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Biomedical subjects

Michel Degrange

Publications and source records attributed to Michel Degrange.

9 recordsLinked to original sources
PubMed2004

Self-etching adhesives improve the shear bond strength of a resin-modified glass-ionomer cement to dentin.

PURPOSE: Despite the improvements of resin-modified glass-ionomer cements, the dentin bond strength of these materials remains inferior to that provided by "bonding system/composite" combinations and limits the clinical use of RMGIC. The objective of this in vitro study was to investigate the effect of new self-etching bonding systems on the adhesion to dentin of Fuji II LC. MATERIALS AND METHODS: Seven recent self-etching systems were studied (Clearfil SE Bond = CSE, Optibond Solo Plus Self-Etching Primer = OSP, One Up Bond F = OUP, Mac Bond II = MB2, Xeno III = XB3, ADPER Prompt-L-Pop = ADP, Unifil Bond = UB) and compared with Cavity Conditioner (C). After the bonding procedure, a resin-modified glass-ionomer cylinder (Fuji II LC) was bonded to the surface using a Teflon mold (diameter: 3 mm; height: 5 mm). The different specimens were tested in a shear bond mode (0.5 mm/min). Statistical analyses were performed with one-way ANOVA and Fischer PLSD test (p < 0.05). RESULTS: The one-way ANOVA revealed a significant influence of the surface treatment parameter (p < 0.0001). The lowest shear bond strength values were obtained with Cavity Conditioner. The highest values were obtained with MB2. The multiple comparisons revealed that ADP = OBP = XB3 = OUB = UB = CSE and that UB = CSE = MB2. CONCLUSION: The application of the 7 self-etching adhesives tested in this study improves the dentin shear bond strengths of Fuji II LC. This increase depended on the adhesive system and ranged from 50% for ADP up to 130% for MB2.

Acrylic Resins↗
PubMed2003

Regional odontodysplasia: expression of matrix metalloproteinases and their natural inhibitors.

Regional odontodysplasia is a localized disorder of tissues of dental origin that results in a ghost-like appearance of the affected teeth. We present a case with a study of gingival tissue around the follicle. The results show evidence of the role of the matrix metalloproteinases and their natural inhibitors by resident cells in this pathosis. An imbalance in the amounts of matrix metalloproteinases and their natural inhibitors is associated with the pathologic breakdown of the collagen.

Blotting, Western↗
PubMed2003

Influence of the number of sections on reliability of in vitro microleakage evaluations.

PURPOSE: To test how the number of sections affects the maximum depth of tracer penetration. MATERIALS AND METHODS: This study was simultaneously performed in three different centers. C-shaped Class V cavities were made on 60 human third molars. The cavities were located across the cementum-enamel junction. One restorative system was used: Scotchbond Multi-Purpose and Z100. After restoration, the samples were thermally cycled 3000 times, between 5 and 55 degrees C with a dwell time immersion of 10 seconds. Silver nitrate was used by two centers and basic fuchsin was used by the third. The teeth were longitudinally sectioned with a diamond saw: 5 sections per tooth provided 10 surfaces for evaluation. The penetration of the tracer was recorded on a scale from 0 to 3. The deepest leakage per restoration was identified for comparison with lesser measured values elsewhere in the tooth. The Spearman test was applied to evaluate the relationship between the reference and data from one, two and three sections (i.e. two, four and six measurements). The Kruskal-Wallis test was applied to compare the three centers. RESULTS: Whatever the study center, the Spearman correlation coefficient (r(s)) increased as a function of the number of sections (S) up to three: Center 1 (1S, 0.47; 2S, 0.68; 3S, 1.0), Center 2 (1S, 0.60; 2S, 0.99; 3S, 0.99), Center 3 (S1, 0.40; 2S, 0.73; 3S, 1.0). No statistically significant difference was found between the three study centers.

Composite Resins↗
PubMed2003

Immediate replacement of a maxillary central incisor associated with severe facial bone loss: use of Bio-Oss collagen--case report.

The loss and replacement of anterior maxillary teeth pose several challenges. Treatment must successfully address immediate tooth replacement, esthetics, patient comfort, and psychologic acceptance. The purpose of this case report is to present a prosthetic and surgical technique for immediate tooth replacement following extraction in an area of severe localized bone loss. Combined full- and partial-thickness flaps associated with the use of Bio-Oss collagen grafting material and a Bio-Gide membrane were used for alveolar ridge reconstruction. To improve the final esthetic result, a connective tissue graft was used to increase ridge volume and papillary height.

Adult↗
PubMed2003

In vitro evaluation of different techniques of enamel preparation for pit and fissure sealing.

