Dablanca-Blanco AB, et al. Restor Dent Endod. 2017 Aug;42(3):240-252. https://doi.org/10.5395/rde.2017.42.3.240

Clinicians should be aware of all the characteristics and capacities of the instruments that are possible to use when conducting a root canal treatment. The wide variety of nickel–titanium (Ni-Ti) rotary systems on the market and the lack of standardisation of this type of instrument makes the choice in each specific case difficult. Therefore, this review is intended to summarize the characteristics that should be taken into account when choosing one instrument over another. It will be essential to know characteristics, of alloy from which the instrument is made. Moreover, the geometry of the instrument will determine its behaviour, being the mass, the one that marks its resistance to a greater extent. The movement performed by the file is another of the fundamental keys to understand rotary instruments. In conclusion, when performing root canal treatment, the characteristics of the instrument and the tooth must be taken into account, and the operator’s own limitations should be known. This paper provides the key points to keep in mind when making this type of treatment.

The aim of this study was to evaluate the effectiveness of smear layer removal after the use of different irrigation methods (passive ultrasonic irrigation (PUI), continuous ultrasonic irrigation (CUI), apical negative pressure irrigation and conventional irrigation) using scanning electron microscopy (SEM) as an analytical tool. A total of 100 single-canal teeth were decoronated and randomly divided into five groups (n = 20) according to the irrigation method used: conventional irrigation with front outlet syringe, conventional irrigation with lateral outlet syringe, apical negative pressure irrigation (EndoVac), PUI with Irrisafe and CUI with ProUltra PiezoFlow ultrasonic irrigation needle. Root canal preparation was performed with the ProTaper Gold system up to the F4 instrument, and 5.25% NaOCl was used as an irrigant. After chemical-mechanical preparation, the roots were split longitudinally, and the coronal, middle and apical thirds were examined. SEM digital photomicrographs were taken at ×1000 magnification to evaluate the amount of smear layer in each root canal third; CUI significantly removed more smear layer than any other irrigant activation protocol (p < 0.05); CUI was more effective in removing the smear layer than the other irrigation protocols. However, none of the irrigation protocols were able to produce root canals completely free from smear layer.

Teeth bleaching is one of the most popular aesthetic dental treatments, uses to address both extrinsic and intrinsic tooth discoloration. However, variations in bleaching efficacy between the upper and lower dental arches are commonly observed. Sublingual salivary glands may play a role in these differences by increasing saliva contamination of bleaching trays, which accelerates the degradation of bleaching gel and may reduce its effectiveness in the lower arch. This study aims is to evaluate and compare the effectiveness of bleaching treatments in the upper and lowe arches. This study employed a prospective observational cohort design with a split-mouth approach. Thirty-two participants completed a three-week bleaching regimen using 16 % carbamide peroxide. Color changes were assessed using the CIELAB, CIEDE2000, and Whiteness Index for Dentistry (WID) formulas, with spectrophotometric measurements taken at baseline and weekly intervals. No statistically significant differences (p > 0.5) in bleaching efficacy for incisors between the two arches. However, upper canines demonstrated significantly greater bleaching effectiveness than lower canines by the second and third weeks (p < 0.05), as indicated by the CIELAB and CIEDE2000 formulas. No significant differences (p > 0.05) were observed using the WID formula. While the lower canines exhibited slightly reduced bleaching effectiveness, these differences were not clinically noticeable, affirming the overall efficacy of the treatment for both arches. At-home bleaching treatment demonstrates equivalent effectiveness in both dental arches. While the lower canines may achieve a slightly reduced degree of bleaching, these differences are not clinically noticeable. Consequently, extending the duration of the bleaching treatment for the lower arch is unnecessary.