Trial document

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Trial Description

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Dimensional accuracy of rapid prototyping methods
applied for facial prostheses manufacturing
(by the example of ear-prostheses)

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Trial Acronym


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URL of the Trial


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Brief Summary in Lay Language

1. Description and brief substantiation of the study
It is a known fact that a considerable number of people are afflicted with some kind of a facial defect each year. This implies significant inconveniences for a patient due to physical disturbances, loss of the function of the impaired facial part and dissatisfaction of physical appearance. As the human face constitutes a center of attention in human relationship, the emotional pressure caused by facial disfigurements can produce a high level of handicap.
Advancements in modern surgical procedures, instruments and equipment let the patients afflicted with facial defects be reintegrated into society through corrective, restorative and plastic surgery.
Whereas surgery is capable of restoring some volume of the lost tissue and its function in part, it has some limitations due to a high age of a patient and other medical contraindications, as far as patient’s preference to avoid a big number of operations.
All these limitations can be overcome by means of facial prostheses manufacturing, which can be produced either using a conventional approach, or with a Computer Aided Design/ Computer Aided Manufacturing (CAD/CAM) and Rapid Prototyping (RP) being employed. Conventional method implies making an impression, trial waxing, producing of the mold and prosthesis manufacturing directly. It is recognized as complex and time consuming task, requiring presence of a patient for a long time and a high number of visits.
A lot of advantages of computerized method to a conventional one have been reported, such as easiness and precision of impression making, decreased average time of production, possibilities to plan the position and the construction of the future prosthesis in beforehand, using an anatomy of the unaffected areas occasionally by means of mirrored imaging.
Nowadays there are a lot of methods of both data acquisition and rapid prototyping. Recently CT, MRI, laser scanning and three-dimensional stereo photogrametry have been used to acquire data about the topography and morphology of a facial defect. The questions of dimensional accuracy and reproducibility of facial landmarks using these methods have been investigated, however there are only few researches concerning the rapid prototyping methods. A lot of RP methods have been recently employed for facial prostheses manufacturing, including stereo lithography, selective laser sintering, fused deposition modeling, laminated object manufacturing and others. However no clearance is settled, which method is mostly precise and could be recommended for facial prosthetics.
Basing on this statement it is to conclude, that further investigations of dimensional accuracy of RP methods for facial prostheses manufacturing are required and will be performed within this research.

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Brief Summary in Scientific Language

2. Purpose and main goals
The main purpose of this research is to define, which method of rapid prototyping among those being employed for the study shows the best accuracy, when producing patterns (duplicates) of facial prostheses, which in their turn are then used for production of a definitive prosthesis. Choice and exception criteria for the chosen RP methods according to their accuracy, easiness of use and costs of ear patterns production will be formulated.

3. Design of the study
Prospective observation. Anonymous Case series.Single arm with intra-individual control

a. Study population
17 participants in age of 18 – 60 years, both genders; Sample size was estimated by the worst case scenario for a single arm control design.

b. Recruitment
Employees at the Centre for Dentistry, Oral- and Maxillofacial Surgery at University of Tuebingen as well as any volunteer.

c. Inclusion criteria
• Visible absence of any facial defects and deformities
• Subsequently, presence of both ears
• Participants in age from 18 to 60 years

4. Study measures: Methods & Materials

After decision what ear to scan by the participant, in the first part of the study the participants will undergo the procedure of the ear anthropometry: The auricular area will be then scanned for the digital data acquisition with the help of a structured light scanner (Artec 3D Spider, Artec Group). This was recently used for such purposes in common researches. Data will be coded with an anonymous ID: “EpiRP-##”.
The gathered STL files will be transferred to the RP machines.
They will produce a duplicate using different methods: stereolithography (STL) (ProJet SD 7000), selective laser sintering (SLS) (SPro 60 HD) and fused deposition modeling (FDM) (Ultimaker 2, IGO 3D).
Afterwards, all dimensions between the landmarks with regards to the chosen anthropometrical approach will be measured with a use of digital calipers. Each dimension will be compared to the same one between the same landmarks, which was previously got from the participants directly.
4.2 Structured Light scanning
Each participant will undergo a scanning process, which will be performed by ARTEC EvaLight Scanner (Artec Group Comp., Luxembourg). The auricular area including the ear will be scanned. Three recordings will be performed, the best one will be chosen. All the gathered STL files will be saved in a database and if needed edited in a special software (Mimics, Materialise, Leuven, Belgium) to eliminate any possible artifacts. All the previously pointed landmarks will be transferred to an STL file by means of the light scanner, though they have a volume and will be imaged like a small spots. The same dimensions will be measured with a use of digital linear in special CAD software (Mimics, Materialise, Leuven, Belgium). This data set (∑s) will be written in a special form. Compared to those dimension, got from the ear directly (∑p), they will set a gold standard for the further study.

