Stress Analysis on Mesiolingual Cavity of Endodontically Treated Molar Restored Using Bidirectional Fiber-Reinforced Composite (Wallpapering Technique).

Introduction: Endodontically treated teeth (ETT) undergo extensive structure change and experience high stress during biomechanical function. Stress distribution is influenced by the restoration material and the type of bond between material and tooth structure. The selection of materials that can distribute stress will affect the resistance and retention of ETT to mastication forces, thus biomechanical functions were achieved. Composite has mechanical properties similar to dentin, it can transmit and distribute stresses throughout the tooth surface. The disadvantage of composites in large cavities is their lack of toughness. The addition of fiber to composites can increase their toughness. Purpose: This research is to determine the stress distribution of a fiber-reinforced composite made of polyethylene and e-glass on the mesiolingual cavity of ETT. Materials and Methods: A three-dimensional model of the mandibular molar was prepared for cavity preparation and the formation of restorations using SolidWorks 2021. The models were analyzed with Abaqus 2020 to determine stress concentrations after given vertical and oblique loading. Results: The maximum and minimum principal stress data were obtained to assess material resistance and interfacial damage criterion. Polyethylene fiber shows a more homogeneous stress distribution because the modulus of elasticity is close to the dentin and has a thickness that can reduce the volume of the composite. The E-glass shows the stress concentration on the circumferential fiber and cavity floor. Conclusion: The stress distribution of fiber-reinforced composite on the buccolingual cavity of ETT using the finite element method did not show structural failure in the polyethylene group because the maximum and minimum principal stresses were lower than the strength of the material. Interfacial bond failure occurs at the enamel portion. The maximum and minimum principal values of e-glass indicate structural failure in the circumferential fiber and the base fiber because the stress exceeds the strength of the material. Interfacial bond failure occurred on the circumferential and the cavity floor.

Stress Distribution of Endodontically Treated Tooth MOD Cavity Restored with Ribbon Fiber-Reinforced Composite (Wallpapering Technique) Using Finite Element Method.

Purpose: This research aimed to describe the stress distribution of an endodontically treated tooth with a mesio-occluso-distal (MOD) cavity restored with direct composite reinforced with polyethylene and e-glass ribbon fiber. Methods: This research was a descriptive study using the finite element method. A 3D model of the mandibular first molar solid after endodontic treatment with class II MOD preparation was prepared using Solidworks software. Finite element simulation was carried out using Abaqus software. In the first simulation, 180 N force was applied (vertically 90° perpendicular to the occlusal surface) at four points of loading: the tip of the mesiobuccal and distobuccal cusp, central fossa, and distal marginal ridge. For the second simulation, a 100 N force was applied at a 45° lateral angle to the occlusal surface at two loading points: the lingual slope of the mesiobuccal and distobuccal cusp. Results: This study showed that the stress concentration was located in the occlusal pit and fissure, CEJ distal area, bifurcation in dentin, and the 1/3 cervical area of root dentin. The stress value generated after vertical and lateral force did not exceed the tooth and restoration's compressive and tensile strength value. The failure occurred at the interface of enamel and composite near the loading point area due to vertical load, both on polyethylene and e-glass fiber ribbon-reinforced composite restoration. Stress distribution of an endodontically treated tooth with a MOD cavity restored with ribbon fiber-reinforced composite using the finite element method showed that the highest stress concentration occurred on the surface close to the loading point, in narrow, concave, and sharp areas, and more apically for endodontically treated teeth. Conclusion: Neither the tooth nor restoration failed after vertical and horizontal loads. The interface between enamel and composite on the occlusal surface failed.

The Role of Duration of Chlorhexidine Gluconate 2% Application on the Shear Bond Strength of a Total Etch Bonding Agent: A Comparative Study.

