Predictability of tooth rotations in patients treated with clear aligners.

Clear aligners are employed daily for the treatment of several malocclusions. Previous clinical studies indicated low accuracy for the correction of tooth rotations. The aim of this study was to evaluate the predictability of tooth rotations with clear aligners. The sample comprised 390 teeth (190 mandibular; 200 maxillary), measured from the virtual models of 45 participants (21 men, 24 women; mean age: 29.2 ± 6.6 years old). For each patient, pre-treatment (T0) digital dental models (STL files), virtual plan (T1) and post-treatment digital dental models (T2) of both the mandibular and maxillary arches were imported onto Geomagic Control X, a 3D metrology software which allows angular measurements. Rotations were calculated by defining reproducible vectors for all teeth in each STL file and superimposing both T0 with T1 to determine the prescribed rotation, and T0 with T2 to determine the achieved rotation. Prescribed and achieved rotations were compared to assess movement's accuracy. The Wilcoxon signed-rank test and paired t-test were used to assess differences between the prescribed and achieved movements (P < 0.05). The overall predictability of rotational movement was 78.6% for the mandibular arch and 75.0% for the maxillary arch. Second molar accuracy was the lowest in both arches. Clear aligners were not able to achieve 100% of the planned movements.

Preformed Elastodontic Appliances: Awareness and Attitude of Orthodontists and General Dental Practitioners.

BACKGROUND: Preformed elastodontic appliances (EAs) have been described as safe, cost-effective, and easy-to-use devices for interceptive orthodontic treatment in growing patients. This study aimed to assess the knowledge and the attitude of dentists toward the use of EAs and to compare the behaviors of orthodontists (Os) with those of general dental practitioners (GDPs). METHODS: An anonymous survey was distributed among dentists through social media. Twenty-two items were divided as follows: characteristics of respondents; general knowledge about EAs; section for EA-users; and section for EA non-users. Chi-squared tests were used to analyze differences in responses between groups. RESULTS: Participants included 226 Os and 168 GDPs. The majority in both groups reported having adequate knowledge about EAs and utilizing them in their practice. GDPs usually use EAs to treat children during the early phase of growth, while Os also use EAs to address orthodontic problems in different stages of dentition, experiencing a chair time reduction compared with traditional appliances. Regarding EA non-users, GDPs seem not to find an application among their patients, whereas Os reported not having enough patient compliance during treatment. CONCLUSIONS: Although treatment with EAs is common among all dentists, differences exist between Os and GDPs in the awareness and application, as well as in the reasons provided for not using EAs.

The Predictability of Transverse Changes in Patients Treated with Clear Aligners.

Arch expansion might be used to correct buccal corridors, improve smile aesthetics, resolve dental cross bite, and gain space to resolve crowding. In clear aligner treatment, the predictability of the expansion is still unclear. The purpose of this study was to evaluate the predictability of dentoalveolar expansion and molar inclination with clear aligners. In the study, 30 adult patients (27 ± 6.1 years old) treated with clear aligners were selected (treatment time: 8.8 ± 2.2 months). The upper and lower arch transverse diameters were measured for canines, first and second premolars, and first molars on two different sides (gingival margins and cusp tips); moreover, molar inclination was measured. A paired t-test and Wilcoxon test were used to compare prescription (planned movement) and achieved movement. In all cases, except for molar inclination, a statistically significant difference was found between achieved movement and prescription (p < 0.05). Our findings showed a total accuracy of 64% for the lower arch, 67% at the cusp level, and 59% at the gingival level, with a total accuracy of 67% for the upper arch, 71% at the cusp level, and 60% at the gingival level. The mean accuracy for molar inclination was 40%. Average expansion was greater at cusps of canines than for premolars, and it was lowest for molars. The expansion achieved with aligners is mainly due to the tipping of the crown rather than bodily movement of the tooth. The virtual plan overestimates the expansion of the teeth; thus, it is reasonable to plan an overcorrection when the arches are highly contracted.

