Color improvement and stability of orthodontic clear aligners following different cleaning protocols.

Aesthetics play a crucial role in patients’ choice of orthodontic clear aligners, as poor color stability can compromise their appearance during wear. This study aimed to evaluate the color and surface stability of different types of orthodontic clear aligners exposed to various concentrations of curcumin solutions in vitro. Four types of clear aligners (Invisalign, Angelalign, Spark, and Dreve), along with non-thermoformed Dreve film, were cut into 5 mm × 5 mm squares and immersed in curcumin solutions of different concentrations and a control solution. The concentrations were determined based on the curcumin content in curry. Anhydrous ethanol was used as the solvent, which may influence surface properties and color stability and partially simulating damage caused by alcohol consumption or bacterial metabolites. After immersion for 12 h and 7 days, the squares were ultrasonically cleaned, and color changes were measured using a colorimeter, then converted to National Bureau of Standards (NBS) units. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface characteristics before and after staining. After 12 h of immersion in 10 µg/ml solutions, all samples except the Dreve film exhibited at least an “Appreciable: marked change,” with Angelalign showing a more pronounced color alteration. After 7 days of immersion, most materials displayed color changes ranging from “Much: extremely marked change” to “Very much: change to other colors.” Across all concentrations and time points, Invisalign aligners exhibited significantly higher ΔE* values than Dreve (P < 0.05). Although SEM and AFM results were not entirely consistent, both indicated that PU-based aligners were more susceptible to surface morphology changes than PET-G-based aligners. Enhancing the aesthetic color stability of orthodontic materials could contribute to improved clinical outcomes.

(1) Background: Clear orthodontic aligners support the development of oral biofilms, which could lead to interferences with the oral microbiota already existing and the deterioration of oral health, with the development of dental caries, periodontal disease and even systemic infections. Therefore, preventive oral health care requires a cleaning and disinfection procedure for aligners. (2) Methods: A systematic review of the literature was conducted across four databases following the PRISMA guidelines up to May 2021, combining an electronic and a manual search. Prospective studies, including randomized controlled trials (RCTs), crossover studies (COSs) and controlled clinical trials (CCTs), published in the English language without time restrictions, evaluating the efficacy of cleaning and disinfection protocols for clear orthodontic aligners by comparing them with a placebo or a negative control, were included. The article selection, data extraction and risk of bias assessment were performed by two independent blinded review authors. In case of disagreement, a third author was solicited throughout the selection process. (3) Results: Among the 221 articles screened in the search process, 4 studies were included in the review, all designed as crossover studies (single arm without randomization with the same sequence of different cleaning and disinfection protocols for each participant). Different cleaning and disinfection methods were studied such as mechanical methods (brushing with toothpaste or vibration), chemical methods/pharmaceutical products (chlorhexidine antibacterial substance, anionic or cationic detergents or effervescent tablets) or combinations of both. (4) Conclusion: Although the determination of the most remarkable method of cleaning and disinfection was impossible because no direct comparison was conducted between all these methods, a multi-step protocol, including the combination of a mechanical and a chemical method, seems to be the most effective approach. Further research is needed to define the most preventive oral health care protocol. Registration: PROSPERO CRD 42021278498.

Assessing colour stability of direct printed and thermoformed aligners: An in vitro study on aesthetics longevity.

In-house printing of clear aligners (CAs) may represent a new revolution in CA therapy, providing a solution for the several limitations associated with indirect manufacturing. This study compared the changes in surface roughness and light transmittance (T%) of directly printed (DP) and thermoformed (TF) CAs after exposure to in vitro aging and different cleaning methods.A total of 48 aligners were fabricated using either multilayer thermoplastic polyurethane (CA Pro + , Scheu Dental; Iserlohn, Germany) or direct three-dimensional-printed resin (Tera Harz TC-85, Graphy; Seoul, Korea). CAs were aged in vitro (thermocycling and artificial saliva) and cleaned for 14 days with the following methods: Polident tablets, an electric toothbrush, Pril dish soap, an ultrasonic cleaning machine, and distilled water. Subsequently, alterations in surface roughness and T% were investigated using atomic force microscopy and spectrophotometry, respectively. This study was conducted from January to July 2025 at the Department of Orthodontics, College of Dentistry, University of Baghdad, Baghdad, Iraq, with additional laboratory work at the University of Technology/Ministry of Science and Technology.Data analysis included descriptive statistics, independent t-tests, one-way analysis of variance, and post hoc tests (Tukey's honestly significant difference or Games-Howell).Compared with the DP aligners, the TF aligners presented greater T% under all conditions, with the highest T% in the as-received condition. The TF and DP aligners showed the lowest T% in ultrasonic cleaning and control conditions, respectively. When excluding the as-received group, most cleaning methods showed statistically significant differences in T%. The surface roughness of the TF aligners was consistently lower than that of the DP aligners, with significant differences observed between the Polident and control groups.Cleaning methods altered the optical and morphological properties of both aligners. Customized cleaning methods are required for CAs.

