Biodegradable Nanoflowers with Abaloparatide Spatiotemporal Management of Functional Alveolar Bone Regeneration.

Post-extraction alveolar bone atrophy greatly hinders the subsequent orthodontic tooth movement (OTM) or implant placement. In this study, we synthesized biodegradable bifunctional bioactive calcium phosphorus nanoflowers (NFs) loaded with abaloparatide (ABL), namely ABL@NFs, to achieve spatiotemporal management for alveolar bone regeneration. The NFs exhibited a porous hierarchical structure, high drug encapsulation efficacy, and desirable biocompatibility. ABL was initially released to recruit stem cells, followed by sustained release of Ca2+ and PO43- for in situ interface mineralization, establishing an osteogenic "biomineralized environment". ABL@NFs successfully restored morphologically and functionally active alveolar bone without affecting OTM. In conclusion, the ABL@NFs demonstrated promising outcomes for bone regeneration under orthodontic condition, which might provide a desirable reference of man-made "bone powder" in the hard tissue regeneration field.

Macrophage M2 polarization promotes pulpal inflammation resolution during orthodontic tooth movement.

Mechanical force induces hypoxia in the pulpal area by compressing the apical blood vessels of the pulp, triggering pulpal inflammation during orthodontic tooth movement. However, this inflammation tends to be restorable. Macrophages are recognized as pivotal immunoreactive cells in the dental pulp. Whether they are involved in the resolution of pulpal inflammation in orthodontic teeth remains unclear. In this study, we investigated macrophage polarization and its effects during orthodontic tooth movement. It was demonstrated that macrophages within the dental pulp polarized to M2 type and actively participated in the process of pulpal inflammation resolution. Inflammatory reactions were generated and vascularization occurred in the pulp during orthodontic tooth movement. Macrophages in orthodontic pulp show a tendency to polarize towards M2 type as a result of pulpal hypoxia. Furthermore, by blocking M2 polarization, we found that macrophage M2 polarization inhibits dental pulp-secreting inflammatory factors and enhances VEGF production. In conclusion, our findings suggest that macrophages promote pulpal inflammation resolution by enhancing M2 polarization and maintaining dental health during orthodontic tooth movement.

miR-20a: a key regulator of orthodontic tooth movement via BMP2 signaling pathway modulation.

AIM: In this study, we aimed to establish a rat tooth movement model to assess miR-20's ability in enhancing the BMP2 signaling pathway and facilitate alveolar bone remodeling. METHOD: 60 male SD rats had nickel titanium spring devices placed between their left upper first molars and incisors, with the right side serving as the control. Forces were applied at varying durations (18h, 24h, 30h, 36h, 42h, 1d, 3d, 5d, 7d, 14d), and their bilateral maxillary molars and surrounding alveolar bones were retrieved for analysis. Fluorescent quantitative PCR was conducted to assess miR-20a, BMP2, Runx2, Bambi and Smad6 gene expression in alveolar bone, and western blot was performed to determine the protein levels of BMP2, Runx2, Bambi, and Smad6 after mechanical loading. RESULT: We successfully established an orthodontic tooth movement model in SD rats and revealed upregulated miR-20a expression and significantly increased BMP2 and Runx2 gene expression and protein synthesis in alveolar bone during molar tooth movement. Although Bambi and Smad6 gene expression did not significantly increase, their protein synthesis was found to decrease significantly. CONCLUSION: MiR-20a was found to be involved in rat tooth movement model alveolar bone remodeling, wherein it promoted remodeling by reducing Bambi and Smad6 protein synthesis through the BMP2 signaling pathway.

Reviewing the benefits and clinical outcomes of oral fibroblasts over mesenchymal stem cells for repairing periodontal defects during or after orthodontic tooth movement.

