ArticleProgress in orthodontics2026
Towards standardizing cytotoxicity testing of 3D-printed orthodontic aligners and retainers: a scoping review.
Article in Progress in orthodontics, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
5 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThree-dimensional (3D) printing enables customized orthodontic aligners and retainers, but concerns persist regarding the biocompatibility of printable resins. Although ISO 10993-5 and ISO 10993-12 provide guidance for in vitro cytotoxicity testing and sample extraction, substantial flexibility in reporting and execution may hinder comparability across studies.
objectiveTo map how in vitro cytotoxicity testing is performed for materials used to 3D-print orthodontic aligners/retainers and to identify variation and reporting gaps in key ISO 10993-5/-12 testing domains.
methodsFollowing PRISMA-ScR, Ovid MEDLINE, Embase, and Web of Science were searched from database inception to 9 April 2025. Peer-reviewed studies assessing in vitro cytotoxicity of 3D-printed aligners/retainers (and closely related intraoral appliances where relevant) were included. Data were charted across extraction protocols (ISO 10993-12-related), cell exposure parameters, and cytotoxicity assays (ISO 10993-5-related).
resultsTwenty-five studies published between 2020 and 2025 were included. Seventeen studies (17/25, 68%) explicitly stated compliance with ISO 10993-5 and/or ISO 10993-12. The remaining studies varied in ISO referencing (threshold-only, intentional deviation, or no ISO reference). Most studies used extract-only testing (15/25, 60%), followed by direct contact only (6/25, 24%) and combined extract-based and direct-contact approaches (3/25, 12%); one study used an alternative indirect monomer-in-ethanol approach (1/25, 4%). Among studies with an extraction component (19/25, 76%), extraction duration ranged from 24 h to 14 days, with 24 h being most common (9/19, 47%) and 14 days reported in 3/19 studies (16%). Extraction medium was reported in 18/19 studies (95%); among these, DMEM/DMEM-based media were most common (12/18, 67%). Numerical surface-area-to-volume reporting, a key ISO 10993-12 parameter, was provided in 11/19 studies (58%), while 8/19 (42%) explicitly did not report it. Most studies relied on a single metabolic activity assay (19/25, 76%), most frequently the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, with limited use of complementary membrane integrity assays (5/25, 20%) or biomass-based assays (1/25, 4%).
conclusionsIn vitro cytotoxicity testing of 3D-printed orthodontic materials shows substantial heterogeneity and frequent reporting gaps across extraction conditions, exposure parameters, and assay strategies. Claims of ISO adherence are common but are variably supported by reporting of key ISO 10993-5/-12 domains. More consistent reporting and harmonization of extraction and testing parameters are needed to improve reproducibility and clinical interpretability.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.