Effect of fluoride exposure on cariostatic potential of orthodontic bonding agents: an in vitro evaluation.
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AIMS: The aims of this in vitro study were to compare the cariostatic potential of a resin modified glass ionomer cement (Fuji Ortho LC) to that of a resin control (Transbond) for bracket bonding and to compare the effect of extrinsic fluoride application on the cariostatic potential of each material. SETTING: Ex vivo study. MATERIALS AND METHODS: Orthodontic brackets were bonded to 40 extracted premolars, 20 with Fuji Ortho LC and 20 with Transbond. The teeth were subjected to pH cycling, pH 4.55, and pH 6.8, over a 30-day period. Ten teeth bonded with each material were immersed in a 1000 ppm fluoride solution for 2 minutes each day. Fluoride release was measured throughout the study from all teeth. After 30 days, the teeth were assessed visually for signs of enamel decalcification. RESULTS: Significant differences in decalcification existed macroscopically between all four groups of teeth, with the exception of those bonded with Fuji Ortho LC alone compared with Transbond alone (P = 0.22), and Fuji Ortho LC alone compared with Transbond with added fluoride (P = 0.3). Fluoride release from Fuji Ortho LC alone fell to minimal values, but with the addition of extrinsic fluoride the levels fell initially and then followed an upward trend. There was minimal fluoride release, from Transbond alone, but with daily addition of extrinsic fluoride, subsequent fluoride release was increased. Significant differences existed in the amount of fluoride released between all groups, except comparing Fuji Ortho LC alone and Transbond with added fluoride. CONCLUSIONS: The results of this study have indicated that with an in vitro tooth-bracket model, the creation of white spot inhibition could best be achieved by the use of a resin-modified glass ionomer cement, supplemented with fluoride exposure. The least protection was afforded by the composite control. The resin-modified glass ionomer cement alone and the composite with added fluoride demonstrated equivalent protection. (+info)
A clinical comparison of two chemically-cured adhesives used for indirect bonding.
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OBJECTIVE: To compare and evaluate the clinical failure rates of the chemically-cured composite bonding resins Sondhi Rapid Set (SD) and Maximum Cure (MC) when used in an indirect bonding technique. SETTING: In vivo study in the private orthodontic practice of a solo practitioner. MATERIALS AND METHODS: Forty consecutive patients meeting the inclusion criteria were assigned to alternating groups in a split-mouth study design. Group 1 had the maxillary right and mandibular left quadrants indirectly bonded using SD adhesive, while the contralateral quadrants were bonded using MC adhesive. Group 2 had the opposite sides bonded to Group 1. One patient was lost from each group. Over a 6-month observation period, all loose brackets were recorded and the data compared with a Wilcoxon sign-rank test. RESULTS: Of the 363 brackets placed in each group, 36 with the SD adhesive came loose (9.9 per cent failure rate) compared with five from the MC group (1.4 per cent failure rate, P = 0.0001). In the maxillary arch, seven brackets from the SD quadrants came loose versus one for the MC (P = 0.109). In the mandibular arch 29 brackets from the SD quadrants came loose during the 6-month observation period compared with four from the MC quadrants (P = 0.001). CONCLUSIONS: Both chemically-cured adhesives (SD and MC) examined in this study were suitable for the indirect bonding of brackets. The SD adhesive had seven times the number of breakages than the MC adhesive in both arches (P = 0.0001). (+info)
Resin-modified glass ionomer, modified composite or conventional glass ionomer for band cementation?--an in vitro evaluation.
