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Biomedical subjects

Jean-François Roulet

Publications and source records attributed to Jean-François Roulet.

15 recordsLinked to original sources
PubMed2006

Caries-preventive potential of an adhesive patch after thermomechanical loading--a microbial-based in vitro study.

PURPOSE: To assess the enamel-protective potential of a newly devised adhesive patch for smooth enamel sealing. MATERIALS AND METHODS: Approximal surfaces of 30 extracted molars were divided into three areas: the buccal thirds were treated with a flowable composite (Tetric Flow, Ivoclar Vivadent) and served as negative control sites, the lingual thirds were left untreated and served as positive control sites, and the middle thirds served as the test areas. This was sealed with either 1. a twofold application of an unfilled resin (Heliobond, Ivoclar Vivadent), 2. an adhesive prototype patch (Ivoclar Vivadent), or 3. an adhesive patch in combination with a flowable composite. After thermomechanical loading and demineralization in a microbial-based artificial caries chamber, demineralization depth was assessed using a confocal laser scanning microscope. RESULTS: Negative control sites treated with the flowable composite showed no signs of demineralization. Areas treated with the patch showed no signs of demineralization, irrespective of whether it was used in combination with a flowable composite or directly bonded to the enamel. Caries-like lesions in untreated sites showed a mean depth of 134.3 +/- 35.9 microm. Demineralization depth at sites treated with the unfilled resin was 76.2 +/- 26.5 microm (p = 0.023). CONCLUSIONS: Under the conditions of the present study, the adhesive patch under investigation completely protected the underlying enamel from demineralization. This merits further study to assess its potential as an interproximal sealant.

Adhesives↗
PubMed2005

Sealing smooth enamel surfaces with a newly devised adhesive patch: a radiochemical in vitro analysis.

OBJECTIVES: To assess the enamel-protective potential of a newly devised adhesive patch when used as a smooth surface sealant. METHODS: Eighty enamel discs were prepared from bovine lower central incisors and then irradiated. Twenty specimens were treated with one of three sealing options: enamel bond in a two-step application, the prototype of an adhesive patch, or a flowable resin. Unsealed enamel served as positive controls. Loss of apatite was determined using a radiochemical liquid scintillation method after immersion of the samples in saliva or lactic acid (n=10 per treatment group) each for up to 21 days, during which this experimental and control enamel surfaces were exposed to ten toothbrush strokes per day. Quantitative liquid scintillation data were verified by polarized light microscopy. RESULTS: With lactic acid exposure, a double layer of enamel bonding showed better enamel protection than untreated controls, but was significantly less effective than the adhesive patch or filled composite (P<0.05). No significant differences were noted between the latter two treatments. SIGNIFICANCE: It was concluded that the adhesive patch under investigation merits further studies to assess its potential as an inter-proximal sealant.

Acrylates↗
PubMed2005

Color stability of resin-based filling materials after aging when cured with plasma or halogen light.

The influence of curing devices and curing times on the color stability of filling resins was investigated by measuring the CIE-Laboratory-values after performing dry storage, water storage, and a Suntest (EN ISO 7491). Eight samples each of Charisma (CH), Durafill (DU), Definite (DE), and Dyract AP (DY) were light cured by using Translux Energy (TE) for 20, 40 or 60 s, or by using Apollo 95E (AP) for 3, 10 or 20 s. Minor color changes occurred for all dry stored materials, devices and curing times. The TE-cured, water-stored samples behaved similarly to the dry-stored ones, but the samples cured with AP revealed very strong color changes, mainly because of a drastic bleaching process. The bleaching of DU was significantly less than that of the other materials, but a strong white shift occurred. CH, DE, and DU showed very little (and even acceptable) discolorations after the Suntest when TE-cured. DY showed a drastically discoloration. All samples cured using AP drastically bleached and shifted to white for DU and DY but to dark for DE. In conclusion, the extent of discoloration depends on (i) the material, (ii) the test method, (iii) curing time, and (iv) the curing device. The halogen light-cured samples performed best.

Color↗
PubMed2004

Secondary caries-like lesions at fissure sealings with Xeno III and Delton--an in vitro study.

