Michel Degrange

Université René Descartes - Paris 5, Lutetia Parisorum, Île-de-France, France

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Publications (55)82.1 Total impact

  • Elsa Vennat · J-P Attal · Denis Aubry · M Degrange
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    ABSTRACT: Dentine is the fundamental substrate of restorative dentistry, and its properties and characteristics are the key determinants of restorative processes. In contemporary restorative techniques, bonding to Dentine is created by the impregnation of the demineralised dentine by blends of resin monomers. In this paper, a numerical model of dentinal infiltration is proposed. The aim is to follow the resin front and to point out the optimal parameter set. The main tool is a level set technique to follow the evolving interface. It is coupled with the Navier-Stokes equation where capillary effect gives rise to the appearance of a new term in the variational approach than discretised by finite elements. Using an appropriate geometry representing demineralised dentine, the moving front is observed. First, a simulation of porosimetry test is achieved in order to validate the model. The two expected pore sizes are detected and the simulation also points out limitations of mercury intrusion porosimetry test in an educational way. Then a wetting fluid (representing the dental resin) is numerically infiltrated. In the dentinal porous network, capillarity is taken into account in our model by including a capillary term. A crucial conclusion is drawn from this study: resin application time by practitioners is sufficient if, in the infiltration process, the wetting phase is the resin.
    No preview · Article · Aug 2012 · Computer Methods in Biomechanics and Biomedical Engineering
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    ABSTRACT: Syntheses of novel 5-(methacryloyloxy)pentylphosphonic acid 1, 5-(methacryloyloxy)pentylidenebisphosphonic acid 2 and 1,1-difluoro-5-(methacryloyloxy)pentylphosphonic acid 3 are described. The ability of these monomers to adhere to hydroxyapatite was demonstrated using 31P CP-MAS NMR spectroscopy. Their copolymerization with N,N′-diethyl-1,3-bis(acrylamido)propane (DEBAAP) was investigated with photo differential scanning calorimetry. These mixtures exhibit a significantly higher reactivity than DEBAAP alone. Bisphosphonic acid 2 was shown to be significantly more reactive than monomers 1 and 3. Adhesive properties of these monomers were also studied. Adhesives based on bisphosphonic acid 2 and difluoromethylphosphonic acid 3 provide significantly higher dentin shear bond strength than the one based on phosphonic acid 1.
    Full-text · Article · Feb 2012 · European Polymer Journal
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    Full-text · Presentation · Jun 2011
  • Laïla Hitmi · Jean-Pierre Attal · Michel Degrange

    No preview · Article · Mar 2011 · l Orthodontie Française
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    M. Derbanne · V. Besse · S. Le Goff · JP Attal · TN Pham · M. Degrange

    Full-text · Article · Dec 2010 · Dental Materials
  • Elsa Vennat · Denis Aubry · Michel Degrange

