References of "MAINJOT, Amélie"
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See detailAging of monolithic zirconia dental prostheses: Protocol for a 5-year prospective clinical study using ex vivo analyses
KOENIG, Vinciane ULg; Wulfman, Claudine; DERBANNE, Mathieu et al

in Contemporary Clinical Trials Communication (2016), 4

Background: Recent introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) monolithic zirconia dental prostheses raises the issue of material low thermal degradation (LTD), a ... [more ▼]

Background: Recent introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) monolithic zirconia dental prostheses raises the issue of material low thermal degradation (LTD), a wellknown problem with zirconia hip prostheses. This phenomenon could be accentuated by masticatory mechanical stress. Until now zirconia LTD process has only been studied in vitro. This work introduces an original protocol to evaluate LTD process of monolithic zirconia prostheses in the oral environment and to study their general clinical behavior, notably in terms of wear. Methods/design: 101 posterior monolithic zirconia tooth elements (molars and premolars) are included in a 5-year prospective clinical trial. On each element, several areas between 1 and 2 mm2 (6 on molars, 4 on premolars) are determined on restoration surface: areas submitted or non-submitted to mastication mechanical stress, glazed or non-glazed. Before prosthesis placement, ex vivo analyses regarding LTD and wear are performed using Raman spectroscopy, SEM imagery and 3D laser profilometry. After placement, restorations are clinically evaluated following criteria of the World Dental Federation (FDI), complemented by the analysis of fracture clinical risk factors. Two independent examiners perform the evaluations. Clinical evaluation and ex vivo analyses are carried out after 6 months and then each year for up to 5 years. Discussion: For clinicians and patients, the results of this trial will justify the use of monolithic zirconia restorations in dental practice. For researchers, the originality of a clinical study including ex vivo analyses of material aging will provide important data regarding zirconia properties. [less ▲]

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See detailComportement clinique des couronnes monolithiques en zircone
KOENIG, Vinciane ULg; Wulfman, Claudine; MAINJOT, Amélie ULg

in Les entretiens d'Odontologie-Stomatologie 2016 (2016, October)

Les études cliniques sur les couronnes et les bridges en zircone Y-TZP ont indiqué des taux d'échecs élevés liés aux fractures cohésives de la céramique d’émaillage (chipping). Pour remédier à ce problème ... [more ▼]

Les études cliniques sur les couronnes et les bridges en zircone Y-TZP ont indiqué des taux d'échecs élevés liés aux fractures cohésives de la céramique d’émaillage (chipping). Pour remédier à ce problème, les fabricants commercialisent des couronnes monolithiques, entièrement en zircone, qui sont simplement maquillées en surface. Cependant, ces restaurations sont suspectées d’être plus sensibles à la fatigue hydrique de la zircone, problème qui aboutit à une baisse des propriétés mécaniques et qui fut à l’origine de nombreux échecs avec les prothèses de hanche. En effet, l’absence de céramique d’émaillage sur les couronnes monolithiques les rend plus vulnérables vis à vis du milieu oral ; de plus, certaines zircones de haute translucidité, spécifiquement développées pour cette indication, sont réputées plus sensibles en raison d’une plus grande métastabilité. Enfin, le recul clinique sur ces restaurations est très faible et leur comportement général, notamment en terme d’usure des dents antagonistes, a besoin d’être étudié. Une étude clinique est actuellement menée à l’Université de Liège, en collaboration avec l’Université Paris Descartes, afin d’évaluer le comportement clinique de la zircone non émaillée en milieu buccal, et particulièrement la fatigue hydrique, sur une période de 5 ans. Les résultats à très court terme (6 mois) mettent en évidence le bon comportement clinique des restaurations monolithiques en zircone, avec cependant une usure rapide de la glaçure, ce qui pourrait promouvoir la fatigue hydrique. Les zones de transformation cristalline détectées soulignent la nécessité d’une cuisson de régénération de la zircone suite aux ajustements occlusaux par fraisage. [less ▲]

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See detailBiocompatibility of polymer-infiltrated-ceramic-network (PICN) materials with Human Gingival Fibroblasts (HGFs).
GRENADE, Charlotte ULg; De Pauw-Gillet, Marie-Claire ULg; Gailly, Patrick ULg et al

in Dental materials : official publication of the Academy of Dental Materials (2016)

OBJECTIVES: Polymer-infiltrated-ceramic-network (PICN) materials constitute an innovative class of CAD-CAM materials offering promising perspectives in prosthodontics, but no data are available in the ... [more ▼]