OBJECTIVES: The aim of the study was to establish a bacterial based in vitro caries model to test the caries preventive effect of fissure sealants and to investigate whether a self-etching adhesive (Xeno III) used as fissure sealant is equally effective in preventing secondary caries compared to a conventional sealant (Delton) when applied on saliva contaminated and non-contaminated fissures. METHODS: Forty caries-free upper premolars were randomly divided into two groups. Group A was sealed with a conventional resin-based fissure sealant (Delton) after phosphoric acid etching. Group B was sealed with a self-etching adhesive (Xeno III) without prior etching. To simulate the clinical situation of saliva contamination, the distal part of each tooth was slightly moistened with saliva before sealant application. After thermo-cycling, the specimens were exposed to a cariogenic Streptococcus mutans biofilm in an artificial mouth model. Depths of demineralization were measured on serial sections by confocal laser scanning microscopy. If a demineralization was detected underneath the whole fissure sealing the sample was rated as 'total failure'. RESULTS: Significantly higher numbers of total failures could be found in the Xeno III group compared to the Delton group in areas without saliva contamination. On contaminated areas, no significant difference could be found. There was no significant difference regarding the depth of the primary carious lesions between groups. CONCLUSION: The study supports our recent findings that our caries model is capable to produce secondary caries-like lesions at fissure sealings. Based on the present in vitro data, it cannot be recommended to use the self-etching adhesive Xeno III solely as a fissure sealant.

Acid Etching, Dental↗
PubMed2004

Color stability of resin matrix restorative materials as a function of the method of light activation.

The purpose was to investigate the influence of curing devices and curing times on the yellow value (b-value) of composites, ormocers and compomers after performing a suntest (EN ISO 7491). Eight samples of Charisma (CH), Durafill (DU), Definite (DE), and Dyract AP (DY) each were light cured with Translux Energy (tungsten halogen light) for 20, 40 or 60 s and with Apollo 95-E (plasma light) for 3, 10 or 20 s. All samples were subjected to a suntest. Before and after the suntest the yellow values (b-values) were determined and the change (Delta b) was calculated. When cured with Translux Energy for 20 and 40 s DU, CH, and DY revealed significantly negative Delta b-values. The b-value of DE remained nearly constant. When cured for 60 s, DU and DE shifted to more yellow while CH and DY still bleached a little. When cured with Apollo 95-E, a dramatic bleaching process of all materials investigated occurred after the suntest (significant negative Delta b). It may be concluded that the bleaching of composites, ormocers and compomers depends on (i) the used light curing device and (ii) the chosen curing times. The tungsten halogen light provided highly significantly superior results.

Ceramics↗
PubMed2004

Clinically controlled study on the quality of class III, IV and V composite restorations after two years.

PURPOSE: The quality of fillings consisting of a hybrid composite was compared with fillings consisting of two different microfilled composites in a clinical examination. MATERIAL AND METHODS: Within the design of a clinically controlled two-year study conducted under practice-relevant conditions, the composites C-Fill MH (Megadenta), Helio Progress (Vivadent), and Visio-Dispers (ESPE) were examined in anterior-tooth cavities in 134 patients by means of the split-mouth technique. The clinical examinations were performed based on modified Ryge criteria (marginal integrity, anatomical form, secondary caries, color, marginal discoloration, surface roughness) after 12 and 24 months. RESULTS: Immediately following filling application, all evaluation criteria except color were assessed as level A. After 12 and 24 months, C-Fill MH was found to be significantly superior to the other materials with regard to marginal integrity, color, and marginal discoloration. CONCLUSION: The hybrid composite C-Fill MH seems to be superior to the microfilled composites and should therefore be preferred as a restorative filling material.

Adult↗
PubMed2002

In situ antimicrobial effectiveness of chlorhexidine and calcium hydroxide: gel and paste versus gutta-percha points.

The aim of this study was to determine the antibacterial effectiveness of either chlorhexidine or calcium hydroxide integrated in gutta-percha points compared with chlorhexidine or calcium hydroxide delivered as gel or paste, respectively. A total of 70 initially sterile roots with open accesses were carried for 1 week in the oral cavities of two volunteers. The roots were then removed, and samples were taken from the root canals for microbial analysis. The roots were medicated with calcium hydroxide paste, 5% chlorhexidine gel, or a chlorhexidine- or calcium hydroxide-containing gutta-percha point. The accesses were closed with bonding material, and the roots incubated for 1 week. After removal of the antimicrobial agents, roots were again checked for bacterial growth. One thioglycolate-soaked paper point was then introduced into each canal, and roots were incubated for 1 week more to observe bacterial regrowth. After 1 week of medication, the absolute bacterial count revealed significant differences compared with the controls. However, only the chlorhexidine-gel and the calcium hydroxide paste group showed no microbial colonization in a considerable number of samples after 1 and 2 weeks.

