Trial document




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  DRKS00013334

Trial Description

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Title

Evaluation of Efficiancy of the aligner therapy by 3d-analysis of the tooth movement during the treatment with removable PET-G aligners.

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Trial Acronym

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URL of the Trial

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Brief Summary in Lay Language

Aligners are mainly used for the treatment of adult patients. The inclusion criterion for this study is an age between 18 and 40 years as well as an anterior crowding of a maximum of 3 mm. Furthermore, only patients with fully erupted and preserved permanent teeth 1-6 will be included in the study.
The subjects are generally treated with Duran® Aligners (Scheu dental GmbH, Iserlohn, Germany), one of the common Polyethelyneteraphtalat-Glycol (PET-G) -Aligner materials. Three common aligner concepts will be examined: The first two methods involve correcting the tooth misalignment in larger setup increments ranging from 0.5 - 1.0 mm with three aligners of different thicknesses per setup step. The common aligner thicknesses in this concept are 0.5 mm, 0.625 mm and 0.75 mm as well as the sequence with the thinner initial aligners (0.4 mm, 0.5 mm and 0.75 mm). The third concept is based on correction of tooth misalignment with a smaller setup icrements ranging between 0.1 - 0.2 mm. In this concept only only one aligner thickness (0.75 mm). Due to the small setup increments, up to 40 setups might be needed to completely correct the misalignment.
All patients meeting the inclusion criteria will be asked if they would be willing to participate in this study and informed that this study does not intervene in the treatment, but only requires additional multiple jaw impressions during therapy. This impressions will be either "analogue" using alginate impressions or "digitally" using intraoral 3D scans.
Prior to the treatment, as the case with any orthodontic treatment, an initial model (AuM) and a control panoramic radiograph will be taken. In this case, both jaws are molded or scanned by dental assistants and then the jaw relation is registered. After creating these documents, a treatment protocol is created using one of the three concepts. The aligners will be changed every 7-10 days. This change ensures maintaining the forces to a therapeutically relevant level, which will cause a further tooth movement. After each aligner change an intermediate impression (ZMX) will be taken. After every third aligner, a new impression will be made, which will be used to create a situation model (SMX), to control the achieved tooth position and, if necessary, to create another therapeutic setup model. If further steps are needed, additional intermediate models (ZMX) must be made. Upon reaching the target tooth position, a final model (AbM) for the documentation of the treatment results will be taken.
If "analogue" jaw impressions are to take place at one time, these situation models are digitized with the aid of a desktp scanner (d-STATION, Breuckmann). Subsequently, the digital situation models will be 3D evaluated, i.e. the position of each tooth on the intermediate models will be compared to the initial tooth position. Taking into account a suitable reference point in the jaw, the 3D tooth movement model can be calculated.
In addition to the usual two-dimensional parameters such as canine and molar distance and arch length, our 3D analysis can also be used to evaluate and determine the 3D tooth translation and rotation.
The study population will comprise a total of 90 subjects in order to obtain a representative study population with even age and gender distribution. From our clinical experience, this number is the maximum number of patients that can be realized for the study. A randomized assignment of the patients to the respective treatment concepts is planned.
Additionally, the patients must fully document the wearing time of the aligners and complete a questionnaire on the intensity and duration of the pressure on the teeth.

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Brief Summary in Scientific Language

The treatment of moderate dental malocclusions in adult patients can be with removable transparent braces (so-called Aligner) performed. These are made individually from thermoplastic thermoformed foils. The conventional aligner therapy includes taking an impression of the teeth, then fabricating a plaster model (setup model), displacement of the teeth (i.e. gradual correction of the misalignments on this setup model), thermoforming of multiple aligners and intraoral application.
Currently, several fundamentally different aligner concepts are competing for correcting tooth misalignment. The first concept involves correcting misalignment in larger increments ranging from 0.5 - 1.0 mm, with three aligners of different thicknesses fabricated for each setup step. The common thicknesses in this concept are 0.5 mm, 0.625 mm and 0.75 mm. The basic advantage of this approach is the need for fewer setups. However, due to the fact that the initial aligner foils currently used show a high rigidity leading to overloading the periodontal structures. This, in turn, has been shown to increase the risk of irreversible root resorption. Therefore, in cooperation with the company Scheu Dental GmbH, two thinner foils of the same material with a thickness of only 0.3 mm or 0.4 mm were developed, which were biomechanically examined in-vitro in our clinic. The results of this study showed a reduction aligner stiffness of 71% and 35% compared to the previously thinnest 0.5 mm film for the 0.3 and 0.4 mm aligners respectively. Our measurements however, showed a shape instability of the 0.3 mm aligners. According to these results we recommended a new aligner sequence of 0.4 mm, 0.5 mm and 0.75 mm.
The second concept is based on correction of tooth misalignment with a much smaller setup increments in the range of 0.1-0.2 mm. These small steps cannot be realized manually by the dental technician, but only in the CAD-CAM procedure. In principle, only one aligner thickness (0.75 mm) is used in this concept. Due to the small setup steps, the number of necessary aligners to the completely correction the malposition increases. The main advantage of this approach is the better fit of the Aligner because of the lower discrepancy between the aligner and the current tooth position.
How the three mentioned different combinations of aligner thickness and extent of the movement steps (method 1: conventional thickness sequence / large setup steps, method 2: new thickness sequence / large setup steps and method 3: only one rail strength / small setup steps) influence the amount of tooth movement, the duration of the treatment and Patient comfort is unclear and has not been systematically investigated. The aim of this study is to determine the effectiveness of the three above-mentioned different concepts of aligner treatment by monitoring the 3D movement of the individual teeth. This should be done on the basis of dental models before the therapy, after each aligner change, after each setup step as well as at the end of the treatment. These digital models will be created either by digitizing plaster models from the patients or directly by using a 3D intraoral scanner.
Additionally, by evaluating the routine pre- and posttreatment panoramic x-ray a direct comparison between the different concepts in regards to the risk for root resorption. Furthermore, the patient comfort, i.e. duration and extent of the pressure on the teeth, for the three approaches should be compared by means of a visual analog scale. The patients will be recruited from the patients’ pool of the Department of Orthodontics and Orthodontics of the University Hospital Ulm, for whom an aligner therapy is indicated.

