Exploration of bone metabolism status in the distal femur of mice at different growth stages.

The mouse femur, particularly the distal femur, is commonly utilized in orthopedic research. Despite its significance, little is known about the key events involved in the postnatal development of the distal femur. Therefore, investigating the development process of the mouse distal femur is of great importance. In this study, distal femurs of CD-1 mice aged 1, 2, 4, 6, and 8 weeks were examined. We found that the width and height of the distal femur continued to increase till the 4th week, followed with stabilization. Notably, the width to height ratio remained relatively consistent with age. Micro computed tomography analysis demonstrated gradual increases in bone volume/tissue volume, trabecular number, and trabecular thickness from 1 to 6 weeks, alongside a gradual decrease in trabecular separation. Histological analysis further indicated the appearance of the secondary ossification center at approximately 2 weeks, with ossification mostly completed by 4 weeks, leading to the formation of a prototype epiphyseal plate. Subsequently, the epiphyseal plate gradually narrowed at 6 and 8 weeks. Moreover, the thickness and maturity of the bone cortex surrounding the epiphyseal plate increased over time, reaching peak cortical bone density at 8 weeks. In conclusion, to enhance model stability and operational ease, we recommend constructing conventional mouse models of the distal femur between 4 and 8 weeks old.

Initial arch wires used in orthodontic treatment with fixed appliances.

