Biomedical subjects

Maria Francesca Sfondrini

Publications and source records attributed to Maria Francesca Sfondrini.

At least 19 recordsLinked to original sources

PubMed2006

Effect of chlorhexidine application on shear bond strength of brackets bonded with a resin-modified glass ionomer.

INTRODUCTION: The purpose of study was to assess the effect of chlorhexidine application on the shear bond strength and bond failure site of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium). METHODS: Forty-five bovine permanent mandibular incisors were randomly divided into 3 groups of 15. Group 1 had no chlorhexidine treatment and served as the control; groups 2 and 3 had chlorhexidine application immediately before and 1 week before bonding, respectively. Stainless steel brackets (DB, Leone, Sesto Fiorentino, Italy) were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and subsequently tested in a shear mode on a testing machine. Analysis of variance (ANOVA) and the Scheffé test were applied to determine significant differences in the shear bond strength values, and the chi-square test was used to determine significant differences in the adhesive remnant index scores among the groups. Significance for all statistical tests was predetermined at P < .05. RESULTS: Group 1 (no chlorhexidine application) showed significantly higher shear bond strength values than group 2 (chlorhexidine applied immediately before bonding). No significant differences were found between groups 1 and 3 (chlorhexidine applied 1 week before bonding). Moreover, significant differences in debond locations were found among the 3 groups. CONCLUSIONS: Chlorhexidine application immediately before bonding significantly lowered the bond strength values of Fuji Ortho LC but did not affect its bond strength when applied 1 week before bonding.

Acrylic Resins↗

PubMed2006

The effect of bleaching on shear bond strength of brackets bonded with a resin-modified glass ionomer.

INTRODUCTION: This study assessed the effect of a 35% hydrogen peroxide bleaching gel on the shear bond strength and bond failure site of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium). METHODS: Forty-five bovine mandibular permanent incisors were randomly divided into 3 groups; each group contained 15 teeth. Bleaching treatment was performed at 2 different times before the bonding procedure. Forty-five stainless steel brackets were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and then tested in shear mode on a testing machine. RESULTS: Group 1 (no bleaching) showed significantly higher shear bond strength values than groups 2 (bleaching immediately before bonding) and 3 (bleaching 1 week before bonding). No significant differences were found between groups 2 and 3. Moreover, no significant differences in debond locations were found among the 3 groups. CONCLUSIONS: Bleaching treatment before bonding significantly lowered the bond strength values of Fuji Ortho LC.

Acrylic Resins↗

PubMed2006

Effect of light-tip distance on the shear bond strengths of resin-modified glass ionomer cured with high-intensity halogen, light-emitting diode, and plasma arc lights.

INTRODUCTION: The purpose of this study was to assess the effect of light-tip distance on the shear bond strength and the failure site of brackets cured with 3 light-curing units (high-intensity halogen, light-emitting diode, and plasma arc). METHODS: One hundred thirty-five bovine mandibular permanent incisors were randomly allocated to 9 groups of 15 specimens each. Stainless steel brackets (Victory Series, Unitek/3M, Monrovia, Calif) were bonded with a resin-modified glass-ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium) to the teeth, and each curing light was tested at 3 distances from the bracket: 0, 3, and 6 mm. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. RESULTS: When the 3 light-curing units were compared at a light-tip distance of 0mm, they showed no significantly different shear bond strengths. At a light-tip distance of 3 mm, no significant differences were found between the halogen and plasma arc lights, but both lights showed significantly higher shear bond strengths than the light-emitting diode light. At a light-tip distance of 6 mm, no significant differences were found between the halogen and light-emitting diode lights, but both showed significantly lower bond strengths than the plasma arc light. When the effect of the light-tip distance on each light-curing unit was evaluated, the halogen and light-emitting diode lights showed no significant differences among the 3 distances. However, the plasma arc light produced significantly higher shear bond strengths at a greater light-tip distance. No significant differences were found among the adhesive remnant index scores of the various groups, except with the LED light at a distance of 3 mm. CONCLUSIONS: In hard-to-reach areas, the plasma arc curing light is suggested for optimal curing efficiency.

