At-home Bleaching with a Novel Carbamide Peroxide Polymeric Nanoparticle Gel: A Multicenter Randomized Controlled Trial.

OBJECTIVES: To compare the risk and intensity of tooth sensitivity (TS) as well the effectiveness of at-home bleaching using two carbamide peroxide bleaching gels, specifically a novel polymeric nanoparticle gel (experimental) and a commercial gel (Opalescence PF, Ultradent, South Jordan, Utah, USA), applied at two application times. METHODS: This multicenter, triple-blind, and split-mouth randomized controlled trial was conducted on 80 healthy adults with canine teeth that were shade A2 or darker. The participants all used the experimental and the control gels on one side of a tray, depending on the group to which they were allocated, for 30 or 60 minutes per day over four weeks. The absolute risk and intensity of TS were assessed daily using the five-point Numeric Rating Scale and the 0-10 Visual Analogue Scale. Color change was evaluated with shade guide units (ΔSGU) and a digital spectrophotometer (ΔEab, ΔE00, and ΔWid) at baseline and 30 days postbleaching. The risk and intensity of TS was evaluated by the McNemar and the Wilcoxon signed-rank tests, respectively. Color change (ΔSGU, ΔEab, ΔE00, and ΔWid) was evaluated by Mann-Whitney and paired t-tests (α=0.05). RESULTS: No differences in the risk and intensity of TS were observed based on the bleaching gels used and the times of application (p>0.05). Thirty days after bleaching, there was no significant difference in color change, in terms of the bleaching gels used or the application times (p>0.05). CONCLUSION: The novel carbamide peroxide polymeric nanoparticles gel, when applied for 30 or 60 minutes, produced effective color change and a low rate of tooth sensitivity, as compared to the control group.

Marginal Fit Metal-Ceramic and In-Ceram Single Crown Cement retained in Implant-supported Abutments.

INTRODUCTION: This study evaluated the cervical fit of cemented metal-ceramic and In-Ceram implant-supported crowns, before and after the cementing procedure. MATERIALS AND METHODS: Twenty crowns cemented on implant abutments are divided into two groups (n = 10): Group 1 -cemented metal-ceramic crowns and group 2 - cemented In-Ceram crowns. The marginal adaptations before and after cementation were evaluated in a comparison microscope with an error of 1 µm. All crowns were cemented with zinc phosphate cement. RESULTS: The cervical misalignment of cemented crowns before cementation (52.65 ± 11.83 and 85.73 ± 14.06 µm) was lower than that after cementation (66.80 ± 15.86 and 89.36 ± 22.66 µm). CONCLUSION: The cementing procedure interferes with the marginal fit of cemented crowns on implant abutments, with the prosthesis having better adaptation before cementation. Cemented metal-ceramic crowns exhibited better cervical adaptation than In-Ceram crowns cemented before and after the cementing procedure. CLINICAL SIGNIFICANCE: The maintenance of gum health and the longevity of prosthetic restorations are closely related to the restoration's marginal integrity.

Shaping Ability of ProTaper Next, WaveOne, and Reciproc in Simulated Root Canals.

INTRODUCTION: The study aimed to compare the shaping and preservation of the original curvature of simulated curved root canals using the following instruments: Reciproc (Rcp), WaveOne (Wo), and the ProTaper Next system (Ptn). MATERIALS AND METHODS: A total of 45 resin blocks with simulated curved root canals were divided into three groups (n = 15), prepared using the Rcp (R25), Wo (25/0.8), and Ptn (X2) instruments. Standardized photographs were taken before and after canal instrumentation. After the superimposition of the images, the amount of resin removed from the curvature's inner and outer walls was measured at six apical levels, at intervals of 1 mm. The canals' angles of curvature before and after instrumentation were subtracted. RESULTS: There were no significant differences between the instruments in terms of the total amount of resin removed of the inner or outer walls of the apical curvature (p > 0.05). The Rcp instruments provided the best resin removed ratios between the walls. The means of the change in angle were as follows: Wo = 2.15°, Ptn = 0.92°, and Rcp = 0.21°. WaveOne caused significantly higher deviations than Rcp. CONCLUSION: All of the instruments demonstrated a tendency to straighten the simulated root canal. Instruments that use rotary movement achieved an effect similar to that of the reciprocating instruments in relation to change in angle. CLINICAL SIGNIFICANCE: Deviations from the original shape of the root canal could have a negative impact on the quality of a filling and consequently on the success of the endodontic treatment.