Background: Deterioration in shear bond strength has been reported after immediate bracket bonding following hydrogen peroxide bleaching. This study compared the effectiveness of three antioxidant agents, namely, alpha-tocopherol, green tea extract, and sodium ascorbate, in reversing the bleaching effect and as possible alternatives to delayed bonding.
Methods: A total of 105 extracted human premolars were arbitrarily assigned to 7 groups (n = 15 each), including group 1 as the unbleached control group and six experimental groups, which were bleached with 40% hydrogen peroxide in three sessions of 15 min each. In experimental group 2, bonding was performed immediately after bleaching, whereas in groups 3 and 4, bonding was delayed for 1 and 2 weeks, respectively; meanwhile, the specimens were immersed in artificial saliva at 37 °C. Groups 5, 6, and 7 were treated immediately after bleaching with 10% of alpha-tocopherol, green tea extract, and sodium ascorbate solutions, respectively, for 15 min. Specimens were processed using 500 thermal cycles between 5 and 55 °C, with a dwell time of 30 s after 24 h of bracket bonding, and then tested for shear bond strength. The adhesive remnant index was examined to evaluate fracture mode. One-way analysis of variance, Kruskal-Wallis H, and post hoc Tukey's honestly significant difference tests were used to compare the data. Significant results were subjected to pairwise comparisons with Bonferroni's correction-adjusted of p values ≤ 0.050.
Results: Shear bond strength was significantly lower (p < 0.001) in the immediate bonding and 1-week delay groups than in the control group. However, no significant difference was detected among the 2-week delay, antioxidant-treated, and control groups (p > 0.05).
Conclusions: Application of 10% alpha-tocopherol, green tea extract, or sodium ascorbate for 15 min could restore shear bond strength after 40% hydrogen peroxide bleaching as an alternative to delay in bracket bonding.
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http://dx.doi.org/10.1186/s12903-023-02894-3 | DOI Listing |
Sci Rep
January 2025
College of Mechanical and Electrical Engineering, Shihezi University, Shihezi, 832003, China.
In response to the rotary ploughing equipment in the stubble land to implement protective operations, the stubble is large in number and strong in toughness, not easy to crush, resulting in rotary ploughing equipment to produce entanglement and increased resistance to rotary ploughing and other issues. In this study, researchers designed a bionic rotary tillage blade (B-RTB) based on the bionic structural equations of the Marmota claw. A straw-soil complex shear performance test was conducted to investigate the effect of straw on soil shear strength.
View Article and Find Full Text PDFJ Prosthet Dent
January 2025
Assistant Professor, Department of Prosthodontic, College of Dental Medicine, Rangsit University, Phatum Thani, Thailand. Electronic address:
Statement Of Problem: Comprehensive data are needed on the performance of chemically activated, chairside hard reline materials when used with computer-aided design and computer-aided manufacturing (CAD-CAM) milled polymethyl methacrylate (PMMA) denture bases and conventionally processed bases. This lack of data affects decisions regarding the chairside reline material to be used for improving the fit and retention of relined complete dentures.
Purpose: The purpose of this in vitro study was to evaluate and compare the shear bond strength (SBS) of 3 chemically activated, chairside hard reline materials on CAD-CAM milled and conventional heat-polymerized PMMA denture bases.
Clin Oral Investig
January 2025
Department of Restorative Dentistry, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
Objectives: To evaluate the shear bond strength (SBS) of universal cements (UCs) to dentin prepared with different diamond burs using various adhesive strategies.
Materials And Methods: One-hundred-twenty molars were prepared to expose the mid-coronal dentin. The teeth were divided into two groups according to diamond bur preparations: coarse and super-fine grit burs.
Eur J Dent
December 2024
Department of Dental Biomaterials, Faculty of Dentistry, Mansoura University, Mansoura City, Egypt.
Objectives: Orthodontic bracket bond failure is an obstacle in clinical orthodontics. This study investigated the influence of pH cycling on the shear bond strength (SBS), adhesive remnant index (ARI), and survival probability of adhesive-precoated flash-free ceramic brackets.
Materials And Methods: Forty mandibular premolars were randomly divided into two groups ( = 20): C: noncoated orthodontic brackets, and F: flash-free adhesive-precoated orthodontic brackets.
J Phys Chem Lett
January 2025
State Key Laboratory of Superhard Materials, Key Laboratory of Material Simulation Methods & Software of Ministry of Education, and Jilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy Materials, Jilin University, Changchun 130012, China.
The multicentered bonds present in planar borophene lead to a more complex structure and richer chemical properties. Herein, we use first-principles calculations to investigate the electronic, mechanical, and superconducting properties of various borophene polymorphs, focusing on the newly synthesized β and β phases. Notably, in order to balance and optimize the electron filling of the valence bond orbitals, the planar borophene structure is composed of a mixture of triangular lattices and hexagonal holes with multicentered bonding, which further enhances the stability of the structure and possesses a rare polymorphic property.
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