Acrylic Resins↗

PubMed2006

Effect of various adhesive systems on the shear bond strength of fiber-reinforced composite.

INTRODUCTION: The purpose of this study was to evaluate the effect of 3 adhesive systems on the shear bond strength of a fiber-reinforced composite (FRC). METHODS: Sixty bovine permanent mandibular incisors were randomly divided into 3 groups of 20. The FRCs (Ortho, Stick Teck Ltd, Turku, Finland) were bonded to the teeth with 3 adhesive systems (Tetric Flow [Ivoclar-Vivadent, Schaan, Liechtenstein], Transbond XT [Unitek/3M, Monrovia, Calif], and Fuji Ortho LC [GC Europe, Leuven, Belgium]). After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. Analysis of variance and the Sheffé post-hoc tests were used at a significance level of P < .05. RESULTS: ANOVA indicated significant differences among the various groups. Fibers bonded with Transbond XT showed significantly higher shear bond strengths than the other 2 groups. No significant differences in shear bond strength values were reported between Tetric Flow and Fuji Ortho LC. No significant differences in debond locations (ARI scores) were found among the various groups. CONCLUSIONS: For maximum bond strength, use Transbond XT for direct bonding of FRC.

Acrylic Resins↗

PubMed2005

Effect of fluoride application on shear bond strength of brackets bonded with a resin-modified glass-ionomer.

PURPOSE: The purpose of this study was to assess the effect of fluoride application at 3 different steps of the bonding process on the shear bond strength and bond failure site of a resin-modified glass ionomer cement. MATERIAL: Sixty stainless steel brackets were bonded to bovine incisors with Fuji Ortho LC (GC Europe, Leuven, Belgium) under 4 different enamel conditions: (1) uncontaminated enamel, (2) enamel precleaned with fluoride-containing prophylaxis paste, (3) 1.1% acidulated phosphate fluoride (APF) gel applied immediately before conditioning, and (4) 1.1% APF gel applied immediately before bonding. After bonding, all samples were stored in distilled water for 24 hours and subsequently tested in shear mode on a universal testing machine. RESULTS: No significant differences were found between groups 1 (uncontaminated enamel) and 2 (fluoride application during prophylaxis). Both groups showed significantly greater shear bond strength values than groups 3 (fluoride application before conditioning) and 4 (fluoride application before bonding). Groups 3 and 4 did not differ significantly. Moreover, no significant differences in debond locations were found among the 4 groups. CONCLUSIONS: Fluoride application during initial prophylaxis does not affect the bond strength values of Fuji Ortho LC, whereas it significantly lowers bond strength values when applied before both conditioning and bonding.

Acid Etching, Dental↗

PubMed2005

Effect of different light sources and guides on shear bond strength of brackets bonded with 2 adhesive systems.

INTRODUCTION: This study assessed the effect of different light sources and light guides on the shear bond strength and failure site of orthodontic brackets bonded with 2 adhesive systems (Quick Cure [Reliance Orthodontic Products, Itasca, Ill] and Transbond XT [3M/Unitek, Monrovia, Calif]). METHODS: Ninety bovine permanent mandibular incisors were randomly divided into 6 groups according to the adhesive system and light-curing procedure used. Each group consisted of 15 specimens; 90 stainless steel brackets were bonded to the teeth. Each adhesive system was light-cured with a halogen light (Ortholux XT, 3M/Unitek) for 20 seconds and the conventional light guide as controls. The remaining groups were cured with a halogen light (Ortho 2000 [Reliance Orthodontic Products, Itasca, Ill]) and a Power Slot light guide (Reliance Orthodontic Products) for 6 and 10 seconds. After bonding, all samples were stored in distilled water for 24 hours and then tested in a shear mode on a universal testing machine. RESULTS: No significant differences in terms of bond strength values were found among the 6 groups, but significant differences in debond locations were found among the 6 groups tested. CONCLUSIONS: Power Slot light guides can be recommended as advantageous alternatives for fast-curing composite resins during orthodontic bonding.

