Objectives: The study is aimed to examine the stress relaxation of 3d-printed aligners, Tera Hartz TC-85 (Graphy Inc. Seoul, South Korea) and Polyamide (Noxi, Sweden and Martina, Due Carrare, Padova, Italy), in comparison to thermoformed aligners, Zendura FLX (Bay Materials LLC, Fremont, California, USA) and Duran (SCHEU, Iserlohn, Germany). Material and Methods: A stress-relaxation test was conducted using a motorized vertical testing bench, TVO-S (AstraLab, Mariano Comense, Italy), applying a constant and controlled pre-set load. Each sample was subjected to a deflection of 0.5 mm while being immersed in water for eight consecutive h at a constant temperature of 37°C. During this period, data were collected at intervals of 1 s. The same test was repeated twice (test 1 and test 2) on the same specimen, in order to simulate the intermittence of deflection force. Results: For both Test 1 and Test 2, a total of 28,800 measurements were recorded for each aligner, with one measurement taken per second over a duration of 8 h/test. A statistically significant difference (P < 0.001) was found for all materials and at all time periods were considered. If the percentage of stress relaxation is considered, a significant difference among the four aligners was found as well. Conclusion: All materials displayed substantial stress decay during the 8-h period of constant load, although significant differences were observed among the various materials under investigation. The Noxi aligner demonstrated the highest force values in both tests, confirmed by low percentages of stress relaxation ranging from 23% to 32%.

(1) Background: the aim of this study was to investigate the transmittance levels of aligners in relation to different thermoforming disks and printers after 14 days of in vitro aging. (2) Methods: the transmittance level of 18 aligners was investigated. Three printers were used to create the aligner: Carbon L1, Prodways LD20 and RapidShape D100+. Each printer produced 6 aligners: three were made of Zendura FLX material and three of Scheu Ca Pro+. Each sample was subjected to spectrophotometry analysis of its transmittance levels, for a total of 54 measurements at T0. Then, all samples were aged in vitro at a constant temperature in artificial saliva supplemented with food coloring for 14 days each. The spectrophotometry protocol was repeated, and the same 54 measurements were collected at T1 (after aging). The resulting data were analyzed and compared by means of ANOVA (p < 0.05). (3) Results: all tested aligners revealed lower transmittance values after aging. Scheu CA Pro+ aligners showed higher transparency at T0, but a significant worsening of its aesthetic at T1. On the other hand, Zendura FLX aligners presented slightly reduced transmittance levels before aging, which, however, remained more stable after 14 days, showing no significant difference. In the specific, aligners produced by Prodways LD20 printers showed better optical properties than the others, both at T0 and T1. (4) Conclusions: Differences in pre-and-post-aging optical properties of aligners are influenced by the manufacturing process. Both the thermoplastic disks and the printers, thanks to new technologies, played a positive role in the final transparency of the product, which improved in all values compared to previous studies.

This study aimed to establish a consensus, thanks to the participation of a large group of experts in the field of aligner therapy, on several of its clinical and extraclinical aspects, with particular reference to its potential and biomechanical limitations. A Delphi study was conducted in 3 rounds. On the basis of the most recent systematic reviews in the literature, the steering committee formulated 35 questions. A group of 36 international experts agreed to participate in the survey and were asked to respond to the questions, choosing their level of agreement on a scale of 1-5 in the first round, then from 1 to 3 in the second, and finally with a yes or no response in the third, progressively narrowing the field of research. The items for which consensus (≥70%) was obtained were accepted; the others were reformulated. On the basis of the analysis of the experts' responses, 68 questions were reformulated for the second round and 28 for the third round. After 3 rounds, the study generated 47 consensus statements regarding biomechanical aspects and extraclinical factors. The study, based on the modified Delphi method, collected the opinion of experts, comparing it with the scientific literature to evaluate the potential and limitations of orthodontic aligners, obtaining 47 consensus statements related to biomechanics and extraclinical factors.

