Nacer Hassani - Academia.edu (original) (raw)

Papers by Nacer Hassani

Quintessence international (Berlin, Germany : 1985), 2008

To quantitatively test the hypothesis that a new paint-on bleaching gel has the potential to ligh... more To quantitatively test the hypothesis that a new paint-on bleaching gel has the potential to lighten tooth color in clinical situations and to evaluate the change of the tooth color six months after the bleaching procedure. Ten adult subjects requesting tooth bleaching were selected to participate in this randomized clinical trial involving a new in-office bleaching technique using VivaStyle Paint On Plus (Ivoclar Vivadent), originally designed as an over-the-counter bleaching gel. Digital images and CIE Lab spectrophotometric measurements were taken at baseline (I), after the bleaching treatment (PB), and 6 months after bleaching (6M). Differences in Lab values were tested with a repeated measures analysis of variance (ANOVA). Differences in Delta E values were tested with a factorial ANOVA. Significant (P < .05) differences were detected in L, as well as in a and b values, between initial (I) and post-bleaching (PB) and between initial (I) and 6 months post-op (6M). In contrast...

Objectifs: le but de cette etude in-vitro etait de comparer l'efficacite de produits de blanc... more Objectifs: le but de cette etude in-vitro etait de comparer l'efficacite de produits de blanchiment a domicile utilises selon le protocole individualise usuel (home bleaching) ou de nouvelles formes d'applications. Materiel et methodes: des echantillons de dents bovines de dimensions standardisees (2.5±0.025 mm) ont ete colores avec du sang avant blanchiment par du peroxyde de carbamide a 10% et 30% (gouttiere) ou du peroxyde d'hydrogene a 6% (gouttiere et vernis). 8.1% (strips) et 9% (gouttiere). Des mesures colorimetriques L*a*b* ont ete realisees avant et apres coloration, puis apres 5, 10 et le nombre recommande d'applications. Resultats: Suivant le nombre d'applications recommande, la difference de couleur ([lambda]Er) a varie entre 15.72 et 29.67 au niveau amelaire et entre 14.91 et 41.43 au niveau dentinaire; les produits appliques en gouttiere se sont montres les plus efficaces, independamment de la nature du produit (CP ou HP) ou de sa concentration.

Collegium antropologicum, 2010

The purpose of this article is to illustrate a new classification of resin based aesthetic materi... more The purpose of this article is to illustrate a new classification of resin based aesthetic materials laying on the characterization of their matrix and their filler morphology. Four samples per material have been prepared for SEM evaluation. Each sample has been treated with chloroform to dissolve its matrix in order to evidence the filler morphology. A general schema of four different matrix systems which characterize the material's level of hydrophobicity can be put in evidence. The subsequent filler analysis individuates a more complex schema based on filler size and construction. A new classification based on matrix nature and filler morphology has been proposed. Based on this concept mechanical and aesthetic characteristics of the materials can be presumed.

Quintessence international (Berlin, Germany : 1985), 2007

This article describes a technique used to treat superficial white spot lesions by a minimally in... more This article describes a technique used to treat superficial white spot lesions by a minimally invasive approach. The proposed technique is based on reactivation of enamel by elimination of its hypermineralized external layer through microabrasion, followed by daily home application of casein phosphopeptide-amorphous calcium phosphate complexes (CCP-ACP). The technique may allow elimination of white spot lesions without involving restorative procedures. Microabrasion followed by long-term daily home application of CCP-ACP may be considered an interesting alternative to the restorative approach for treatment of white spot lesions.