Objective To evaluate the stain resistance and color stability of four Clear aligners (CA) brands against various beverages at different intervals, along with assessing the elaboration of cleaning agents. Methods In a strictly controlled lab environment, 48 CAs from four different companies (Invisalign, EON, Clear Cap, and K clear) were immersed for seven days in six different beverages based on their pH (Pepsi, orange juice, milk, coffee, and black tea), as well as a control solution (distilled water). The VITA Easy-Shade compact colorimeter used the Commission International lightening L*a*b* color scheme to evaluate the color change of the aligners at four intervals. T0: before immersing in the solution; T1: twelve hours after immersion; T2: seven days after immersion; and T3/T4: fifteen minutes after exposure to two cleaning agents. The color values were then converted into National Bureau of Standards System (NBS) units. The statistical analysis was carried out using SPSS. A one-way ANOVA test was used to compare the mean color change values of all aligners and staining agents. Results A significant color change in aligners was observed after immersion in the stated solutions (p = 0.01). Additionally, there is a difference when washing with Invisalign foam and M3 cleaners (p < 0.001). Similarly, there were significant color variations between twelve hours and seven days after soaking (p = 0.01). Nonetheless, there were no significant differences in discoloration among the CAs’ manufacturing materials. Conclusions CAs’ staining ability at different time intervals after immersion in various solutions was clearly visible. Aligner cleanser use has a substantial influence on reducing acquired pigmentation. However, there were minimal differences in discoloration across CA brands.

The aim of this study was to evaluate and compare the colour stabilities of three types of orthodontic clear aligners exposed to staining agents in vitro. Sixty clear orthodontic aligners produced by three manufacturers (Invisalign, Angelalign, and Smartee) were immersed in three staining solutions (coffee, black tea, and red wine) and one control solution (distilled water). After 12-h and 7-day immersions, the aligners were washed in an ultrasonic cleaner and measured with a colourimeter. The colour changes (ΔE*) were calculated on the basis of the Commission Internationale de I'Eclairage L*a*b* colour system (CIE L*a*b*), and the results were then converted into National Bureau of Standards (NBS) units. Fourier transformation infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were conducted to observe the molecular and morphologic alterations to the aligner surfaces, respectively. The three types of aligners exhibited slight colour changes after 12 h of staining, with the exception of the Invisalign aligners stained with coffee. The Invisalign aligners exhibited significantly higher ΔE* values (ranging from 0.30 to 27.81) than those of the Angelalign and Smartee aligners (ΔE* values ranging from 0.33 to 1.89 and 0.32 to 1.61, respectively, P<0.05). FT-IR analysis confirmed that the polymer-based structure of aligners did not exhibit significant chemical differences before and after the immersions. The SEM results revealed different surface alterations to the three types of aligner materials after the 7-day staining. The three types of aesthetic orthodontic appliances exhibited colour stability after the 12-h immersion, with the exception of the Invisalign aligners stained by coffee. The Invisalign aligners were more prone than the Angelalign and Smartee aligners to pigmentation. Aligner materials may be improved by considering aesthetic colour stability properties.