Predictability of Maxillary Molar Distalization and Derotation with Clear Aligners: A Prospective Study.

Clear aligners are employed daily for the treatment of Class II malocclusions, when a valid option involves distalization and derotation of the upper first and second molars. Evidence regarding the predictability of these movements is slight, and the treatment outcome that clinicians plan may not be achieved. Therefore, the purpose of this study is to assess the accuracy of distalization and derotation with clear aligners. Geomagic Control X, a 3D quality control software, was used to superimpose digital models of the pre-treatment, post-treatment, and virtual plan (ideal post-treatment) measurements of 16 patients (4 M, 12 F; mean age 25.7 ± 8.8 years). Linear and angular measurement tools were used to calculate the amount of tooth movement prescribed and achieved. Distal displacement of the buccal cusps had an overall accuracy of 69% for the first molar and 75% for the second molar. The accuracy of molar derotation was higher for the first molar (77.5%) than for the second molar (62.7%). The aligners were not able to achieve 100% of the ideal post-treatment result; thus, planning of refinements is often needed. However, clear aligners can be regarded as a valuable option for the distalization of first and second molars.

Clear Aligners Treatment of Class III Subdivision with an Extraction of a Lower Bicuspid.

The aim of this study was to show a case of a Class III subdivision adult patient treated with clear aligners (CA) and the extraction of a lower bicuspid. A 19-year-old male with a class III canine and molar relationship on the right side and a deviation of lower dental midline to the left asked for an aesthetic treatment. He refused orthognathic surgical procedures, so he was offered a camouflage orthodontic treatment with the extraction of lower right first premolar to achieve a canine Class I relationship and to center the lower midline. The treatment was performed with clear aligners and the use of Class III elastics to maintain distal anchorage on the right side during the canine distalization. At the end of the treatment, the occlusal objectives were achieved.

Three-Dimensional Evaluation of Condyle-Glenoid Fossa Complex Following Treatment with Herbst Appliance.

The purpose of the present retrospective observational study was to compare the effects of treatment with Herbst appliance and fixed therapy with elastics on the condyle and glenoid fossa complex. Thirty patients aged between twelve and sixteen years with skeletal Class II malocclusion who met the inclusion criteria were included in the study: fifteen patients treated with Herbst appliance (Group 1), and fifteen patients treated with orthodontic camouflage using MBT prescription (MBTTM Versatile+ Appliance System) (Group 2). For Group 2, patients had CBCT scans taken before treatment either after Herbst appliance removal or at the end of treatment. CBCT scans were evaluated for changes in condyle-glenoid fossa complex using the In Vivo Dental 5.1 software. Statistical significance was set at p ≤ 0.05. On inter-group comparison, the Herbst group showed statistically significant increases in the condylar height of 1.35 mm (p ≤ 0.001) on the right and 1.21 mm (p ≤ 0.01) on the left side, and a condylar volume of 111.03 mm3 (p ≤ 0.01) on the right and 127.80 mm3 (p ≤ 0.001) on the left side. The Herbst group showed anterior remodelling on the postero-superior aspect of glenoid fossa. Herbst appliance treatment induced growth at the condylar head and anterior remodelling of glenoid fossa, thereby improving the maxilla-mandibular relationship in growing skeletal Class II patients.

Pseudo Hemifacial Microsomia With Condylar-Coronoid Collapse: New Therapeutic Approach in Growing Patients.

The purpose of this study is to describe the management of 2 dimorphic patients affected by Hemimandibular Hypoplasia with Condylar-Coronoid Collapse (HH-CCC), also called Pseudo Hemifacial Microsomia, where the orthopedic treatment gave an excellent long-term follow-up. The patients were a 7-year-old female and a 6-year-old male with a HH-CCC on the left side, an asymmetrical face with chin deviation, class II dental malocclusion and canting of the occlusal plane. An X-ray evaluation and clinical observation confirmed the unilateral mandibular deficiency and the collapse of the condyle on the coronoid process on the affected side. The treatment plan consisted of the use of an asymmetrical functional appliance with a vertical screw. The appliance was gradually activated on the vertical plane on one side by a screw incorporated on an acrylic plate. It was used for 22 hours/day, including sleep time but not during meals. This treatment improved the patient' s facial appearance. HH-CCC showed a positive response to functional therapy.

