The purpose of this study was to investigate the effects of four restorative materials under various occlusal loading conditions on the stress distribution at the CEJ of buccal, palatal surface and central groove of occlusal surface of endodontically treated maxillary second premolar, using a 3D finte element analysis.

A 3D finite element model of human maxillary second premolar was endodontically treated. After endodontic treatment, access cavity was filled with Amalgam, resin, ceramic or gold of different mechanical properties. A static 500N forces were applied at the buccal (Load-1) and palatal cusp (Load-2) and a static 170N forces were applied at the mesial marginal ridge and palatal cusp simultaneously as centric occlusion (Load-3). Under 3-type Loading condition, the value of tensile stress was analyzed after 4-type restoration at the CEJ of buccal and palatal surface and central groove of occlusal surface

Excessive high tensile stresses were observed along the palatal CEJ in Load-1 case and buccal CEJ in Load-2 in all of the restorations. There was no difference in magnitude of stress in relation to the type of restorations. Heavy tensile stress concentrations were observed around the loading point and along the central groove of occlusal surface in all of the restorations. There was slight difference in magnitude of stress between different types of restorations. High tensile stress concentrations around the loading points were observed and there was no difference in magnitude of stress between different types of restorations in Load-3.

The aim of the present study is to compare the corrosion tendency using two kinds of NiTi files in the various environmental conditions through the visual examination and electrochemical analysis. ProTaper Universal S2, 21 mm (Dentsply Maillefer, Ballaigues, Switzerland) and Hero 642, 0.06 tapers, size 25, 21 mm (Micromega, Besancon, France) rotary instruments were tested. The instruments were randomly divided into eighteen groups (n = 5) by the immersion temperature, the type of solution, the brand of NiTi rotary instrument and the presence of mechanical loading. Each file was examined at various magnifications using Scanning Electron Microscope (JEOL, Akishima, Tokyo, Japan) equipped with energy dispersive X-ray microanalysis (EDX). EDX was used to determine the components of the endodontic file alloy in corroded and noncorroded areas. The corrosion resistance of unused and used NiTi files after repeated uses in the human teeth was evaluated electrochemically by potentiodynamic polarization test using a potentiostat (Applied Corrosion Monitoring, Cark-in-Cartmel, UK).

Solution temperature and chloride ion concentration may affect on passivity of NiTi files. Under the conditions of this in vitro study, the corrosion resistance is slightly increased after clinical use.

Citations

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• Comparing Cyclic Fatigue Resistance and Free Recovery Transformation Temperature of NiTi Endodontic Single-File Systems Using a Novel Testing Setup
  Emad Youssef, Holger Jungbluth, Søren Jepsen, Manfred Gruener, Christoph Bourauel
  Materials.2024; 17(3): 566.     CrossRef
• The Determination of the Corrosion Rates of Rotary Ni-Ti Instruments in Various Irrigation Solutions
  Tolga Özcan, Bade Sonat, Meltem Dartar Öztan, Fatma Basmaci, Umut Aksoy
  Cyprus Journal of Medical Sciences.2023; 8(2): 136.     CrossRef
• A Nonlinear Probabilistic Pitting Corrosion Model of Ni–Ti Alloy Immersed in Shallow Seawater
  Špiro Ivošević, Gyöngyi Vastag, Nataša Kovač, Peter Majerič, Rebeka Rudolf
  Micromachines.2022; 13(7): 1031.     CrossRef
• Corrosion resistance assessment of nickel-titanium endodontic files with and without heat treatment
  Tatiana Dias Costa, Elison da Fonseca e Silva, Paula Liparini Caetano, Marcio José da Silva Campos, Leandro Marques Resende, André Guimarães Machado, Antônio Márcio Resende do Carmo
  Restorative Dentistry & Endodontics.2021;[Epub]     CrossRef
• Effect of Sodium Hypochlorite, EDTA, and Chitosan Solution on Corrosion and Quantity of Extruded Nickel Ions Using Two Rotary Instruments (In Vitro)
  Eltica Oktavia, Trimurni Abidin
  World Journal of Dentistry.2019; 10(3): 207.     CrossRef

The purpose of this study was to compare the sealing abilities of four endodontic temporary restorative materials using a methylene blue dye penetration test under dynamic loading. Standardized access cavities were prepared in forty-four intact human permanent molar teeth, and the cavities were restored with Caviton, MD-Temp, IRM, or ZOE. After thermocycling, an intermittent load of 98 N at 1 Hz was applied for 1,000 cycles to the long axis of the functional cusp of each of the teeth, which were immersed in a 1% methylene blue solution. The teeth were split in half, and the linear depth of dye penetration was evaluated according to the criteria. The results were analyzed using one-way ANOVA (p = 0.05) and Duncan's multiple range test. The results demonstrated that Caviton and MD-Temp showed significantly lower microleakage than IRM and ZOE. It was concluded that Caviton and MD-Temp exhibited better sealing ability than IRM and ZOE under dynamic loading.

Citations

Citations to this article as recorded by  

• Coronal microleakage of four temporary restorative materials in Class II-type endodontic access preparations
  Sang-Mi Yun, Lorena Karanxha, Hee-Jin Kim, Sung-Ho Jung, Su-Jung Park, Kyung-San Min
  Restorative Dentistry & Endodontics.2012; 37(1): 29.     CrossRef