# Next-Generation Orthodontics: Functional Resins, Biomechanics, Biocompatibility, and Current Clinical Reality of Direct 3D-Printed Aligners

## TL;DR

This review explores the rise of 3D-printed aligners in orthodontics, their materials, functionality, and clinical potential compared to traditional methods.

## Contribution

The paper introduces the functional and clinical advancements of direct 3D-printed aligners, including integrated drug delivery and antibacterial features.

## Key findings

- Direct 3D-printed aligners offer better dimensional control and eliminate waste compared to traditional aligners.
- Functional resins can be engineered with antibacterial agents and remineralization fillers for added benefits.
- Clinical data is limited, and long-term trials are needed to confirm safety and efficacy of DPAs.

## Abstract

The orthodontic landscape is currently witnessing a significant technological evolution with the emergence of direct 3D-printed aligners (DPAs), which promise to close the digital workflow loop by eliminating the geometric limitations and solid model waste inherent to traditional thermoformed clear aligners (TCAs). This review provides a comprehensive analysis of the material science governing this transition from inert thermoplastic sheets to reactive photocurable resins. We explore the fundamental chemistry of DPA materials, and the pivotal role of post-processing in ensuring mechanical integrity and biocompatibility. Beyond passive mechanics, this review highlights preclinical research in functional material engineering, detailing how experimental DPAs are being investigated for the integration of antibacterial agents, remineralization fillers, and drug delivery systems. Furthermore, we evaluate the limited but emerging clinical data on DPAs, contrasting their shape-memory properties and force delivery profiles with conventional appliances, while critically addressing emerging safety concerns regarding monomer elution and microplastic generation. We conclude that while DPA technology offers superior dimensional control, comprehensive life cycle assessments and long-term in vivo trials are essential to fully substantiate their clinical efficacy, overall sustainability, and potential as advanced orthodontic appliances.