BACKGROUND: Initial arch wires are the first arch wires inserted into fixed appliance at the beginning of orthodontic treatment. With a number of different types of orthodontic arch wires available for initial tooth alignment, it is important to understand which are most efficient and which cause the least amount of root resorption and pain during the initial aligning stage of treatment. This is the third update of a Cochrane review first published in 2010. OBJECTIVES: To assess the effects of initial arch wires for the alignment of teeth with fixed orthodontic braces, in terms of the rate of tooth alignment, amount of root resorption accompanying tooth movement, and intensity of pain experienced by patients during the initial alignment stage of treatment. SEARCH METHODS: We searched Cochrane Oral Health's Trials Register, CENTRAL, MEDLINE, Embase, and two ongoing trials registries on 4 July 2022. SELECTION CRITERIA: We included randomised controlled trials (RCTs) of different initial arch wires used to align teeth with fixed orthodontic braces. We included people with full-arch fixed orthodontic appliances on the upper arch, lower arch, or both arches. DATA COLLECTION AND ANALYSIS: Two independent review authors were responsible for study selection, data extraction, and assessment of risk of bias in included studies. We contacted corresponding authors of included studies to obtain missing information. We resolved disagreements by discussion between the review authors. Our main outcomes were alignment rate (movement of teeth in mm), root resorption, time to alignment, and intensity of pain measured on a 100-mm visual analogue scale (VAS). We pooled data from studies with similar interventions and outcomes using random-effects models. We reported mean differences (MDs) with 95% confidence intervals (CIs) for continuous data, risk ratios (RRs) with 95% CIs for dichotomous data, and alignment rate ratios with 95% CIs for time-to-event data. Two independent review authors assessed the certainty of evidence. We resolved disagreements by discussion between the review authors. MAIN RESULTS: We included 29 RCTs with 1915 participants (2581 arches) in this review. Studies were generally small (sample sizes ranged from 14 to 200 participants). Duration of follow-up varied between three days and six months. Eleven studies received funding, six received no funding, and 12 provided no information about funding sources. We judged eight studies at high risk of bias, nine at low risk, and 12 at unclear risk. We grouped the studies into six main comparisons. Multistrand stainless steel wires versus wires composed of other materials Six studies with 409 participants (545 arches) evaluated multistrand stainless steel (StSt) wires versus wires composed of other materials. We are very uncertain about the effect of multistrand StSt wires versus other wires on alignment rate (4 studies, 281 participants, 417 arches; very low-certainty evidence). There may be little to no difference between multistrand StSt wires and other wires in terms of intensity of pain (MD -2.68 mm, 95% CI -6.75 to 1.38; 2 studies, 127 participants, 127 arches; low-certainty evidence). Conventional nickel-titanium wires versus superelastic nickel-titanium wires Four studies with 266 participants (274 arches) evaluated conventional nickel-titanium (NiTi) wires versus superelastic NiTi wires. There may be little to no difference between the different wire types in terms of alignment rate (124 participants, 124 arches, 2 studies; low-certainty evidence) and intensity of pain (MD -0.29 mm, 95% CI -1.10 to 0.52; 2 studies, 142 participants, 150 arches; low-certainty evidence). Conventional nickel-titanium wires versus thermoelastic copper-nickel-titanium wires Three studies with 210 participants (210 arches) evaluated conventional Ni-Ti versus thermoelastic copper-nickel-titanium (CuNiTi) wires. We are very uncertain about the effects of the different arch wires on alignment rate (1 study, 66 participants, 66 arches; very low-certainty evidence). There may be little to no difference between conventional NiTi wires and thermoelastic CuNiTi wires in terms of time to alignment (alignment rate ratio 1.30, 95% CI 0.68 to 2.50; 1 study, 60 participants, 60 arches; low-certainty evidence). Superelastic nickel-titanium wires versus thermoelastic nickel-titanium wires Twelve studies with 703 participants (936 arches) evaluated superelastic NiTi versus thermoelastic NiTi wires. There may be little to no difference between superelastic NiTi wires and thermoelastic NiTi wires in alignment rate at four weeks (MD -0.28 mm, 95% CI 0.62 to 0.06; 5 studies, 183 participants, 183 arches; low-certainty evidence). We are very uncertain about the effects of the different wires on root resorption (2 studies, 52 participants, 312 teeth; very low-certainty evidence). Superelastic NiTi wires compared with thermoelastic NiTi wires may result in a slight increase in time to alignment (MD 0.5 months, 95% CI 0.21 to 0.79; 1 study, 32 participants, 32 arches; low-certainty evidence) but are probably associated with a slight increase in intensity of pain (MD 6.96 mm, 95% CI 1.82 to 12.10; 3 studies, 94 participants, 138 arches, moderate-certainty evidence). Single-strand superelastic nickel-titanium wires versus coaxial superelastic nickel-titanium wires Three studies with 104 participants (104 arches) evaluated single-strand superelastic NiTi versus coaxial superelastic NiTi wires. Use of single-strand superelastic NiTi wires compared with coaxial superelastic NiTi wires probably results in a slight reduction in alignment rate at four weeks (MD -2.64 mm, 95% CI -4.61 to -0.67; 2 studies, 64 participants, 64 arches, moderate-certainty evidence). Different sizes of nickel-titanium wires Two studies with 149 participants (232 arches) compared different types of NiTi wires. There may be little to no difference between different sizes of NiTi wires in terms of pain (low-certainty evidence). AUTHORS' CONCLUSIONS: Superelastic NiTi wires probably produce slightly more pain after one day than thermoelastic NiTi wires, and single-strand superelastic NiTi wires probably have a lower alignment rate over four weeks compared with coaxial superelastic NiTi wires. All other evidence on alignment rate, root resorption, time to alignment, and pain is of low or very low certainty in all comparisons. Therefore, there is insufficient evidence to determine whether any particular arch wire material or size is superior to any other. The findings of this review are imprecise and unreliable; well-designed larger studies are needed to give better estimates of the benefits and harms of different arch wires. Orthodontists should exercise caution when interpreting the findings of this review and be prepared to adapt their treatment plans based on individual patient needs.

Biomechanical analysis of the effect of Class II traction configurations and aligner overtreatment on molar distalization: a finite-element study.

OBJECTIVE: This study aimed to evaluate the biomechanical effects of aligner overtreatment on molar distalization using clear aligners. METHODS: Various models were created and integrated into finite-element software. Six distinct study models were devised for analysis. The first three models examined second molar distalization with different configurations of attachments, i.e. no attachment, horizontal or vertical attachment on the second molar. For the fourth and fifth models, Class II elastic traction, either implemented via a precision cut or button on canines, was applied. Lastly, aligner overtreatment with varying degrees of root distal tipping (0°, 2°, 4°, 6°, 8°, 10°, and 12°) for the second molar was designed in the last study model. RESULTS: Distalization of the second molar produced buccal tipping, distal tipping and intrusion of the second molar, and labial proclination and intrusion of the central incisor. These displacement tendencies were enhanced by adding attachments on the second molar, especially the vertical attachment. Class II elastic tractions enhanced molar distalization and diminish anchorage loss, with the precision-cut configuration being biomechanically superior to the button design. Aligner overtreatment produced bodily molar distalization and mitigated adverse biomechanical effects on anchorage teeth. LIMITATIONS: The study's limitations include the use of finite-element models, which may not fully represent real clinical scenarios, and the lack of consideration for individual patient variability. CONCLUSIONS: We suggest that Class II elastic traction via the precision-cut configuration and the design of vertical attachment on the second molar be applied for molar distalization. Appropriate aligner overtreatment helps achieve bodily molar distalization and minimizes adverse biomechanical effects on anchorage teeth.