The aim of this study was to evaluate the effect of aging and mechanical brushing on the color stability and translucency of three-dimensionally (3D) printed and thermoformed transparent aligners (clear aligners [CAs]) of different thicknesses. Three types of CAs (Dentsply Sirona Essix [Group 1], Scheu-Dental Thermoforming Foils [Group 2], and 3D-printed Nexdent [Group 3]) in two thicknesses (0.75 mm and 1.0 mm) were used. Each group was divided into cleaned and noncleaned subgroups (n = 10). Samples were aged in artificial saliva and subjected to mechanical brushing. Color differences (ΔE00) and relative translucency parameter values (RTP00) were recorded at 1-week intervals over 4 weeks. Statistical analyses included generalized linear models and repeated measures analyses of variance (ANOVAs) for normally distributed parameters, and robust ANOVAs and Friedman tests for nonnormally distributed parameters (P < .05). Group 1 had the highest mean RTP00 values, while Group 3 had the lowest mean RTP00 values. Noncleaned CAs exhibited higher RTP00 values than cleaned CAs (P < .05). RTP00 values decreased significantly over time, with Group 3 showing notable differences between cleaned and noncleaned subgroups. Thinner materials (0.75 mm) displayed greater color changes than thicker ones (1 mm). 3D-printed CAs demonstrated more significant color variation and less translucency in comparison to thermoformed CAs. Regular cleaning helps maintain translucency and color stability, but the choice of aligner material is crucial.

As clear aligner technology (CAT) gains prominence, the performance of composite attachments - critical devices for optimizing aligner retention and tooth movement control - require systematic evaluation. This study assesses three light-cured composites (Filtek™ Z250 XT, Z350 XT, and P60; 3M ESPE) regarding color stability, shear bond strength (SBS), and durability to establish evidence-based selection criteria. Attachments were bonded to mandibular premolars, simulating the clinical process, and materials were tested for color changes (after immersion in coffee, cola, or iced tea), SBS, and durability (wear volume, surface roughness, morphology, post-aging SBS). The data obtained from the study were statistically evaluated via the Shapiro-Wilk test, the Levene test, t-tests, one-way analysis of variance and chi-square test. A p-value < 0.05 was considered statistically significant. Z250 showed significantly higher coffee - induced discoloration than Z350 (p < 0.05) and P60 (p < 0.01), exceeding clinical acceptability (ΔE00 ≥ 3.3). Z250 also emerged similar trends with cola and iced tea. Z350 exhibited the highest immediate SBS (p < 0.05 vs. Z250) that may cause enamel damage. P60 demonstrated superior wear resistance, with significantly lower surface roughness (Sq / Sa) than Z250 (p < 0.001) and Z350 (p < 0.01), and the smallest post-wear defect volume (p < 0.01 vs. Z250). The SBS differences in immediate groups were eliminated through aging treatment. Z250 underperformed in color stability, SBS, and durability versus Z350/P60, though demonstrated cost-effectiveness. Z350 offers outstanding color durability and higher SBS but risks enamel damage from interfacial delamination. P60 excels with color stability, acceptable adhesive remnants, and exceptional wear resistance, serving diverse clinical needs. Clinical decisions could prioritize P60 for function-aesthetic balance, with targeted Z350/Z250 use in special scenarios.

To determine effects of printing layer thickness and build orientation on mechanical properties and color stability of direct 3D-printed clear aligner resin. Specimens were printed using 3D printed clear aligner resin with two printing layer thicknesses (50 µm, 100 µm) and three build orientations (90°, 60°, and 45°). Mechanical properties (tensile stress, tensile strain, and elastic modulus), color stability in coffee and artificial saliva, and roughness were then evaluated. Specimens printed with a 50 µm layer thickness and orientation at 90° demonstrated superior color stability in artificial saliva. However, all specimens showed high susceptibility to coffee staining regardless of layer thickness or orientation. Mechanical properties were improved in the order of 90° < 60° < 45° build orientation, showing statistically significant differences (P < .05). Surface roughness was increased in the order of 90° < 60° < 45° build orientation, showing statistically significant differences (P < .05). Printing layer thickness and orientation exerted significant effects on mechanical properties, color stability, and surface roughness of 3D-printed clear aligner resin.

