Thermoformed vs 3D-printed orthodontic appliances

Iveta Ramonaite, Dental Tribune International

Tue. 20 October 2026

save

LONDON, England: In the literature on 3D-printed orthodontic appliances, laboratory, ageing and safety findings are often discussed as though they carry the same clinical weight as studies involving patients. This ambiguity means that dental professionals may have to rely on manufacturers’ claims. A recent scoping review has examined the evidence on thermoformed and 3D-printed orthodontic appliances and the associated materials to clarify what clinicians can conclude about appliance performance and where important clinical questions remain.

Dr Stefan Abela, lead author of a recent scoping review on 3D-printed and thermoformed aligners. (Image: Dr Stefan Abela)

“I wanted to bring together what the research actually shows so that dental professionals can make an informed choice with confidence,” lead author Dr Stefan Abela, a consultant in orthodontics, told Dental Tribune International.

Of the 22 studies included in the review, the majority concerned performance in the laboratory or material safety, reflecting the fact that the field is still in its early stages. Only two compared clinical outcomes between 3D-printed and thermoformed appliances.

The laboratory findings indicate that 3D printing is a promising and technically viable manufacturing method that offers potential advantages for in-office production and customised appliance production. For example, several laboratory studies reported acceptable or favourable dimensional accuracy under controlled conditions.

However, the review found considerable variation in dimensional accuracy depending on the printer, print orientation, resin and post-processing steps. “A printed aligner is only as good as the workflow behind it,” Dr Abela explained.

Studies of intra-oral ageing showed that material behaviour after use may differ from initial laboratory measurements. Safety investigations examined leaching, cytotoxicity and degree of conversion, identifying resin formulation and post-processing as important variables.

Importantly, the review could not establish whether 3D printing improves treatment results or long-term retainer stability, largely because of the limited clinical comparisons and short follow-up. To address these gaps, the researchers recommended sufficiently large clinical studies that follow patients from the start of treatment through to retention to compare the precision of tooth movement and the stability of outcomes across the different production methods.

Questions about clinical predictability and the long-term behaviour of 3D-printing aligner materials were also raised by Dr Rooz Khosravi, the US ambassador for the European Aligner Society, in an interview with Dental Tribune International. Such evidence matters increasingly as aligners are used in a greater range of cases.

Dr Abela explained: “Thermoforming remains a reliable method with a long track record. Printing offers greater design freedom and can save steps, but it places more responsibility on the clinician or laboratory to follow the resin manufacturer’s instructions closely—particularly for post-curing, which affects both the aligner’s performance and the material’s safety in the mouth.”

The study, titled “Direct 3D printing versus thermoforming for clear aligners and retainers: A scoping review and evidence map”, was published online on 3 September 2026 in Digital and Aligner Orthodontics.