Dentoalveolar Fractures: New Orthodontic Protocol Proposal and Pilot Study.

The goal of fracture treatment that includes the dentoalveolar process is to obtain the anatomic bone healing and the pre-injury occlusion restoration with functional and aesthetic recovery, avoiding dental or periodontal lesions. Fractures activates, in the damaged tissue, the Regional Acceleratory Phenomenon, a physiological healing process that can also be activated during orthodontic overloads. Orthodontic treatment in the traumatized area could exploit this phenomenon in order to sustain the cellular activity.The aim of this study is to propose a treatment protocol for dentoalveolar fractures based on the use of orthodontics in order to sustain the physiological healing process known as Regional Acceleratory Phenomenon.The authors present 2 cases of an 18 year old woman and 23 year old man affected by dentoalveolar fracture. The operative protocol the authors applied foresaw three steps of treatment: orthodontic brackets application, surgery, orthodontic treatment.The patients showed complete healing at the 3 months follow-up and were treated up to 18 months for further orthodontic treatment.The operative protocol proposed by the Authors appears to be a rational choice since it allows a single orthodontic device to be an "active splinting system", with fast application time, good acceptance by the patient, low complications rate; moreover, it produces any planned dental movements for further orthodontic treatments.

Orthodontics First in Hemimandibular Hyperplasia. "Mind the Gap".

A 32-year-old man was referred to the Division of Orthodontics of the University of Naples "Federico II", with a 15-year history of gradually increasing right-sided facial asymmetry. Clinical and radiological examinations was consistent to hemimandibular hyperplasia, a rare developmental asymmetry characterized by three-dimensional enlargement of one-half of the mandible. The standard surgical-orthodontic management was proposed to the patient. However, he refused to undergo bimaxillary orthognatic surgery. Therefore, a different treatment was proposed based on the orthodontic technique of pre-surgical decompensation and post-surgical refinement used in bimaxillary orthognatic surgery planning, and surgical intervention with a condylectomy. The dental arches were evenly levelled out with a multi-bracket treatment and then the condylectomy was performed. Orthodontic treatment continued with a levelling and torque control by 0.19 × 0.25 SS arch and physiotherapy. At the three-month follow-up, the patient showed anterior and posterior bite rebalancing, arch intercuspation recovery, and anterior open bite closure due to muscular self-rebalancing. The two-year follow-up showed regular mandibular dynamic, orthodontic appliances were removed, and the patient was instructed to wear retainer for the following months. The final result was aesthetically reasonable for the patient, although slight asymmetry of the chin persisted.

Relationship between the Condylion-Gonion-Menton Angle and Dentoalveolar Heights.

An accurate estimation of both facial growth and the dentoalveolar dimension is key to successful treatment. The aim of this study was to analyze the relation between the Condylion-Gonion-Menton angle (CoGoMe^) and dentoalveolar heights in a population of patients from southern Italy. This retrospective study analyzed 270 cephalograms of 115 males (42.1%, mean age 15.5 ± 5.2 years) and 155 females (57.9%, mean age 15.6 ± 5.9 years). The facial divergency was evaluated with the Sella-Nasion and Gonion-Gnation angle (SN^GoGn), mandibular structure with the CoGoMe^, and dentoalveolar heights were assessed in four measurements: upper anterior (UADH), lower anterior (LADH), upper posterior (UPDH), and lower posterior (LPDH). Data were analyzed by means of Pearson's correlation and linear regression model (p < 0.05). All the dentoalveolar heights were strongly correlated among them (p < 0.001). The UADH was correlated with the SN^GoGn (r = 0.145; p = 0.017), while the LPDH was correlated with the CoGoMe^ (r = -0.183; p = 0.003). Moreover, there was a positive association between the UADH and the SN^GoGn (B = 0.08; 95% CI: 0.014-0.144; p = 0.017), and a negative association between the CoGoMe^ and the LPDH (B = -0.098; 95% CI: -0.161-0.035; p = 0.003). Facial divergency and mandibular structure are associated with dentoalveolar heights.

