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Orthodontic appliances of simple construction have been described. They are valuable in intercepting the deforming action of perioral muscle function or malfunction. The same muscles that have the deforming potential may be enlisted to correct dental malocclusions. Early interception often prevents a problem of considerably greater magnitude at a later date.
Most orthodontic appliances and archwires are stainless steel or nickel-titanium (NiTi) alloys that can release metal ions, with saliva as the medium. To measure metal released from the fixed orthodontic appliances currently in use, we fabricated simulated fixed orthodontic appliances that corresponded to half of the maxillary arch and soaked them in 50 mL of artificial saliva (pH 6.75 +/- 0.15, 37 degrees C) for 3 months. We used brackets, tubes, and bands made by Tomy (Tokyo, Japan). Four groups were established according to the appliance manufacturer and the type of metal in the .016 x .022-in archwires. Groups A and B were stainless steel archwires from Ormco (Glendora, Calif) and Dentaurum (Ispringen, Germany), respectively, and groups C and D were both NiTi archwires with Ormco's copper NiTi and Tomy's Bioforce sentalloy, respectively. Stainless steel archwires were heat treated in an electric furnace at 500 degrees C for 1 minute and quenched in water. We measured the amount of metal released from each group by immersion time. Our conclusions were as follows: (1) there was no increase in the amount of chromium released after 4 weeks in group A, 2 weeks in group B, 3 weeks in group C, and 8 weeks in group D; (2) there was no increase in the amount of nickel released after 2 weeks in group A, 3 days in group B, 7 days in group C, and 3 weeks in group D; and (3) there was no increase in the amount of iron released after 2 weeks in group A, 3 days in group B, and 1 day in groups C and D. In our 3-month-long investigation, we saw a decrease in metal released as immersion time increased.
The objective of this three treatment, three period, single blind, cross-over trial was to evaluate the efficacy of three toothbrushes in a cohort of children undergoing fixed appliance orthodontic therapy. The brushes used were: (1) Dental Logic HP550 with regular brush head HP5924 (Philips, U.K.); (2) Braun Oral B Plaque Remover (D7) with dedicated orthodontic brush head OD5-1 (Braun AG, Germany); and (3) a manual dedicated orthodontic toothbrush (P35, Oral B Laboratories, Calif.). Sixty orthodontic patients, aged 10 to 16 years and wearing upper and lower fixed appliances, were screened and recruited with parental consent. After an oral soft tissue examination at baseline, the percentage of plaque-covered tooth surfaces and gingival bleeding sites were recorded using visible plaque and gingival bleeding indexes. Each subject was randomly allocated to one of three groups (n = 20) with brushing sequences 1-2-3, 2-1-3, 3-2-1. The first brush was given 2 weeks after baseline (visit 1). The time interval for using each brush was 4 weeks at the end of which visible plaque and gingival bleeding indexes were recorded and a further prophylaxis given. Statistical analysis was undertaken with analysis of variance. Data were analyzed on a site-specific basis; buccal smooth and interproximal surfaces, lingual smooth and interproximal surfaces. At baseline the mean visible plaque index for all subjects were; buccal smooth, 52.5% (+/- 22.5%); buccal interproximal, 70.5% (+/- 18.5%); lingual smooth, 68.5% (+/- 21%); lingual interproximal, 76% (+/- 16%). At visit 1, the plaque scores at all surfaces had reduced significantly compared to baseline, but there had been no active treatment. This was attributed to a Hawthorne effect. Subsequently, there were no significant effects on visible plaque (or gingival bleeding) indexes with any toothbrush at any tooth surfaces. This suggests that the new HP550 is equally effective as specifically designed orthodontic toothbrushes in removing plaque from patients with fixed orthodontic appliances.
The objective of this prospective single-blind crossover clinical trial was to evaluate the efficacy of 4 toothbrushes in 33 children undergoing fixed appliance orthodontic therapy. The toothbrushes included in this study were the Braun Oral-B 3D Plaque Remover (Kronberg, Germany), the Philips-Jordan HP 510 (Philips Domestic Appliances, Groningen, The Netherlands), the Lactona orthodontic toothbrush (Bergen op Zoom, The Netherlands), and the Oral-B Advantage Control Grip (Braun); the first 2 are electric, and the last 2 are manual. Every patient tested each type of toothbrush in a randomly designed sequence. Plaque and gingival scores were recorded at baseline and after every 4-week test period. All patients received professional prophylaxis after each clinical evaluation. The data were analyzed with the Friedman test, which showed no significant differences among the 4 brushes for any of the parameters measured. The Wilcoxon signed rank test, comparing the plaque and the gingival scores between the upper and lower jaw for each brush, indicated that plaque removal was more efficient in the lower jaw than in the upper.
