In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance
Background: Clear aligner therapy (CAT) has become increasingly popular for treating mild to moderate malocclusions. However, discrepancies between predicted and achieved tooth movement remain a concern, partly due to the limited understanding of aligner material behavior under clinical conditions....
Saved in:
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
|
| Series: | Applied Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-3417/15/13/7516 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849704582491406336 |
|---|---|
| author | Gavin Nugent Alvaro Munoz Chris Louca Alessandro Vichi |
| author_facet | Gavin Nugent Alvaro Munoz Chris Louca Alessandro Vichi |
| author_sort | Gavin Nugent |
| collection | DOAJ |
| description | Background: Clear aligner therapy (CAT) has become increasingly popular for treating mild to moderate malocclusions. However, discrepancies between predicted and achieved tooth movement remain a concern, partly due to the limited understanding of aligner material behavior under clinical conditions. Since these materials must deliver controlled and sustained forces, their flexural properties are critical for treatment efficacy. Objective: To identify and analyze in vitro studies investigating the flexural properties of thermoplastic clear aligner materials, summarize their testing methodologies, and examine the factors that may influence their clinical performance. Methods: A scoping review was conducted following the PRISMA-ScR guidelines. Three electronic databases (PubMed, Scopus, and Web of Science) were systematically searched. Studies were screened based on predefined eligibility criteria, and data extraction included testing methods, materials, and clinically relevant variables. Risk of bias was assessed using the QUIN tool. Results: Seventeen studies published between 2008 and 2024 were included. All studies used three-point bending to assess mechanical properties. Common influencing factors included thermoforming, liquid absorption, temperature changes, loading conditions, and material thickness. Most studies reported that these factors negatively affected force delivery. The most frequently tested material was Duran (PET-G). Polyurethane-based materials, such as Zendura, showed comparatively better stress relaxation properties. Conclusions: Thermoforming, intraoral temperature changes, liquid exposure, and prolonged or repeated loading can compromise the mechanical properties and force delivery capacity of aligner materials. Standardized testing methods and further investigation of newer materials are essential to enhance the predictability and performance of clear aligner therapy. |
| format | Article |
| id | doaj-art-c92188f31c0a43ae912ca10a0d9e9b6e |
| institution | DOAJ |
| issn | 2076-3417 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj-art-c92188f31c0a43ae912ca10a0d9e9b6e2025-08-20T03:16:42ZengMDPI AGApplied Sciences2076-34172025-07-011513751610.3390/app15137516In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical RelevanceGavin Nugent0Alvaro Munoz1Chris Louca2Alessandro Vichi3School of Dental, Health and Care Professions, University of Portsmouth, Portsmouth PO1 2QG, UKSchool of Dental, Health and Care Professions, University of Portsmouth, Portsmouth PO1 2QG, UKSchool of Dental, Health and Care Professions, University of Portsmouth, Portsmouth PO1 2QG, UKSchool of Dental, Health and Care Professions, University of Portsmouth, Portsmouth PO1 2QG, UKBackground: Clear aligner therapy (CAT) has become increasingly popular for treating mild to moderate malocclusions. However, discrepancies between predicted and achieved tooth movement remain a concern, partly due to the limited understanding of aligner material behavior under clinical conditions. Since these materials must deliver controlled and sustained forces, their flexural properties are critical for treatment efficacy. Objective: To identify and analyze in vitro studies investigating the flexural properties of thermoplastic clear aligner materials, summarize their testing methodologies, and examine the factors that may influence their clinical performance. Methods: A scoping review was conducted following the PRISMA-ScR guidelines. Three electronic databases (PubMed, Scopus, and Web of Science) were systematically searched. Studies were screened based on predefined eligibility criteria, and data extraction included testing methods, materials, and clinically relevant variables. Risk of bias was assessed using the QUIN tool. Results: Seventeen studies published between 2008 and 2024 were included. All studies used three-point bending to assess mechanical properties. Common influencing factors included thermoforming, liquid absorption, temperature changes, loading conditions, and material thickness. Most studies reported that these factors negatively affected force delivery. The most frequently tested material was Duran (PET-G). Polyurethane-based materials, such as Zendura, showed comparatively better stress relaxation properties. Conclusions: Thermoforming, intraoral temperature changes, liquid exposure, and prolonged or repeated loading can compromise the mechanical properties and force delivery capacity of aligner materials. Standardized testing methods and further investigation of newer materials are essential to enhance the predictability and performance of clear aligner therapy.https://www.mdpi.com/2076-3417/15/13/7516clear alignersInvisalignthermoplastic materialsorthodontic appliancesflexural strengthforce |
| spellingShingle | Gavin Nugent Alvaro Munoz Chris Louca Alessandro Vichi In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance Applied Sciences clear aligners Invisalign thermoplastic materials orthodontic appliances flexural strength force |
| title | In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance |
| title_full | In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance |
| title_fullStr | In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance |
| title_full_unstemmed | In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance |
| title_short | In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance |
| title_sort | in vitro flexural testing of clear aligner materials a scoping review of methods results and clinical relevance |
| topic | clear aligners Invisalign thermoplastic materials orthodontic appliances flexural strength force |
| url | https://www.mdpi.com/2076-3417/15/13/7516 |
| work_keys_str_mv | AT gavinnugent invitroflexuraltestingofclearalignermaterialsascopingreviewofmethodsresultsandclinicalrelevance AT alvaromunoz invitroflexuraltestingofclearalignermaterialsascopingreviewofmethodsresultsandclinicalrelevance AT chrislouca invitroflexuraltestingofclearalignermaterialsascopingreviewofmethodsresultsandclinicalrelevance AT alessandrovichi invitroflexuraltestingofclearalignermaterialsascopingreviewofmethodsresultsandclinicalrelevance |