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Background: To measure the actual moving direction and displacement of the root and crown of maxillary teeth before and after treatment in molar distalization cases using clear aligners(CAs). Materials and methods: This retrospective study included 28 adult patients who received maxillary distalization treatment with CAs. The pre- and post-treatment CBCT were superimposed and the crown and root of all maxillary teeth were marked. Achieved and predicted three-dimensional displacement of maxillary teeth were then compared using the paired t test. Mixed-effect model was used to explore the influence of different staging design (one-molar distalization vs. two-molar distalization) and anchorage (TAD vs. Class II elastic vs. no extra anchorage management). Results: Labial displacement happened to the anterior teeth even the palatal displacement was prescribed. Body distalization of maxillary posterior teeth could not be fully achieved as predicted. The premolars and molars achieved greater distal tipping, buccal inclination, and less distal displacement than predicted. In buccal-palatal dimension, the greatest buccal tipping tendency happened to the 2nd premolar and decreased toward the distal portion of the aligner. In the mesial-distal dimension, the highest accuracy of molar distalization was found in the 2nd molars while the lowest in the 1st premolars. No significant difference was found between two molar distalization patterns. Extra anchorage management devices could not diminish the difference between the predicted and achieved displacement. Conclusions: The achieved molar distalization displacement and anterior teeth retraction is not as good as expected using CAs. The anterior and posterior anchorage loss cannot be completely avoided despite extra anchorage management devices are adopted. The potential reason for the correction of class II malocclusion needs further exploration. [ABSTRACT FROM AUTHOR]

Introduction: To evaluate topographic changes of enamel surface in 3-dimensional after different debonding methods of aligner attachments formed with 2 different composite resins. Methods: Vertical rectangular attachments were created on 88 premolar teeth and divided into two composite resin groups (Group 1:flowable, Group 2:packable) (N = 44). These were then divided into two subgroups (N = 22) using different debonding methods. In Group A, the attachments were firstly removed using an attachment debonding plier and then with white fiberglass. Following, the tooth surfaces were polished with blue fiberglass. In Group B, the excess attachment composite was removed with a 12-blade carbide bur, followed by a 24-blade carbide bur, and tooth surfaces were polished with Renew stone. The remaining composite volume was measured using Geomagic Control X software. Enamel surface roughness and morphological change were compared between the groups. Results: Residual composite resin volume did not show a statistically significant difference between composite resin groups (1–2 A). The enamel demineralization volume and area changes in Group 2 A were significantly higher than observed in 2B (p < 0.05). Roughness parameters Ra (T1-T0), Ra (T2-T0), Rq (T1-T0), and Sa (T1-T0) were significantly higher in Group 1B compared to Group 1 A (p < 0.05). Similarly, Ra (T1-T0), Sa (T1-T0), and Sq (T1-T0) parameters were significantly higher in Group 2B compared to Group 2 A (p < 0.05). Conclusions: Fiberglass with a debonding plier produced a smoother enamel surface compared to carbide burs, but caused significantly more enamel demineralization, as seen in micro-CT evaluations after polishing. [ABSTRACT FROM AUTHOR]

Objectives: Anterior open bite can be treated non-surgically via molar intrusion using temporary skeletal devices (TAD). Clear aligner therapy (CAT) is recognized as a viable therapeutic modality for non-extraction treatment of adults with mild open bite. This study aimed to compare the treatment effect and mechanisms of open bite closure between patients treated with braces and TADs double arch intrusion and those treated with CAT. Treatment success at T3 was based on 1- positive overbite on ceph; 2- Change in the vertical dimension 3- post treatment POSI score equal to zero. Material and Methods: The TAD group includes 18 consecutively treated patients from the main author. The CAT group consisted of 16 selected patients from three different orthodontists. The observation time points were as follows: pretreatment (T1), end of molar intrusion and positive overbite achieved (T2), end of treatment (T3), at least 6-month follow-up (T4). Treatment changes were assessed by cephalometric analysis and frontal intraoral photo. Results: At the end of treatment, 100% of the patient of the TAD group and 78,6% of the CAT group had a posi score of 0. The TAD group showed a significant reduction in vertical measurements (SN-MPA: -1,55° ± 0.41, LAFH: -3,05 ± 0.51 mm, U6-PP: -1.48 ± 0.30 mm), but the CAT group did not have significant changes for these variables. Both groups had significant increases in overbite from T1 to T3 (TAD: 4,32 ± 0,5 mm; CAT: 2,33 ± 0.56 mm), and overbite remained stable at T4. The CAT group did not have a significant upper molar intrusion, but a significant extrusion of 1.22 ± 0.42 mm of the lower incisor occurred. Conclusion: The TAD group achieved bite closure by upper molar intrusion, lower molar and incisors vertical control, and mandibular plane counterclockwise rotation, resulting in an improved AP and vertical relationship. The CAT group achieved bite closure through the lower incisor extrusion without significant change in the vertical dimension. Clinical relevance: This study provides relevant information about the skeletal and dental changes of open bite treatment with TADs double arch intrusion. The comparison with a control group treated with CAT confirms known information. [ABSTRACT FROM AUTHOR]