During orthodontic treatment, pain and discomfort of the oral mucosa can be experienced as a result of trauma from the appliances caused by increased friction between mucosal tissue and the surface of the brackets. Currently, orthodontists have few remedies to prevent or relieve this mucosal irritation. The orthodontist can give the patient wax to cover the brackets as a prophylactic measure or to use as needed on specific irritating appliances. Orthodontic wax contains no analgesic components. The purpose of this study was to determine the efficacy of an orthodontic wax containing benzocaine that is released over time in a controlled manner. This randomized, prospective, double-blind, clinical trial compared patients' responses to the wax with benzocaine and the currently used unmedicated orthodontic wax. Seventy patients, 35 in each treatment group, were instructed to apply the wax in a specific manner, and their pain levels were recorded at 6 different time points. The pain levels were analyzed with a repeated-measure analysis of variance (ANOVA) model with factors of treatment (medicated wax vs unmedicated wax) and times (6 levels). Post-hoc pair-wise comparisons were made on the basis of the Fisher least significant difference procedure. The results of this study clearly indicated that the pain profile over time of the group that received the wax containing benzocaine was significantly different from that of the subjects who received the unmedicated wax. The medicated group had significantly lower pain levels at every time point after the first hour (P <.0003 in each case) compared with the unmedicated group. The medicated wax was effective immediately and continued to reduce pain in greater magnitude than did the unmedicated wax. A wax applied to orthodontic brackets that slowly and continuously releases benzocaine is significantly more effective at reducing the pain associated with mucosal irritation than is the current option used by most orthodontists.
In orthodontics the degree of treatment outcome largely depends on patient cooperation. In this article factors related to cooperation with removable appliance wear are discussed.
The use of orthodontic appliances may contribute to local gingivitis, often attributed to increased plaque retention. Gingivitis of bacterial origin cannot clinically be distinguished from local tissue irritation caused by corrosion products. The purpose of this investigation was to assess the cytotoxic effect of various metallic components used in orthodontics. Multicomponent devices such as facebows, molar bands, and brackets along with single-component brackets and archwires were tested by the agar overlay cytotoxicity test with mouse fibroblast cells. None of the archwires caused any cytotoxic effect, even though some contained 54 per cent nickel. However, the multi-component devices, which were joined with silver- and copper-based brazing alloys were more cytotoxic than the single-component devices. Copper is more cytotoxic than nickel, which could explain the greater cytotoxic effect of the samples with brazing materials. It is speculated that cytotoxic corrosion products from orthodontic appliances might contribute to localized gingivitis.
Occasionally orthodontic appliances or parts of orthodontic appliances have caused problems with either the airway or the gastrointestinal tract. The type of appliances that have caused problems and their clinical management are discussed. A case is described in which an upper removable appliance with inadequate retention became lodged in a patient's pharynx lacerating the palatine tonsils. Suggestions are made to try and avoid the problems that were encountered in this case and others reported in the literature in patients undergoing orthodontic treatment.
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The deformations of orthodontic appliances used for space closure are large so that any mathematical analysis will require a nonlinear approach. Existing incremental finite element and finite difference numerical methods suffer from excessive computational effort when analyzing these problems. An accurate segmental technique is proposed to handle these difficulties in an extremely efficient fashion. The segmental technique starts by assuming that an orthodontic appliance is composed of a number of smaller segments, the ends of which undergo small relative rotation. With an appropriate choice of local coordinate system the equilibrium equations for each segment are linearized and solved in a straightforward manner. The segments are then assembled using geometric and force compatibility relations similar to the transfer matrix method. Consequently, the original nonlinear boundary value problem is solved as a sequence of linear initial value problems which converge to the required boundary conditions. As only one segment need be considered at a time, the computations can be performed accurately and efficiently on a PC type computer. Although an iterative solution is used to match the boundary conditions, the time required to solve a given problem ranges from a few seconds to a couple of minutes depending on the initial geometric complexity. The accuracy of the segmental technique is verified by comparison with an exact solution for an initially curved cantilever beam with an end load. In addition, comparisons are made with existing experimental and numerical results as well as with a new set of experimental data. In all cases the segmental technique is in excellent agreement with the results of these other studies.
