INTRODUCTION:The aim of this in vitro study was to assess an alternative method using light-curing composite for removing fractured endodontic instruments with a tube technique. METHODS:Two different stainless steel endodontic instruments (ISO 20: Hedstrom files, K-files; VDW, Munich, Germany) were cut at the diameter of 0.4 mm. These fragments were fixed in a vise leaving a free end of 1 or 2 mm. Cyanoacrylate (Instant Fix; Henry Schein Dental, Melville, NY), dual-curing Rebilda DC (VOCO, Cuxhaven, Germany), and light-curing SureFil SDR (Dentsply, York, PA) were placed into microtubes (N'Durance Syringe Tips; Septodont, Saint-Maur, France) and shifted over the instruments (n = 20 in each group). After polymerization, pull-out tests were performed with a constant speed of 2 mm/min; failure load was measured digitally. Data were analyzed using the Kruskal-Wallis test followed by the Dunn test for pairwise comparison. RESULTS:The median failure load was up to 62.5 N for SDR, 35.8 N for Rebilda, and 14.7 N for cyanoacrylate, respectively. Both tested composites yielded significantly higher values in pull-out tests than cyanoacrylate. The disconnecting force was highest when light-cured composite SDR was used for fixation. Removing Hedstrom files resulted in higher values than removing K-files. The median force when using SDR was 79.7 N (interquartile range, 66.0-86.8 N) in Hedstrom files and 53.3 N (interquartile range, 47.1-58.5 N) in K-files. CONCLUSIONS:Within the limitations of this study, the use of light-curing composite inside of the microtube was superior compared with the use of cyanoacrylate or chemically cured composite, which are being used presently.

INTRODUCTION:The aim of this study was to compare the shear bond strength of Biodentine, ProRoot MTA (MTA), glass ionomer cement (GIC) and composite resin (CR) on dentine. METHODS:120 extracted human third molars were embedded in cold-cured-resin and grinned down to the dentine. For each material 30 specimens were produced in standardised height and width and the materials were applied according to manufacturers´ instructions on the dentine samples. Only in the CR group a self-etching dentine-adhesive was used. In all other groups the dentine was not pre-treated. All specimens were stored at 37.5 °C and 100% humidity for 2d, 7d and 14d. With a testing device the shear bond strength was determined (separation of the specimens from the dentine surface). The statistical evaluation was performed using ANOVA and Tukey-test (p < 0.05). RESULTS:At all observation periods the CR showed the significant highest shear bond strength (p < 0.05). After 2d significant differences in the shear bond strength were detectable between all tested materials, whereby CR had the highest and MTA the lowest values (p < 0.05). After 7d and 14d the shear bond strengths of MTA and Biodentine increased significantly compared to the 2d investigation period (p < 0.05). Biodentine showed a significantly higher shear bond strength than MTA (p < 0.05), while the difference between Biodentine and GIC was not significant (p > 0.05). CONCLUSIONS:After 7d Biodentine showed comparable shear bond values than GIC, whereas the shear bond values for MTA were significantly lower even after 14d. The adhesion of Biodentine to dentine surface seams to be superior compared to that of MTA.

The aim of this study was to compare solubility, microhardness, radiopacity, and setting time of Biodentine with ProRoot MTA.

Una paciente de 14 anos fue remitida a nuestro centro para que se le practicara una apicectomia del diente 36. La radiografia panoramica existente mostraba una osteoIisis apical avanzada y una obturacion de conductos radiculares incompleta en el diente 36. El abordaje terapeutico se centro en la remision de la osteolisis mediante la reiterada aplicacion de hidroxido de calcio dentro del conducto. Tras la revision de la obturacion radicular se realizo una conductometria. Se aplico hidroxido de calcio como medicacion intraconducto y se cerro la cavidad de acceso. Dada la reducida colaboracion de la paciente, el tratamiento sufrio retrasos en mas de una ocasion. Al cabo de 4 meses se realizo una radiografia con presencia de puntas maestras. Tres meses mas tarde se procedio a la obturacion radicular con condensacion lateral. A los 8 meses el diente recibio una corona metalica de recubrimiento parcial. El diente se mostro asintomatico a lo largo de todo el tratamiento. Tampoco se apreciaron particularidades clinicas ni radiologicas a los dieciseis meses de la finalizacion del tratamiento.

PURPOSE To assess and compare the pulp chamber temperature increase during resin-based composite polymerization with two different light-curing units. METHODS A Class I cavity was prepared in an extracted lower molar under standardized conditions using a specially designed industrial robot system. The dentin layer between the pulp chamber and the floor of the cavity was 1 mm thick. Pulp chamber temperature rises (starting temperature: 20.0 +/- 0.1 degrees C) were recorded for four different series of investigations using both the halogen curing lamp Elipar Visio (light-curing: 40 s) and the plasma arc lamp Apollo 95E (light-curing: 3 seconds): Group A: Operation of the light-curing units directly over the untreated, empty cavity; Group B: Resin-based composite polymerization without previously applied cement base or bonding agent; Group C: Resin-based composite polymerization with a previously applied cement base; Group D: Resin-based composite polymerization with a previously applied bonding agent. In each of the four groups 10 measurements were carried out for every light-curing unit. Data were statistically analyzed using ANOVA, post-hoc Scheffé test and t-test. RESULTS The lowest temperature increase (0.3 degrees C) was recorded during composite polymerization with a previously applied cement base using the Apollo 95E unit (Group C, P < 0.05). The highest temperature increase was induced when using the Elipar Visio unit directly over the untreated cavity (Group A, P < 0.05). In Groups A, C and D higher pulp chamber temperature measurements were obtained when using the Elipar Visio unit as compared to the Apollo 95E plasma arc lamp (P < 0.01). In Group B, no significant differences were recorded during the composite polymerization when using the two different light-curing units (P > 0.05).