The Journal of Prosthetic Dentistry, 2007

The use of hydrogen peroxide to bleach teeth was first reported in 1884. 1 In 1918, Abbot describ... more The use of hydrogen peroxide to bleach teeth was first reported in 1884. 1 In 1918, Abbot described the chairside bleaching method, as it is known today, using 35% hydrogen peroxide together with heat and light to boost the oxidation reaction. Initially, vital bleaching techniques were aimed at correcting severe discolorations, mainly endemic fluorosis. 2-5 The technique remained confidential until its use for tetracycline-stained teeth was fostered by the increased use of these drugs. 6 Later , bleaching also became a cosmetic procedure, which significantly expanded its use. 7 Bleaching became even more popular after it was proposed for athome application. 8 Since then, millions of patients have satisfactorily bleached their teeth using the home bleaching technique, an inexpensive yet simple procedure compared to traditional chairside methods. 8

Dental Materials Journal, 2014

In this study, we evaluated in vitro the staining susceptibility of an infiltration resin (Icon, ... more In this study, we evaluated in vitro the staining susceptibility of an infiltration resin (Icon, DMG, Hamburg, Germany) and compared it with several marketed bonding systems. Fifty 1-mm-thick disk-shaped specimens were prepared for Icon and for each bonding material. Initial specimen color was assessed by a spectrophotometer. Specimens in each group were then randomly divided into five subgroups and stored in an incubator at 37˚C in the dark for 60 days. Groups 4 and 5 were used as negative controls by being stored dry and in tap water respectively. Test groups were stored in (1) coffee, (2) tea, or (3) red wine. After 60 days of storage, new spectrophotometric measurements were performed and dE (color difference) was calculated to determine color change. Icon showed higher staining susceptibility. The clinician should be aware of the staining potential of infiltration resins over time.

Dental Materials, 2010

Pilot in vivo image spectrophotometric evaluation of optical properties of pure enamel and enamel... more Pilot in vivo image spectrophotometric evaluation of optical properties of pure enamel and enamel-dentin complex Dent Mater. 7 (2010), pp. e205-210.

Comptes Rendus De L Academie Des Sciences Serie 1 Mathematique, 1988

In this Note, we consider a general class of dynamical semi-systems which have a first integral. ... more In this Note, we consider a general class of dynamical semi-systems which have a first integral. In this setting, we can show that the asymptotic behaviour of solutions depends only on the first integral On considere une classe assez generale de semi-systemes dynamiques monotones ayant une integrale premiere monotone. Dans ce cadre, on montre que le comportement asymptotique des solutions ne depend que de l'integrale premiere

Quintessence international (Berlin, Germany : 1985), 2008

To quantitatively test the hypothesis that a new paint-on bleaching gel has the potential to ligh... more To quantitatively test the hypothesis that a new paint-on bleaching gel has the potential to lighten tooth color in clinical situations and to evaluate the change of the tooth color six months after the bleaching procedure. Ten adult subjects requesting tooth bleaching were selected to participate in this randomized clinical trial involving a new in-office bleaching technique using VivaStyle Paint On Plus (Ivoclar Vivadent), originally designed as an over-the-counter bleaching gel. Digital images and CIE Lab spectrophotometric measurements were taken at baseline (I), after the bleaching treatment (PB), and 6 months after bleaching (6M). Differences in Lab values were tested with a repeated measures analysis of variance (ANOVA). Differences in Delta E values were tested with a factorial ANOVA. Significant (P < .05) differences were detected in L, as well as in a and b values, between initial (I) and post-bleaching (PB) and between initial (I) and 6 months post-op (6M). In contrast...

Objectifs: le but de cette etude in-vitro etait de comparer l'efficacite de produits de blanc... more Objectifs: le but de cette etude in-vitro etait de comparer l'efficacite de produits de blanchiment a domicile utilises selon le protocole individualise usuel (home bleaching) ou de nouvelles formes d'applications. Materiel et methodes: des echantillons de dents bovines de dimensions standardisees (2.5±0.025 mm) ont ete colores avec du sang avant blanchiment par du peroxyde de carbamide a 10% et 30% (gouttiere) ou du peroxyde d'hydrogene a 6% (gouttiere et vernis). 8.1% (strips) et 9% (gouttiere). Des mesures colorimetriques L*a*b* ont ete realisees avant et apres coloration, puis apres 5, 10 et le nombre recommande d'applications. Resultats: Suivant le nombre d'applications recommande, la difference de couleur ([lambda]Er) a varie entre 15.72 et 29.67 au niveau amelaire et entre 14.91 et 41.43 au niveau dentinaire; les produits appliques en gouttiere se sont montres les plus efficaces, independamment de la nature du produit (CP ou HP) ou de sa concentration.

