1,721,111 research outputs found
EFFECTS OF MAGNETIC RESONANCE ON TEMPERATURE AND ADHESION EFFICACY OF ORTHODONTIC DEVICES
Full text linkMagnetic resonance (MRI) is a widely used diagnostic technique. Often, patients wearing orthodontic appliances are requested to remove appliance even when the MRI exam involves anatomic areas far from mouth, in order to avoid metal heating and appliance detachment. The purpose of the present investigation was to measure and compare temperature changes and adhesion to enamel of orthodontic appliances after different MRIs. 220 orthodontic bracket were bonded on bovine incisors and wires with different materials (stainless steel and nickel titanium) and sizes (0.014’’ and 0.019’’x0.025’’) were engaged. Appliances were submitted to MRI at two different powers (1.5T and 3T). Temperatures of brackets and wires were measured before and after MRI. Subsequently, shear bond strength (SBS) and adhesive remnant index (ARI) scores were recorded. Statistical analysis was performed. After MRI a significant increase of temperatures was found both for brackets and wires in some groups, even if the mean temperature increase was clinically not significant, as it ranged between 0.05°C and 2.4°C for brackets and between 0.42°C and 1.74°C for wires. MRI did not conditioned bracket adhesion in any group. No differences were reported when comparing 1.5T with 3T groups. ARI Scores were significantly lower after MRI. The results of the present report show that under MRI orthodontic appliances present low temperature rise and no debonding risk. Therefore, the removal of orthodontic appliance would not be recommended routinely, but could be suggested only in case of void risk or interference in image quality.Magnetic resonance (MRI) is a widely used diagnostic technique. Often, patients wearing orthodontic appliances are requested to remove appliance even when the MRI exam involves anatomic areas far from mouth, in order to avoid metal heating and appliance detachment. The purpose of the present investigation was to measure and compare temperature changes and adhesion to enamel of orthodontic appliances after different MRIs. 220 orthodontic bracket were bonded on bovine incisors and wires with different materials (stainless steel and nickel titanium) and sizes (0.014’’ and 0.019’’x0.025’’) were engaged. Appliances were submitted to MRI at two different powers (1.5T and 3T). Temperatures of brackets and wires were measured before and after MRI. Subsequently, shear bond strength (SBS) and adhesive remnant index (ARI) scores were recorded. Statistical analysis was performed. After MRI a significant increase of temperatures was found both for brackets and wires in some groups, even if the mean temperature increase was clinically not significant, as it ranged between 0.05°C and 2.4°C for brackets and between 0.42°C and 1.74°C for wires. MRI did not conditioned bracket adhesion in any group. No differences were reported when comparing 1.5T with 3T groups. ARI Scores were significantly lower after MRI. The results of the present report show that under MRI orthodontic appliances present low temperature rise and no debonding risk. Therefore, the removal of orthodontic appliance would not be recommended routinely, but could be suggested only in case of void risk or interference in image quality
Plasma arc versus halogen light-curing of adhesive-precoated orthodontic brackets: a 12-month clinical study of bond failures.
No full textThe 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
Effect of various adhesive systems on the shear bond strength of fiber-reinforced composite.
Full text linkINTRODUCTION: 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 theteeth 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
Shear bond strength of fibre-reinforced composite nets using two different adhesive systems
No full textThe purpose of this study was to evaluate the effect of two different adhesive systems (Tetric Flow and Transbond XT) in combination with fibre-reinforced composites (FRC) net (Ever Stick) on the shear bond strength (SBS) of orthodontic brackets. Eighty bovine permanent mandibular incisors were randomly divided into four equal groups. Stainless steel maxillary central incisor brackets with a 0.018 inch slot (DB Leone) were bonded to the teeth using the two different adhesive systems. Fifty per cent of the brackets were bonded without and 50 per cent with a FRC net under the bracket base. After bonding, all samples were
stored in distilled water at room temperature for 24 hours and subsequently tested for SBS. Analysis of variance indicated significant differences among the various groups. Brackets bonded with FRC nets under the base showed a significantly lower SBS than those bonded without nets (P < 0.05). Moreover,
teeth bonded with Transbond XT showed a significantly higher SBS than the other groups. Additionally, significant differences in debond locations [adhesive remnant index (ARI) score] were found among the various groups. Transbond XT can successfully be used for direct bonding of FRC nets, thus improving their SBS
values
Shear bond strength of self-ligating brackets
No full textThe aim of this study was to compare the shear bond strength (SBS) and adhesive remnant index (ARI) scores of conventional and self-ligating brackets.
Conventional stainless steel brackets (group 1, Step®; Leone) and three different passive and interactive self-ligating brackets (group 2, Smart Clip®, 3M Unitek; group 3, Quick®, Forestadent; and group 4, Damon 3MX®, Ormco) were tested. Four groups of 20 specimens each were bonded with an adhesive system (Ortho Solo® primer, Ormco and Transbond XT resin, 3M Unitek) onto bovine enamel and subsequently tested using an Instron universal testing machine. SBS values and adhesive failure rate were recorded. Statistical analysis was performed with analysis of variance and Scheffé tests to determine bond strength values, whereas a chi-square test was used for ARI scores. Groups 2 and 4 showed significantly higher SBS values than the other two groups. Moreover, groups 1 and 3 showed a higher frequency of ARI score 1, whereas groups 2 and 4 showed higher frequency of ARI score 2. All the brackets demonstrated a clinically adequate SBS
Effect of blood contamination on shear bond strength of orthodontic brackets and disinclusion buttons
No full textOur aim was to assess the effect of blood contamination on the shear bonding strength and sites of failure of orthodontic brackets and bondable buttons. We randomly divided 160 bovine permanent mandibular incisors into 8 groups of 20 specimens each. Both orthodontic brackets (Step brackets, Leone, Sesto
Fiorentino, Italy) and bondable buttons (Flat orthodontic buttons, Leone, Sesto Fiorentino, Italy) were tested on four different enamel surfaces: dry; contamination with blood before priming; after priming; and before and after priming. Brackets and buttons were bonded to the teeth and subsequently tested using a Instron universal testing machine. Shear bonding strength and the rate of
adhesive failures were recorded. Data were analysed using the analysis of variance (ANOVA), Scheffè tests, and the chi-square test. Uncontaminated enamel surfaces showed the highest bonding strengths for both brackets and buttons. When they were contaminated with blood, orthodontic brackets had significantly lower shear strengths than bondable buttons (P=0.0001). There were significant differences in sites of failure among the groups for the various enamel surfaces (P=0.001). Contamination of enamel by blood during bonding lowers the strength of the bond, more so with orthodontic brackets than with bondable buttons
Effetto della contaminazione con acqua sulla forza di distacco al taglio di attacchi ortodontici autoleganti
No full textConfronto clinico tra splintaggio in metallo e splintaggio in fibre di polietilene attraverso l’analisi dei distacchi
No full textCommentary on “Craniofacial Syndromes and class III phenotype: common genotype fingerprints? A scoping review and meta-analysis”
No full textIl ricondizionamento dei brackets self-ligating: uno studio sulle forze di distacco al taglio
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