OBJECTIVES: Polymer-infiltrated-ceramic-network (PICN) materials constitute an innovative class of CAD-CAM materials offering promising perspectives in prosthodontics, but no data are available in the literature regarding their biological properties. The objective of the present study was to evaluate the in vitro biocompatibility of PICNs with human gingival fibroblasts (HGFs) in comparison with materials typically used for implant prostheses and abutments. METHODS: HGF attachment, proliferation and spreading on discs made of PICN, grade V titanium (Ti), yttrium zirconia (Zi), lithium disilicate glass-ceramic (eM) and polytetrafluoroethylene (negative control), were evaluated using a specific insert-based culture system (IBS-R). Sample surface properties were characterized by XPS, contact angle measurement, profilometry and SEM. RESULTS: Ti and Zi gave the best results regarding HGF viability, morphology, number and coverage increase with time in comparison with the negative control, while PICN and eM gave intermediate results, cell spreading being comparable for PICN, Ti, Zi and eM. Despite the presence of polymers and their related hydrophobicity, PICN exhibited comparable results to glass-ceramic materials, which could be explained by the mode of polymerization of the monomers. SIGNIFICANCE: The results of the present study confirm that the currently employed materials, i.e. Ti and Zi, can be considered to be the gold standard of materials in terms of HGF behavior, while PICN gave intermediate results comparable to eM. The impact of the present in vitro results needs to be further investigated clinically, particularly in the view of the utilization of PICNs for prostheses on bone-level implants. [less ▲]

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See detailDental ceramics: classification and indications
Mainjot, Amélie ULg

in Esthetics in Dentistry (2016)

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See detailA new method using insert-based systems (IBS) to improve cell behavior study on flexible and rigid biomaterials.
GRENADE, Charlotte ULg; Moniotte, Nicolas; Rompen, Eric ULg et al

in Cytotechnology (2016)

In vitro studies about biomaterials biological properties are essential screening tests. Yet cell cultures encounter difficulties related to cell retention on material surface or to the observation of ... [more ▼]

In vitro studies about biomaterials biological properties are essential screening tests. Yet cell cultures encounter difficulties related to cell retention on material surface or to the observation of both faces of permeable materials. The objective of the present study was to develop a reliable in vitro method to study cell behavior on rigid and flexible/permeable biomaterials elaborating two specific insert-based systems (IBS-R and IBS-F respectively). IBS-R was designed as a specific cylindrical polytetrafluoroethylene (PTFE) system to evaluate attachment, proliferation and morphology of human gingival fibroblasts (HGFs) on grade V titanium and lithium disilicate glass-ceramic discs characteristics of dental prostheses. The number of cells, their covering on discs and their morphology were determined from MTS assays and microscopic fluorescent images after 24, 48 and 72 h. IBS-F was developed as a two components system to study HGFs behavior on guided bone regeneration polyester membranes. The viability and the membrane barrier effect were evaluated by metabolic MTS assays and by scanning electron microscopy. IBS-R and IBS-F were shown to promote (1) easy and rapid handling; (2) cell retention on biomaterial surface; (3) accurate evaluation of the cellular proliferation, spreading and viability; (4) use of non-toxic material. Moreover IBS-F allowed the study of the cell migration through degradable membranes, with an access to both faces of the biomaterial and to the bottom of culture wells for medium changing. [less ▲]

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See detailFrom Artisanal to CAD-CAM Blocks: State of the Art of Indirect Composites
MAINJOT, Amélie ULg; DUPONT, Nathalie ULg; OUDKERK, Julie ULg et al

in Journal of Dental Research (2016), 95(5), 487-495

Indirect composites have been undergoing an impressive evolution over the last few years. Specifically, recent developments in computer- aided design–computer-aided manufacturing (CAD-CAM) blocks have ... [more ▼]