Artificial intelligence-assisted determination of available sites for palatal orthodontic mini implants based on palatal thickness through CBCT.

OBJECTIVES: To develop an artificial intelligence (AI) system for automatic palate segmentation through CBCT, and to determine the personalized available sites for palatal mini implants by measuring palatal bone and soft tissue thickness according to the AI-predicted results. MATERIALS AND METHODS: Eight thousand four hundred target slices (from 70 CBCT scans) from orthodontic patients were collected, labelled by well-trained orthodontists and randomly divided into two groups: a training set and a test set. After the deep learning process, we evaluated the performance of our deep learning model with the mean Dice similarity coefficient (DSC), average symmetric surface distance (ASSD), sensitivity (SEN), positive predictive value (PPV) and mean thickness percentage error (MTPE). The pixel traversal method was proposed to measure the thickness of palatal bone and soft tissue, and to predict available sites for palatal orthodontic mini implants. Then, an example of available sites for palatal mini implants from the test set was mapped. RESULTS: The average DSC, ASSD, SEN, PPV and MTPE for the segmented palatal bone tissue were 0.831%, 1.122%, 0.876%, 0.815% and 6.70%, while that for the palatal soft tissue were 0.741%, 1.091%, 0.861%, 0.695% and 12.2%, respectively. Besides, an example of available sites for palatal mini implants was mapped according to predefined criteria. CONCLUSIONS: Our AI system showed high accuracy for palatal segmentation and thickness measurement, which is helpful for the determination of available sites and the design of a surgical guide for palatal orthodontic mini implants.

Characteristics of oral microbiota and oral health in the patients treated with clear aligners: a prospective study.

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.

The effects of aligner anchorage preparation on mandibular first molars during premolar-extraction space closure with clear aligners: A finite element study.

INTRODUCTION: This study aimed to determine the effectiveness of different aligner anchorage preparations on mandibular first molars during premolar-extraction space closure with clear aligners and to assess the effects of different modes of Class II elastics on mandibular first molars. METHODS: Finite element models were constructed on the basis of cone-beam computed tomography data from an orthodontic patient. The models comprised maxilla, mandible, maxillary and mandibular teeth without first premolars, periodontal ligaments, attachments and aligners. Tooth displacement tendencies were calculated using different aligner anchorage preparations and Class II elastics on the models from the same patient. Three group sets were designed on the basis of the positions of aligner cutouts and buttons (mesiobuccal, distobuccal and lingual). Four groups were established in each of the 3 group sets. Four groups were created: (1) no elastic traction + no anchorage preparation, (2) anchorage preparation only, (3) elastic traction only, and (4) elastic traction + anchorage preparation. Different aligner anchorage preparations (0°, 1°, 2°, 3°) were applied on mandibular second premolars and molars. The Class II traction force was set to 100 g. RESULTS: With clear aligners, mandibular first molars were subject to mesial tipping, lingual tipping and intrusion. In the condition of no elastic traction, aligner anchorage preparation resulted in distal tipping, buccal tipping, and extrusion effect on mandibular first molars. Aligner anchorage preparation was more effective in the distal and lingual cutout groups than in the mesial cutout group. In the condition of Class II elastic traction, the bodily movement of mandibular first molars was achieved with a 3° anchorage preparation for the mesial cutout group and a 1.7° anchorage preparation for distal and lingual cutout groups. Absolute maximal anchorage was achieved with a 2° anchorage preparation for distal and lingual cutout groups. CONCLUSIONS: Clear aligner therapy caused mesial tipping, lingual tipping and intrusion of mandibular first molars during premolar-extraction space closure. Aligner anchorage preparation effectively prevented mesial and lingual tipping of mandibular molars. Distal and lingual cutout modes were more effective than mesial cutout modes in aligner anchorage preparation. For each aligner stage (0.25 mm), 1.7° aligner anchorage preparation and Class II elastics with distal or lingual cutouts led to the bodily movement of mandibular first molars, whereas 2° anchorage preparation reached absolute maximal anchorage.