Animals↗

PubMed2005

Effect of light-tip distance on the shear bond strengths of composite resin.

The purpose of this study was to assess the effect of light-tip distance on the shear bond strength and failure site of brackets cured with three different light curing units: a high-intensity halogen (Astralis 10, 10-second curing), a light-emitting diode (LED, e-Light, six-second curing), and a plasma arc (PAC System, four-second curing). One hundred and thirty-five bovine permanent mandibular incisors were randomly allocated to nine groups of 15 specimens each. Stainless steel brackets were bonded with a composite resin to the teeth, and each curing light was tested at zero, three, and six mm from the bracket. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. When the three light curing units were compared at a light-tip distance of zero mm, the three lights showed no significantly different shear bond strengths. At light-tip distances of three and six mm, no significant differences were found between the halogen and plasma arc lights, but both lights showed significantly higher shear bond strengths than the LED light. When evaluating the effect of the light-tip distance on each light curing unit, the halogen light showed no significant differences between the three distances. However, the LED light produced significantly lower shear bond strengths at a greater light-tip distance, and the plasma arc lamp showed significantly higher shear bond strengths at a greater light-tip distance. In hard-to-reach areas, the use of PAC system is suggested, whereas the LED evaluated in this study is not recommended.

Acrylic Resins↗

PubMed2004

Plasma arc versus halogen light curing of orthodontic brackets: a 12-month clinical study of bond failures.

The purpose of this randomized clinical trial was to evaluate the clinical performance of brackets cured with 2 different light-curing units (conventional halogen light and plasma arc light); 83 patients treated with fixed appliances were included in the study. With the "split-mouth" design, each patient's mouth was divided into 4 quadrants. In 42 randomly selected patients, the maxillary left and mandibular right quadrants were cured with the halogen light, and the remaining quadrants were cured with the plasma arc light. In the other 41 patients, the quadrants were inverted. A total of 1434 stainless steel brackets were examined: 717 were cured with a conventional halogen light for 20 seconds; the remaining 717 were cured with the plasma arc light for 5 seconds. The number, cause, and date of bracket failures were recorded for each light-curing unit over 12 months. Statistical analysis was performed with the Fisher exact test, the Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences were found between the total bond failure rates of the brackets cured with the halogen light and those cured with the plasma arc light. Neither were significant differences found when the clinical performances of the maxillary versus mandibular arches or the anterior versus posterior segments were compared. These findings demonstrate that plasma arc lights are an advantageous alternative to conventional light curing, because they significantly reduce the curing time of orthodontic brackets without affecting the bond failure rate.

Acid Etching, Dental↗

PubMed2004

Plasma arc versus halogen light-curing of adhesive-precoated orthodontic brackets: a 12-month clinical study of bond failures.

The purpose of this randomized clinical trial was to evaluate the performance of adhesive-precoated brackets cured with 2 different light-curing units (conventional halogen light and plasma arc light). Thirty patients treated with fixed appliances were included in the investigation. Each patient's mouth was divided by the split-mouth design into 4 quadrants. In 15 randomly selected patients, the maxillary left and mandibular right quadrants were cured with the halogen light, and the remaining quadrants were cured with the plasma arc light. In the other 15 patients, the quadrants were inverted. A total of 600 adhesive precoated stainless steel brackets were examined: 300 were cured with a conventional halogen light for 20 seconds, and the others were cured with the plasma arc light for 5 seconds. The number, cause, and date of bracket failures were recorded for each light-curing unit over 12 months. Statistical analysis was performed with the Fisher exact test, Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences in bond failure rates were found between the adhesive-precoated brackets cured with the halogen light and those cured with the plasma arc light; neither were any significant differences in performance found with each light-curing unit between the maxillary and mandibular arches. Plasma arc lights can be considered an advantageous alternative to conventional light curing, because they enable the clinician to reduce the curing time of adhesive-precoated orthodontic brackets without significantly affecting their bond failure rate.