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The aims of this study were to compare the mean shear-peel bond strength and predominant site of bond failure of micro-etched orthodontic bands cemented with resin-modified glass ionomer cement (RMGIC; Fuji Ortho LC or 3M Multi-Cure), a modified composite or a conventional GIC. The survival time of bands was also assessed following simulated mechanical stress in a ball mill. One hundred and twenty molar bands were cemented to extracted human third molars. Eighty bands (20 cemented with each cement) were used to assess the debonding force and 40 bands (10 cemented with each cement) were used to determine survival time. The specimens were prepared in accordance with the manufacturers' instructions for each cement. After storage in a humidor at 37 degrees C for 24 hours, the shear debonding force was assessed for each specimen using a Nene M3000 testing machine with a crosshead speed of 1 mm/minute. The predominant site of band failure was recorded visually for all specimens as either at the band/cement or cement/enamel interface. Survival time was assessed following application of mechanical stress in a ball mill. There was no significant difference in mean shear-peel bond strength between the cement groups (P = 0.816). The proportion of specimens failing at each interface differed significantly between cement groups (P < 0.001). The predominant site of bond failure for bands cemented with the RMGIC (Fuji Ortho LC) or the modified composite was at the enamel/cement interface, whereas bands cemented with 3M Multi-Cure failed predominantly at the cement/band interface. Conventional GIC specimens failed mostly at the enamel/cement interface. The mean survival time of bands cemented with either of the RMGICs or with the modified composite was significantly longer than for those cemented with the conventional GIC. The findings indicate that although there appears to be equivalence in the mean shear-peel bond strength of the band cements assessed, the fatigue properties of the conventional GIC when subjected to simulated mechanical stress seem inferior to those of the other cements for band cementation. (+info)
Decontamination of tried-in orthodontic molar bands.
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Molar bands are commonly used to retain orthodontic attachments on posterior teeth and due to the variation in the size of such teeth, it is usually necessary to 'try in' several bands before the correct one is selected. A possible concern with re-using such bands is the lack of cross-infection control, even following autoclaving, due to the presence of one or more small bore lumen (the archwire and headgear tubes). The aim of this experiment was, therefore, to determine whether such bands could be successfully decontaminated so that they could be re-used without a cross-infection risk. Two hundred orthodontic molar bands that had previously been tried in patients' mouths, but not cemented into place, were tested. Each band was decontaminated using an enzymatic cleaner/disinfectant and then sterilized using either a downward displacement (n = 100) or a vacuum cycle autoclave (n = 100). Following autoclaving each band was inoculated into brain heart infusion culture broth and incubated at 37 degrees C for 5 days. None of the decontaminated bands exhibited growth after 5 days. It would appear that, using this methodology, there is little risk of a cross-infection hazard occurring with the re-use of previously tried-in and decontaminated molar bands. (+info)
A comparative study of the static and kinetic frictional resistance of titanium molybdenum alloy archwires in stainless steel brackets.
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This ex vivo study compared the static and kinetic frictional resistance of eight different archwires tested in a single, stainless steel, zero base 0.022 x 0.028 inch (0.56 x 0.711 mm) slot standard edgewise bracket. The archwires evaluated were 0.019 x 0.025 inch (0.483 x 0.636 mm) in dimension, manufactured from the following alloys: beta titanium (TMA), 'low friction' coloured beta titanium (aqua, honeydew, purple and violet), ion-implanted beta titanium, Timolium and a stainless steel control. Prior to friction testing, bracket and archwire dimensions were measured by direct digital imaging via a desktop computer linked to a binocular light microscope. Frictional force was evaluated using an Instron universal testing machine. All experiments were carried out at room temperature, with no ligation, in the dry state with 20 degrees of added torque. The results demonstrated that static and kinetic friction were statistically significant (P < 0.001) for all archwire types. Ion-implanted and standard TMA archwires were found to have no significant advantage over stainless steel. The archwire alloys may be ranked as follows: stainless steel produced the lowest frictional resistance followed by honeydew, ion-implanted TMA and Timolium, with aqua, purple and violet producing frictional resistance values as high as standard TMA. It was also found that the percentage difference between the archwire and bracket slot dimensions claimed by the manufacturers and those measured in this experiment produced tolerances ranging from +5.37 to -6.67 per cent. (+info)
The aim of this paper is to familiarize the readers with some of the clinical considerations necessary to ensure successful use of mid-palatal implants. Both surgical and technical aspects will be discussed along with a description of impression techniques used. (+info)
An ex vivo assessment of gingivally offset lower premolar brackets.