Objectives: In this prospective clinical study, the effect of clear aligners on periodontal health and oral hygiene was examined. As the same time, microbial changes of the aligner tray and subgingival microbiota community were investigated. Methods: The study recruited fifteen patients, and clinical parameters were recorded at three different time points: before the initiation of aligner treatment (T0), 1 month after treatment onset (T1), and 3 months after treatment onset (T3). Plaque samples were collected from the inner surface of aligners and subgingival sulcus at each of these time points. The microbial composition of the samples was analyzed using 16S rRNA gene sequencing, and changes were evaluated based on the abundance of amplicon sequence variants (ASVs). Results: Reduction in plaque index and improvement in periodontal health were observed. In aligner tray plaque samples, the relative abundance of Streptococcus increased significantly, as well as the richness and diversity of microbiota decreased substantially as the duration of treatment time. In subgingival plaque samples, alpha and beta diversity of microbiota did not change significantly. Conclusions: During the clear aligner treatment, the patients' periodontium remained in a healthy condition, and clear aligner treatment had no significant impact on the composition of subgingival microbiota. The structure of the aligner tray microbiota altered significantly at both phylum and genus levels and attracted a unique and less diverse microbiota community. Clabsinabsical relevance: Clear aligner treatment has no significant impact on periodontal health and subgingival microbiota composition of patients. [ABSTRACT FROM AUTHOR]

Objective: To investigate the antibacterial and enamel remineralization performances as well as physicochemical properties and biocompatibility of a fluoride-coated clear aligner plastic (FCAP). Materials and methods: FCAP and normal clear aligner plastic (CAP) was bought from the manufacturer (Angelalign Technology Inc, China). The FCAP was observed under scanning electron microscopy. Its element composition, resistance to separation, contact angle, and protein adhesion performance were characterized. Colony-forming unit (CFU) count and 3-(4,5)-dimethylthiazol(-z-y1)-3,5-diphenyltetrazolium bromide (MTT) assay were used to evaluate the antibacterial ability of Streptococcus mutans. Fluoride release-recharge patterns were obtained. Apatite formation was evaluated after immersing FCAP in artificial saliva. Enamel remineralization capability was evaluated in the demineralization model (immersing samples in demineralization solution for 36 h) and pH cycling model (immersing samples in demineralization solution and remineralization solution in turns for 14 days). Cell Counting Kit-8 (CCK-8) and live/dead cell staining kits were used for cytotoxicity assay. Results: The FCAP showed uniformly distributed fluoride and did not compromise protein adhesion performance. CFU count (5.47 ± 0.55 for CAP, 3.63 ± 0.38 for FCAP) and MTT assay (0.41 ± 0.025 for CAP, 0.28 ± 0.038) indicated that the FCAP had stronger antibacterial activity compared with normal CAP (P < 0.05 for both evaluations). The FCAP could release fluoride continuously for 14 days and could be recharged after immersing in NaF solution. The FCAP could induce the formation of hydroxyapatite in artificial saliva and could reduce the microhardness decrease, color change, and mineral loss of enamels in both two models (P < 0.05 for all evaluations). CCK-8 and live/dead cell staining analyses showed that the coating did not compromise the biocompatibility of the clear aligner (P > 0.05 for CCK-8 evaluation). Conclusions: The FCAP had antibacterial, fluoride recharge, and enamel remineralization abilities while it did not compromise physicochemical properties and biocompatibility. Clinical relevance: The FCAP has the potential to prevent enamel demineralization during clear aligner treatment. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the available evidence regarding clinical effectiveness of clear aligner treatment (CAT). Materials and methods: A comprehensive literature search was conducted for systematic reviews investigating effectiveness of CAT published up to July 15, 2021. This was accomplished using different electronic databases. No language restriction was applied. Screening, quality assessment, and data extraction were performed by two authors independently. Information was categorized and narratively synthesized for the key findings from moderate and high-quality reviews. Results: A total of 361 potentially eligible reviews were identified. After excluding the non-relevant/low-quality reviews, 18 systematic reviews were included. CAT was found to be effective for mild to moderate malocclusions, and was associated with inferior outcomes when treating severe cases or with achieving specific tooth movements. There were conflicting results regarding treatment duration; however, CAT may be associated with shorter treatment in mild to moderate cases. Relapse was greater with CAT, while periodontal health was better. The risk of root resorption tended to be lower with CAT. Regarding pain, the results were unclear, although CAT was found to be more comfortable and associated with a reduced impact on eating and chewing. Conclusions: The level of evidence regarding CAT is moderate; hence, further high-quality randomized clinical trials are required. Evidence supports use of aligners as an alternate to fixed appliances in patients with mild-to-moderate malocclusion but not in severe cases. Advancement in technology could enhance the accuracy of CAT in delivering planned outcomes. Clinical relevance: CAT can be used effectively for selected cases with mild to moderate malocclusion. Registration: PROSPERO registration number: CRD42021246855. [ABSTRACT FROM AUTHOR]