Pomegranate extract on eroded dentin: antioxidant action, bond strength and morphology of the adhesive interface after aging.

Objectives: This study aimed to evaluate the effect of pomegranate solution (Punica granatum) on eroded dentin through antioxidant action, shear bond strength (SBS) and interface morphology. Materials and Methods: The 10% pomegranate peel extract was prepared by the lyophilization method. Punicalagin polyphenol was confirmed by high-performance liquid chromatography. Antioxidant activity was evaluated by capturing the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. For the SBS, 48 dentin fragments were divided into sound or eroded, and subdivided according to the pretreatment (n = 12): water or P. granatum. The surfaces were restored with self-etch adhesive and a bulk-fill resin (Ecosite; DMG). The SBS was done immediately (24 hours) and after thermal cycling + water storage (12 months). For scanning electron microscopy, 48 dentin fragments (24 sound and 24 eroded) received the same treatments as for SBS (n = 6), and they were analyzed after 24 hours and 12 months. Results: The P. granatum had antioxidant action similar (p = 0.246) to the phenolic standard antioxidants. After 24 hours, eroded dentin had lower SBS than sound dentin (p < 0.001), regardless of the pretreatment. After 12 months, P. granatum maintained the SBS of sound dentin (13.46 ± 3.42 MPa) and eroded dentin (10.96 ± 1.90 MPa) statistically similar. The lowest values were found on eroded dentin treated with water (5.75 ± 1.65 MPa) (p < 0.001). P. granatum on eroded dentin caused peritubular demineralization and hybrid layer with resin tags. Conclusions: The pomegranate extract had antioxidant action and preserved the adhesive interface of the eroded dentin.

Impact of Endodontic Kinematics on Stress Distribution During Root Canal Treatment: Analysis of Photoelastic Stress.

INTRODUCTION: Structural defects created by endodontic treatment are the most common cause of major dental failures. This study analyzed levels of stress produced by endodontic instruments during the root canal treatment by photoelastic analysis of stress. METHODS: Twenty-four human premolars were randomly divided into 4 groups (n = 6) according to instrumentation protocol: ProTaper Next (GPT), One Shape (GOS), Wave One Gold (GWO), and TF Adaptive (GTF). The evaluation of the photoelastic model was performed at 4 dental zones: dental-crown region, cervical third of root, middle third of root, and apical third of root. Silicone molds were prepared (2 × 15 mm), and pinjets were used inside the root canals to fixate teeth. Photoelastic resin (2:1 ratio) was poured into the silicone molds to form photoelastic models. A transmission polariscope was used to analyze the positions of interest and recorded with a digital camera. Tardy's method was used to quantify the fringe order (n) and calculate the maximum stress value (τ) at each selected point. Data were analyzed with two-way analysis of variance, Tukey test (P < .05), fringe descriptive analysis. RESULTS: All groups showed a significant increase in the level of stress created during biomechanical preparation of the root canals. In the quantitative analysis, there was no statistically significant difference among the groups (P > .05). In the qualitative analysis, GPT and GTF instruments achieved greater levels of stresses compared with GWO and GOS instruments. At the beginning of instrumentation, stresses were concentrated at the coronary level and the end of instrumentation at the middle and apical root level. CONCLUSIONS: All endodontic systems resulted in accumulation of stress along the dental structure. Stress was found in different concentrations along the tooth and at different levels.

Experimental Sealers Containing Metal Methacrylates: Physical and Biological Properties.

INTRODUCTION: The aim of this study was to evaluate the physical properties, the antimicrobial effect, and the biocompatibility of dual polymerization experimental sealers after the incorporation of dibutyltin (ET) or calcium (EC) methacrylate at concentrations of 0.5%, 1%, 2%, and 5%. METHODS: RealSeal (RS; SybronEndo, Glendora, CA) was used as a commercial control. Materials were evaluated regarding film thickness, degree of conversion, radiopacity, antimicrobial effect against Enterococcus faecalis using the modified direct contact test, and cell viability. Data were analyzed using analysis of variance followed by the Tukey test or the Student-Newman-Keuls test in SigmaPlot 12.0 (Systat Software, Inc, Point Richmond, CA) (P = .05). RESULTS: The film thickness of the dibutyltin and calcium were greater than experimental sealers following the standards given by ISO 6876:2012. For degree of conversion, dual polymerization was not influenced by the addition of metal methacrylate. Regarding the modified direct contact test, calcium and dibutyltin at all concentrations showed antimicrobial activity when compared with the positive control after 48 hours of contact (P < .05). In cell viability, ET at all concentrations showed high cytotoxicity similar to RS, and EC at concentrations of 0.5%, 1%, and 2% showed moderate cytotoxicity that was less than 5% of calcium and RS. CONCLUSIONS: It was concluded that calcium and dibutyltin methacrylate incorporation in experimental sealers promoted the antimicrobial effect. The incorporation of calcium methacrylate at 0.5%, 1%, and 2% seemed to be a good treatment option to provide antimicrobial activity associated with moderate cytotoxicity and adequate physical properties.