In vitro cytotoxicity of different thermoplastic materials for clear aligners

Martina, Stefano; Rongo, Roberto; Bucci, Rosaria; Razionale, Armando Viviano; Valletta, Rosa; D’Antò, Vincenzo

doi:10.2319/091718-674.1

Cited by 61 publications

(50 citation statements)

References 20 publications

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“…Clear aligner treatment has been introduced in the last decades to satisfy the aesthetic and comfort requirements of adult orthodontic patients. This treatment is based on removable thermoplastic splints covering all the teeth and part of the marginal aspects of the gingiva, which progressively move the teeth into an ideal position [13]. Thanks to the satisfactory mechanical proprieties of these devices and to the valuable progresses of the aligners technology, nowadays this therapy is suitable for the correction of a wide spectrum of malocclusions [14].…”

Section: Introductionmentioning

confidence: 99%

Impact of Fixed Orthodontic Appliance and Clear Aligners on the Periodontal Health: A Prospective Clinical Study

et al. 2020

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This study aimed to evaluate the periodontal health of orthodontic patients with supportive periodontal therapy in a 3 month follow-up. The sample comprised 20 patients (mean age 20.6 ± 8.1 years) in treatment with multibracket fixed appliances (fixed group—FG) and 20 patients (mean age 34.7 ± 12.5 years) in treatment with clear aligners (clear aligners group—CAG). At baseline (T0) and after 3 months (T1), probing depth (PD), plaque index (PI), bleeding on probing (BOP), and gingival recession (REC) were measured. Patients were trained to perform an individualized tooth brushing technique, and every 2 weeks they were re-called to reinforce the oral hygiene instructions. The intra-group comparisons (T1 vs. T0) were calculated with the Wilcoxon signed-rank test, while a linear regression model was used for the inter-group comparisons (FG vs. CAG). The significance level was set at p < 0.05. Statistically significant decrease in both groups was found for PD (FG: Δ, −9.2 inter-quartile range (IQR), −22.5, −5.5; CAG: Δ, −12.6 IQR, −25.4, −4.8), BOP (FG: Δ, −53.5 IQR, −70.5, −37; CAG: Δ, −37.5 IQR, −54.5, −23), and PI (FG: Δ, −17.5 IQR, −62.5, 14.5; CAG: Δ, −24 IQR, −49.5, −5). The result of the linear regression models suggested that the type of appliance did not have any effects on the improvement of periodontal variables. Therefore, patients undergoing orthodontic treatment with fixed appliances and clear aligners did not show differences in gingival health when followed by a dental hygienist.

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Section: Introductionmentioning

confidence: 99%

Impact of Fixed Orthodontic Appliance and Clear Aligners on the Periodontal Health: A Prospective Clinical Study

et al. 2020

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“…Most previous studies of aligner effects on oral cells used eluate settings [13][14][15]. In our recent study, we investigated for the first time the behavior of oral squamous carcinoma cells directly grown on SmartTrack ® aligner material and found no adverse effect on these cells [19].…”

Section: Discussionmentioning

confidence: 86%

“…To depict the effects of aligner material on oral cells, aligner eluates have been studied on multiple cells, including gingival fibroblasts, keratinocytes, and breast cancer cells. These studies reported a relatively weak cytotoxic effect of aligners under in vitro conditions [13][14][15]. Further, a recent meta-analysis reported inconsistency in the current literature concerning safety considerations.…”

Section: Introductionmentioning

confidence: 99%

Behavior of Primary Human Oral Keratinocytes Grown on Invisalign® SmartTrack® Material

