[Orthodontic appliance design. Diverse, small orthodontic measurements (II)].
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Equipment Design↗
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[A computer-controlled flexing test for determining the elastic parameters of highly flexible orthodontic wires].
Metals are the most commonly used materials in the construction of orthodontic appliances designed for the correction of malocclusions. Knowledge of the force systems at work is a prerequisite for judging the functionality of these appliances. The elasticity parameters (Young's E-moduli, strain limits) of the alloys employed can be drawn upon to calculate numerically forces and torsional moments. Both tensile tests and bending experiments are used to determine the E-moduli and strain limits of standard steel and highly flexible NiTi wires frequently used in orthodontics. However, parameters obtained by tensile tests are less suited for studying the mechanical properties of orthodontic appliances. Since bending deformation prevails, bending experiments should be preferred method for ascertaining the relevant parameters. This study, therefore, presents a new experimental method for testing the bend ability of highly flexible materials and the determination of the underlying material parameters. A comparison of calculated force systems with direct measurements revealed that bending parameters lead to an appropriate description of forces and moments generated during clinical treatment, whereas calculations based on tensile test parameters differ substantially. The bending test proposed here is, thus, a suitable means for dependably predicting the force systems produced by an orthodontic appliance and the test therefore can contribute to an accurate design of new types of therapeutic devices.
Computer-Aided Design↗
The prediction of distortion in formed orthodontic appliances.
The theoretical prediction of the onset of distortion within a retraction U-loop as derived from a knowledge of the maximum bending moment, the wire characteristics and the loop dimensions was found to be in good agreement with the experimental measurements carried out on large scale models of the U-loops. The ability to predict distortion in appliances should be of use in any comparison of the properties of the different designs of U-loop or in the evaluation of different designs of orthodontic appliance.
Chemical Phenomena↗
Transitional Twin Block.
When FJO is integrated with fixed orthodontic treatment possibilities are greater than with one system only. Given proper case selection and patient corroboration consistent results are achieved. The Comfort Twin Block design enhances patient acceptance and compliance. Transitional Twin Block Methods to encourage active eruption of teeth result in faster case completion. The Twin Block is a versatile and effective appliance in the correction of Class II malocclusions.
Adolescent↗
[Lingual orthodontics: why is it progressing?].
At the early stages of the 80's, most of the practitioners and the patients have been seduced by lingual orthodontic. But the difficulties of the technic have rapidly given a disappointment. Today ten years later the authors present the progress which have been realized: the evolution of the brackets, the accuracy of their placement in the lab procedure with the new targ, the making of the wire, the patient's comfort increase. The placement brackets are customized by making an anatomical resin pad. Placement of the brackets have evoluted from a quantized system in two dimensions (Targ 1) to a no quantized system in three dimensions (Class System) and finally to a real quantized system in three dimensions (Targ 2 with a compass of thickness with measures the first order band). Data System DALI (Drawing Arch Lingual Ideal) allows to draw the exact design of the wire. A video tape shows the different laboratory and clinical phases. By using light cured periodontal protection like Barricaid from Caulk: the patients have a greater adaptation with their appliance. All this progress give to lingual orthodontic credibility. Lingual is a reality to day and it's the first concept with customized brackets extremely accuracy, full quantized in the three orders, using the computer progress.
Dental Bonding↗
[The effects of twin-block magnetic appliance on the early skeletal Class III malocclusion].
OBJECTIVE: The aim of this study was to evaluate the effect of magnetic functional and orthopedic approach on treatment of early skeletal class III malocclusion. METHODS: A new type of magnetic twin-block appliance (TMA) was developed and used on 32 growing subjects with skeletal class III malocclusion. RESULTS: The class III dentofacial profile significantly improved and class III molar relationship was corrected in most cases. CONCLUSION: The Nd2-Fe14-B TMA could be used as effective orthopedic approach in treating class III malocclusion, which had many advantages, such as force prediction, well-controlled anchorage, small and comfortable design of appliance and good cooperation from patients.
Adolescent↗
One-couple orthodontic appliance systems.
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.
Cuspid↗
Treatment of Class II high angle malocclusions with the Herbst appliance: a cephalometric investigation.