Clear aligner treatment is an orthodontic treatment that is custom-made with 3D printers without the use of conventional metal or porcelain wires and brackets. It is a modern orthodontic method used to correct tooth positions that need to be corrected aesthetically and functionally. Aim This study aimed to compare the discolouration of teeth and clear aligners after 15 days of full-time use of clear aligners. Materials and methods The 20 patients in the study group had used clear aligners for 45 days, including three different clear aligners for 15 days. In addition, 20 patients were included as a control group to measure the difference in tooth discolouration. Retaining attachments using G-Aenial (GC Corp, Tokyo, Japan) and 3M ESPE (St. Paul, MN, USA) flowable composites were placed crosswise to each patient in the distal regions of all lateral and canine teeth. The performance of three aligner plates (Zendura Flex (Bay Materials LLC, Fremont, CA, USA); Duran (ScheuDental GmbH, Iserlohn, Germany); and Taglus (Laxmi Dental Export Pvt. Ltd, Mumbai, India)), two fluid composite attachments, and two clear aligner cleaners regarding discoloration were tested. Each aligner was used for 15 days, and then the patient was moved to the next aligner. Colour change on the aligners and the patients' teeth were assessed from the canine to the middle third and mid-plane of the canine tooth using a VITA Easyshade V spectrophotometer (Bad Säckingen, Germany). An aligner cleaner was used immediately after the patients used their clear aligners, and then the measurements of the aligner color values were completed. The 120 aligners obtained were divided into two groups. Sixty aligners were treated with Fresh Guard (Efferdent, Lynchburg, VA, USA), and the other 60 were treated with Corega (GlaxoSmithKline, London, UK) tablets and stored in a glass of water. Results The colour stability of G-Aenial Flo was higher than that of the 3M ESPE fluid composite (p=0.040 and p=0.024). Our study determined that staining occurred in all the teeth we measured as a result of using aligner. Fresh Guard aligner cleaner caused more discoloration on Zendura and Duran aligners than Corega aligner cleaner (p<0.05). Taglus plaque was found to have more discoloration than Zendura and Duran aligner (p<0.05). Conclusion In conclusion, Duran clear aligners are preferable to other clear aligners in terms of discoloration. In addition, G-Aenial Flo can be recommended as an attachment or fluid composite because of its better color stability results.

The objective of this article was to systematically review the literature to determine how effective tooth whitening procedures are when carried out in tandem with orthodontic clear aligners. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Online searches of PubMed, Medline via Ovid, Science Direct, the Cochrane database of systematic reviews via Ovid, Scopus, and Google Scholar as well as manual searches of the references of the selected articles were conducted. Clinical studies which assessed the efficacy of dental bleaching using orthodontic clear aligners were included in the present study. Data from the included studies were extracted and assessed for risk of bias using the Cochrane risk of bias tool. Three studies met the inclusion and exclusion criteria and were included in this study. One study compared the efficiency of tooth bleaching between clear aligners and conventional bleaching trays. One study evaluated the effectiveness of dental bleaching using clear aligners by comparing the tooth shade of those patients to a control group of patients who did not receive dental bleaching during orthodontic clear aligner treatment. One study evaluated the effectiveness of different concentrations of different bleaching agents using clear aligners. All the included studies showed an improved tooth shade when using clear aligners as bleaching trays.

To compare incisor angulation and/or position changes among orthodontically treated patients with metal brackets and clear aligners. A total of sixty-two participants of both sexes, aged-16-40 years old, with CL I skeletal pattern and mild crowding following strict eligibility criteria were included. The patients were divided into two groups based on their treatment approach. Pre and post lateral cephalograms were collected from Riyadh Elm University (REU) and then digitally analyzed using WEBCEPH (Medical Image Analysis) software. Eight angular and two linear measurements were used for the assessment. The upper incisor angulation and position showed statistically significant differences when orthodontic clear aligners were used. In contrast, no significant difference was observed with the conventional orthodontic treatment. However, the upper incisal palatal root torque decreased after clear aligner therapy compared to conventional treatment. The inter-incisal angle demonstrated a significant increase with clear aligners compared to conventional treatment. The current study revealed the importance of definitive guidelines upon and after treatment, in addition to determining incisor changes. Orthodontic clear aligners are distinct from conventional treatments in controlling the incisors' angulation and position. The expansion treatment modality precedes Interproximal reduction in increasing the arch perimeter.