    No preview · Article · Oct 2010
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    Full-text · Presentation · Oct 2010
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    V Besse · Y Catel · F Chen · W D Cook · M Degrange · L Le Pluart · P-J Madec · N Pham
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    ABSTRACT: RESUME : L'étude porte sur la synthèse de nouveaux monomères acides pour une application dans les adhésifs dentaires. Dans ce cadre, la synthèse de nouveaux acrylamides, porteurs de fonctions acide phosphonique, a été mise au point. Ces monomères, stables en milieu aqueux, ont été préparés en quatre étapes, avec des rendements globaux satisfaisants (26%-43%). De nouveaux primaires d'adhésion, stables dans le temps, ont été formulés à partir de ces monomères. L'utilisation de ces derniers lors de tests d'adhérence à la dentine a montré que l'utilisation de tels monomères mène à des résultats comparables aux formulations rencontrées sur le marché.
    Full-text · Conference Paper · Oct 2010
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    Elsa Vennat · Denis Aubry · Michel Degrange
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    ABSTRACT: In dentin restoration, collagen fiber network infiltration is an issue. Using data from the litterature, we have constructed a relevant numerical geometrical model of the network. The specificity of our model is that the fibers are taken into account implicitly using a regularized Heaviside function. This function is either used to set the viscosity or to localize the contact line where capillary forces are applied. A level set technique with respect to fluid infiltration front tracking in five fiber networks using the level set method and Navier-Stokes equations with capillary terms is used to point out efficient critical infiltration parameters. A variational formulation which can be implemented in FEM is proposed both for the infiltration front and the contact line. Because of lack of knowledge on fiber orientation, different configurations were tested through permeability assessment of the whole network. Fiber orientation, interfibrillar space and contact angle influence were investigated.
    Full-text · Article · Sep 2010 · Transport in Porous Media
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    Full-text · Poster · May 2010
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    Full-text · Poster · Apr 2010
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    Congxiao Zhang · Michel Degrange
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    ABSTRACT: The purpose of this study was to assess the bond strengths of three self-adhesive resin cements (Rely X Unicem, Maxcem and Multilink Sprint) fixing dentine to four different restorative substrates (Ni-Cr alloy, E-Max glass-ceramic, Y-TZP Zirconia and Adoro micro-filled composite) and to compare their performances with those of two conventional dual-cured luting cements (Variolink II + Total-etch Excite DSC and Multilink Automix + Self-etching Primer A + B). Cylindric specimens (5 x 5 mm) were prepared with the four restorative materials for bonding to human dentine. Three surface treatments were performed depending on the restorative material: (i) Al2O3 50 microm sandblasting (Ni-Cr, Adoro), (ii) #800 SiC polishing (Zirconia, E-Max), (iii) hydrofluoric acid (HF)-etching (E-Max). Twenty-five groups (n = 10) were designed according to luting cements, restorative materials and surface pre-treatments. In some experimental groups, Variolink II and Multilink Automix were coupled with, respectively, a silane primer (Monobond S) and an alloy/zirconia primer (Multilink A/Z primer). Specimens were stored in distilled water at 37 degrees C for 24 h and then loaded in shear until failure. Variolink II and Multilink Automix showed the highest bond strengths, regardless of the restorative substrate, when used with dentine bonding systems and primers, while the weakest bonds were with Maxcem. The bond strength recorded with the two other self-adhesive cements depended on the nature of the restorative substrate. Increasing retention at the interfaces (i.e., HF ceramic etching) and using specific primers significantly improves the bond strength of luted restorative materials to dentine.
    Preview · Article · Mar 2010 · Journal of Biomaterials Science Polymer Edition
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    ABSTRACT: Four new monomers, 3-(N-methylacrylamido)propylidenebisphosphonic acid, 3-(N-propyl-acrylamido)propylidenebisphosphonic acid, 3-(N-hexylacrylamido)propylidenebisphosphonic acid, and 3-(N-octylacrylamido)propylidenebisphosphonic acid, have been synthesized in good yields and fully characterized by 1H, 13C, 31P NMR, and HRMS. The copolymerization of these monomers with N,N′-diethyl-1,3-bis(acrylamido)propane (DEBAAP) has been investigated with differential scanning calorimetry. These mixtures show a higher reactivity than DEBAAP. New self-etch dental primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on these bisphosphonic acids assure a strong bond between the tooth substance and a dental composite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5258–5271, 2009
    Full-text · Article · Oct 2009 · Journal of Polymer Science Part A Polymer Chemistry
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    ABSTRACT: The aim of this study was to evaluate the compatibility between five self-etching bonding systems (SEBSs) and two resin luting cements (RLCs) assessed by use of an in vitro dentin shear bond test. The selected RLCs were: Variolink II in a dual-cure mode and Multilink in a self-cure mode. The SEBSs combined with the RLCs were: two one-step SEBSs (One Up Bond F and Xeno III) and three two-step SEBSs (Clearfil SE Bond, Unifil Bond, and Xeno III primer coupled with Clearfil SE Bond bonding resin as an experimental combination). One hundred fifty human molars were divided into ten groups of fifteen samples each. The samples were tested in shear after seven days of storage at 100% RH and 37°C. After each test, the failure mode was recorded. Significant differences in shear bond strength (SBS) were observed according to both the curing mode of the RLC and the adhesive. The one-step systems Xeno III and One Up Bond F revealed a total incompatibility when bonded with the chemical-curing RLC. Conversely, the two-step SEBSs were compatible with chemical and dual-curing RLC. Failure modes and shear values were in good agreement. A positive correlation was found between the pH of the tested adhesive solutions or resins and the SBS data
    Full-text · Article · Sep 2009 · The journal of adhesive dentistry
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    Elsa Vennat · Denis Aubry · Michel Degrange · Jean-Marie Fleureau
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    ABSTRACT: A slightly deformable network may be considered as a particular porous media with a connected void phase. In this paper, a fluid flow through a collagen network is analyzed with applications in the area of restorative dentistry. Infiltration of a fluid into a network already saturated by another fluid is a complex issue especially when the fibers are so tightly distributed (10 to 100 nm between them in a dentinal collagen network) that capillary forces are significant (the bond and capillary number are small). In a general framework, the equation of the capillary membrane with variable curvature and the associated boundary condition at the contact line between the two fluids and the fiber wall are discussed. The resulting solution is approximated by the finite element method together with a level set technique to track the smeared front. The expected meniscus shape around a fiber and the capillary membrane advancing front in different networks are obtained. The influence of fiber orientation and interfibrillar space is discussed. This type of simulation is an essential step towards a refined understanding of the macroscopic behavior of a porous medium like the collagen network in order to estimate e. g. the equivalent capillary pressure or relative permeability.
    Full-text · Article · Jun 2009
  • N Lehmann · R Debret · A Roméas · H Magloire · M Degrange · F Bleicher · P Sommer · D Seux
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    ABSTRACT: In adhesive restorations, one major problem is hybrid layer degradation. At present, this deterioration is explained by the activation of the endogenous matrix metalloproteinases (MMPs) present in dentin due to the acidic property of adhesive systems. We hypothesized that self-etching adhesive should also stimulate the expression of MMPs in odontoblasts. In cultured tooth slices, we evaluated the changes in MMP-2 and proMMP-9 expression in the dentin-pulp complex after self-etching adhesive treatment on dentin cavities in immunochemistry and by zymography. The treatment resulted in increased MMP-2 expression in odontoblasts, as shown by immunohistochemistry. Zymography showed increased proMMP-9 and MMP-2 in dentin under self-etching treatment when pulp was present. These results showed that self-etching adhesive stimulates the secretion of MMPs from the dentin-pulp complex and, more precisely, by odontoblasts, suggesting that odontoblasts participate in hybrid layer degradation.
    No preview · Article · Feb 2009 · Journal of dental research
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    ABSTRACT: The objectives of this study were to assess demineralized dentin porosity and quantify the different porous features distribution within the material using mercury intrusion porosimetry (MIP) technique. We compared hexamethyldisilazane (HMDS) drying and lyophilization (LYO) (freeze-drying) in sample preparation. Fifty-six dentin discs were assigned into three groups. The control (CTR) group discs were superficially acid-etched (15s 37% H(3)PO(4)) to remove the smear layer and then freeze-dried whereas LYO and HMDS groups samples were first totally demineralized using EDTA 0.5M and then freeze-dried and HMDS-dried respectively. MIP was used to determine open porosity and pore size distribution of each pair of samples. Field emission scanning electron microscopy (FESEM) was used to illustrate the results. The results showed two types of pores corresponding either to tubules and micro-branches or to inter-fibrillar spaces created by demineralization. Global porosity varied from 59% (HMDS-dried samples) to 70% (freeze-dried samples). Lyophilization drying technique seems to lead to less shrinkage than HMDS drying. FESEM revealed that collagen fibers of demineralized lyophilized samples are less melted together than in the HMDS-dried samples. Demineralized dentin porosity is a key parameter in dentin bonding that will influence the hybrid layer quality. Its characterization could be helpful to improve the monomers infiltration.
    Full-text · Article · Feb 2009 · Dental materials: official publication of the Academy of Dental Materials
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    ABSTRACT: Novel monomers 2-(N-methylacrylamido)ethylphosphonic acid, 6-(N-methylacrylamido)hexylphosphonic acid, 10-(N-methylacrylamido)decylphosphonic acid, and 4-(N-methylacrylamidomethyl)benzylphosphonic acid have been prepared in good yields for use in dental adhesives. They have been fully characterized by 1H-NMR, 13C-NMR, 31P-NMR, and by HRMS. All monomers are hydrolytically stable in aqueous solution. Free radical homopolymerizations of these monomers have been carried out in solution of ethanol/water (2.5/1:v/v), using 2,2′-azo(2-methylpropionamidine) dihydrochloride (AMPAHC) as initiator. They lead to homopolymers in moderate to excellent yields. Structure of the polymers has been confirmed by SEC/MALLS and 1H-NMR spectra. The photopolymerization behavior of the synthesized monomers with N,N′-diethyl-1,3-bis(acrylamido)propane has been investigated by DSC. New self-etch primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on (N-methylacrylamido)alkylphosphonic acids assure a strong bond between the tooth substance and a dental composite. Moreover, the monomer with the longest spacer group provides the highest shear bond strength. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7074–7090, 2008
    No preview · Article · Nov 2008 · Journal of Polymer Science Part A Polymer Chemistry
  • Elsa Vennat · Denis Aubry · Michel Degrange · Jean-Marie Fleureau