Background: Regardless of the treatment protocol, stability in Class III patients always represents a major concern. The aim of this study was to assess the short and long-term skeletal and dentoalveolar modifications in a group of class III patients treated with hybrid rapid maxillary expander (RME) and facemask (FM). Indeed, no long-term studies have been conducted yet with the objective of evaluating the effects of this kind of approach when applied to patients who have already gone thought their peak of growth. Material and methods: 27 patients with skeletal Class III malocclusion were treated using hybrid RME according to alternating rapid maxillary expansion and constriction (ALT-RAMEC) protocol, followed by 4 months of facemask therapy. After the orthopaedic phase, each patient underwent orthodontic treatment with fixed multibracket appliances. A mean follow-up of 7 years, 10 months was performed. Pre-treatment (TO), post-treatment (T1) and follow up (T2) cephalometric tracing were analysed, comparing dental and skeletal measurements. Results: Point A advanced by a mean of 3.5 mm with respect to VerT, then relapsed by 0.7 in the post-facemask period, thereby yielding of a mean advancement of 2.7 at T2. The sagittal relationship significantly changed after RME + facemask protraction (3.8° of ANB and 5.189 mm of Wits). Although both Wits and ANB values worsened over time, the improvement from T0 is still appreciable at T2. Conclusion: Despite the physiological relapse due to mandibular growth, the long-term cephalometric follow-up confirms the maintenance of all positive outcomes of the previous orthopaedic treatment with hybrid RME and facemask.

The aim was to compare the soft tissue changes in pretreatment and posttreatment facial scans of patients who had undergone various orthopedic treatments vs a control group of untreated growing patients. Facial scans were performed before (T0) and after (T1) orthopedic treatment in 15 patients prescribed rapid palatal expander (RPE), 15 cervical headgear (HG), and 15 facemasks (FM), as well as 6 months apart in 15 untreated growing patients. After best-fit scan alignment using Geometric Control X software (3D Systems Inc, Rock Hill, SC), a 3-dimensional (3D) analysis of soft tissue changes was performed, comparing 3D reference points (total 22) and 8 areas on T0 and T1 scans. Kruskal-Wallis nonparametric tests and pairwise comparison with Bonferroni's correction were applied to identify any statistically significant differences among groups (P <0.05). All analyses were conducted with SPSS software (version 28; IBM, Armonk, NY). At T1, reduced soft tissue projection was found at the nose and upper lip in the HG group, the lower lip in the HG and RPE groups, and the chin in the FM and RPE groups. The RPE group displayed a statistically significant increase in facial divergence, confirmed by gnathion position (RPE vs FM [P = 0.018] and RPE vs control [P = 0.046]), as well as an increase in the soft tissue projection of both cheeks (left cheek in range of 1-2 mm [P = 0.030] and range of 0 to -1 mm [P = 0.022]; right cheek in range of 1-2 mm [P = 0.003] and range -1 to -2 mm [P = 0.001]). There were no clinically significant differences among groups in mandibular right and left body areas. The 3D facial analysis revealed significant differences in soft tissues among orthopedic treatments, especially at the upper and lower lip and chin areas, as compared with untreated patients.

Objective: The purpose of this retrospective preliminary study was to analyze the skeletal and dentoalveolar effects of a new clear functional appliance in a sample of patients close to growth spurt with class II malocclusion attributable to mandibular retrusion. Materials and methods: A sample of growing patients underwent functional Class II correction using F22^® (Sweden and Martina, Due Carrare (PD), Italy) Young, realized combining the aesthetic characteristics of the F22^® clear aligner with the structural features of a functional appliance. For each patient, a digital setup was performed by a single operator to plan a mandibular advancement to the therapeutic position. Cephalometric analysis before and after treatment was performed. The purpose of the statistical analysis was to evaluate dental and skeletal changes associated with F22^® Young device, and whether there were statistically significant differences in anatomical measurements between the beginning and end of treatment. Results: 15 patients, 7 females and 8 males of average age 10.3, were treated with the F22^® Young appliance for an average period of 10 months ± 0.5 (maximum 11.5 months, minimum 10.5 months). The data showed that the SNB angle increase was statistically significant from T0 to T1, leading to a reduction in the ANB angle. Values for the mandible length, both total (Co-Gn) and at the base (Go-Pg), significantly increased. Conclusions: According to this preliminary study, F22^® Young appliance is effective in promoting mandibular advancement when used near the pubertal growth peak. The device is comfortable and aesthetic, which certainly promoted patient compliance, a key factor for treatment success.