Introduction: Matrix metalloproteinases enzymes (MMPs) can degrade the hybrid layer which can cause failure of composite restorations. Chlorhexidine gluconate 2% can reduce MMPs activity and increase the bond strength of the resin to dentin. Purpose: This study aims to determine the role of the duration of chlorhexidine gluconate 2% application on shear bond strength of a total-etch bonding agent. Methods: A total of 36 freshly extracted maxillary premolars were removed occlusally by one-third of the crown using a carborundum disc until the dentin was exposed. Specimens were divided into four groups n(9). The dentin surfaces were etched for 5s. Group A is the control group. In group B, chlorhexidine gluconate 2% was applied for 30s. In group C, chlorhexidine gluconate 2% was applied for 60s. In group D, chlorhexidine gluconate 2% was applied for 90s. The universal adhesive was applied afterwards and then followed by composite to the dentin surface. All specimens were stored in artificial saliva at 37°C for 24 hours. The shear bond strength was tested using a universal testing machine. Results: There was an increase in the shear bond strength of the bonding agent along with the additional application duration of chlorhexidine gluconate 2%. All groups gave higher MPa values than the control group. The shear bond strength in group A (control) was 12.64 MPa; Group B (30s of chlorhexidine) was 16.93 MPa; Group C (60s chlorhexidine) was 18.23 MPa; group D (90s of chlorhexidine) was 18.47MPa. Conclusion: Duration of chlorhexidine gluconate 2% application affects the shear bond strength of the bonding agent with the total-etch system. The effective duration of chlorhexidine gluconate 2% for the restorative procedure is 60 seconds.

Comparative Evaluation of the Increase in Enamel Hardness Post-External Bleaching after Using Casein Phosphopeptide Amorphous Calcium Phosphate Fluoride (CPP-ACPF) and 5% Sodium Fluoride (NaF) Remineralizing Agents.

OBJECTIVE: The purpose of this study was to analyze the increase in enamel hardness post-external bleaching after remineralized with casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACPF) and 5% sodium fluoride (NaF) and the difference in increased enamel hardness between CPP-ACPF and NaF materials. MATERIALS AND METHODS: The study was true experimental in vitro using 30 samples of mandibular premolars. All samples were bleached using 40% hydrogen peroxide. The samples were divided into three groups of 10 samples each; group I as a control without application of remineralization material, group II was given an application of CPP-ACPF (GC Tooth Mousse Plus: GC Europe, Lot #201130B), and group III was given an application of 5% NaF (Clinpro White Varnish: 3M ESPE, Lot #NA62322) Then the entire samples were stored in artificial saliva. The hardness of the samples was measured using a Vickers hardness tester before bleaching, after bleaching, and after remineralization for 7, 14, and 21 days. STATISTICAL ANALYSIS: Analysis of the data used was an analysis of variance test to assess differences in the increase in enamel hardness between groups and paired t-tests and to determine differences in enamel hardness in each group. RESULTS: This study showed that there was an increase in the enamel hardness after bleaching which was remineralized with CPP-ACPF and 5% NaF. There was a difference in the increased enamel hardness between teeth remineralized with CPP-ACPF and 5% NaF. The enamel hardness of CPP-ACPF was higher compared with 5% NaF after remineralization of 7, 14, and 21 days. CONCLUSION: There was an increase in the enamel hardness after external bleaching that was remineralized with CPP-ACPF and 5% sodium fluoride (NaF). There was a difference in the increased enamel hardness between teeth remineralized with CPP-ACPF and 5% sodium fluoride (NaF). CPP-ACPF showed a higher enamel hardness value than 5% NaF.

Design, synthesis and evaluation of novel ß-carboline ester analogues as potential anti-leishmanial agents.

Leishmaniasis is one of today's most neglected diseases. The emergence of new anti-leishmanial therapies emphasizes several study groups funded by the World Health Organization. The present investigation will focus on the research to determine a few new potential derivatives of ß-carboline ester derivatives against leishmaniasis. The in-silico predicted ADMET properties of most of the titled compounds are in an acceptable range and having drug like properties. Among all the tested analogs, compound ES-3 (EC50 3.36 µM; SI > 29.80) showed comparable and equipotent anti-leishmanial activity as that of standard drug miltefosine (EC50 4.80 µM; SI > 20.80) against amastigote forms of the tested L. infantum strain. Two compounds ES-6 and ES-10 exhibited significant activity with EC50 10.16, 13.56 µM; SI > 4.90, 7.37, respectively. In-silico based molecular docking and dynamics study of the significantly active analog also performed to study the putative binding mode, interaction pattern at the active site of the target leishmanial trypanothione reductase enzyme as well as stability of the target-ligand complex. The changes in the conformation of molecules during MD (frame wise trajectory analysis) provided new insights for the development of novel potent molecules. These findings will further give insight that will help modify the compound ES-3 for better potency and the design of novel inhibitors for leishmaniasis.Communicated by Ramaswamy H. Sarma.