Orthodontic therapy applies forces to teeth, causing an inflammatory reaction in the periodontal ligament. This is repaired by remodeling of the periodontium, allowing tooth displacement. Although orthodontic therapy is mostly initiated during childhood and adolescence, the number of adults seeking this treatment is increasing as our society's esthetic awareness rises. However, adults may already have periodontal tissue abnormalities, rendering orthodontic treatment inefficient because a healthy periodontium is essential for success. Numerous risk factors have been linked to periodontal lesions, with orthodontic tooth movement possibly playing a minimal influence. Although such tissue damages are mostly of esthetic rather than functional concern for patients, restoration frequently requires invasive procedures. Autologous cells for the treatment of periodontal complications have grown in popularity as a less intrusive alternative. The present review analyzed the literature on the use of mesenchymal stem cells and oral tissue-derived fibroblasts for the healing of periodontal defects that may be related to orthodontic tooth movement. Furthermore, the advantages and challenges of the two cell types have been examined. Although the number of clinical studies is currently limited, our study demonstrates that oral fibroblasts have the potential to be the next emergent frontrunners for tissue engineering in the periodontium.

Applications of nanotechnology in orthodontics: a comprehensive review of tooth movement, antibacterial properties, friction reduction, and corrosion resistance.

Nanotechnology has contributed important innovations to medicine and dentistry, and has also offered various applications to the field of orthodontics. Intraoral appliances must function in a complex environment that includes digestive enzymes, a diverse microbiome, mechanical stress, and fluctuations of pH and temperature. Nanotechnology can improve the performance of orthodontic brackets and archwires by reducing friction, inhibiting bacterial growth and biofilm formation, optimizing tooth remineralization, improving corrosion resistance and biocompatibility of metal substrates, and accelerating or decelerating orthodontic tooth movement through the application of novel nanocoatings, nanoelectromechanical systems, and nanorobots. This comprehensive review systematically explores the orthodontic applications of nanotechnology, particularly its impacts on tooth movement, antibacterial activity, friction reduction, and corrosion resistance. A search across PubMed, the Web of Science Core Collection, and Google Scholar yielded 261 papers, of which 28 met our inclusion criteria. These selected studies highlight the significant benefits of nanotechnology in orthodontic devices. Recent clinical trials demonstrate that advancements brought by nanotechnology may facilitate the future delivery of more effective and comfortable orthodontic care.

Effect of estrogen depression on alveolar bone microarchitecture and periodontal ligament cells during orthodontic movement.

This study aimed to evaluate the effects of the estrogen depression during orthodontic tooth movement on alveolar bone microarchitecture and periodontal ligament. Female Wistar rats were divided into two groups, one consisting of non-ovariectomized animals subjected to orthodontic tooth movement, and one comprising ovariectomized animals subjected to orthodontic tooth movement. Micro-CT assessment of bone volume to total volume (BV/TV), total porosity, trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp) in the alveolar bone of the orthodontically moved tooth was performed. Histomorphometric analyses were made in the periodontal ligament, and immunoexpression of RANK, RANKL, OPG, and TUNEL were quantified. Orthodontic tooth movement in the group of ovariectomized rats was faster than in non-ovariectomized animals. The alveolar bone area showed lower values of BV/TV and trabecular thickness, and higher bone porosity and trabeculae numbers in the ovariectomized rats. Histological analyses in the ovariectomized group revealed an increase in collagen fibers in the periodontal ligament. The apoptotic cell counts in the periodontal ligament were higher in the group of ovariectomized rats than in the sham-operated rats. Ovariectomy resulted in an increase in tooth movement and alteration of the alveolar bone microstructure in the first 7 day of orthodontic tooth movement, and in the presence of apoptotic cells in the periodontal ligament.

In vitro biomechanics of divot use, and their placement, in orthodontic aligner therapy.