Collegium antropologicum, 2010

The purpose of this article is to illustrate a new classification of resin based aesthetic materi... more The purpose of this article is to illustrate a new classification of resin based aesthetic materials laying on the characterization of their matrix and their filler morphology. Four samples per material have been prepared for SEM evaluation. Each sample has been treated with chloroform to dissolve its matrix in order to evidence the filler morphology. A general schema of four different matrix systems which characterize the material's level of hydrophobicity can be put in evidence. The subsequent filler analysis individuates a more complex schema based on filler size and construction. A new classification based on matrix nature and filler morphology has been proposed. Based on this concept mechanical and aesthetic characteristics of the materials can be presumed.

Quintessence international (Berlin, Germany : 1985), 2007

This article describes a technique used to treat superficial white spot lesions by a minimally in... more This article describes a technique used to treat superficial white spot lesions by a minimally invasive approach. The proposed technique is based on reactivation of enamel by elimination of its hypermineralized external layer through microabrasion, followed by daily home application of casein phosphopeptide-amorphous calcium phosphate complexes (CCP-ACP). The technique may allow elimination of white spot lesions without involving restorative procedures. Microabrasion followed by long-term daily home application of CCP-ACP may be considered an interesting alternative to the restorative approach for treatment of white spot lesions.

The Journal of Prosthetic Dentistry, 2007

The use of hydrogen peroxide to bleach teeth was first reported in 1884. 1 In 1918, Abbot describ... more The use of hydrogen peroxide to bleach teeth was first reported in 1884. 1 In 1918, Abbot described the chairside bleaching method, as it is known today, using 35% hydrogen peroxide together with heat and light to boost the oxidation reaction. Initially, vital bleaching techniques were aimed at correcting severe discolorations, mainly endemic fluorosis. 2-5 The technique remained confidential until its use for tetracycline-stained teeth was fostered by the increased use of these drugs. 6 Later , bleaching also became a cosmetic procedure, which significantly expanded its use. 7 Bleaching became even more popular after it was proposed for athome application. 8 Since then, millions of patients have satisfactorily bleached their teeth using the home bleaching technique, an inexpensive yet simple procedure compared to traditional chairside methods. 8

Dental Materials Journal, 2014

In this study, we evaluated in vitro the staining susceptibility of an infiltration resin (Icon, ... more In this study, we evaluated in vitro the staining susceptibility of an infiltration resin (Icon, DMG, Hamburg, Germany) and compared it with several marketed bonding systems. Fifty 1-mm-thick disk-shaped specimens were prepared for Icon and for each bonding material. Initial specimen color was assessed by a spectrophotometer. Specimens in each group were then randomly divided into five subgroups and stored in an incubator at 37˚C in the dark for 60 days. Groups 4 and 5 were used as negative controls by being stored dry and in tap water respectively. Test groups were stored in (1) coffee, (2) tea, or (3) red wine. After 60 days of storage, new spectrophotometric measurements were performed and dE (color difference) was calculated to determine color change. Icon showed higher staining susceptibility. The clinician should be aware of the staining potential of infiltration resins over time.

Dental Materials, 2010

Pilot in vivo image spectrophotometric evaluation of optical properties of pure enamel and enamel... more Pilot in vivo image spectrophotometric evaluation of optical properties of pure enamel and enamel-dentin complex Dent Mater. 7 (2010), pp. e205-210.

Comptes Rendus De L Academie Des Sciences Serie 1 Mathematique, 1988

In this Note, we consider a general class of dynamical semi-systems which have a first integral. ... more In this Note, we consider a general class of dynamical semi-systems which have a first integral. In this setting, we can show that the asymptotic behaviour of solutions depends only on the first integral On considere une classe assez generale de semi-systemes dynamiques monotones ayant une integrale premiere monotone. Dans ce cadre, on montre que le comportement asymptotique des solutions ne depend que de l'integrale premiere