Comparison of three-dimensional maxillary growth across spheno-occipital synchondrosis maturation stages.

BACKGROUND: This study aimed to three-dimensionally compare the maxillary growth among the spheno-occipital synchondrosis (SOS) maturation stages in both genders. METHODS: This is a cross-sectional study of a retrospective type in which cone-beam computed tomography (CBCT) images of 500 patients aged 6 to 25 years (226 males and 274 females) were analyzed. The SOS was evaluated using the four-stage scoring system; completely open, partially fused, semi-fused, or completely fused. The SOS scoring and three-dimensional cephalometric measurements were analyzed by Invivo 6.0.3 software. Descriptive and analytical statistics were performed and a P-value < 0.05 was considered statistically significant. RESULTS: There was a statistically significant difference in maxillary measurements among SOS maturation stages in both genders (P < 0.05). The mean differences in the maxillary growth among the SOS maturation stages between SOS stages 2 and 3 were higher than those between stages 1and 2 and stages 3 and 4 for maxillary length and height in both genders. However, the mean difference in the maxillary width was higher between SOS stages 1 and 2 than those stages 2 and 3 and stages 3 and 4. On other hand, there may be lesser maxillary growth between SOS stages 3 and 4 for maxillary width, length (in males), and height. The growth curves showed high active growth of the maxilla as the SOS was still fusing (especially stage 2 and 3) than those of the fused (stage 4). Moreover, the acceleration of growth occurred earlier in females than males regarding chronological age but not for SOS maturation stages. CONCLUSIONS: The SOS maturation stages are valid and reliable maxillary skeletal maturation indicators for three-dimensional maxillary growth in both genders.

Molecular mechanism in trigeminal nerve and treatment methods related to orthodontic pain.

BACKGROUND: Orthodontic treatment is the main treatment approach for malocclusion. Orthodontic pain is an inevitable undesirable adverse reaction during orthodontic treatment. It is reported orthodontic pain has become one of the most common reason that patients withdraw from orthodontic treatment. Therefore, understanding the underlying mechanism and finding treatment of orthodontic pain are in urgent need. AIMS: This article aims to sort out the mechanisms and treatments of orthodontic pain, hoping to provide some ideas for future orthodontic pain relief. MATERIALS: Tooth movement will cause local inflammation. Certain inflammatory factors and cytokines stimulating the trigeminal nerve and further generating pain perception, as well as drugs and molecular targeted therapy blocking nerve conduction pathways, will be reviewed in this article. METHOD: We review and summaries current studies related to molecular mechanisms and treatment approaches in orthodontic pain control. RESULTS: Orthodontics pain related influencing factors and molecular mechanisms has been introduced. Commonly used clinical methods in orthodontic pain control has been evaluated. DISCUSSION: With the clarification of more molecular mechanisms, the direction of orthodontic pain treatment will shift to targeted drugs.

NGF-Induced Upregulation of CGRP in Orofacial Pain Induced by Tooth Movement Is Dependent on Atp6v0a1 and Vesicle Release.