INTRODUCTION: To evaluate biomechanics of an aligner utilizing divots and the effect of their vertical placement on the right maxillary central incisor. METHODS: An in vitro Orthodontic SIMulator (OSIM) was used to test forces and moments generated by aligners incorporating divots. The OSIM arch was scanned to generate a. STL version that was modified to create four models by placing divots on different positions of the right central maxillary incisor: GI - divots on gingival-third of lingual surface and incisal-third of labial surface; GM - divots on gingival-third of lingual surface and middle-third of labial surface; MI - divots on middle-third of lingual surface and incisal-third of labial surface; MM - divots on middle-third of lingual surface and middle-third of labial surface. Aligners (n = 30/model) were fabricated using a 0.75 mm thick polyethylene terephthalate material and Biostar® machine following the manufacturer's recommendations. A one-way MANOVA followed by one-way ANOVA (α = 0.05) was utilized to test effect of models on buccolingual force (Fy) and mesiodistal moment (Mx) at 0.20 mm of lingual displacement of the right maxillary central incisor. RESULTS: Mean Mx for GI (-5.68 ± 7.38 Nmm), GM (3.75 ± 5.54 Nmm), MI (-4.27 ± 1.48 Nmm) and MM (1.96 ± 0.99 Nmm) models showed statistical differences between GI and GM, GI and MM, GM and MI and MI and MM. GI exerted the largest Fy (1.87 ± 0.75 N) followed by GM (1.10 ± 0.47 N), MI (0.70 ± 0.23 N) and MM (0.28 ± 0.08 N) with significant differences between GI and GM, GI and MI, GI and MM and GM and MM models. CONCLUSIONS: Vertical divot placement on a right central incisor had a significant effect on aligner biomechanics. Buccolingual forces exerted by models GI, GM and MI were within the range suggested by literature for bodily tooth movement without major root tipping for GM and MI models.

Effect of orthodontic space closure on dental pulp sensitivity. Prospective clinical trial.

BACKGROUND: Orthodontic tooth movement (OTM) is a biological process that can influence the function of the pulp, including its innervation. The excitability of the nerve fibres of the pulp may be altered by forces exerted on the nerve fibres or by reduced blood flow to the pulp. The aim of this clinical study was to evaluate the sensitivity of the dental pulp during levelling and during the phase of space closure, to assess the role of certain controlled risk factors. METHODS: Twenty-two adolescent participants requiring orthodontic space closure in transcanine sector were enrolled in a prospective clinical study. Patients were observed before OTM, after levelling and 1 month during active space closure. The sensitivity threshold of the pulp was measured using the electric pulp test (EPT). Dental models were obtained using an intraoral scanner, allowing measurement of interdental distances and calculation of OTM speed. The teeth were categorized according to position and tooth type. RESULTS: The EPT values increased significantly during orthodontic treatment (one-way RM-ANOVA, P = .014). There was a significant difference in EPT values between the tooth categories. Teeth with a single root adjacent to the residual space had the highest EPT thresholds (two-way RM-ANOVA, P < .001; Holm-Sidak, P < .05). CONCLUSIONS: OTM reduced pulpal sensitivity. Pulpal sensitivity during active space closure was similar to sensitivity during the levelling phase. The pulpal sensitivity of molars was less affected by OTM than that of single-rooted teeth, while teeth closer to the gap had a significantly higher pulpal sensitivity threshold during active OTM.

Effect of thermomechanical ageing on force transmission by orthodontic aligners made of different thermoformed materials: An experimental study.

OBJECTIVES: Investigating the impact of thermal and mechanical loading on the force generation of orthodontic aligners made from various thermoplastic materials and different compositions. MATERIALS AND METHODS: Five distinct materials were utilized including, three multi-layer (Zendura FLX, Zendura VIVA, CA Pro) and two single-layer (Zendura A and Duran). A total of 50 thermoformed aligners (n = 10) underwent a 48-hour ageing protocol, which involved mechanical loading resulting from a 0.2 mm facial malalignment of the upper right central incisor (Tooth 11) and thermal ageing through storage in warm distilled water at 37°C. The force exerted on Tooth 11 of a resin model was measured both before and after ageing using pressure-sensitive films and a biomechanical setup. RESULTS: Before ageing, pressure-sensitive films recorded normal contact forces ranging from 83.1 to 149.7 N, while the biomechanical setup measured resultant forces ranging from 0.1 to 0.5 N, with lingual forces exceeding facial forces. Multi-layer materials exhibited lower force magnitudes compared to single-layer materials. After ageing, a significant reduction in force was observed, with some materials experiencing up to a 50% decrease. Notably, multi-layer materials, especially Zendura VIVA, exhibited lower force decay. CONCLUSIONS: The force generated by aligners is influenced by both the aligner material and the direction of movement. Multi-layer materials exhibit superior performance compared to single-layer materials, primarily because of their lower initial force, which enhances patient comfort, and their capability to maintain consistent force application even after undergoing ageing.