Adolescent↗

PubMed2004

Effects of blood contamination on the shear bond strengths of conventional and hydrophilic primers.

The purpose of this study was to assess the effect of blood contamination on the shear bond strength and failure site of 2 orthodontic primers (Transbond XT and Transbond MIP; 3M/Unitek, Monrovia, Calif) when used with adhesive-precoated brackets (APC II brackets; 3M/Unitek). One hundred twenty bovine permanent mandibular incisors were randomly divided into 8 groups; each group contained 15 specimens. Each primer-adhesive combination was tested under a different enamel surface condition: dry, blood contamination before priming, blood contamination after priming, or blood contamination before and after priming. Stainless steel APC II brackets were bonded to the teeth. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. Noncontaminated enamel surfaces had the highest bond strengths for both conventional and hydrophilic primers; their values were almost the same. Under blood-contaminated conditions, both primers showed significantly lower shear bond strengths. For each type of primer, no significant differences were reported among the blood-contaminated groups. Significant differences in debond locations were found among the groups bonded with the 2 primers under the various enamel surface conditions. Blood contamination of enamel during the bonding procedure of conventional and hydrophilic primers significantly lowers their bond strength values and might produce a bond strength that is not clinically adequate.

Adhesives↗

PubMed2004

Effect of blood contamination on shear bond strength of brackets bonded with conventional and self-etching primers.

This study assessed the effect of blood contamination on the shear bond strength and bond failure site of 2 different orthodontic primers (Transbond XT and Transbond Plus Self-Etching Primer, both from 3M Unitek, Monrovia, Calif) used with adhesive-precoated brackets. Four different enamel surface conditions were tested: (1) dry, (2) blood contamination before priming, (3) blood contamination after priming, and (4) blood contamination before and after priming. Noncontaminated enamel surfaces had the highest bond strengths for both conventional and self-etching primers, which produced almost the same strength values. Under blood-contaminated conditions, both primers showed significantly reduced shear bond strengths. For the conventional primer, no significant differences were reported among the blood-contaminated groups, whereas when the self-etching primer was used, condition 4 reduced significantly the bond strength values. Significant differences in debond locations were found among the groups bonded with the 2 primers under the various enamel surface conditions.

Acid Etching, Dental↗

PubMed2004

Effect of blood contamination on shear bond strength of brackets bonded with a self-etching primer combined with a resin-modified glass ionomer.

This study assessed the effect of blood contamination on the shear bond strength and bond failure site of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium) used with 3 enamel conditioners (10% polyacrylic acid, 37% phosphoric acid, and self-etching primer). One hundred twenty bovine permanent mandibular incisors were randomly divided into 8 groups; each group consisted of 15 specimens. Two enamel surface conditions were studied: dry and contaminated with blood. One hundred twenty stainless steel brackets were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and then tested in shear mode on a testing machine. The groups conditioned with self-etching primer and 37% phosphoric acid had the highest bond strengths for both dry and blood-contaminated enamel. The groups conditioned with 10% polyacrylic acid showed significantly lower shear bond strength value, and the unconditioned groups had the lowest bond strengths. For each enamel conditioner, no significant difference was reported between dry and blood-contaminated groups. Significant differences in debond locations were found among the groups bonded with the different conditioners. Blood contamination of enamel during the bonding procedure of Fuji Ortho LC did not affect its bond strength values, no matter which enamel conditioner was used.

Acid Etching, Dental↗

PubMed2004

A 12 month clinical study of bond failures of recycled versus new stainless steel orthodontic brackets.