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OBJECTIVES: To compare the force to failure of standard premolar brackets to that of gingivally offset brackets and evaluate the site of bond failure between the two bracket types through the use of the Adhesive Remnant Index (ARI). DESIGN: An ex vivo study. SETTING: Dental Materials Science Laboratory, Dundee Dental School, Dundee. MATERIALS AND METHODS: Forty extracted lower premolar teeth (caries free, extracted as part of orthodontic treatment, all donors living in a non-fluoridated area), divided into two equal size sample groups, as follows: Group 1: Victory Series (3M Unitek, Monrovia CA, USA) lower premolar brackets bonded to buccal surfaces with Transbond XT (3M Unitek, Monrovia CA). Group 2: Victory Series Gingivally Offset Bicuspid Brackets (3M Unitek, Monrovia CA) bonded to buccal surfaces with Transbond XT (3M Unitek, Monrovia CA). Force was applied in the occluso-gingival direction using an Instron Model 4469 Universal Testing Machine (Instron Ltd, High Wycombe, UK) operating at a cross-head speed of 0.5 mm/min and its value at failure determined. Following debond, the site of bond failure and ARI were recorded. OUTCOME: Force to failure, site of bond failure and adhesive remnant index. RESULTS: The Weibull analysis gave higher values for the force to failure at 5% level (200 v. 159 N) and at all other levels of probability of failure for the gingivally offset bracket. The non-parametric survival analysis using Gehan-Wilcoxon tests with Breslow's algorithm (p < 0.0001) showed significant difference in force to failure between bracket types. Chi-square tests showed no significant (p = 0.55) relationship between the site of bond failure and the bracket types. CONCLUSION: Ex vivo testing suggests that there is a significant difference in the force to failure between gingivally offset and standard lower premolar brackets when force application is from an occluso-gingival direction. The site of failure (as given by the ARI) is insensitive to bracket types and force to failure. (+info)
Fluoridated elastomers: effect on disclosed plaque.
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OBJECTIVE: To investigate the effect of fluoridated elastomers on the quantity of disclosed dental plaque surrounding an orthodontic bracket in vivo. DESIGN: A randomized, prospective, longitudinal clinical trial, employing a split mouth, crossover design. SETTING: The Orthodontic Departments of Liverpool and Sheffield Dental Hospitals. SUBJECTS AND METHODS: The subjects were 30 individuals about to start fixed orthodontic treatment. The study consisted of two experimental periods of 6 weeks with a washout period between. Fluoridated elastomers were randomly assigned at the first visit to be placed around brackets on 12, 11, 33 or 22, 21, 43. Non-fluoridated elastomers were placed on the contra-lateral teeth. After 6 weeks (visit 2) the elastomers were removed, the teeth disclosed and a photograph taken. Non-fluoridated elastomers were placed on all brackets for one visit to allow for a washout period. At visit 3, fluoridated elastomers were placed on the contra-lateral teeth to visit 1. At visit 4, the procedures at visit 2 were repeated. The photographs were scanned, then the area and proportion of the buccal surface covered with disclosed plaque was measured using computerized image analysis. A mixed-effects ANOVA was carried out with the dependent variable being the area or percentage area of disclosed plaque. RESULTS: There was no evidence of a systematic error and substantial agreement for the repeat readings of the same images. The only significant independent variable for the area of disclosed plaque was the subject (p < 0.001). The significant independent variables for the proportion of disclosed plaque were the subject (p < 0.001) and the tooth type (p = 0.002). The independent variable describing the use of fluoridated or non-fluoridated elastomers was not significant for either the area or the proportion of disclosed plaque. CONCLUSION: Fluoridated elastomers do not affect the quantity of disclosed plaque around an orthodontic bracket. (+info)