et al. 2021

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Orthodontic clear aligner treatment is gaining tremendous popularity. The world market leader is Align Technology® and its product Invisalign®. Although numerous patients are treated with Invisalign® aligners, only little is known about the cellular effects of aligner material on oral epithelial cells. In the present study, we aimed to investigate the effects of SmartTrack® clear aligner material on directly cultured primary human oral keratinocytes (HOKs). Cell morphology and behavior were investigated by scanning electron microscopy and bright field microscopy. Aligner effects on viability were detected by cell-counting-kit (CCK)-8 and live/dead staining. Gene expression of several inflammatory and barrier proteins was assessed by qPCR. Cells cultured on tissue culture plastic served as control. Cell proliferation/viability was significantly lower in cells cultured on aligner material (p < 0.05) in comparison to control. Live/dead staining did not reveal an increase in the number of dead cells on aligner surfaces. After two and seven days of incubation, interleukin (IL)-6 expression decreased, and IL-8 expression increased in HOKs cultured on aligner surfaces. The expression of intercellular adhesion molecule 1 (ICAM-1) significantly decreased after seven days. Gene expression of epithelial barrier markers showed that integrin (ITG)-α6 significantly decreased after two and seven days. A significant decrease in ITG-β4 and E-cadherin expression levels compared to control could only be seen after seven days. We did not find any cytotoxic effect, but alterations in the cell’s barrier functions and inflammatory reaction were obvious. Clinical studies are required to give further insights into clinical reactions on the underlying aligner material of this quickly expanding orthodontic appliance.

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“…In vitro cytotoxicity of human primary gingival fibroblasts of four thermoplastic materials was assessed after 14 days of exposure, namely Duran (Scheu-Dental GmbH, Iserlohn, Germany), Biolon (Dreve Dentamid GmbH, Unna, Germany), Zendura (Bay Materials LLC, Fremont, CA, USA), and SmartTrack (Align Technology, San Jose, CA, USA) [23]. Each material exhibited a slight level of cytotoxicity that was comparable to other dental materials, e.g., miniscrews or bonding materials.…”

Section: Materials For Thermoformed Alignersmentioning

confidence: 99%

“…Technical properties and cytotoxicity parameters of the most used thermoplastic materials and printing resins are summarized in Table 1 [19,23,29,36].…”

Section: Development Of Clear Aligners-3d Printingmentioning

confidence: 99%

Direct 3D Printing of Clear Orthodontic Aligners: Current State and Future Possibilities

et al. 2021

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The recent introduction of three-dimensional (3D) printing is revolutionizing dentistry and is even being applied to orthodontic treatment of malocclusion. Clear, personalized, removable aligners are a suitable alternative to conventional orthodontic appliances, offering a more comfortable and efficient solution for patients. Including improved oral hygiene and aesthetics during treatment. Contemporarily, clear aligners are produced by a thermoforming process using various types of thermoplastic materials. The thermoforming procedure alters the properties of the material, and the intraoral environment further modifies the properties of a clear aligner, affecting overall performance of the material. Direct 3D printing offers the creation of highly precise clear aligners with soft edges, digitally designed and identically reproduced for an entire set of treatment aligners; offering a better fit, higher efficacy, and reproducibility. Despite the known benefits of 3D printing and the popularity of its dental applications, very limited technical and clinical data are available in the literature about directly printed clear aligners. The present article discusses the advantages of 3D printed aligners in comparison to thermoformed ones, describes the current state of the art, including a discussion of the possible road blocks that exist such as a current lack of approved and marketed materials and limited existence of aligner specific software. The present review suggests the suitability of 3D direct printed aligners is superior to that of thermoformed manufactured aligners because of the prior’s increased accuracy, load resistance, and lower deformation. It is an overall more stable way to produce an aligner where submillimeter movements can make a difference in treatment outcome. Direct 3D printing represents a complex method to control the thickness of the aligner and therefore has a better ability to control the force vectors that are used to produce tooth movement. There is currently no other approved material on the market that can do this. The conclusion of this article is that we encourage further in vitro and in vivo studies to test these new technologies and materials.

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In vitro cytotoxicity of different thermoplastic materials for clear aligners

Cited by 61 publications

References 20 publications

Impact of Fixed Orthodontic Appliance and Clear Aligners on the Periodontal Health: A Prospective Clinical Study

Impact of Fixed Orthodontic Appliance and Clear Aligners on the Periodontal Health: A Prospective Clinical Study

Behavior of Primary Human Oral Keratinocytes Grown on Invisalign® SmartTrack® Material

Direct 3D Printing of Clear Orthodontic Aligners: Current State and Future Possibilities

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