Biomodulation effects induced by ultrasound stimulation in periodontal cells implicated in orthodontic tooth movement: A systematic review.

Accelerating orthodontic tooth movement (OTM) is increasingly important for shorter treatment times, which reduces periodontal risks, root resorption and dental caries. Techniques to accelerate OTM focus on stimulating bone remodelling by enhancing osteoclast and osteoblast activity and include both surgical and non-surgical methods. The therapeutic potential of ultrasounds is highly recognized among many medical areas and has shown promising results in modulating bone remodelling and inflammation phenomena. This systematic review aims to collect and analyse the current scientific in vitro and ex vivo evidence on ultrasound stimulation (US) bioeffects in cells implicated in tooth movement. This review was conducted according to PRISMA 2020 guidelines. A bibliographic search was carried out in the PubMed, Scopus and Web of Science databases. Sixteen articles were selected and included in this review. The revised studies suggest that US of 1.0 and 1.5 MHz, delivered at 30 mW/cm2, 10 to 30 min daily over three to 14 days seems to be effective in promoting osteoclastogenic activity, while US of 1.5 MHz, 30 to 90 mW/cm2, in 5- to 20-min sessions delivered daily for 5 to 14 days exhibits the potential to stimulate osteogenic activity and differentiation. Previous research yielded varied evidence of the effectiveness of US in orthodontics. Future animal studies should employ the recommended US parameters and investigate how distinct protocols can differentially impact tissue remodelling pathways. The knowledge arising from this review will ultimately potentiate the application of US to accelerate OTM in the clinical setting.

Comparison of the efficiency of initial dental alignment with Invisalign® aligners changed every 7 or 14 days in mature adults: Randomized clinical trial.

OBJECTIVE: To compare the anterior crowding correction after sequential use of the first 5 aligners between two aligner exchange protocols (7 and 14 days) in mature adult patients. MATERIALS AND METHODS: Thirty-six patients over 35 years who received orthodontic treatment with Invisalign® were randomly allocated to two different aligner replacement sequence protocols: Group 1: exchange every 7 days (n = 18); and Group 2: exchange every 14 days (n = 18). All patients were scanned with iTero Element 5D® (Align Technology) in two treatment times: at pre-treatment (T1) and after using the first five aligners (T2). Little's Irregularity Index (LII) and arch widths were evaluated with OrthoCAD software. Intra and intergroup comparisons were performed with the dependent and independent t-tests. The results were considered significant for P < .05. RESULTS: Thirty-five patients completed the study. Both groups' maxillary and mandibular Irregularity Indexesi were significantly lower at T2. There was no significant difference in inter-canine, inter-premolar, and intermolar distances. G2 (14 days) presented a greater decrease in mandibular irregularity than G1 (7 days). CONCLUSION: Both exchange protocols (7 and 14 days) effectively correct anterior crowding in the initial phase of orthodontic treatment with aligners in mature adult patients. However, the 14-day exchange protocol provided a greater correction in mandibular anterior crowding in the evaluated period than the 7-day exchange protocol.

How accurate is predicted root movement achieved in four first-premolar extraction cases with Invisalign?