PURPOSE: To compare the penetration and the imperviousness of two pit and fissure sealants according to surface treatments involving different cleaning procedures with or without subsequent acid etching. MATERIALS AND METHODS: Two sealants were used: a resin-based sealant (Concise White Sealant) and a compomer-based material (Dyract Seal) coupled with an enamel-dentin bonding agent (Dyract Seal and Prime&Bond NT). Extracted molars (n = 120) were randomly divided into 12 groups: 4 control and 8 experimental groups that received different surface treatments. Pumice, alumina, or bicarbonate was used to clean the surfaces. Phosphoric acid or non-rinse conditioner was used as acid etching agents. After sealing, the Concise White Sealant groups were directly thermocycled for 1800 cycles, while the Dyract Seal groups were stored in water for one month before thermocycling. After apex sealing and varnish coating, the fillings were stained with silver nitrate and embedded. Three to 6 cross sections of 200 microm each were made per sample to assess both sealant penetration (% of the length of the fissure) and the imperviousness of the seal (scores method). RESULTS: Concise White Sealant achieves a better enamel sealing than Dyract Seal when the teeth are treated with air abrasion or air polishing followed by etching. Acid etching is essential for good sealing, whatever the material and cleaning technique tested. Only the combination of air abrasion and phosphoric acid etching yielded a leak-free joint. CONCLUSION: This study clearly shows that penetration and sealing are two different phenomena. Ideally, an efficient sealant must have a good sealing ability and a high rate of infiltration as well, but these two properties probably do not have the same clinical relevance. The imperviousness of the seal remains the most important requirement.

Acid Etching, Dental↗
PubMed2002

[The various families of composite adhesives: presentation and experimentation].

Today, manufacturers provide the orthodontist with a range of adhesive systems which is so wide that is often difficult for the orthodontist to make his choice between them. The adhesive systems fall into four categories: traditional hydrophobic bonding systems, hydrophilic bonding systems, self-etching bonding systems, resin-modified glass ionomer-cements. This article will attempt to examine the first three categories which correspond to those of the composite bonding systems. Following a presentation of bonding assembling and of the required specification of the bonding systems used in orthodontic practice, the three composite bonding systems will be examined along with their advantages/disadvantages before a closing description of the corresponding clinical protocol to be followed. Whenever one of our laboratory experiments enables us to provide experimental evidence, a presentation is made within the related chapters.

Acid Etching, Dental↗
PubMed2002

Bonding to dentin achieved by general practitioners.

The objectives of this study were (1) to investigate the effect of operator variability on the shear bond strength of adhesives to dentin and (2) to determine the effectiveness of education on bonding performance for different types of adhesives. Thirty general practitioners were recruited for a CE course by a regional mailing. They used bovine dentin as a substrate for bonding the adhesive system they routinely used in practice and two other materials (no previous experience). Each adhesive OptiBond FL, ScotchBond Multipurpose Plus, ScotchBond 1 and Clearfil SE was applied according to manufacturer's instructions and immediately tested using a shear bond strength test. Shear bond strengths between adhesives and dentin were compared before and after a 90 min lecture on bonding principles and materials. For dentists with and without previous experience with a material, there were no statistically significant differences seen before and after the lecture (paired t-tests, p < or = 0.05). However, in every case, the bond strengths after the lecture were higher than those before (range of improvement from 15 to 150%). For dentists with routine experience with a particular material, all materials were statistically equivalent after the lecture, although the OptiBond FL was the highest. For dentists who had no previous experience with a material, the ScotchBond 1 had lower bond strengths than the other materials after the lecture. There was a large range in the ability of dentists to manipulate adhesive systems correctly. However, if a dentist has sufficient experience and receives sufficient education, any of these materials can give reasonable results.

Analysis of Variance↗
PubMedDate not supplied

In vitro push-out strength of seven luting agents to dentin.

PURPOSE: New luting agents, described as resin-modified glass-ionomer cements and compomers, have been developed during the last decade to improve the retention of cemented restorations. The aims of this study were to (1) compare the push-out strength of these new luting materials against both conventional cements and bonding luting agents, and (2) evaluate the influence of dentin surface treatment on both glass-ionomer cement and 4-META adhesive resin push-out strength. MATERIALS AND METHODS: Conical standardized cavities were drilled in the center of coronal dentin disks. Ninety sandblasted Ni-Cr inlays, divided into nine batches, were luted into the cavities according to the surface treatment and the nature of the following luting agents: zinc phosphate cement, zinc polycarboxylate cement, type 1 glass-ionomer +/- polyacrylic acid, resin-modified glass-ionomer, polyacid-modified composite resin, filled bis-GMA phosphate ester resin, and 4-META adhesive resin +/- application of activated monomer. Each specimen was placed in a holding device, and a steel rod was used to apply a force on the inlay until rupture occurred. The push-out strength was calculated, and the failure mode was controlled. RESULTS: There were significant differences between some of the groups. The highest push-out strength was achieved by the 4-META adhesive resin after application of activated monomer. The lowest value was attained with zinc phosphate and polycarboxylate cements. CONCLUSION: Both resin-modified glass-ionomer and polyacid-modified composite resin luting materials exhibited a push-out strength similar to resin-based materials. Specific dentin surface treatments significantly enhanced the push-out strengths of glass-ionomer cement and 4-META adhesive resin.

Acid Etching, Dental↗