Promising Scaffold-Free Approaches in Translational Dentistry.

Regenerative medicine has recently improved the principal therapies in several medical fields. In the past ten years, the continuous search for novel approaches to treat the most common dental pathologies has developed a new branch called regenerative dentistry. The main research fields of translational dentistry involve biomimetic materials, orally derived stem cells, and tissue engineering to populate scaffolds with autologous stem cells and bioactive growth factors. The scientific literature has reported two main research trends in regenerative dentistry: scaffold-based and scaffold-free approaches. This article aims to critically review the main biological properties of scaffold-free regenerative procedures in dentistry. The most impactful pros and cons of the exosomes, the leading role of hypoxia-based mesenchymal stem cells (MSCs), and the strategic use of heat shock proteins in regenerative dentistry will be highlighted and discussed in terms of the use of such tools in dental regeneration and repair.

Evaluation of Profile Changes in Class II Individuals Treated by Means of Herbst Miniscope Appliance.

BACKGROUND: To evaluate the profile changes following orthopedic/orthodontic treatment with the Herbst Miniscope® appliance in subjects affected with Class II malocclusion with mandibular retrusion. METHODS: A total of 44 patients presenting a skeletal Angle Class II malocclusion (ANB > 4°) due to mandibular retrusion and a cervical maturation stage between CS2 and CS3 were included in the study. Of these 44 patients, 22 (mean age 11.9 ± 1.3, HBT group) were treated using the Herbst appliance, while 22 (mean age 10.6 ± 1.3, CTR group) were followed for a 12-month observational period. A cephalometric tracing was performed at the beginning of treatment (T0) and after 12 months (T1). RESULTS: In both groups there was a significant advancement of soft tissue pogonion (HBT = 3.5 ± 3.0 mm, p < 0.001; CTR = 2.2 ± 2.9 mm, p < 0.001), but the difference between the two groups was not significant (p = 0.172). On the contrary, both groups had a significant advancement of the mandibular sulcus (HBT = 3.7 ± 2.8 mm, p < 0.001; CTR = 1.2 ± 2.2 mm, p < 0.001) and a lower lip protrusion (HBT = 3.45 ± 2.51 mm, p < 0.001; CTR = 1.7 ± 2.7 mm, p = 0.008), but in both cases the HBT group showed a statistically significant greater increase in sulcus protrusion (p = 0.002) and lower lip protrusion (p = 0.029) than controls. There were no statistically significant effects on the upper jaw. CONCLUSIONS: The Herbst appliance advanced the lower jaw soft tissues.

Management of Endodontic and Periodontal Lesions: the Role of Regenerative Dentistry and Biomaterials.

Regenerative dentistry represents a novel interdisciplinary approach involving biomaterials, several molecules and mesenchymal stem cells (MSCs), preferably derived from oral tissues. The pivotal role of MSCs depends on the fact that they can differentiate into different cell lineages and have the strategic role to release bioactive substances that stimulate the renewal and regeneration of damaged tissues. The role of regenerative dentistry is promising in all the branches of dentistry: the most intriguing application is related to the management of endodontic and periodontal defects, overcoming the surgical approach and the implantology as a consequence of a poorly efficient therapeutic plan.

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

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.

Two-dimensional versus three-dimensional Frӓnkel Manoeuvre: a reproducibility study.