The nerve growth factor (NGF) and calcitonin gene-related peptide (CGRP) play a crucial role in the regulation of orofacial pain. It has been demonstrated that CGRP increases orofacial pain induced by NGF. V-type proton ATPase subunit an isoform 1 (Atp6v0a1) is involved in the exocytosis pathway, especially in vesicular transport in neurons. The objective was to examine the role of Atp6v0a1 in NGF-induced upregulation of CGRP in orofacial pain induced by experimental tooth movement. Orofacial pain was elicited by ligating closed-coil springs between incisors and molars in Sprague-Dawley rats. Gene and protein expression levels were determined through real-time polymerase chain reaction, immunostaining, and fluorescence in situ hybridization. Lentivirus vectors carrying Atp6v0a1 shRNA were used to knockdown the expression of Atp6v0a1 in TG and SH-SY5Y neurons. The release of vesicles in SH-SY5Y neurons was observed by using fluorescence dye FM1-43, and the release of CGRP was detected by Enzyme-Linked Immunosorbent Assy. Orofacial pain was evaluated through the rat grimace scale. Our results revealed that intraganglionic administration of NGF and Atp6v0a1 shRNA upregulated and downregulated CGRP in trigeminal ganglia (TG) and trigeminal subnucleus caudalis (Vc), respectively, and the orofacial pain was also exacerbated and alleviated, respectively, following administration of NGF and Atp6v0a1 shRNA. Besides, intraganglionic administration of NGF simultaneously caused the downregulation of Atp6v0a1 in TG. Moreover, the release of vesicles and CGRP in SH-SY5Y neurons was interfered by NGF and Atp6v0a1 shRNA. In conclusion, in the orofacial pain induced by experimental tooth movement, NGF induced the upregulation of CGRP in TG and Vc, and this process is dependent on Atp6v0a1 and vesicle release, suggesting that they are involved in the transmission of nociceptive information in orofacial pain.

The effects of aligner overtreatment on torque control and intrusion of incisors for anterior retraction with clear aligners: A finite-element study.

INTRODUCTION: The objective of this study was to analyze the effects of aligner overtreatment on torque control and intrusion of incisors for anterior retraction with clear aligners. METHODS: Models including a maxillary dentition without first premolars, maxilla, periodontal ligaments, attachments, and aligners were constructed and imported to finite-element software. Two groups of models were created: (1) without canine attachment and (2) with canine attachment. Overtreatment degrees (0°, 1°, 2°, 3°, 4°, and 5°) were applied for both groups. RESULTS: Clear aligner therapy caused lingual tipping and extrusion of incisors, distal tipping and extrusion of canines, and mesial tipping and intrusion of posterior teeth, which was more significant with canine attachments except for second premolars. Aligner overtreatment produced palatal root torquing and intrusion of incisors, distal tipping of canines, and mesial tipping of second premolars, with more significant in the condition with canine attachments. With canine attachments, 1.2° overtreatment could cause bodily retraction of central incisors. Without overtreatment, stress was concentrated on apical and cervical area of both labial and lingual surfaces of periodontal ligaments. The stress value was higher with canine attachments. However, when overtreatment was added, the stress was distributed more evenly. CONCLUSIONS: Clear aligner therapy produced lingual tipping and extrusion of incisors during anterior retraction. Overtreatment can achieve incisor intrusion and palatal root torquing, and the effect could be augmented by adding attachments on canines, which required more anchorage from posterior teeth. Appropriate overtreatment with placing attachments on canines should be designed to ensure bodily retraction and the least root resorption.

Quantitative analysis of facial symmetry by using three-dimensional technology.

BACKGROUND: Facial symmetry is becoming increasingly important in today's orthodontic treatment. But the asymmetrical boundary is not clearly demarcated. Stereophotogrammetry has a clear advantage in measuring facial asymmetry. The aim of this study was to quantify the facial asymmetry by three-dimensional (3D) technology as well as to study whether the evaluation by non-experts about facial asymmetry was consistent with the analysis by 3D technology. METHODS: The facial symmetry of 330 patients was evaluated by 10 non-experts. 3D facial images were taken using 3dMD stereophotogrammetry equipment. The original face and its mirror shell were divided into 7 regions and the surface matching was measured in the whole face and all regional areas. The degree of symmetry was calculated by the software 3-matic STL 9.0. The difference between the two groups was analyzed by Independent-Samples T Test and the diagnostic efficiency of symmetry degree was analyzed by ROC curve analysis. The consistency between the symmetric degree and the result of evaluation was analyzed by Pearson correlation analysis. RESULTS: The ROC analysis revealed significant diagnostic values in the determination of the facial asymmetry of lip, chin, cheek and lateral mandible areas. The cut-off values of symmetry degree were between 60 and 80%. The evaluation was middle correlation with the symmetric degree of the whole face. CONCLUSIONS: The chin and lateral mandible contribute most significantly to the facial symmetry. The objective measurement of facial symmetry, 3D technology, is reliable.

m6A regulator-mediated RNA methylation modification patterns are involved in immune microenvironment regulation of periodontitis.