BackgroundStaining clear aligners from beverages commonly occurs and can affect a patient’s self-esteem and confidence in social interactions. The aim of the present study was to evaluate the color stability of clear aligners when exposed to several types of beverages.MethodsA total of 704 (seven hundred four, 176 per brand) clear aligner samples from four brands (Beforedent®, Käse Aligner®, Invisalign® and ClearCorrect®) were immersed in three types of beverages (tea, coffee and cola) and a control solution (artificial saliva) for 6 and 12 hours. The color before immersion (T0), after 6 hours (T1) and 12 hours after immersion (T2) were measured in the CIE L*-a -b system, the color difference (ΔE*) and the National Bureau of Standard Unit (NBS) were calculated. Fourier transform infrared spectroscopy (FTIR) and 3D laser scanning microscopy were performed to identify the polymer composition and surface properties. The data were analyzed via two-way ANOVA and multiple comparisons using Bonferroni corrections, with P < 0.05 indicating statistical significance.ResultsAfter 6 and 12 hours, Invisalign® in coffee and tea presented significantly greater color differences than ClearCorrect®, Beforedent®, and Käse Aligner® did. No significant color changes were observed in the cola or artificial saliva (control) for any of the brands. According to the FTIR analysis, Invisalign® is made from polyurethane, ClearCorrect® from polyester, and both Beforedent® and Käse Aligner® from polyethylene terephthalate. The highest degree of roughness and porosity was shown on the surface of Invisalign®. The spectral features of samples immersed in colored beverages almost overlapped with as receive samples before immersion.ConclusionsInvisalign® made from polyurethane resulted in the most color changes, followed by ClearCorrect® Beforedent® and Käse Aligner® had the least and equivalent color changes. Coffee caused the most discoloration on clear aligners, followed by tea, cola, and artificial saliva (control). After 6 and 12 hours of immersion, all the groups presented good color stability, except for Invisalign® immersed in coffee for 6–12 hours, and ClearCorrect® immersed in coffee for 12 hours. The removal of clear aligner before beverage consumption is recommended.

It is difficult to find research papers collecting comparative results about characterization studies of clear aligners. Therefore, the aim of this paper is to provide the first comparative analysis of most commercial clear aligners, in terms of their stability towards intra-oral staining agents, their physicochemical and optical properties, as well as their water absorption behavior. Five types of aligners, characterized by different techniques, are considered: Erkodur, Essix Plastic, Ghost Aligner, Zendura, and Invisalign. The obtained results show that clear aligners are made up of PETG, semi rigid PU, and a mixture of PU and PETG, with different degrees of crystallinity which affect the transparency of each aligner. In particular, the PETG-based materials reveal the highest value of short-range order and the highest properties in terms of transparency in the visible range. After 14 days of immersion into red wine and coffee, PETG and PU-based aligners reveal a perceivable change in color (NBS values from 1.5 to 3), corresponding to a loss of transparency due to the deposition of impurities on the surface. These results are particularly marked for Invisalign, showing changes towards other colors (NBS up to 35), probably due to the thermoforming process which led to the formation of a wrinkled surface entrapping the impurities.

Aim The present study aimed to analyse and compare the colour stability of three types of orthodontic clear aligners following in vitro exposure to cigarette smoking and alcohol by using the attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) method. Materials and methods The study included 144 clear aligners divided into 3 groups of 48 each based on different manufacturers and comprised: Group A—Invisalign, Group B—KiyoClear, Group C—OrthoFX. The samples were tested for colour stability related to translucency after exposure to cigarette smoke and alcoholic drinks at times, T0: before exposure (as-received aligner), T1: after a seven-day exposure, T2: after a fourteen-day exposure using the ATR-FTIR method. Data were analysed using one-way ANOVA, Tukey’s post hoc test, Repeated Measures of ANOVA, Bonferroni’s post hoc test, and Independent Student’s t test accepting a p-value &lt; 0.05. Results There was a statistically significant difference in the mean translucency values between the three groups at T0, T1, and T2. All groups exhibited mean translucency values which significantly decreased over time following smoking and alcohol exposure. Conclusion: OrthoFX, KiyoClear and Invisalign showed decreasing translucency values following smoking and alcohol exposure, with smoking causing a greater reduction. Both types of exposure should be avoided to maintain an aesthetic orthodontic appearance.