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Aim: To compare the cross-sectional area of sealer plus voids of gutta-percha/AH Plus and Resilon/ RealSeal following root canal preparation with rotary nickel-titanium ProTaper instruments and different apical preparation sizes. Materials and Methods: Forty-eight extracted maxillary anterior teeth were instrumented with the ProTaper system to apical sizes of 25 (F2), 40 (F4) and 60 (F5 + K-files) (n = 16 each). The teeth were divided into six groups (n = 8) for obturation as follows: group 1, apical preparation size 0.25 mm + gutta-percha/AH Plus sealer; group 2, apical preparation size 0.25 mm + Resilon/ RealSeal; group 3, apical preparation size 0.40 mm + gutta-percha/AH Plus sealer; group 4, apical preparation size 0.40 mm + Resilon/RealSeal; group 5, apical preparation size 0.60 mm + guttapercha/ AH Plus; group 6, apical preparation size 0.60 mm + Resilon/RealSeal. All root canals were filled using the warm vertical compaction technique. Horizontal sections were obtained every 1 mm, up to 3 mm from the apical foramen. Samples were observed by scanning electron microscopy under x200 magnification. Sections were digitally photographed under a stereomicroscope and the images were transferred to a compatible PC for image analysis. Using a computer program, the surface areas of voids were calculated and compared statistically for different preparation sizes and obturation systems at all levels, using the Kruskal-Wallis test with Sidak correction and Mann- Whitney U test (P < 0.05). Results: Comparisons within each obturation group (gutta-percha/AH Plus and Resilon/RealSeal) showed the presence of voids, but there were no significant differences between the two groups for apical preparation sizes of 25 and 40 (P < 0.05), irrespective of the level of sectioning. The only significant difference was obtained for canals prepared to an apical size 60: canals obturated with Resilon/RealSeal showed significantly more voids than those filled with gutta-percha/AH Plus, especially at the 3-mm level. Conclusions: Resilon/RealSeal did not achieve better results in terms of sealing ability in the apical third when compared to the conventional obturation materials gutta-percha/AH Plus. [ABSTRACT FROM AUTHOR]

The purpose of this study is to determine the CO2 laser irradiation in comparison with sandblasting (Sb), hydrofluoric acid (Hf) and silane coupling agent (Si) on shear bond strength (SBS), roughness (Rg) and wettability (Wt) of resin cement to CAD/CAM ceramics. Sixty (CAD/CAM) ceramic discs were prepared and distributed into six different groups: group A, control lithium disilicate (Li); group B, control zirconia (Zr); group C, Li: CO2/HF/Si; group D, Li: HF/Si; group E, Zr: CO2/Sb/Si; group F, Zr: Sb/Si. Result showed significant difference between irradiated and non-irradiated in terms of shear bond strength for zirconia ceramics (p value = 0.014). Moreover, partial surface wettability for irradiated and non-irradiated ceramics. Irradiated surface demonstrated more rough surface in lithium disilicate than zirconia ceramics. CO2 irradiation could increase shear bond strength, surface roughness and wettability for both CAD/CAM ceramics. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this in vitro study was to test the effect of 2 finishing-polishing sequences (QB, combining a 12/15-fluted finishing bur and an EVO-Light polisher; QWB, adding a 30-fluted polishing bur after the 12/15-fluted finishing bur used in the QB sequence) on 5 nanotech-based resin composites (Filtek Z500, Ceram X Mono, Ceram X Duo, Tetric Evoceram, and Tetric Evoceram Bulk Fill) by comparing their final surface roughness and hardness values to those of a Mylar strip control group (MS)., Materials and Methods: Twelve specimens of each nanocomposite were prepared in Teflon moulds. The surface of each resin composite was finished with QB (5 samples), QWB (5 samples), or MS (2 samples), and then evaluated (60 samples). Roughness was analysed with an optical profilometer, microhardness was tested with a Vickers indenter, and the surfaces were examined by optical and scanning electron microscopy. Data were analysed using the Kruskal-Wallis test ( p < 0.05) followed by the Dunn test., Results: For the hardness and roughness of nanocomposite resin, the QWB sequence was significantly more effective than QB ( p < 0.05). The Filtek Z500 showed significantly harder surfaces regardless of the finishing-polishing sequence ( p < 0.05)., Conclusions: QWB yielded the best values of surface roughness and hardness. The hardness and roughness of the 5 nanocomposites presented less significant differences when QWB was used., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Background and Aims: The purpose of this study is to determine the effect of CO 2 laser irradiation in comparison with sandblasting (Sb), hydrofluoric acid (Hf) and silane coupling agent (Si) on shear bond strength (SBS) of resin cement to CAD/CAM ceramics bonded to dentin., Material and Methods: Forty-eight (CAD/CAM) ceramic discs were prepared and grouped by material, i.e. lithium disilicate (Emax CAD) and zirconia ceramic (Emax ZirCAD), distributed into four different groups: group A, lithium disilicate (Li) CO 2 /HF/Si; group B, Li: HF/Si; group C, zirconia (Zr) CO 2 /Sb/Si; group D, Zr: Sb/Si., Results: It was shown significant difference between irradiated and non-irradiated groups in terms of shear bond strength for zirconia ceramics (p value = 0.039)., Conclusion: CO 2 laser irradiation increases shear bond strength for both CAD/CAM ceramics bonded to dentin.