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Simulated fixed orthodontic appliances were constructed, immersed and incubated in artificial saliva for periods up to three months. Two types of stainless steel archwires and two types of NiTi wires were used. The surface corrosion of the archwires was determined macroscopically, with scanning electron microscopy, and with spectrophotometry. The deposits on the wires were identified with X-ray diffraction. Uniform corrosion was observed on stainless steel wires, and a slight colour change was detected on the NiTi wires beneath stainless steel ligatures. The corrosion product on the stainless steel wires increased with immersion time, and the surface oxide films were easily detached from the underlying matrix. Crevice corrosion was observed under deposits of oxide, and at the interface between bracket and band. Such corrosion may weaken a wire or weld leading to fracture. In contrast, the NiTi archwires did not corrode, and there was no significant difference in surface morphology. The stainless steel archwires showed a significant loss of reflectance after heat treatment and immersion in artificial saliva. The NiTi archwires had the same reflectance before and after the immersion test. NiTi archwires are significantly more stable and resistant to corrosion than stainless steel archwires.
The appliance hygiene performance and its relationship with stomatitis lesions were investigated on 124 patients who were using maxillary removable orthodontic appliance. The patients were divided into five groups according to the appliance wearing periods. Appliance hygiene index (AHI) showed no significant difference between the groups except the fifth group and the prevalence of stomatitis was found as 8.9 percent. There was not any significant correlation between the quantity of plaque and the degree of stomatitis.
One-couple orthodontic appliances are capable of applying well-defined forces and couples to effect controlled tooth movement during treatment. There are two sites of attachment: one in which the appliance is inserted into a bracket or tube where both a couple and force is generated, and one at which the appliance is tied as a point contact where only a force is produced. Using relatively simple designs, powerful biomechanical force systems that are easy to discern clinically can be applied to move teeth according to a prescribed plan. Several one-couple appliances are described to move individual or groups of teeth in all three dimensions. A complete biomechanical analysis of each appliance is presented and clinical reports follow each description.
The objective of this study was to evaluate the effects of an orthodontic appliance and of its components (brackets, bands, and arch wires) on some cell functions. Fibroblasts were cultured either in the presence of one unwashed orthodontic appliance, or one orthodontic appliance immersed in MEM for 28 days before use (washed appliance), or in the presence of MEM in which the appliances had been immersed. At the end of in vitro maintenance, morphological studies were carried out with SEM and TEM. Cell proliferation and GAG synthesis and secretion by radio-labeled precursors were assessed. The data indicated that unwashed appliances were more cytotoxic than washed ones. Moreover, the arch wire was the most biocompatible component of the orthodontic appliance, and the bracket was the least biocompatible. A comparative study into the effects on cell proliferation of the most common metal ions released by the appliances was also carried out. At the concentration released by one orthodontic appliance immersed for 28 days, the highest reduction in DNA synthesis was observed in the presence of Cu(++).
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Various removable and fixed orthodontic appliances were rated by interview and questionnaire by 42 myofunctional therapists in the Hamburg area with respect to their influence during myofunctional therapy. The Nance holding arch was given the most negative rating of all appliances covering the palate area. For the active plate, marking the rest position of the tongue by roughening the acrylic surface or by reproducing the palatal relief was considered beneficial. The quadhelix expansion device and Hyrax palatal expander were rated as unfavorable because of their positioning in the palatal area. Among the functional appliances, Fränkel's function regulator was given the best rating. Regular fixed appliances (brackets, bands) were not considered a disturbance. Habit reminders (plates and spurs) were given a very negative rating by ca. 80% of the therapists because they disturbed the myofunctional exercises and led to adaptive dysfunctions. Since many patients with dysfunction of the orofacial musculature undergo simultaneous myofunctional and orthodontic therapy, treatment planning and choice of orthodontic appliances should be carefully coordinated.
Cementation of a fixed orthodontic appliance requires careful attention to detail. Certain procedures can be used to improve fit of the stainless steel band and enhance the cementing procedure. This paper outlines a technique for cementation that optimizes the chances for an ideal long-term band-cement-tooth bond.