Evaluation of the thermoplasticity of different gutta-percha cones and ...

Thermoplasticity of Gutta-Percha and Resilon®M. Tanomaru-Filho et al.Table 1 Endodontic filling materials used in the experimental groupsMaterialManufacturerDentsply (conventionalgutta-percha)Dentsply TP (thermoplasticgutta-percha)Endopoints (conventionalgutta-percha)Endopoints TP (thermoplasticgutta-percha)Resilon®Dentsply Indústria e Comércio Ltda.,Petrópolis, RJ, BrazilDentsply Indústria e Comércio Ltda.,Petrópolis, RJ, BrazilEndopoints Indústria E Comércio Ltda.,Paraiba do Sul, RJ, BrazilEndopoints Indústria E Comércio Ltda.,Paraiba do Sul, RJ, BrazilPentron Clinical Technologies, Wallingford,PT, USA4.8 kg0.2 kgFigure 1 Apparatus used for the test.Glass slabstheir thermoplastic properties (18). As these properties areessential for the success of numerous root canal fillingtechniques, the purpose of this study was to assessthe thermoplasticity of different commercially availablebrands of conventional and thermoplastic gutta-perchacones compared with Resilon ® synthetic polymer.Materials and methodsFor thermoplasticity analysis, five cylindrical specimens(10 mm in diameter, 1.5-mm thick) were made from eachexamined brand of gutta-percha or Resilon ® , as describedin Table 1.The material samples were kept in water at 70°C for60 s using a thermometer-controlled heating apparatus(Righetto e Cia., Campinas, São Paulo, Brazil).The heated materials were then placed into standardisedrings with the above-mentioned dimensions, andwere pressed between two glass slabs under a controlledand constant force of 0.5 N for 1 min. Thereafter, the specimenswere removed from the moulds, the excess materialwas trimmed and the dimensions were checked using adigital pachymeter. The specimens were kept at a temperaturebetween 25–30°C for 24 h and then returned to theheating apparatus at 70°C for 60 s. Next, each sample wasonce again positioned between two glass slabs, and a 5-kgweight was placed on top of the slabs to produce a compressiveforce for 2 min (Fig. 1). Digital images of eachspecimen were obtained before and after compression,and were examined using an image analysis software(UTHSCSA Image Tool for Windows version 3.0, SanAntonio, TX, USA) to determine its area. The thermoplasticityof the materials was determined by the differencebetween final and initial areas of each specimen.The data were analysed statistically by ANOVA, and multiplecomparisons among the experimental groups weredone by Tukey’s post-hoc test. The significance level wasset at 5%.Figure 2 Means in mm 2 (±SD) of the differences between initial and finalareas of each obturation material used in the experimental groups. Meansfollowed by the same letter did not present statistically significant difference(P > 0.05).ResultsMeans and standard deviation for the differences betweeninitial and final areas of each material are shown inFigure 2. Statistical analysis showed that Resilon ® had thehighest thermoplasticity means, while Endopoints conventionalgutta-percha had the lowest thermoplasticitymeans of all tested materials (P < 0.05). Among the guttaperchacones, Endopoints TP (thermoplastic) (EndopointsIndústria E Comércio Ltda., Paraiba do Sul, RJ, Brazil) presentedthe highest thermoplasticity means and differedsignificantly from the other commercially available brands(P < 0.05).DiscussionBecause few studies (18,22) have focused on the differencesbetween commercially available brands of guttapercha,no specific methodology for testing the thermoplasticityof gutta-percha has been described. In this study,the American Dental Association specification No. 57 (forendodontic sealers) was adapted to gutta-percha testing.(ISO 6876:2002 – Dental Root Canal Sealing Materials). Toevaluate the flowing ability of endodontic sealers, a 120-g24 © 2007 The AuthorsJournal compilation © 2007 Australian Society of Endodontology