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Organizational Data

  •   DRKS00013334
  •   2018/06/08
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  •   yes
  •   Approved
  •   411/16, Ethik-Kommission der Universität Ulm
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Secondary IDs

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Health Condition or Problem studied

  •   K07.3 -  Anomalies of tooth position
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Interventions/Observational Groups

  •   Aligner therapy with the conventional sequence 0.5/0.625./0.75
  •   Aligner therapy with the ulmer sequence 0.4/0.5/0.75
  •   Aligner therapy with only one foil thickness (0.75) and smaller setup steps
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Characteristics

  •   Interventional
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  •   Randomized controlled trial
  •   Blinded
  •   patient/subject
  •   Active control (effective treament of control group)
  •   Treatment
  •   Parallel
  •   IV
  •   N/A
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Primary Outcome

Amount of tooth movement
Parameter: The tooth position will be determined on each of the 3D models. The achieved 3D tooth position will be compared with the initially planned tooth position.
When: after completing the treatment

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Secondary Outcome

Amount of tooth resorption
Parameter: Panorama x-rays at the beginning and the end of the treatment
When: after completing the treatment

Uniformity of tooth movement
Parameter: The tooth position will be determined on each of the intermediate 3D models. In this manner the tooth position within each aligner change within the same setup step can be separately evaluated.
When: After each aligner change.

Wearing duration
Parameter: The wearing duration will be documented by the patient in a special wearing card.
When: during the wearing period of each aligner

Amount of the pressure on the teeth
Parameter: The amount of the pressure on each tooth will be documented by the patient on a visual ordinal scale.
When: during the wearing period of each aligner

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Countries of Recruitment

  •   Germany
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Locations of Recruitment

  • University Medical Center 
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Recruitment

  •   Planned
  •   2018/08/01
  •   90
  •   Monocenter trial
  •   National
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Inclusion Criteria

  •   Both, male and female
  •   18   Years
  •   40   Years
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Additional Inclusion Criteria

-Completely erupted permanent teeth 1 – 6
-Anterior crowding of up to 3 mm
-No extractions
-Indicated aligner therapy
-Good compliance and oral hygiene
-Voluntary readiness to undergo an impression taking or an intraoral scan every 7 – 10 days
-No contraindication for x-ray radiographs

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Exclusion Criteria

Anterior crowding of more than 3 mm
Signs of pronunced root resorption

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Addresses

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    • Klinik für Kieferorthopädie und OrthodontieUniversitätsklinik Ulm
    • Mr.  Prof. Dr. Dr.  Bernd  Lapatki 
    • Albert-Einstein-Allee 11
    • 89081  Ulm
    • Germany
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    • Klinik für Kieferorthopädie und OrthodontieUniversitätsklinik Ulm
    • Mr.  Dr.  Fayez  Elkholy 
    • Albert-Einstein-Allee 11
    • 89081  Ulm
    • Germany
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    • Klinik für Kieferorthopädie und OrthodontieUniversitätsklinik Ulm
    • Mr.  Dr.  Fayez  Elkholy 
    • Albert-Einstein-Allee 11
    • 89081  Ulm
    • Germany
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Sources of Monetary or Material Support

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    • SCHEU-DENTAL GmbH
    • Am Burgberg 20
    • 58642  Iserlohn
    • Germany
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Status

  •   Recruiting planned
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Trial Publications, Results and other Documents

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