OBJECTIVES: This study aims to compare the achieved and predicted root movements in adults after four first-premolar extractions and Invisalign treatment. MATERIALS AND METHODS: Thirty-three consecutive adults (22 Class I, 9 Cusp-to-cusp Class II and 2 Cusp-to-cusp Class III) from a single clinical division who completed the first series of aligners after premolar extractions were included in this retrospective study. A pretreatment cone-beam computed tomography model was registered onto the pretreatment surface-scanned dental model (SSDM) to locate the pretreatment root apices of the whole dentition. These were copied and transferred to the predicted and achieved post-treatment SSDMs to acquire the locations of the predicted and achieved post-treatment root apices. The differences between predicted and achieved root movements (DPARMs) were tested using the paired t-test or Wilcoxon signed rank test. RESULTS: In the anteroposterior direction, posterior root movements of maxillary and mandibular anterior teeth were poorly achieved (3.24-5.74 mm DPARMs, p < .05). In the vertical direction, roots of maxillary anterior teeth achieved greater intrusion (0.70-0.93 mm DPARMs, p < .05), while those of mandibular incisors achieved less intrusion (0.57-0.65 mm DPARMs, p < .05) than predicted. In the mediolateral direction, lateral incisor roots did not move distally (-0.65 to -0.96 mm DPARMs, p < .05), while those of canines did not move buccally, compared with the prediction (-0.75 mm DPARMs, p < .05). CONCLUSIONS: In the four first-premolar extraction treatments with Invisalign, root movements were not achieved as predicted, particularly for anterior teeth in the anteroposterior direction.

Salivary levels of Osteoprotegerin and receptor activator of nuclear factor-kappa ligand during orthodontic tooth movement-A prospective pilot study.

OBJECTIVES: The aim of this study was to monitor changes in Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa ligand (RANKL) levels in the saliva during orthodontic tooth movement (OTM). MATERIALS AND METHODS: Nine healthy females (15-20 y of age) with four pre-molar extractions and fixed appliance were included. In total, 134 stimulated and 134 unstimulated saliva samples were collected: at baseline and then every 6-8 weeks at follow-up appointments during the whole orthodontic treatment. Twelve age-matched females with no active orthodontic treatment served as a control group. Saliva samples were analysed by enzyme-linked immunosorbent assay (Elisa). The mean levels of OPG and RANKL were calculated according to the different orthodontic treatment stages: alignment, space closure and finishing. A mixed model analysis was used to compare the means of treatment stages. Baseline OPG levels were compared with the control group using an independent t-test. OPG levels were measured in stimulated saliva due to low levels in unstimulated saliva. RESULTS: No significant difference was observed between baseline OPG values and the control group. OPG increased significantly at all treatment stages: alignment, space closure and finishing compared with baseline (P = 0.002, P = 0.039, P ≤ 0.001, respectively). The salivary levels of OPG increased gradually, except during space closure, reaching peak levels at finishing. RANKL was undetectable in stimulated and unstimulated saliva by sandwich Elisa during OTM. CONCLUSIONS: This novel approach shows the changes in the levels of OPG in OTM and indicates how and when to sample saliva during orthodontic treatment to analyse bone remodelling.

Effects of isotretinoin on tooth movement, orthodontically induced and non-orthodontic root resorption: A micro-CT and study.

OBJECTIVES: This study aims to investigate whether cumulative dose-dependent isotretinoin (Roaccutane®) could affect orthodontic tooth movement (OTM) and root resorption. MATERIALS AND METHODS: Ninety male Wistar Albino rats were divided into 4 groups. While, the control (SALINE), solvent (SOYBEAN) and orthodontic drug (ISOTM) groups underwent orthodontic force, the non-orthodontic drug group (ISO) did not. The rats were administrated saline, soybean oil (SBO) and isotretinoin diluted in SBO (ISOTM, ISO) for 30 days, respectively. Six rats were euthanized in each orthodontic group. Fifty grams of orthodontic force was applied to the remaining rats' first molars using the incisors as anchorage. Six more rats in each group were euthanized on the 7th, 14th and 21st days of the force application. In the ISO group, six rats were euthanized on the 37th, 44th and 51st days of administration. Six rats that were euthanized for ISOTM on the 30th day were also used for ISO to reduce the number of rats used. Micro-computed tomography (micro-CT) and histological analysis were performed. RESULTS: Independent of orthodontic force, isotretinoin caused root resorption in the apical region. However, there was no statistically significant influence of isotretinoin on OTM and orthodontically induced root resorption (OIRR). CONCLUSIONS: Despite the lack of strong evidence supporting the orthodontically induced resorptive effect of isotretinoin, this study provided findings regarding the resorptive effects of isotretinoin on non-orthodontic root resorption. Therefore, the present results underscore the importance of close monitoring during orthodontic treatment to mitigate potential root resorption in patients who use isotretinoin because of acne complaints.