Indirect composites have been undergoing an impressive evolution over the last few years. Specifically, recent developments in computer- aided design–computer-aided manufacturing (CAD-CAM) blocks have been associated with new polymerization modes, innovative microstructures, and different compositions. All these recent breakthroughs have introduced important gaps among the properties of the different materials. This critical state-of-the-art review analyzes the strengths and weaknesses of the different varieties of CAD- CAM composite materials, especially as compared with direct and artisanal indirect composites. Indeed, new polymerization modes used for CAD-CAM blocks—especially high temperature (HT) and, most of all, high temperature–high pressure (HT-HP)—are shown to significantly increase the degree of conversion in comparison with light-cured composites. Industrial processes also allow for the augmentation of the filler content and for the realization of more homogeneous structures with fewer flaws. In addition, due to their increased degree of conversion and their different monomer composition, some CAD-CAM blocks are more advantageous in terms of toxicity and monomer release. Finally, materials with a polymer-infiltrated ceramic network (PICN) microstructure exhibit higher flexural strength and a more favorable elasticity modulus than materials with a dispersed filler microstructure. Consequently, some high- performance composite CAD-CAM blocks—particularly experimental PICNs—can now rival glass-ceramics, such as lithium-disilicate glass-ceramics, for use as bonded partial restorations and crowns on natural teeth and implants. Being able to be manufactured in very low thicknesses, they offer the possibility of developing innovative minimally invasive treatment strategies, such as “no prep” treatment of worn dentition. Current issues are related to the study of bonding and wear properties of the different varieties of CAD-CAM composites. There is also a crucial need to conduct clinical studies. Last, manufacturers should provide more complete information regarding their product polymerization process, microstructure, and composition, which significantly influence CAD-CAM material properties. [less ▲]

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See detailRecent advances in composite CAD/CAM blocks.
Mainjot, Amélie ULg

in International Journal of Esthetic Dentistry (2016), 11(2), 275-80

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See detailInfluence of thermal expansion mismatch on residual stress profile in veneering ceramic layered on zirconia: Measurement by hole-drilling.
Mainjot, Amélie ULg; Najjar, Achref; Jakubowicz-Kohen, Boris D. et al

in Dental materials : official publication of the Academy of Dental Materials (2015)

OBJECTIVES: Mismatch in thermal expansion coefficient between core and veneering ceramic (Deltaalpha=alphacore-alphaveneer, ppm/ degrees C) is reported as a crucial parameter influencing veneer fractures ... [more ▼]

OBJECTIVES: Mismatch in thermal expansion coefficient between core and veneering ceramic (Deltaalpha=alphacore-alphaveneer, ppm/ degrees C) is reported as a crucial parameter influencing veneer fractures with Yttria-tetragonal-zirconia-polycrystal (Y-TZP) prostheses, which still constitutes a misunderstood problem. However, the common positive Deltaalpha concept remains empirical. The objective of this study is to investigate the Deltaalpha dependence of residual stress profiles in veneering ceramic layered on Y-TZP frameworks. METHODS: The stress profile was measured with the hole-drilling method in bilayered disc samples of 20mm diameter with a 0.7mm thick Y-TZP framework and a 1.5mm thick veneer layer. 3 commercial and 4 experimental veneering ceramics (n=3 per group) were used to obtain different Deltaalpha varying from -1.3ppm/ degrees C to +3.2ppm/ degrees C, which were determined by dilatometric analyses. RESULTS: Veneer fractures were observed in samples with Deltaalpha>/=+2.3 or </=-0.3ppm/ degrees C. Residual stress profiles measured in other groups showed compressive stresses in the surface, these stresses decreasing with depth and then becoming more compressive again near the interface. Small Deltaalpha variations were shown to induce significant changes in residual stress profiles. Compressive stress near the framework was found to decrease inversely to Deltaalpha. SIGNIFICANCE: Veneer CTE close to Y-TZP (+0.2ppm/ degrees C Deltaalpha) gived the most favorable stress profile. Yet, near the framework, Deltaalpha-induced residual stress varied inversely to predictions. This could be explained by the hypothesis of structural changes occurrence within the Y-TZP surface. Consequently, the optimum Deltaalpha value cannot be determined before understanding Y-TZP's particular behavior when veneered. [less ▲]

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See detailCeramic Materials for Dental Prostheses
MAINJOT, Amélie ULg

in Biomaterials (2014)

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See detailResidual stress profiles in veneering ceramic on Y-TZP, alumina and ZTA frameworks: Measurement by hole-drilling
Fukushima, K. A.; Sadoun, M. J.; Cesar, P. F. et al

in Dental materials (2014), 30(2), 105-111

OBJECTIVES: The residual stress profile developed within the veneering ceramic during the manufacturing process is an important predicting factor in chipping failures, which constitute a well-known ... [more ▼]