The role of epigenetic regulation in immunity is emerging, especially for RNA N6-methyladenosine (m6A) modification. However, little is known about the role of m6A in the regulation of the immune microenvironment of periodontitis. Thus, we aim to investigate the impact of m6A modification in periodontitis immune microenvironment. The RNA modification patterns mediated by 23 m6A-regulators were systematically evaluated in 310 periodontitis samples. The impact of m6A modification on immune microenvironment characteristics was explored, including infiltrating immunocytes, immune reaction gene-sets and HLAs (human leukocyte antigen) gene. m6A phenotype-related immune genes were also identified. 17 m6A regulators were dysregulated and a 15-m6A regulator signature can well distinguish periodontitis and control samples. ALKBH5 and FMR1 are closely related to infiltrating monocyte abundance. ELAVL1 and CBLL1 are significant regulators in immune reaction of TNF_Family_Members_Receptors and Cytokine. The expression of HLA-B and HLA-DOA is affected by ALKBH5 and LRPPRC. 3 distinct RNA modification patterns mediated by 23 m6A regulators were identified. They differ from immunocyte abundance, immune reaction and HLA gene. 1631 m6A phenotype-related genes and 70 m6A-mediated immune genes were identified, and the biological functions of these were explored. Our finding demonstrated the m6A modification plays a crucial role in the diversity and complexity of the immune microenvironment of periodontitis.

N/OFQ modulates orofacial pain induced by tooth movement through CGRP-dependent pathways.

BACKGROUND: Nociceptin/orphanin FQ (N/OFQ) has been revealed to play bidirectional roles in orofacial pain modulation. Calcitonin gene-related peptide (CGRP) is a well-known pro-nociceptive molecule that participates in the modulation of orofacial pain. We aimed to determine the effects of N/OFQ on the modulation of orofacial pain and on the release of CGRP. METHODS: Orofacial pain model was established by ligating springs between incisors and molars in rats for the simulation of tooth movement. The expression level of N/OFQ was determined and pain level was scored in response to orofacial pain. Both agonist and antagonist of N/OFQ receptor were administered to examine their effects on pain and the expression of CGRP in trigeminal ganglia (TG). Moreover, gene therapy based on the overexpression of N/OFQ was delivered to validate the modulatory role of N/OFQ on pain and CGRP expression. RESULTS: Tooth movement elicited orofacial pain and an elevation in N/OFQ expression. N/OFQ exacerbated orofacial pain and upregulated CGRP expression in TG, while UFP-101 alleviated pain and downregulated CGRP expression. N/OFQ-based gene therapy was successful in overexpressing N/OFQ in TG, which resulted in pain exacerbation and elevation of CGRP expression in TG. CONCLUSIONS: N/OFQ exacerbated orofacial pain possibly through upregulating CGRP.

The Effects of Static Magnetic Field on Orthodontic Tooth Movement in Mice.

The application of static magnetic field (SMF) has been considered an effective and noninvasive method to accelerate orthodontic tooth movement. The objective of this study was to explore the effects of SMF on orthodontic tooth movement in mice. A total of 105 Balb/c mice (body mass: 25-30 g) were divided into experimental group (SMF + force, 48), control group (force only, 48), and blank group (neither SMF nor force, 9). After the placement of orthodontic appliances, the experimental group was exposed to the SMF environment generated by Neodymium-iron-boron (NdFeB) magnets with an intensity of 20-204 mT. At 1, 3, 7, 14, 21, and 28 days after appliance insertion, eight animals in both experimental and control groups were sacrificed and the left maxillae were dissected to measure the distance of tooth movement, respectively. Meanwhile, the width of periodontal ligament (PDL), length of hyalinized zone, and the number of osteoclasts were evaluated by hematoxylin-eosin and tartrate-resistant acid phosphatase staining. We finally found that the experimental group demonstrated an enhanced rate and greater cumulative amount of tooth movement than the control group (0.2887 ± 0.0041 mm vs. 0.2114 ± 0.0089 mm, P < 0.05). On Days 7, 14, and 28, the experimental group also displayed a significantly greater width of PDL. Earlier formation and removal of the hyalinized zone, and significantly more osteoclasts were observed in the experimental group as well. The results suggested that SMF may be a promising nonsurgical intervention to accelerate orthodontic tooth movement. © 2021 Bioelectromagnetics Society.