Clinical and preclinical evidence on the bioeffects and movement-related implications of photobiomodulation in the orthodontic tooth movement: A systematic review.

Photobiomodulation (PBM) has been demonstrated as a non-invasive and painless technique with great potential to accelerate orthodontic tooth movement (OTM). However, there is a great inconsistency among PBM protocols and reported outcomes, probably due to the poor translatability of preclinical knowledge into early clinical practice. Hence, this review aims to fill this gap by establishing the state-of-the-art on both preclinical and clinical applications of PBM, and by comprehensively discussing the most suitable stimulation protocols described in the literature. This review was conducted according to PRISMA guidelines. A bibliographic search was carried out in the PubMed, Scopus and Cochrane databases using a combination of keywords. Only studies written in English were eligible and no time limit was applied. A total of 69 studies were selected for this review. The revised literature describes that PBM can effectively reduce orthodontic treatment time and produce analgesic and anti-inflammatory effects. We found that PBM of 640 ± 25, 830 ± 20 and 960 ± 20 nm, delivered at a minimum energy density per irradiation point of 5 J/cm2 daily or every other day sessions is robustly associated with increased tooth movement rate. Pain relief seems to be achieved with lower irradiation doses compared to those required for OTM acceleration. For the first time, the bioeffects induced by PBM for the acceleration of OTM are comprehensively discussed from a translational point of view. Collectively, the evidence from preclinical and clinical trials supports the use of PBM as a coadjuvant in orthodontics for enhancing tooth movement and managing treatment-associated discomfort. Overall, the revised studies indicate that optimal PBM parameters to stimulate tissue remodelling are wavelengths of 830 ± 20 nm and energy densities of 5-70 J/cm2 applied daily or every other day can maximize the OTM rate, while lower doses (up to 16 J/cm2 per session) delivered in non-consecutive days seem to be optimal for inducing analgesic effects. Future research should focus on optimizing laser parameters and treatment protocols customized for tooth and movement type. By fine-tuning laser parameters, clinicians can potentially reduce treatment times, improve patient comfort and achieve more predictable outcomes, making orthodontic care more efficient and patient-friendly, thus consolidating PBM usage in orthodontics.

Small nucleolar RNA host gene 5 plays a role in orthodontic tooth movement by inhibiting osteoclast differentiation.

BACKGROUND AND OBJECTIVES: The alveolar bone remodelling promoted by reasonable mechanical force triggers orthodontic tooth movement (OTM). The generation of osteoclasts is essential in this process. However, the mechanism of mechanical force mediating osteoclast differentiation remains elusive. Small nucleolar RNA host gene 5 (SNHG5), which was reported to mediate the osteogenic differentiation of bone marrow mesenchymal stem cells in our previous study, was downregulated in human periodontal ligament cells (hPDLCs) under mechanical force. At the same time, the RANKL/OPG ratio increased. Based on this, we probed into the role of SNHG5 in osteoclast formation during OTM and the relevant mechanism. MATERIALS AND METHODS: SNHG5 and the RANKL/OPG ratio under different compressive forces were detected by western blotting (WB) and qRT-PCR. Impact of overexpression or knockdown of SNHG5 on osteoclast differentiation was detected by qRT-PCR, WB and transwell experiments. The combination of SNHG5 and C/EBPß was verified by RNA immunoprecipitation and RNA pull-down assays. The expression of SNHG5 and osteoclast markers in gingiva were analysed by qRT-PCR and the paraffin sections of periodontal tissues were used for histological analysis. RESULTS: Compressive force downregulated SNHG5 and upregulated the RANKL/OPG ratio in hPDLCs. Overexpression of SNHG5 inhibited RANKL's expression and osteoclast differentiation. SNHG5 combined with C/EBPß, a regulator of osteoclast. The expression of SNHG5 in periodontal tissue decreased during OTM. CONCLUSION: SNHG5 inhibited osteoclast differentiation during OTM, achieved by affecting RANKL secretion, which may provide a new idea to interfere with bone resorption during orthodontic treatment.

