Effects of alpha-tocopherol on fracture resistance after endodontic treatment, bleaching and restoration

Abstract

This study evaluated the effects of 10% alphatocopherol on the fracture resistance of endodontically treated teeth subjected to tooth bleaching with hydrogen peroxide and immediately restored with composite resin. Fifty bovine incisors were selected, including 10 sound teeth that constituted the control group (G1 (C)). The remaining 40 teeth, which were endodontically treated, were divided into four groups (n = 10): G2 (CR), consisting of teeth immediately restored with composite resin; G3 (HP + CR), consisting of teeth subjected to tooth bleaching with 38% hydrogen peroxide and immediately restored with composite resin; G4 (HP + SA + CR), which received treatment similar to that used for G3, but with 10% sodium ascorbate gel applied after the bleaching protocol; and G5 (HP + AT + CR), which was similar to G4 but included 10% alphatocopherol gel as an antioxidant. After 24 h, composite restorations were performed, and teeth were subjected to a fracture resistance test at a speed of 0.5 mm/min in an electromechanical testing machine. The axial force was applied with an angle of incidence of 135° relative to the long axis of the root. Data were subjected to ANOVA and Tukey tests (p = 0.05). G1 exhibited the highest fracture resistance (p < 0.05). No significant differences among the other experimental groups were observed. The 10% sodium ascorbate and 10% alphatocopherol gels did not improve the fracture resistance of endodontically treated teeth subjected to bleaching with 38% hydrogen peroxide.

Effects of Photodynamic Therapy on the Adhesive Interface of Fiber Posts Cementation Protocols

“…The PDT/CC group presented lower dentinal penetrability in the cervical and apical thirds. It can be associated with the high concentration of oxygen, which worked as a mechanical barrier and hampered the penetration of the adhesive system in the dentinal tubules (10). Moreover, Grandini et al (24) have observed that higher incidences of gaps and cementation failures occurred in the apical third of the prosthetic space, similar to the specimens in the PDT/CC group, because of the presence of oxygen.…”

“…Thus, the degree of conversion and the adhesion of resinous materials to the dentin are compromised by the substances that interact with these free radicals, such as sodium hypochlorite, which degrades in sodium hydroxide and hypochlorous acid and, consequently, leads to singlet oxygen formation (7)(8)(9). Moreover, the presence of oxygen can also work as a barrier in the adhesive interface, which hampers hybrid layer formation in dentin (10).…”

Influence of eugenol-based materials and cleaning procedures previously to resin composite restoration on microleakage after 1-year storage

“…Next, a size 15 K-file (Dentsply Maillefer) was inserted, and the canals were prepared according to a stepback technique up to a size 60 K-file. The canals were irrigated with 1 mL of 1.0 % NaOCl at each change of the file during chemomechanical preparation and then filled with 2 mL of 17 % EDTA for 3 min, flushed with 2 mL of 1 % NaOCl and dried with absorbent paper points (Dentsply Maillefer) [26].…”

Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth

“…1,2 Hydrogen peroxide is a strong oxidizing agent, which produces free radicals, reactive oxygen molecules, and HP anions that act on the pigments converting them into small molecules with reduced light absorption and low molecular weight, easier to be removed from the dental structure. 3,4 To improve the physical and chemical properties of HP, various components have been added to the bleaching gel, such as thickeners, desensitizers, remineralizers, and pigments. 5,6 Pigments facilitate the gel visualization and accelerate the chemical reaction that triggers tooth bleaching due to the bleaching gel having greater light absorption properties.…”