Anti-Infective Agents, Local↗
PubMed2002

Mechanical properties and bond strength of glass-ionomer cements.

PURPOSE: The objective of this study was to evaluate the mechanical properties and bond strength of glass-ionomer cements (GICs) and resin-modified GICs (RM-GICs) that are indicated as restorative materials for the Atraumatic Restorative Treatment (ART) technique. MATERIALS AND METHODS: Fifteen disk specimens for the diametral tensile strength (DTS) test and fifteen cylindrical specimens for the compressive strength (CS) test were made of each GIC: Ketac-Fil, Ketac-Molar (ESPE), Fuji IX and Fuji PLUS (GC). Forty human molars were sectioned and embedded in resin with either buccal or lingual surfaces exposed for the tensile bond strength (TBS) test. The surface was ground until a flattened area of enamel or dentin was obtained. After conditioning, inverted truncated cones of GICs were prepared on the flat tooth surfaces. The powder:liquid ratio of Fuji PLUS was adjusted for restorative purposes. Prior to testing, specimens were stored for 24 h (TBS test) and for 1 h, 24 h, and 7 days (CS and DTS tests) in deionized water at 37 degrees C. They were then loaded at a crosshead speed of 1.0 mm/min for CS and 0.5 mm/min for DTS and TBS tests until failure occurred. The data were submitted to two-way ANOVA at 0.05 level of significance, followed by a Tukey-Kramer test for multiple comparisons. RESULTS: The mean CS values ranged from 90.27 to 170.73 MPa and DTS means from 6.21 to 22.32, with test periods from 1 h to 7 days. The means for TBS ranged from 4.90 to 11.36 MPa and from 2.52 to 5.55 MPa in enamel and dentin, respectively. No differences were found between materials with the CS test except at 1 hour. The resin-modified GIC (RM-GIC) had the highest DTS, with no changes between the test periods, and the highest TBS for both enamel and dentin. CONCLUSION: Among the GICs tested, RM-GIC showed higher values of DTS and TBS.

Analysis of Variance↗
PubMed2002

Enamel fluoride retention after application of fluoride-containing rubber cups.

PURPOSE: To compare the fluoride retention in bovine enamel after using fluoride-containing rubber cups or a conventional rubber cup in combination with a fluoride-containing polishing paste. MATERIALS AND METHODS: From each of 20 bovine incisors, 5 enamel slabs with a diameter of 3 mm were sectioned and assigned to 5 groups (A,B,C,D,E). Group A was left untreated and served as the negative control. Group B was polished with a rubber cup combined with a fluoride-containing prophylaxis paste for 10 s (Hawe Cleanic). Groups C and D were treated in the same manner by using a fluoride-containing rubber cup with 2,262 ppm or 9,048 ppm fluoride as NaF. Group E enamel was brushed for 10 s with a toothbrush and a slurry of distilled water and fluoride gel with 12,500 ppm fluoride as NaF and AmF (Elmex Gelee) and served as the positive control. Th e specimens were analyzed using the method of Caslavska et al. After determining the KOH soluble fluoride on the enamel surface, the content of structurally bound fluoride was analyzed in three consecutive layers of 30 microm. ANOVA with Bonferroni correction was used for statistical analysis (P< 0.05). RESULTS: For the KOH-soluble fluoride, Groups B and D accumulated more KOH-soluble fluoride than the negative control and less than the positive control. With respect to the structurally bound fluoride, the accumulation in Group D was higher when compared to all other groups. It was concluded that a rubber cup with 9,048 ppm fluoride may be an effective alternative to the use of a fluoride-containing prophylaxis paste.

Amines↗
PubMed2002

Resin/Resin bonding: a new adhesive technology.