The effect of salbutamol sulphate inhalation (an anti-asthmatic medication) on the surfaces of orthodontic Archwires.

OBJECTIVES: This study aimed to compare the surface roughness and friction of different orthodontic archwires after exposure to salbutamol sulphate inhalation, an anti-asthmatic medication. METHODS: Orthodontic archwires (stainless-steel [StSt], nickel-titanium [NiTi], beta-titanium [ß-Ti], and copper-NiTi [Cu-NiTi]) were equally divided into two groups. The exposed groups were subjected to 20 mg salbutamol sulphate for 21 days and kept in artificial saliva. The control groups were only kept in artificial saliva. Surface changes were visualized using scanning electron microscopy (SEM). The average surface roughness (Ra) was evaluated using atomic force microscopy (AFM), and friction resistance forces were assessed using a universal testing machine. Statistical analyses were performed using t-tests and ANOVA followed by post hoc tests. RESULTS: Salbutamol sulphate did not change the surface roughness of StSt and NiTi archwires (p > .05). However, the change in the surfaces of ß-Ti and Cu-NiTi archwires was significant (p < .001). The frictional forces of exposed StSt, NiTi, and Cu-NiTi archwires did not change (p > .05). However, the frictional forces of ß-Ti archwires increased significantly after exposure to salbutamol sulphate (p = .021). Brushing with fluoride after exposure to salbutamol sulphate increased the frictional forces of ß-Ti only (p = .002). CONCLUSIONS: Salbutamol sulphate inhalation significantly affected the surface texture of ß-Ti and Cu-NiTi orthodontic archwires and increased the friction of ß-Ti archwires. These deteriorating effects were not detected on the surface of StSt and NiTi archwires. Therefore, we suggest that ß-Ti and copper titanium archwires should be used cautiously in individuals under salbutamol sulphate inhalation treatment.

Effect of attachment configuration and trim line design on the force system of orthodontic aligners: A finite element study on the upper central incisor.

OBJECTIVES: To use the finite element method (FEM) to investigate the effect of various attachment configurations and trimming line designs of orthodontic aligners on their biomechanical performance. METHOD: A 3D upper jaw model was imported into 3D design software. The upper right central incisor tooth (Tooth 11) was made mobile, and its periodontal ligament (PDL) and bone structures were designed. Aligners were modelled with three distinct attachment configurations: No attachment, rectangular horizontal, rectangular vertical, and two trimming line designs; scalloped and straight extended, with a homogeneous thickness of 0.6 mm. These models were then imported into an FE software. Simulations were conducted for three different movements, including facial translation, distalization, and extrusion. RESULTS: Forces were recorded at 1.3-2.6 N during facial translation, 1.4-5.9 N in distalization, and 0.0-2.0 N in extrusion. The straight extended trimming line consistently generated higher forces than the scalloped design. Attachments had no significant impact on force components during facial translation but were more effective in distalization and extrusion. The combination of a straight extended trimming line with horizontal attachments exhibited the least stresses at the apical third during distalization, and the highest stresses during extrusion, suggesting superior retention. CONCLUSIONS: Rectangular attachments offer limited benefits in facial translation, but horizontal rectangular attachments can intensify load in distalization and are crucial for force generation in extrusion. Horizontal attachments are preferred over vertical options. Additionally, the straight extended trim line enhances control of tooth movement and can replace attachments in certain cases. CLINICAL RELEVANCE: These findings provide biomechanical evidence and an optimal protocol to guide clinical practice in planning diverse teeth movements. The emphasis is on the influence of attachment utilization and the specific design of aligner trimming lines to enhance control over tooth movement.

Effects of coenzyme Q10 on orthodontic tooth movement and alveolar bone remodeling in rats.

