## 5 Conclusions  
This research explored two significantly different clinical outcomes based on different 3D designs of 3D printed orthodontic power-arms. Clinical orthodontists can engage in better personalization of their intraoral biocompatible appliances. Results confirmed a significantly less frequent loss of PA attachment in the updated variant II. This tool will provide more predictable treatment outcomes and thus more efficient orthodontic treatment. When comparing the 3D printed power-arms to current hand-crafted or prefabricated power-arms, we can conclude that biocompatible AM provides solution to many frequent impediments of non-AM power-arms, such as:  
1. Patient discomfort (AM-PA have a more round-ergonomic design respecting individual patient anatomy because of the digital intraoral scan);
2. Loss of power-arm attachment (the individual base is superior to the prefabricated-one);
3. Aesthetical handicap (the power-arm is transparent and has an aesthetical advantage over metallic-ones). As the result of this research is based on stress distribution analysis and finite element modelling, we have managed to increase the strength by 7% (in the new variant II) and reduce the stress by up to 82% in the more resilient 3D printed biocompatible power-arm (variant II). This has been confirmed by clinical evaluation of critical debonding incidents, where the new power-arm design (variant II) had approximately four times less frequent debonding and cracking than variant I. The following Supplementary Materials--full dataset--clinical evaluation is available online at [[https://www.mdpi.com/article/10.3390/app11209693/s1](https://www.mdpi.com/article/10.3390/app11209693/s1)]([https://www.mdpi.com/article/10.3390/app11209693/s1](https://www.mdpi.com/article/10.3390/app11209693/s1)). Conceptualization, A.T. and I.V. ; methodology, A.T.; software, F.K. ; validation, L.C., B.N. and I.V. ; formal analysis, F.K. ; investigation, F.K. ; resources, A.T.; data curation, F.K. ; writing--original draft preparation, F.K. ; writing--review and editing, A.T.; visualization, A.T.; supervision, I.V. ; project administration, A.T.; funding acquisition, I.V. All authors have read and agreed to the published version of the manuscript. This research was funded by the KEGA grant agency of the Ministry of Education, Science, Research, and Sport of the Slovak Republic (Grant No. 081 UK-4/2021). The study was conducted according to the guidelines of the Declaration of Helsinki, and no approval was necessary by the Ethics Committee. Ethical review and approval were waived for this study, due to the fact that no experimental materials or approaches were used. All used materials and machines were fully certified and are still available on the market. Dental LT Clear is tested at NAMSA, Chasse sur Rhone in France, and is certified biocompatible per EN-ISO 10993-1-2009/ AC:2010. The biocompatible resin material is in compliance with ISO Standards: EEN ISO 1641:2009, EN-ISO 10993-1:2009/ AC:2010, EN-ISO 10993-3:2009, EN-ISO 10993-5:2009, EN 908:2008. 3D printer--Formlabs Form 2 was the first and only stereolithography 3D printer to be validated by Materialise as part of the Materialize first FDA-cleared process to create accurate patient-specific anatomical models for diagnostic use. Formlabs electrical equipment is manufactured in facilities with the following QMS certifications. Form 2 (Quality system standards) ISO 9001:2015 and ISO 14001:2015. Formlabs, Inc., located in Somerville, Massachusetts, USA, certifies that: Formlabs Form 2 3D printers are assembled within the European Union in Hungary and Formlabs Dental SG Resin and LT Clear Resin are manufactured within the European Union in The Netherlands. This research was not conducted on humans. Only the evaluation of different resiliency between original power-arm and improved variant II was evaluated (after clinical application). Patients with power-arm as a part of their orthodontic treatment plan had applied either original design or improved design.