PURPOSE: Evaluation of a new surface treatment method to obtain a good bond strength between a luting composite and (1) a light-cured, (2) a heat-cured and (3) a thermoplastic resin. MATERIALS AND METHODS: Specimens were prepared and tests conducted according to ISO 10477, Amend. 1. The surfaces of Targis (light cured), SR Isosit (heat cured), and Dental D (thermoplastic) were ground under water cooling with 400-grit grinding paper, polished with 800-grit paper and air dried. Each resin material was divided into 3 groups of 10 specimens each. Group 1 was flame treated with a PyrosilPen for 5 s/2 cm2, group 2 for 10 s/2 cm2, and group 3 for 20 s/2 cm2. Subsequently, a methacryl silane was applied, followed by a luting composite. Prior to measuring shear bond strength, the specimens were thermocycled 5000 times in a water bath between 5 degrees C and 55 degrees C. SEM, FTIR investigations, and fracture analysis were also done. Etched and silanized Empress II - the gold standard - was used as a control. RESULTS: The following shear bond strengths were found: treatment time 5 s/2 cm2, Targis 25 (+/- 12) MPa, SR Isosit 17 (+/- 11) MPa; treatment time 10 s/2 cm2, Targis 23 (+/- 12) MPa, SR Isosit 26 (+/- 8) MPa; treatment time 20 s/2 cm2, Targis 29 (+/- 5) MPa, SR Isosit 26 (+/- 9) MPa. All Dental D specimens failed completely so that shear bond strength could not be measured. The control achieved 27 (+/- 6) MPa. No significant differences were found between the materials or the flaming times. On all flamed surfaces, Si was detected by FTIR. SEM showed that no heat destruction occurred at a flaming time of 5 s/2 cm2, a slight change at 10 s/2 cm2, and a significant change at 20 s/2 cm2. CONCLUSION: This new bonding technology is an effective method for surface-treating polymerized composite resin materials to obtain good bonding to luting composites. The method fails on thermoplastic resins.

Acrylic Resins↗
PubMedDate not supplied

Intracoronal bleaching of discolored non-vital teeth.

This clinical study compared the effectiveness of bleaching non-vital teeth with an open pulp chamber during bleaching using 10% carbamide peroxide compared to the modified walking bleach technique and extracoronal bleaching. Sixty discolored, non-vital teeth were treated. They were divided into three groups. Each group was treated with one of the bleaching materials and methods: extracoronally using 10% carbamide peroxide for two weeks as negative control (Group A), intracoronally using sodium perborate mixed with 3% hydrogen peroxide (modified walking bleach technique) (Rotstein, Mor & Friedman, 1993) for four weeks (Group B) and intracoronally and extracoronally using 10% carbamide peroxide for two weeks (Group C) (Liebenberg, 1997). Tooth color was measured at baseline, (BL), immediately post-bleaching (IP) and six months post-bleaching (SP) with a colorimeter (Castor, Sigma, Germany) using a tooth-positioning jig. The color was determined according to the CIELAB system, which records lightness as L* and chromaticity coordinates as a* and b*. The difference in L* and b* among the three groups was significant between BL and IP examination. The post-bleaching, whitening effect in Group C was significantly better, but after six months, in Group C, it was as effective as in Group B.

Adult↗
PubMedDate not supplied

Tensile bond strength of composite to air-abraded dentin.

This study evaluated the influence of air abrasive treatment of dentin surfaces on the tensile bond strength between dentin and two different composite-adhesive-systems Multi-Purpose/Z100 and OptiBond FL/Herculite XR). The crowns of 200 maxillary central incisors were embedded in resin and then ground to expose a dentin surface 5 mm in diameter. The surfaces were etched or abraded by using a KCP 1000 device with different treatment conditions. Adhesive systems were applied according to the manufacturer's instructions and composite cylinders were bonded to the conditioned dentinal surface using a split mold. Tensile bond strength values and failure modes were then determined. Tensile bond strength values of the acid-etched dentin-composite-interface were significantly higher than for the interface between air-abraded dentin and composite, independent of the composite-adhesive-system used. The light microscopic evaluation showed mainly adhesive and combined adhesive-cohesive fractures. Significantly more adhesive fractures could be observed between abraded dentin and composite than between etched dentin and composite.

Acid Etching, Dental↗