BACKGROUND/OBJECTIVES: To assess intra- and inter-observer reproducibility of the evaluation of the Frӓnkel Manoeuvre (FM) on three-dimensional (3D) scans and to compare it to the assessment on two-dimensional (2D) pictures. MATERIALS/METHODS: This study included 44 individuals with a skeletal Class II malocclusion [9-16-years old mean age ± standard deviation: 13.5 ± 2.01 years]. All patients had a full Class II molar relationship, overjet ≥6 mm and point A, Nasion, point B angle (ANB) ≥5 degrees. During the FM, each patient was invited to bite in centric occlusion and then to posture the mandible forward to reach a Class I molar relationship. The FM was recorded both by a normal camera and a 3D scanner (3dMD system). Six examiners divided into two groups according to their orthodontic clinical experience (<5 and >10 years), and one gold standard in the evaluation of FM, commented twice (every 15 days) on both 2D photographs (T0 and T2) and 3D scans (T1 and T3). The intra-observer agreement and the inter-observer agreement compared to the gold standard were evaluated by computing the Cohen's K. RESULTS: The agreement between observations for each examiner ranged from 0.36 to 1 on 2D pictures (T0 versus T2), and from 0.22 to 0.69 on 3D scans (T1 versus T3). The overall agreement was 0.63 (95 per cent CI = 0.35-0.91) in 2D analysis and 0.5 (95 per cent CI = 0.35-0.64) in 3D analysis. CONCLUSIONS/IMPLICATIONS: The FM was less reproducible when performed on 3D records than on 2D pictures.

A New Appliance for Class III Treatment in Growing Patients: Pushing Splints 3.

Several orthopedic procedures have been used in early treatment to reduce the need for orthognathic surgery in skeletal Class III. The most used treatment is Rapid Maxillary Expansion and Facemask. This procedure also determines a clockwise rotation of the mandible, increasing the vertical dimensions of the lower third of the face. Therefore, the control of vertical dimension appears to be a key objective in Class III hyperdivergent patients. This article shows two skeletal Class III patients treated with a new appliance (Pushing Splints 3), that is able to correct sagittal discrepancy with a good control of the vertical growth. In both cases, Class I relationship with a proper Overjet and Overbite was achieved with improvement of profile. The final cephalometric values demonstrated a stable sagittal relationship and a good control of the vertical growth. The specific biomechanic features of the PS3 appliance permit the improvement of the sagittal jaw relationship, delivering at the same time vertical vectors that are able to control the alveolar and skeletal components of the vertical growth. This could be useful in the treatment of Class III hyperdivergent patients.

Distribution of the Condylion-Gonion-Menton (CoGoMe

The condylion-gonion-menton angle (CoGoMe^) is commonly used as a pre-treatment indicator of responsiveness in Class II patients treated with functional appliances. The distribution of this angle in the Caucasian population is still unknown. This study aimed to determine the distribution of the CoGoMe^ and its relationship with age, sagittal jaw relationship (ANPg^), and mandibular inclination (SN^GoGn) in patients from Southern Italy. The sample included 290 subjects (median14 years of age; Interquartile range, IQR, 12-17) with lateral cephalograms taken before the orthodontic treatment. The distribution of the CoGoMe^ was assessed with the Shapiro-Wilk test, and the differences according to the ANPg^ and the SN^GoGn were estimated using one-way ANOVA. Linear regression analysis was performed to evaluate how the CoGoMe^ varied according to age. The statistical significance was set at P < 0.05. The results showed that the CoGoMe^ was normally distributed (P = 0.290) with a mean value of 127.2° ± 7.7°. The distribution of the CoGoMe^ in groups with different SN^GoGn angles was significantly different (P < 0.001). These angles showed a positive association (Beta coefficient B = 0.6; 95% CI: 0.51, 0.67; P < 0.001). In growing patients, the CoGoMe^ decreased every year by 0.6° (B = -0.6; 95% CI: -1.05, -0.12; P = 0.014). In conclusion, the CoGoMe^ was associated with mandibular inclination and could be considered to be a predictor of vertical growth patterns.

The Psychological Impact of Dental Aesthetics in Patients with Juvenile Idiopathic Arthritis Compared with Healthy Peers: A Cross-Sectional Study.