    No preview · Article · Jun 2008
  • Nicolas Cheleux · Patrick Sharrock · Michel Degrange
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    ABSTRACT: Fibre-reinforced composite posts are currently used to restore endodontically-treated teeth. Push-out tests were carried out to evaluate the performance of several bonding agents on the retention of an endodontic quartz fibre post to a composite resin core. Five bonding agents were investigated in both self-cure and light-cure modes. Ten experimental groups of 10 posts each were constituted as a function of curing mode and bonding agent. Specimens were mounted in a dedicated Teflon mould. This experimental set-up allowed the determination of true shear strength. One-way ANOVA and Student-Newman-Keuls tests were used for statistical analysis. The bonding strengths ranged from 23.4 MPa to 35.3 MPa. The best results were obtained with a light-cure self-etch bonding agent; in all cases photo-polymerisation led to statistically higher bonding strengths compared to chemical auto-polymerisation. Shear bond strength at the post-adhesive interface was also found to be significantly dependent on the nature of the bonding agent. AdheSe self-etch bonding agent was more effective than etch-and-rinse single-component bonding agents.
    No preview · Article · Feb 2008 · Journal of Biomaterials Science Polymer Edition

Publication Stats

1k Citations
82.10 Total Impact Points

Institutions

  • 2003-2012
    • Université René Descartes - Paris 5
      • • Faculty of dental surgery
      • • Faculté de Chirurgie Dentaire
      Lutetia Parisorum, Île-de-France, France
  • 2000
    • Semmelweis University
      Budapeŝto, Budapest, Hungary
  • 1995
    • IT University of Copenhagen
      København, Capital Region, Denmark