The effect of different light sources on microleakage of bleached enamel.

This study evaluated the immediate effects of halogen, LED (light-emitting diode), and plasma are curing units on microleakage of bleached enamel. The buccal and lingual enamel surfaces of experimental groups (n=30) were bleached with 16% carbamide peroxide for a period of 10 days, with a daily contact time of 90 minutes. Box-shaped Class V cavities were also prepared on 60 extracted molar teeth (n=30, control group). For all groups, a composite resin (Grandio) was bonded with one of the two employed adhesive systems, Single Bond 2 or Prime & Bond NT. After restoration, all specimens were thermocycled for 200 cycles between 5 degrees C and 55 degrees C with a dwell time of 60 seconds in each bath, and then exposed to a dye. In the control groups, microleakage was statistically lower than the bleached groups (p<0.01). Groups cured with QTH and PAC showed no statistical differences (p>0.05). However, groups cured with LED system showed statistically significant differences (p<0.01) in microleakage.

In vivo evaluation of ProPex electronic apex locator.

The aim of this in vivo study was to evaluate the performance of ProPex apex locator after extirpation and in presence of different irrigation solutions: 2.5% NaOCl, 0.9% NaCl, and 0.2% chlorhexidine gluconate solutions. Twenty-seven single-rooted human teeth scheduled for extraction with mature apices were selected for this study. Measurements were performed by using ProPex after extirpation and in presence of the irrigation solutions. After extraction of the teeth, a stereomicroscope was used to confirm visually the relationship of the tip of the endodontic file to the apical foramen, and actual lengths (ALs) were determined by reducing 0.5 mm from these lengths. The data were statistically analyzed with cluster analysis. The results of this study showed that measurements after extirpation had the smallest distance to the ALs. Among the irrigation solution groups, chlorhexidine gluconate group had the smallest distance to the ALs, whereas saline group had the greatest. Most accurate measurements were obtained after extirpation.

Influence of light-curing units on dentin bond strength after bleaching.

PURPOSE: The aim of this in vitro study was to comparatively evaluate the influence of three different light curing units (QTH Hilux, LED SmartLite, PAC Plasmaster) on shear bond strength of an adhesive system (Clearfil SE Bond ) after bleaching. MATERIALS AND METHODS: Sixty molars were used for this study. Carbamide peroxide was applied to the floor and wall of the dentin surfaces in bleached groups for 3 weeks. Each week the paste was renewed for the bleached group. Teeth were sectioned mesiodistally. The roots of the sectioned teeth were mounted in a cylindrical mold using chemically cured acrylic resin. Composite resin was added to the center of flattened dentin surfaces with an internal diameter of 3 mm and height of 3 mm. The bonding procedure was performed in the bleached test groups as follows: G1: immediately/QTH; G2: after 1 week/QTH; G3: after 2 weeks/QTH; G4: immediately/LED; G5: after 1 week/LED; G6: after 2 weeks/LED; G7: immediately/PAC; G8: after 1 week/PAC; G9: after 2 weeks/PAC. The non-bleached groups (control group) were G10: QTH; G11: LED; G12: PAC. Specimens were mounted in a universal testing machine and shear load was applied at a crosshead speed of 1 mm/min until failure. Bond strength values were calculated as MPa and the comparisons were made statistically using one-way ANOVA with light source and bleaching treatment) as the two factors. RESULTS: The mean values of shear bond strength in MPa were: G1 (12.23), G2 (19.18), G3 (23.08), G4 (13.07), G5 (21.01), G6 (25.27), G7 (12.55), G8 (19.06), G9 (25.41), G10 (24.54), G11 (26.99), G12 (25.97). No statistical difference was found between the control group and groups bonded two weeks later. The bond strength values of the control group and those bonded 2 weeks later were higher than other groups. Statistically significant differences were found between the immediate and 1-week groups (p < 0.01). Immediately bonded groups had the lowest bond strength compared to the others (p < 0.05). No significant differences in bond strength were observed among three lightcuring units (p > 0.05). CONCLUSION: It was concluded that different light-curing units had no effect on shear bond strength of bleached dentin. A 2-week delay in restoration after bleaching improved the reduced bond strength of resin composite.

The treatment of unusual foreign objects in a root canal: a case report.

A 14-year-old female with a history of unsuccessful endodontic treatment of a maxillary central incisor was referred for treatment. Radiographic examination showed an unusual foreign object in the root canal. This report describes the permanent successful treatment of the tooth.