The purpose of this study was to examine the results of treatment of Class II malocclusions by using two different designs of the Herbst appliance. Cephalometric records from lateral headplates of 19 consecutively treated Class II cases were evaluated. The headplates were taken before and after the treatment stage in which the Herbst appliance was used. The patients were divided into two groups: the first group, normohypodivergent, was treated with the Herbst appliance attached to bands; the second group, hyperdivergent, was treated with the Herbst appliance attached to acrylic splints in which a high-pull headgear was also used. The results were compared between these groups and with a control group age-matched from Bolton standards to match the changes in the Herbst samples against what might be expected in case of normal growth during similar periods of time. The results of the investigation revealed the following: (1) 9 months of treatment resulted in Class I dental arch relationships in all 19 cases; (2) the Herbst appliance attached to bands did not significantly modify the vertical growth pattern of the normohypodivergent patients; and (3) in hyperdivergent patients, the use of a Herbst appliance attached to acrylic splints in conjunction with the use of a high-pull headgear allowed a better control of the vertical dimension, as assessed by the cephalometric parameters (FA, FMA, Go-Gn-SN). The clinician should be aware of the different dentofacial changes induced in the vertical plane by different designs of the Herbst appliance to better program treatment strategy.
Adolescent↗
Use of a modified twin block appliance following partial maxillectomy: case report.
A case is described in which a Class II malocclusion with severe Class II skeletal pattern was treated with a modified Twin Block Appliance. The patient, an 11-year-old girl, had initially presented with an ameloblastoma located in the right maxilla. The subsequent defect produced by surgery was obturated by the appliance during her orthodontic treatment, which was undertaken during her pubertal growth spurt. Two years later the result was stable, allowing the provision of a more definitive prothesis to restore the occlusion.
Ameloblastoma↗
Perspectives in posterior vertical dimension: three case reports.
Using a powerful three dimensional perspective, it is possible to control the vertical components of bite opening appliances, which can prove to be valuable in design and application of functional appliances. Several cases are presented to illustrate this orthopedic technique.
Cephalometry↗
[Bone anchorage in orthodontics. A review].
The achievement of absolute anchorage in orthodontics overcoming the reaction forces and moments has been problematic for a long time. This was caused on the one hand by the limitations of the devices available and on the other hand by the dependence on patient cooperation. The introduction of bone anchorage systems changed the traditional way of thinking on orthodontic anchorage. Whereas the application of anchor systems, such as palatal implants and onplants, has specific indications, bone screws with or without plates seem to have the potential of being used on a routine basis. However, appropriate data for more complete understanding of the biological and biomechanical background of this concept of orthodontic anchorage are still lacking. Furthermore, studies on the effectiveness of these systems when compared to the traditional orthodontic anchorage and based on large groups of patients are not available. Well-designed prospective clinical trials substantiating the evidence-based use of these devices are needed.
Bone Screws↗
Magnetic activator device II (MAD II) for correction of Class II, division 1 malocclusions.
A magnetically active, two-piece (upper and lower), functional orthopedic appliance has been developed, magnetic activator device (MAD) for the correction of Class II malocclusions. The magnetic forces are used to give freedom of mandibular movement and to allow for continuous functioning of the orofacial muscles when the appliance is worn. Samarium cobalt (Sm2Co17) magnets are incorporated on the buccal aspects of the upper and lower appliances. Magnetic forces ranging from 150 to 600 gm per side have been used on patients, and it seems that the skeletal versus dental response depends on the intensity of the magnetic force used. A force of 300 gm, when the magnets are in contact, on each side has been found to be an appropriate value in patients age 7 to 12 years. The use of this less bulky design rather than a traditional orthopedic appliance, along with the freedom of function it permits, has enabled patients to wear the appliance nearly 24 hours in most cases.
Activator Appliances↗
Severe Class II division 1 malocclusion treated by orthodontic miniplate with tube.
A miniplate with tube (C-tube) was placed in the interdental spaces between both left and right upper second premolars and first molars in a 15-year-8 month-old male patient with a Class II malocclusion who with severe anterior protrusion and lower anterior crowding. The treatment plan consisted of extracting both upper first premolars, en masse retraction of the upper six anterior teeth and lower anterior decrowding. C-tubes were used as substitutes for posterior dental anchorage during upper anterior retraction. The particular design of the C-tubes made it possible to retract fully with minimal gingival irritation. The correct overbite and overjet were obtained by intruding and retracting the maxillary incisors to their proper positions and this correction remained stable for at least 27 months after debonding. Also, facial balance was improved. The active treatment period was 14 months. The application of this new appliance, consideration of case selection, and sequence of treatment are presented.
Adolescent↗
An audit of the laboratory service provided to the Health Service Executive Orthodontic Department, St James Hospital, Dublin.
