were measured using the histogram analysis function of Photoshop 7.0. A graph of radiographic density versus thickness of the aluminium was drawn for each image from which the radiographic densities of the materials were determined in relation to the aluminium thickness. The mean was calculated, and the data were analysed using repeated measures anova and Bonferroni tests ( P < 0.05). Results There were significant differences between different imaging modalities ( P = 0.018) and root filling materials ( P < 0.001). A statistically significant interaction between imaging modality and material was also observed ( P < 0.001). All materials had radiopacity above 3 mm of aluminium regardless of the imaging technique. The radiopacity of Resilon and Epiphany was significantly higher on digital images compared with digitized E-speed film images ( P < 0.001). Conclusion The choice of imaging system may effect radiopacity measurements. It is possible that radiopacity as recorded on traditional or digitized films is not indicative of the radiopacity as recorded on a digital sensor. [ABSTRACT FROM AUTHOR]

Some clinical techniques for the placement of gutta-percha root fillings involve the application of heat. This study was undertaken to assess the effects of intracanal heating techniques on the following properties of gutta-percha: coefficient of thermal expansion, softening temperature, phase transition temperature and organic content. Samples from each of four products were prepared by three different methods. The materials were studied by thermomechanical analysis, simultaneous thermogravimetry and differential thermal analysis, and by measurement of weight loss on ashing. It was shown that the techniques of gutta-percha placement involving heating in the root canal caused reversible physical changes in the materials without any apparent change in chemical composition. The average coefficient of thermal expansion was 137 × 10-6/°C, the softening temperature was 55.5°C, there were two characteristic phase changes, and the organic content was 25%. [ABSTRACT FROM AUTHOR]

The present work studied the reaction caused in the connective tissue of rats by implantation of two brands of gutta- percha cones, and thermoplasticized gutta-percha cylinders. thirty-six rats were used, in groups of 12. for periods oil 15, 30, and 60 days. Each animal received one test implant of each material, and one implant of Teflon as control. The cylinders, and one of' the brands of gutta-percha cones, were welI tolerated by the connective tissue. The cones of the other brand elicited different reactions, of which the possible causes are herein discussed. [ABSTRACT FROM AUTHOR]