OBJECTIVES: To evaluate the effects of coenzyme Q10 (CoQ10) on alveolar bone remodeling and orthodontic tooth movement (OTM). MATERIALS AND METHODS: An orthodontic appliance was placed in 42 female Sprague‒Dawley rats were divided into two groups: the orthodontic force (OF) group (n = 21) and the OF + CoQ10 (CoQ10) treatment group (n = 21). Each group was divided into 3 subgroups, and the rats were sacrificed on days 3, 7 and 14. The rats in CoQ10 and OF groups were administered 100 mg/kg b.w./day CoQ10 (in 1 mL/b.w. soybean oil) and 1 mL b.w./day soybean oil, respectively, by orogastric gavage. The OTM was measured at the end of the experiment. The osteoclast, osteoblast and capillary numbers; vascular endothelial growth factor (VEGF), receptor activator nuclear kappa B ligand (RANKL) and osteoprotegrin (OPG) levels in tissue; and total antioxidant status (TAS) and total oxidant status (TOS) in blood were determined. RESULTS: Compared with the OF group, the CoQ10 treatment group exhibited decreased orthodontic tooth movement and osteoclast and capillary numbers. Indeed, the levels of VEGF and RANKL decreased, while the levels of OPG increased except on day 7. Additionally, the CoQ10 treatment group exhibited lower TOS and higher TAS on days 7 and 14 (p < 0.05). Histological findings showed that the morphology of osteoblasts changed in the CoQ10 group; however, there was no significant difference in the number of osteoblasts between the groups (p > 0.05). CONCLUSION: Due to its effect on oxidative stress and inflammation, CoQ10 regulates bone remodeling by inhibiting osteoclast differentiation, promoting osteoblast differentiation and reducing the amount of OTM. CLINICAL RELEVANCE: Considering that OTM may be slowed with the use of CoQ10, topics such as orthodontic treatment duration, orthodontic force activation and appointment frequency should be considered in treatment planning. It is predicted that the use of CoQ10 will support the effectiveness of treatment in clinical applications such as preventing relapse in orthodontic treatment by regulating bone modulation and anchorage methods that suppress/optimize unwanted tooth movement.

Effect of material composition and thickness of orthodontic aligners on the transmission and distribution of forces: an in vitro study.

OBJECTIVES: To investigate the effects of material type and thickness on force generation and distribution by aligners. MATERIALS AND METHODS: Sixty aligners were divided into six groups (n = 10): one group with a thickness of 0.89 mm using Zendura Viva (Multi-layer), four groups with a thickness of 0.75 mm using Zendura FLX (Multi-layer), CA Pro (Multi-layer), Zendura (Single-layer), and Duran (Single-layer) sheets, and one group with a thickness of 0.50 mm using Duran sheets. Force measurements were conducted using Fuji® pressure-sensitive films. RESULTS: The lowest force values, both active and passive, were recorded for the multi-layered sheets: CA Pro (83.1 N, 50.5 N), Zendura FLX (88.9 N, 60.7 N), and Zendura Viva (92.5 N, 68.5 N). Conversely, the highest values were recorded for the single-layered sheets: Duran (131.9 N, 71.8 N) and Zendura (149.7 N, 89.8 N). The highest force was recorded at the middle third of the aligner, followed by the incisal third, and then the cervical third. The net force between the incisal and cervical thirds (FI-FC) showed insignificant difference across different materials. However, when comparing the incisal and middle thirds, the net force (FI-FM) was higher with single-layered materials. Both overall force and net force (FI-FM) were significantly higher with 0.75 mm compared to those with a thickness of 0.50 mm. CONCLUSIONS: Multi-layered aligner materials exert lower forces compared to their single-layered counterparts. Additionally, increased thickness in aligners results in enhanced retention and greater force generation. For effective bodily tooth movement, thicker and single-layered rigid materials are preferred. CLINICAL RELEVANCE: This research provides valuable insights into the biomechanics of orthodontic aligners, which could have significant clinical implications for orthodontists. Orthodontists might use this information to more effectively tailor aligner treatments, considering the specific tooth movement required for each individual patient. In light of these findings, an exchangeable protocol for aligner treatment is suggested, which however needs to be proven clinically. This protocol proposes alternating between multi-layered and single-layered materials within the same treatment phase. This strategy is suggested to optimize treatment outcomes, particularly when planning for a bodily tooth movement.