The purpose of this prospective longitudinal randomized study was to compare the clinical performance of recycled brackets with that of new stainless steel brackets (Orthos). Twenty patients treated with fixed appliances were included in the investigation. Using a 'split-mouth' design, the dentition of each patient was divided into four quadrants. In 11 randomly selected patients, the maxillary left and mandibular right quadrants were bonded with recycled brackets, and the remaining quadrants with new stainless steel brackets. In the other nine patients the quadrants were inverted. Three hundred and ten stainless steel brackets were examined: 156 were recycled and the remaining 154 were new. All the brackets were bonded with a self-cured resin-modified glass ionomer (GC Fuji Ortho). The number, cause, and date of bracket failures were recorded over 12 months. Statistical analysis was performed by means of a paired t-test, Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences were found between: (a) the total bond failure rate of recycled and new stainless steel brackets; (b) the upper and lower arches; (c) the anterior and posterior segments. These findings demonstrate that recycling metallic orthodontic brackets can be of benefit to the profession, both economically and ecologically, as long as the orthodontist is aware of the various aspects of the recycling methods, and that patients are informed about the type of bracket that will be used for their treatment.

Acrylic Resins↗

PubMed2003

Effect of water and saliva contamination on shear bond strength of brackets bonded with conventional, hydrophilic, and self-etching primers.

This study assessed the effect of water and saliva contamination on the shear bond strength and bond failure site of 3 different orthodontic primers (Transbond XT, Transbond Moisture Insensitive Primer, and Transbond Plus Self Etching Primer; 3M Unitek, Monrovia, Calif) used with a light-cured composite resin (Transbond XT). Bovine permanent mandibular incisors (315) were randomly divided into 21 groups (15 in each group). Each primer-adhesive combination was tested under 7 different enamel surface conditions: (1) dry, (2) water application before priming, (3) water application after priming, (4) water application before and after priming, (5) saliva application before priming, (6) saliva application after priming, and (7) saliva application before and after priming. Stainless steel brackets were bonded in each test group with composite resin. After bonding, all samples were stored in distilled water at room temperature for 24 hours and then tested for shear bond strength. Noncontaminated enamel surfaces had the highest bond strengths for conventional, hydrophilic, and self-etching primers, which produced the same strength values. In most contaminated conditions, the self-etching primer had higher strength values than either the hydrophilic or conventional primers. The self-etching primer was the least influenced by water and saliva contamination, except when moistening occurred after the recommended 3-second air burst. No significant differences in debond locations were found among the groups bonded with the self-etching primer under the various enamel conditions.

Acid Etching, Dental↗

PubMed2003

Evaluation of friction of conventional and metal-insert ceramic brackets in various bracket-archwire combinations.

The purpose of the study was to measure and compare the level of frictional resistance generated between conventional ceramic brackets (Transcend Series 6000, 3M Unitek, Monrovia, Calif), ceramic brackets with stainless steel slot (Clarity, 3M Unitek), conventional stainless steel brackets (Victory Series, 3M Unitek), and 3 different orthodontic wire alloys: stainless steel (stainless steel, SDS Ormco, Glendora, Calif), nickel-titanium (Ni-Ti, SDS Ormco), and beta-titanium (TMA, SDS Ormco). All brackets had a 0.022-in slot, and orthodontic wire alloys were tested in 3 different sections: 0.016 in, 0.017 x 0.025 in, and 0.019 x 0.025 in. Each of the 27 bracket-archwire combinations was tested 10 times, and each test was performed with a new bracket-wire sample. Static and kinetic friction were measured on a specially designed apparatus. All data were statistically analyzed (analysis of variance and Scheffé for the bracket effect, Kruskal-Wallis and Mann Whitney for the alloy and section effects). Metal-insert ceramic brackets generated significantly lower frictional forces than did conventional ceramic brackets, but higher values than stainless steel brackets, in agreement with the findings of the few previous reports. Beta-titanium archwires had higher frictional resistances than did stainless steel and nickel-titanium archwires. No significant differences were found between stainless steel and nickel-titanium archwires. All the brackets showed higher static and kinetic frictional forces as the wire size increased. Metal-insert ceramic brackets are not only visually pleasing, but also a valuable alternative to conventional stainless steel brackets in patients with esthetic demands.

Analysis of Variance↗

PubMed2003

Evaluation of friction of stainless steel and esthetic self-ligating brackets in various bracket-archwire combinations.

