This study aimed to compare the effects of different irrigants on root dentine microhardness, erosion and smear layer removal. A total of 72 root dentine slices were divided into six groups, according to the final irrigants used: Group 1: 17% ethylenediamine tetra-acetic acid (EDTA) + 2.5% NaOCl, Group 2: 7% maleic acid (MA) + 2.5% sodium hypochloride (NaOCl), Group 3: 1.3% NaOCl + mixture of tetracycline, acid and detergent (MTAD), Group 4: Smear Clear + 2.5% NaOCl, Group 5: 5% NaOCl, Group 6: saline. Vickers microhardness values were measured before and after treatment. In total, 42 root-halves were prepared for scanning electron microscope to evaluate the amount of smear and erosion in the coronal, middle and apical thirds. Data were analysed using two-way anova, Duncan and two-proportion z-tests. Maleic acid showed the greatest reduction in dentine microhardness (P < 0.05), followed by EDTA and MTAD. EDTA, maleic acid, MTAD and Smear Clear removed smear layer efficiently in the coronal and middle thirds of root canal. However, in the apical region, maleic acid showed more efficient removal of the smear layer than the other irrigants (P < 0.05).

The use of a NaOCl + HEBP mixture activated with XP-endo Finisher was an effective irrigation regimen for removing simulated organic tissues from artificial internal root resorption cavities in the straight root canals of single-rooted teeth.

The purpose of this study was to investigate the effects of different irrigation solutions on the smear layer removal and marginal adaptation of a resin-based sealer to root canal dentine. A total of 152 instrumented roots were irrigated with the following irrigants: 9,18% etidronic acid (HEBP), 0.5, 1,2% peracetic acid (PAA), 17% ethylenediaminetetraacetic acid (EDTA), saline. The amount of smear layer was evaluated using scanning electron microscope (SEM) in seventy root samples.Eighty-two roots were filled with AH Plus and gutta-percha. Slices obtained from apical third of each specimen were viewed with SEM to assess marginal adaptation. Use of 9% and 18% HEBP resulted in more efficient smear layer removal in the apical third than the other chelators (p < 0.05). Higher smear layer scores in the coronal and middle thirds were obtained from 0.5%, 1% PAA groups. Regarding marginal adaptation, 18% HEBP group showed the lowest gap size values (p < 0.05), and better marginal adaptation. Etidronic acid is a promising candidate for final irrigation of root canals.

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The objective of the study was to observe the morphological changes on root canal dentin after Er:YAG laser and Nd:YAG laser treatment. Twenty-one teeth biomechanically prepared were divided into three groups with seven teeth of each. Group A was unlased as a control. In group B, Er:YAG laser and in group C, Nd:YAG laser was applied to the root canal dentin. The roots were split longitudinally and examined using a scanning electron microscopy for the evaluation of debris, smear layer, and recrystallization. There was no statistically significant difference between the groups. This study indicates that laser beam is not effective in removing debris and smear layer.

Kıvanç BH, Alaç am T, Ulusoy Ö _ IA, Genç Ö , Gö rgü l G. Aim To compare the fracture resistance of thin-walled roots after restoration with different types of post systems.Methodology One hundred and sixty-five decoronated maxillary central incisors were root filled and randomly assigned to three groups with respect to the remaining dentine thickness of root (1.0 mm, 1.5 mm, 2.0 mm). Each group was randomly divided into five equal subgroups. The subgroups were restored with one of the following post systems: polyethylene woven fibre (R), composite resin cured by light-transmitting post + glass fibre post (L), electrical glass fibre post (E), composite corono-radicular restoration (C) and cast metal post (M). Standard cores were constructed using composite resin in the first four groups. The samples were subjected to a gradually increasing force (1 mm min). The force required to fracture was recorded. The data was analysed with anova and Tukey test (P = 0.05). Results The cast metal post group had the highest fracture strength (P < 0.001). There was no significant difference in fracture resistance between the other four groups. Fracture resistance was affected largely by the remaining dentine thickness in fibre post groups; however, the difference was not significant. On the contrary in the cast metal post group load failure was inversely influenced by axio-proximal dimension of dentine walls. Conclusion The cast post group had a higher fracture strength than resin groups. The force required to fracture the roots was similar for all fibre post systems and for all dentine thicknesses.

This study aimed to compare the pulp chamber temperature changes that occur with the use of different light sources during vital bleaching with and without application of bleaching agents. One hundred and forty-four mandibular incisor teeth were divided into four groups (n = 36) according to the use of halogen light, light-emitting diode, 3 W and 1.5 W diode laser. The teeth in the main groups were divided into three subgroups (n = 12). First subgroup had no bleaching gel application. By White and Whiteness HP were applied with a thickness of 2 mm to the other subgroups respectively. The labial surfaces of the teeth were irradiated with a total time of 20 s. Temperature changes in the pulp chamber were measured and analysed by using anova and Tukey test. The 3 W diode laser induced the highest pulp chamber temperature rise (P = 0.000). Bleaching gel application reduced the temperature changes in the diode laser groups (P < 0.05). Diode laser activation during vital bleaching induces pulp chamber temperature rise, which may cause thermal tissue damage.

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