Dental Tribune International

Dental resins used in 3D printing may impair reproductive health

By Dental Tribune International
February 11, 2021

CHICAGO/EVANSTON, Il., U.S.: The recent development of resins marketed as biocompatible has led to the widespread application of 3D-printable resins, for example in medical devices and tissue engineered constructs. However, researchers from Northwestern University in Chicago and in Evanston have found that two 3D-printable resins for use in dental applications leach compounds that can cause severe toxic effects in the oocyte, the immature precursor to the ovum that can eventually be fertilized.

Although there have been previous studies investigating potential toxicities from exposure to 3D-printed materials, there have been no studies examining the potential reproductive toxicities induced by these materials in mammals.

“Despite the revelations surrounding BPA almost 20 years ago, it is still rare that the potential impact new materials may have on reproductive health are rigorously and systematically studied despite their ubiquitous nature in our day-to-day lives,” said Dr. Francesca Duncan, co-author of the study and assistant professor of obstetrics and gynecology at Northwestern University Feinberg School of Medicine, in a university press release.

According to her, the clear aligner market that uses resins such as Formlab’s Dental SG (DSG) and Dental LT (DLT) has become a multibillion-dollar business in recent years, and some companies utilize 3D-printing techniques in manufacturing, owing to their rapid production abilities.

The research team discovered the toxicity while using 3D-printing technology to create the first ex vivo model of the female reproductive tract. They found that the toxic outcomes of DLT were more severe than those of DSG. Owing to that and because DTL is intended for manufacturing of oral retainers, which individuals would wear over extended periods, resulting in long-term exposure, the researchers focused on DTL for their analysis.

They characterized the leachates of DLT resins using mass spectroscopy and identified Tinuvin 292 (BASF), a commercial light stabilizer that is commonly used in the production of plastic materials, as a major component. The researchers attributed the significant ovo-toxicity to this substance.

“Our results are important because they demonstrate leachates from commonly used materials in 3D printing slated as ‘biocompatible’”

The significance of the study’s findings may extend far beyond 3D-printing processes, however, because Tinuvin 292 is a common additive used in the production of many different types of plastic consumer products, said Duncan.

“Our results are important because they demonstrate leachates from commonly used materials in 3D printing slated as ‘biocompatible’ but may have adverse effects on reproductive health,” she added and emphasized that “there is a critical need to better understand the identity and biological impact of compounds that leach from these materials.”

The research group highlighted that, even though both DSG and DLT are marketed as biocompatible photopolymers, their “results demonstrate that the context for biocompatibility is critical.” They pointed out that, despite the importance of reproductive health, the certification of biocompatibility by the International Organization for Standardization does not require reproductive health safety testing, except in cases where materials come into direct contact with reproductive tissue.

“The results demonstrate reproductive toxicity should be a priority when characterizing all materials humans may come into contact with either in a medical setting or in their day-to-day lives,” emphasized Duncan.

The researchers stated that further studies are needed to investigate in vivo effects, since the current study provided only evidence in an in vitro setting. Additionally, it will be important to examine the toxicity on the male reproductive system and to identify any sex differences. Another field of interest is the characterization of the release and the exposure levels of Tinuvin 292 in humans, in the case of both medical products as well as consumer products.

The study, titled “Dental resins used in 3D printing technologies release ovo-toxic leachates,” was published in Volume 270 of Chemosphere.

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