This study aimed to assess whether dental aesthetics had a different impact on the psychosocial domains of adolescents with juvenile idiopathic arthritis (JIA) as compared with healthy peers. Fifty JIA patients and eighty controls aged between 13 and 17 years were enrolled. The Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) was administered along with tools for the self-assessment of malocclusion and self-esteem. An objective evaluation of malocclusion severity was performed through a clinical evaluation with the Dental Aesthetic Index (DAI). The sample was divided according to the DAI stages of malocclusion severity; a two-way analysis of variance (ANOVA) was performed to assess whether there was a difference in the studied variables according to the malocclusion and the presence of JIA. The results showed no interaction between the malocclusion severity and the presence of JIA in all analyzed variables (all p > 0.05). According to the DAI stages, the Dental Self-Confidence domain of the PIDAQ and the Perception of Occlusion Scale showed statistically significant differences only within the controls (p = 0.027 and p = 0.014, respectively). Therefore, JIA adolescents seem to be less concerned about their dental aesthetics compared with healthy peers, and clinicians should take particular care when proposing orthodontic treatments aiming only to improve dental aesthetics.

Differences in craniofacial growth of Class II individuals from different decades: A retrospective study.

OBJECTIVES: To detect changes in mandibular growth between a historical group (HG) from the American Association of Orthodontics Foundation Craniofacial Growth Legacy Collection (AAOF Legacy) and a contemporary group (CG) of normodivergent or hypodivergent Class II untreated subjects. SETTING AND SAMPLE POPULATION: The sample included radiographs from the AAOF Legacy and from the University of Naples 'Federico II' collected during a previous RCT. MATERIALS & METHODS: The HG was composed of 26 individuals (around 1960) from the AAOF Legacy (15 from the Burlington Growth Study, nine from the Oregon Growth Study and two from the Michigan Growth Study) who were matched by sex, age and race with the 26 individuals of the CG (around 2010). Two lateral cephalograms obtained at T0 and T1 (12 months) were selected, and one examiner performed the cephalometric measurements according to Pancherz's method. The normal distribution of data was confirmed by the Shapiro-Wilk test, MANOVA analysis and t test for paired and unpaired data were performed. The level of significance was set according to Bonferroni's correction. RESULTS: At T0 and T1, the between-group comparisons revealed greater linear dimensions for Maxillary base, Maxillary incisor and Mandibular incisor in the CG than in the HG (P ≤ 0.002). No significant difference was found in the growth rate for linear skeletal measurement between the HG and the CG. CONCLUSIONS: In this study, the cephalometric analysis showed larger maxillary dimensions for the CG than the HG, while no differences were shown between the growth rate and direction of the two groups.

In vitro cytotoxicity of different thermoplastic materials for clear aligners.

OBJECTIVES: To investigate the in vitro cytotoxicity of different thermoplastic materials for clear aligners on human primary gingival fibroblasts (HGFs). MATERIALS AND METHODS: Four materials for clear aligners were considered in this study: 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). Three out of four materials (Duran, Biolon, Zendura) were assessed as thermoformed and nonthermoformed, whereas the SmartTrack was assessed only as thermoformed. The samples were placed at 37°C in airtight test tubes containing Dulbecco's Modified Eagle's Medium (DMEM; 0.1 mg/mL) for 14 days. The cell viability of HGFs cultured with this medium was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Data were analyzed by means of one-way and two-way analysis of variance and post hoc tests (α = 0.05). RESULTS: Each material exhibited a slight cytotoxic effect after 14 days. The highest cytotoxicity level on HGFs was achieved by Biolon (64.6% ± 3.3 of cell viability), followed by Zendura (74.4% ± 2.3 of cell viability), SmartTrack (78.8% ± 6.3 of cell viability), and finally Duran (84.6% ± 4 of cell viability), which was the least cytotoxic. In the comparison between nonthermoformed and thermoformed materials for Duran, Biolon, and Zendura, the thermoformed materials showed the highest level of cytotoxicity (P < .001). CONCLUSIONS: Under the experimental conditions of this study, all the materials for clear aligners presented a slight cytotoxicity. Biolon was the most cytotoxic and the thermoforming process increased the cytotoxicity of the materials.