Background and Aims: The aim of this study was to measure the microhardness values of irradiated computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics surfaces before and after thermal treatment., Materials and Methods: Sixty CAD/CAM ceramic discs were prepared and grouped by material, i.e. lithium disilicate ceramic (Emax CAD) and zirconia ceramic (Emax ZirCAD). Laser irradiation at the material surface was performed with a carbon dioxide laser at 5 Watt (W) or 10 W power in continuous mode (CW mode), or with a neodymium:yttrium aluminum perovskite (Nd:YAP) laser at 10 W on graphite and non-graphite surfaces. Vickers hardness was tested at 0.3 kg f for lithium disilicate and 1 kg f for zirconia., Results: Emax CAD irradiated with CO 2 at 5 W increased microhardness by 6.32 GPa whereas Emax ZirCAD irradiated with Nd:YAP decreased microhardness by 17.46 GPa., Conclusion: CO 2 laser effectively increases the microhardness of lithium disilicate ceramics (Emax CAD).

Background and Aims: The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces., Material and Methods: Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation., Results: The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation., Conclusion: CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications.

Aim: The aim of this study is to evaluate the influence of final canal taper on the sealing ability of Thermafil by using microcomputed tomography (micro-CT)., Materials and Methods: Fifty-four single-rooted teeth were instrumented to apical size 40 taper 4, 6 and 8%. Teeth were divided into three groups. All teeth were filled with Thermafil (Dentsply,Tulsa Dental Products). Using micro-CT, roots were scanned and volume measurements of voids at 1, 3 and 5 mm from the apex were calculated using specialized CT software. Measurements were analyzed statistically with ANOVA followed by Bonferroni multiple comparison correction., Results: Data analysis showed that 0.08 preparations provided better results than 0.06 and 0.04% tapered samples especially at 1 mm from the apex. Mean percentage of voids were significantly higher with Thermafil taper 0.06% (p = 0.05). None of the root canals filled teeth were gap free. Root canal preparations with bigger taper exhibited less voids than smaller tapered preparations., Clinical Significance: In our daily practice, enlarging the apical third (last 3 mm) of root canals to an 8% taper gives a better sealing ability and thus long-term success for our root canal obturations.

This in vitro study sought to evaluate the influence of calcium hydroxide on the sealing ability of vertically condensed warm gutta-percha filling. Sixty single-rooted teeth were instrumented with a rotary system and divided randomly into two groups of 26 teeth each; the remaining eight teeth were divided into two groups of four to serve as negative and positive controls. The canals in the first group were filled with calcium hydroxide paste while the canals in the second group received no medication. Seven days after incubation, root canal dressings were removed by irrigation, using 5.25% sodium hypochlorite associated with ultrasonics and 50% citric acid. All specimens were filled using the warm gutta-percha vertical compaction technique, placed in test tubes containing India ink, and centrifuged at 30 G for five minutes; at that point, the dye penetration level was scored. Under the conditions of this study, the calcium hydroxide group showed significantly greater dye penetration than the non-medicated group.