4.3 Rapid prototyping
All the gathered digital files is STL (solid-to-layer) format will be used to produce ear patterns of each participant. Different RP methods, such as stereolithography (ProJet SD 7000), selective laser sintering (SPro 60 HD) and fused deposition modeling (Ultimaker 2, IGO 3D) will be employed. So the three ear patterns of each patient will be manufactured. Each pattern will be prescribed a special number. All the landmarks will remain on the surface of the ear patterns, thought the have a volume.

4.4 Dimensional measurements and analysis
All the ear patterns will be measured with regards to the anthropometrical landmarks being put on them. Three measurements for each dimension will be performed and entered into a special form, producing subsequently three data sets (∑1, ∑2, ∑3) for each method of rapid prototyping.
Each data set of dimensions will be compared to those, being got from the participants directly (∑p) with a use of Dunnett’s test.

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Organizational Data

  •   DRKS00007184
  •   2014/11/07
  •   [---]*
  •   yes
  •   Approved
  •   387/2014BO2, Ethik-Kommission an der Medizinischen Fakultät der Eberhard-Karls-Universität und am Universitätsklinikum Tübingen
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Secondary IDs

  • [---]*
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Health Condition or Problem studied

  •   Z90.0 -  Acquired absence of part of head and neck
  •   Q17.9 -  Congenital malformation of ear, unspecified
  •   H61.9 -  Disorder of external ear, unspecified
  •   healthy participants
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Interventions/Observational Groups

  •   Rapid Prototyping with stereolithography (STL)
  •   Rapid Prototyping with selective laser sintering (SLS)
  •   Rapid Prototyping with Fused Deposit Modelling (FDM)
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  •   Non-interventional
  •   Other
  •   Other
  •   Open (masking not used)
  •   [---]*
  •   Active control (effective treament of control group)
  •   Basic research/physiological study
  •   Other
  •   N/A
  •   N/A
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Primary Outcome

If there is an inaccuracy of 15% regarding the measures within one plane of the repoductions compared to the in-vivo measurements (gold standed) the method is redarded as failed.

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Secondary Outcome


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Countries of Recruitment

  •   Germany
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Locations of Recruitment

  • University Medical Center 
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  •   Actual
  •   2014/12/01
  •   17
  •   Monocenter trial
  •   National
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Inclusion Criteria

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

• Visible absence of any facial defects and deformities
• Subsequently, presence of both ears

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Exclusion Criteria

one ear absent

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  • start of 1:1-Block address primary-sponsor
    • Poliklinik für zahnärztliche Prothetik am ZZMK des UKT
    • Mr.  Prof.Dr.  Heiner  Weber 
    • Osianderstr.2-8
    • 72076  Tuebingen
    • Germany
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    • STUDIENZENTRALE MEDIZINPRODUKTEPoliklinik für Zahnärztliche Prothetik mit Propädeutikam Zentrum Zahn-, Mund- und Kieferheilkundedes Universitätsklinikums Tübingen
    • Mr.  OA Dr.  Fabian  Huettig 
    • Osianderstr. 2-8
    • 72070  Tuebingen
    • Germany
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    • Department of Prosthodontics and Section “Medical Materials and Technology” Center of Dentistry, Oral Medicine, and Maxillofacial SurgeryUniversity Hospital Tuebingen
    • Mr.  Dr.  Alexey  Unkovskiy 
    • Osianderstr. 2-8
    • 72076  Tuebingen
    • Germany
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Sources of Monetary or Material Support

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    • Poliklinik für Zahnärztliche Prothetik mit Propädeutik
    • Osianderstr. 2-8
    • 72076  Tuebingen
    • Germany
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    •   [---]*
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    • Scholarships of the President of the Russian Federation for Students and PhD Students Training Abroad at the The Ministry of education and science of the Russian Federation
    • Mr. 
    • Tverskaya street, 11
    • 125993  Moscow
    • Russian Federation
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  •   Recruiting complete, follow-up complete
  •   2014/12/12
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Trial Publications, Results and other Documents

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* This entry means the parameter is not applicable or has not been set.