PURPOSE OF THE STUDY: To evaluate the service purchased from contracted orthodontic laboratories used by HSE (SWA) regional orthodontic unit, St. James's Hospital, Dublin and identify deficiencies in the current service. MATERIALS AND METHODS: A data collection questionnaire was designed and distributed to the departmental orthodontists for a period of three months (October-December 2004). Gold standards, drawn up based on the authors' ideal requirements and published guidelines, were supplied to grade the work returned. RESULTS: During the study period 363 items of laboratory work were requested. 20% of the laboratory work arrived late and most of the delayed work was delayed for more than 24 hours. Most laboratory delays occurred with functional appliances, retainers and study models. Prior to fit, 20% of the appliances required adjustments for more than 30 seconds. 65% of laboratory work returned to the department met all of the gold standards. 10% of appliances were considered unsatisfactory. Functional appliances were most often ill fitting accounting for almost half of the unsatisfactory laboratory work. CONCLUSIONS: The majority of the laboratory work returned to the department met our gold standards and arrived on time. Forty six percent of the appliances required adjustments. Functional appliances required the most adjustments; one in five of all functional appliances ordered were considered unsatisfactory.
Dental Audit↗
Oral appliance therapy for obstructive sleep apnea.
Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive, complete or partial closure of the upper airway during sleep, resulting in sleep fragmentation and oxygen desaturation. The disorder causes significant morbidity, particularly in terms of impairment of daytime functioning and the impact this has on quality of life. There is also evidence that links OSA to long-term cardiovascular morbidity, including hypertension, myocardial infarction, and stroke, and increased risk of motor vehicle accidents. There is clear evidence that effective treatment of OSA provides major benefit to patients. Nasal continuous positive airway pressure (CPAP) is the current treatment of choice, but its cumbersome nature makes tolerance and compliance less than optimal. This gives rise to the need for other alternatives that are equally effective, but more tolerable. There is growing interest in the use of oral appliances to treat snoring and OSA. The rationale is that advancement of the mandible and tongue impacts positively on upper airway caliber and function. There are many such types of appliances, and they have potential advantages over CPAP in that they are unobtrusive, make no noise, do not need a power source, and are potentially less costly. There is a growing evidence base to support the use of oral appliances in the management of OSA. Recent evidence from randomized controlled trials indicates that oral appliance therapy is effective in controlling OSA in up to 50% of patients, including some patients with more severe forms of OSA. This is associated with a significant improvement in symptoms, including snoring and daytime sleepiness. This evidence is strong for short term, and emerging for long-term treatment of OSA with oral appliances. Whilst direct comparisons with CPAP indicate the superiority of CPAP overall, similar outcomes between the two treatments appear to be achieved in a substantial subgroup of patients. Patient acceptance has, in general, been in favor of oral appliances. Notwithstanding the expanding role of oral appliance therapy, there are a number of limitations that are yet to be overcome. Key issues include the inability to reliably predict treatment outcome, the apparent need for an acclimatization period to attain maximal efficacy of treatment, uncertainty about selection of the appropriate 'dosage' of mandibular advancement required to control OSA in the individual patient, uncertainty about the influence of appliance design on treatment outcome and adverse effects, adherence to treatment, and potential long-term complications of therapy. These issues require resolution before oral appliance therapy can surpass CPAP as first-line treatment for OSA.
Continuous Positive Airway Pressure↗
A modified, lingually supported cantilevered Herbst appliance.
This new, fixed-functional appliance/Herbst/Bioprogressive system is designed for patient comfort and mandatory compliance. It also combines the positive clinical effects of four fixed-functional systems. It allows rapid palatal expansion of the upper arch, alveolar uprighting of the lower arch, upper and lower incisor alignment, and sagittal correction of Class II malocclusions to occur simultaneously with one appliance fixed in both arches. It is indicated for use in growing patients with skeletal Class II malocclusions. The ideal timing for treatment is the late mixed dentition. Being able to remove the appliance after one year with the upper second bicuspids erupting slightly Class III so the clinician can immediately begin fixed finishing mechanics would be ideal. This new Herbst design will reduce the frequency of orthognathic surgery and upper bicuspid extraction to camouflage Class II malocclusions. At the same time, it gives total control to the clinician in treating some more difficult, non-compliant patients. Fixed-functional appliances, which improve treatment efficiency and treatment results and provide for patient comfort, while at the same time give the treating clinician almost total control of the three planes of facial growth will open new doors for orthodontic treatment and research in the next century.
Child↗
Mechanical assessment of interocclusal clearance.
Appropriate design considerations for pediatric or adult appliances are a part of diagnosis as well as therapy. These include occlusal factors. The occlusal considerations warrant accurately accommodating the cast metal framework or wire elements of a removable appliance. A gauge measurement can be accomplished utilizing the device we describe.
Dental Occlusion, Traumatic↗