This study measured and compared the level of frictional resistance generated between stainless steel self-ligating brackets (Damon SL II, SDS Ormco, Glendora, Calif), polycarbonate self-ligating brackets (Oyster, Gestenco International, Göthenburg, Sweden), and conventional stainless steel brackets (Victory Series, 3M Unitek, Monrovia, Calif), and 3 different orthodontic wire alloys: stainless steel (Stainless Steel, SDS Ormco), nickel-titanium (Ni-Ti, SDS Ormco), and beta-titanium (TMA, SDS Ormco). All brackets had a.022-in slot, whereas the orthodontic wire alloys were tested in 3 different sections:.016,.017 x.025, and.019 x 0.025 in. Each of the 27 bracket and archwire combinations was tested 10 times, and each test was performed with a new bracket-wire sample. Both static and kinetic friction were measured on a custom-designed apparatus. All data were statistically analyzed (Kruskal-Wallis and Mann Whitney U tests). Stainless steel self-ligating brackets generated significantly lower static and kinetic frictional forces than both conventional stainless steel and polycarbonate self-ligating brackets, which showed no significant differences between them. Beta-titanium archwires had higher frictional resistances than stainless steel and nickel-titanium archwires. No significant differences were found between stainless steel and nickel-titanium archwires. All brackets showed higher static and kinetic frictional forces as the wire size increased.

Dental Alloys↗

PubMed2003

Use of a self-etching primer in combination with a resin-modified glass ionomer: effect of water and saliva contamination on shear bond strength.

The purpose of this study was to evaluate the effects of 3 different enamel conditioners (10% polyacrylic acid, 37% phosphoric acid, and self-etching primer) on the shear bond strength and site of bond failure of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium) bonded onto dry, water-moistened, and saliva-moistened enamel. One hundred eighty bovine permanent mandibular incisors were randomly divided into 12 groups; each group consisted of 15 specimens. Three different enamel surface conditions were studied: dry, soaked with water, soaked with saliva. One hundred eighty stainless steel brackets were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and then tested in a shear mode on a testing machine. After self-etching primer application, Fuji Ortho LC produced the highest shear bond strengths under all the different enamel surface conditions; these values were significantly higher than those achieved in the remaining groups, except when Fuji Ortho LC was used in combination with 37% phosphoric acid on dry enamel. Fuji Ortho LC bonded without enamel conditioning produced the lowest shear bond strengths. The bond strength of the groups conditioned with 10% polyacrylic acid was significantly lower than that of the groups etched with 37% phosphoric acid, except when both conditioners were used on enamel soaked with water.

Acid Etching, Dental↗

PubMed2003

Effect of pulse vs continuous micro-xenon irradiation on the shear bond strength of a light-cured orthodontic composite resin.

The aim of the study was to evaluate the effect of pulse vs. continuous irradiation on the shear bond strength of a conventional orthodontic composite resin cured with a micro-xenon light (Aurys, Degrè K, Schiltigheim, France). Ninety freshly extracted bovine permanent mandibular incisors were randomly assigned to one of six groups; each group consisting of 15 specimens. Three groups were exposed to continuous irradiation of micro-xenon light for 10, 5, and 2 s, respectively, and used as controls. The remaining three groups were exposed to pulse irradiation of the same light source for 10, 5, and 2 s, respectively. After 24 h, all samples were tested in a shear mode on an Instron Machine (Instron Corp., Canton, MA, USA). Analysis was made by ANOVA with Scheffé's test for comparisons. The chi-square test was used to determine significant differences in the Adhesive Remnant Index scores. The mean shear bond strength of the brackets continuously cured for 10 s was not statistically different from that of the brackets pulse-activated for the same curing time. Also, no statistically significant differences were found between both groups cured for 5 s. The group pulse-activated for 5 s, however, had a significantly lower mean shear bond strength than the control group cured for 10 s. Finally, the group pulse-activated for 2 s showed significantly lower bond strength values than all the other groups tested. Compared with continuous light curing, the micro-xenon pulse activation provides similar shear bond strength values, except when used for only 2 s; but despite lower performance characteristics, the shear bond strength may be clinically acceptable.

Analysis of Variance↗