Adhesive thickness effects on the bond strength of a light-cured resin-modified glass ionomer cement.
ABSTRACT These in vitro studies investigated the effect of adhesive thickness on the tensile and shear bond strength of a light-cured, resin-modified glass-ionomer cement (FO). A light-cured conventional composite resin (CO) was used as the control material. Mesh-based metal brackets were bonded to extracted human premolars using FO and CO. The adhesive thickness was controlled by a special device and 0, 0.25, and 0.5 mm thicknesses were tested for both bonding agents. All bonded specimens were stored in distilled water at 37 degrees C for 48 hours and thermocycled between 5 degrees C and 55 degrees C for 200 cycles before testing. Analysis of variance showed that bond strength was significantly affected by the adhesive thickness (P < .001) and type of adhesive (P = .001). There were statistically significant differences between the mean bond strengths of the groups at the P < .05 level of significance. For all adhesive thicknesses, CO had higher bond strength values than those of FO in both test modes. The bond strength values were also analyzed using a Weibull analysis, which showed the most favorable adhesive thickness, and the 5% and 90% probabilities of failures was 0.25 mm in the FO groups. Bracket-adhesive interface failure was predominant for all groups in tensile testing, but enamel-adhesive interface failures increased with increased adhesive thickness in shear testing for the FO. This study suggests that adhesive thickness under a bracket could be particularly important when using a FO in direct bonding.
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- "A small amount of Transbond XT resin (3M Unitek, Monrovia, CA, USA) was placed on the bracket's mesh, and the brackets were then immediately placed in the centres of the vestibular surfaces. Previous studies (Arici et al., 2005; Muguruma et al., 2010) have shown that the resin thickness affect the bond strength; thus, a force of 453.59 g was applied to the centre of each bracket aided by a Gillmore needle to standardize the resin thickness. "
ABSTRACT: Objective: To determine the influence on shear bond strength and bond failure location of four cleaning methods for orthodontic bracket custom bases. Design: In vitro laboratory study. Material and methods: Eighty bovine teeth were divided at random into four groups. The bracket custom bases were cleaned with different methods: group 1 with methyl methacrylate monomer, group 2 with acetone, group 3 with 50 μm aluminium oxide particles and group 4 with detergent. The brackets were indirectly bonded onto the teeth with the Sondhi Rapid-Set self-curing adhesive. The maximum required shear bond strength to debond the brackets was recorded. The bond failure location was evaluated using the Adhesive Remnant Index (ARI). One-way analysis of variance (ANOVA) analysis (P<0·05) was used to detect significant differences in the bond strength. Kaplan-Meier survival plots and log-rank test were done to compare the survival distribution between the groups. The Kruskal-Wallis test (P<0·05) was used to evaluate the differences in the ARI scores. Results: The mean bond strengths in groups 1, 2, 3 and 4 were 23·7±5·0, 25·3±5·1, 25·6±3·7 and 25·7±4·2 MPa, respectively. There were no significant statistically differences in either the bond strength or the ARI score between the groups. Conclusion: The four custom base-cleaning methods presented the same efficiencies on indirect bond of the brackets; thus, practitioners can choose the method that works best for them.Journal of Orthodontics 02/2014; 41(3). DOI:10.1179/1465313313Y.0000000090
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ABSTRACT: The aim of this research is to use finite element analysis (FEA) to quantify the effect of the sample shape and the imperfections induced during the manufacturing process of samples on the bond strength and modes of failure of dental adhesive systems through microtensile test. Using the FEA prediction for individual parameters effect, estimation of expected variation and spread of the microtensile bond strength results for different sample geometries is made. The estimated stress distributions for three different sample shapes, hourglass, stick and dumbbell predicted by FEA are used to predict the strength for different fracture modes. Parameters such as the adhesive thickness, uneven interface of the adhesive and composite and dentin, misalignment of axis of loading, the existence of flaws such as induced cracks during shaping the samples or bubbles created during application of the adhesive are considered. Microtensile experiments are performed simultaneously to measure bond strength and modes of failure. These are compared with the FEA results. The relative bonding strength and its standard deviation for the specimens with different geometries measured through the microtensile tests confirm the findings of the FEA. The hourglass shape samples show lower tensile bond strength and standard deviation compared to the stick and dumbbell shape samples. ANOVA analysis confirms no significant difference between dumbbell and stick geometry results, and major differences of these two geometries compared to hourglass shape measured values. Induced flaws in the adhesive and misalignment of the angle of application of load have significant effect on the microtensile bond strength. Using adhesive with higher modulus the differences between the bond strength of the three sample geometries increase. The result of the research clarifies the importance of the sample geometry chosen in measuring the bond strength. It quantifies the effect of the imperfections on the bond strength for each of the sample geometries through a systematic and all embracing study. The results explain the reasons of the large spread of the microtensile test results reported by various researchers working in different labs and the need for standardization of the test method and sample shape used in evaluation of the dentin-adhesive bonding system.Dental Materials 05/2008; 24(4):536-47. DOI:10.1016/j.dental.2007.06.022 · 4.16 Impact Factor
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ABSTRACT: The aim of the study was to evaluate whether resonance frequency analysis (RFA) using a wireless transducer can be used to assess the primary stability of orthodontic mini-implants. Fifteen orthodontic mini-implants were placed in three ilium bone segments of country pigs. The wireless resonance frequency transducer was bonded to the head of the mini-implants, and RFA values of the mini-implants in bone were detected and converted into implant stability quotient (ISQ) values by the RFA monitor. In addition, the percussion test value, peri-implant radiographic bone density, and cortical bone thickness were measured. The ISQ values of mini-implants correlated linearly with peri-implant radiographic bone density (r = 0.92, P < .0001), cortical bone thickness (r = 0.90, P < .0001), and percussion test values (r = -0.91, P < .0001), respectively. In addition, by means of the calculation of 99% confidence intervals, the absolute values of the three correlation coefficients ranged from 0.61 to 0.98. This in vitro animal study showed that the presented RFA method using a wireless transducer might have potential to provide an alternative noninvasive assessment of the primary stability of an orthodontic mini-implant.The International journal of oral & maxillofacial implants 01/2009; 24(4):647-54. · 1.49 Impact Factor