OBJECTIVES: The residual stress profile developed within the veneering ceramic during the manufacturing process is an important predicting factor in chipping failures, which constitute a well-known problem with yttria-tetragonal-zirconia polycrystal (Y-TZP) based restorations. The objectives of this study are to measure and to compare the residual stress profile in the veneering ceramic layered on three different polycrystalline ceramic framework materials: Y-TZP, alumina polycrystal (AL) and zirconia toughened alumina (ZTA). METHODS: The stress profile was measured with the hole-drilling method in bilayered disk samples of 19mm diameter with a 0.7mm thick Y-TZP, AL or ZTA framework and a 1.5mm thick layer of the corresponding veneering ceramic. RESULTS: The AL samples exhibited increasing compressive stresses with depth, while compressive stresses switching into interior tensile stresses were measured in Y-TZP samples. ZTA samples exhibited compressive stress at the ceramic surface, decreasing with depth up to 0.6mm from the surface, and then becoming compressive again near the framework. SIGNIFICANCE: Y-TZP samples exhibited a less favorable stress profile than those of AL and ZTA samples. Results support the hypothesis of the occurrence of structural changes within the Y-TZP surface in contact with the veneering ceramic to explain the presence of tensile stresses. Even if the presence of Y-TZP in the alumina matrix seems to negatively affect the residual stress profiles in ZTA samples in comparison with AL samples, the registered profiles remain positive in terms of veneer fracture resistance. [less ▲]

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See detailInfluence of firing time and framework thickness on veneered Y-TZP discs curvature.
Jakubowicz-Kohen, Boris D.; Sadoun, Michael J.; Douillard, Thierry et al

in Dental materials : official publication of the Academy of Dental Materials (2014), 30(2), 242-248

OBJECTIVES: The objective of the present work was to study the curvature of very thinly, veneered Y-TZP discs of different framework thicknesses submitted to different firing times. METHODS: Fifteen 20-mm ... [more ▼]

OBJECTIVES: The objective of the present work was to study the curvature of very thinly, veneered Y-TZP discs of different framework thicknesses submitted to different firing times. METHODS: Fifteen 20-mm-wide Y-TZP discs were produced in three different thicknesses: 0.75, 1, 1.5mm. One disc from each group was left unveneered while the others were layered with a 0.1mm veneering ceramic layer. All discs underwent five firing cycles for a total cumulative firing time of 30min, 1, 2, 5 and 10h at 900 degrees C. The curvature profile was measured using a profilometer after the veneering process and after each firing cycle respectively. A fitted curve was then used to estimate the, curvature radius. The coefficient of thermal expansion (CTE) measurements were taken on veneering, ceramic and Y-TZP beam samples that underwent the same firing schedule. Those data were used to calculate the curvature generated by CTE variations over firing time. RESULTS: All bilayered samples exhibited a curvature that increased over firing time inversely to framework thickness. However non-veneered samples did not exhibit any curvature modification. SIGNIFICANCE: The results of the present study reveal that even a very thin veneer layer (0.1mm) can induce a significant curvature of Y-TZP discs. The dilatometric results showed that Tg and CTE, variations are not sufficient to explain this curvature. A chemical-induced zirconia volume, augmentation located at the framework sub-surface near the interface could explain the sample, curvature and its increase with firing time. [less ▲]

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See detailY-TZP and in-mouth low thermal degradation: a pilot prospective clinical study.
KOENIG, Vinciane ULg; El Mokaddam, F; Wulfman, Claudine et al

Poster (2014)

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See detailThermal mismatch influence on residual stress in veneer on zirconia
MAINJOT, Amélie ULg; Najjar, Achref; Jakubowicz-Kohen, Boris et al

in Dental Materials (2014)

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See detailEchecs des prothèses dentaires et implantaires en zircone: le point sur les facteurs de risque
DUPONT, Nathalie ULg; KOENIG, Vinciane ULg; VAN HEUSDEN, Alain ULg et al

in Revue Médicale de Liège (2014), (hors-série 2014),

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See detailInfluence of firing time and framework thickness on layered Y-TZP discs curvature
Jakubowicz, Boris; MAINJOT, Amélie ULg; Sadoun, Michael

in Dental Materials (2013, December), 29(E25-E26),

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See detailResidual stress in veneering ceramic layered on Y-TZP, alumina, and ZTA polycrystalline ceramics
Fukushima, Karen; Sadoun, Michael; Cesar, Paulo et al

in Dental Materials (2013, December), 29(E10-E11),

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See detailA new in vitro protocol to study HGF/HGK attachment and proliferation on prostheses materials
GRENADE, Charlotte ULg; MAINJOT, Amélie ULg; VAN HEUSDEN, Alain ULg et al

in Dental Materials (2013, December), 29(E15-E16),

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