Placebo modulation in orthodontic pain: a single-blind functional magnetic resonance study.

OBJECTIVES: The mechanism of orthodontic pain modulation with a placebo remains largely unknown. This study aimed to investigate the placebo modulation of brain activity associated with orthodontic pain using functional magnetic resonance imaging (fMRI). METHODS: This longitudinal fMRI experiment recruited 23 volunteers and a self-contrast method was used. At first time, the participants were scanned without placebo (first period), followed by a 30-day washout, the participants were scanned again with placebo administration (second period). Orthodontic pain was caused by orthodontic separators placement between the lower right molars for both two periods. 24 h after placement, the MRI scans were taken, including a bite/non-bite task fMRI and a resting-state fMRI. A generalized linear model was used to identify pain-regulating network from task fMRI. Functional connectivity analysis of pain-related brain regions was performed to study the placebo effect on connectivity of pain-regulating networks using resting-state fMRI. RESULTS: The results of brain activation patterns were largely similar under placebo and non-placebo conditions. Under the non-placebo condition, the activities in multiple brain regions, including the pre-central gyrus, superior frontal gyrus, superior parietal lobule, and supramarginal gyrus, were significantly higher than that of the placebo condition. However, the anterior cingulate cortex (ACC) was activated under the non-placebo condition but not in the placebo one. The functional connectivities between ACC and orbitofrontal cortex, and the dorsolateral prefrontal cortex and orbitofrontal cortex were reduced under placebo condition. CONCLUSION: Participants demonstrated similar brain activation patterns for orthodontic pain with or without placebos. With placebo, reduced activation in primary sensory cortex and decreased activation in ACC indicated that ACC could be fundamental in analgesia.

A comparison of resin infiltration and microabrasion for postorthodontic white spot lesion.

INTRODUCTION: The objective of this research was to evaluate and compare the effectiveness of microabrasion and resin infiltration for white spot lesions (WSLs). METHODS: Patients with postorthodontic WSLs were enrolled and randomly assigned to the control, microabrasion, and resin-infiltration groups. Intraoral photographs were taken before and after (6 months later) treatment. WSL sizes were determined through ImageJ (Wayne Rasband, Kensington, Md). Integrated optical density (IOD) was determined for a WSL and its surrounding normal enamel through Image-Pro Plus (version 6.0; Media Cybernetics, Rockville, Md), and their differences of IOD were considered as the IOD surrogate for that WSL. The color change of WSL were measured through ΔE. RESULTS: A total of 27 eligible patients were enrolled; 9 subjects were assigned to each group, resulting in 56 teeth in the control group, 72 in the microabrasion group, and 58 in the resin-infiltration group. The ratios of WSL size (after/before) were similar between the microabrasion and resin-infiltration group (43.94 ± 0.03% vs 45.02 ± 0.03%; P = 0.96 > 0.05), but those of the 2 groups were significantly lower than those of the control group (92.15 ± 0.02%) (P <0.001). Moreover, the ratios of IOD (after/before) were significantly lower in the resin-infiltration group (22.94 ± 0.02%) than in the microabrasion (78.11 ± 0.03%) and control (83.79 ± 0.02%) (P <0.001) groups. The highest ΔE improvement was obtained by infiltration, but there was no significant difference between microabrasion and control group. CONCLUSIONS: Resin infiltration and microabrasion are comparably effective in reducing the sizes of WSL, but resin infiltration enjoys an esthetic advantage over microabrasion.

Comparison of pain perception, anxiety, and impacts on oral health-related quality of life between patients receiving clear aligners and fixed appliances during the initial stage of orthodontic treatment.

BACKGROUND AND OBJECTIVES: Clear aligner is an advanced orthodontic method with benefits of comfort, aesthetics, and convenience. This study aimed to compare pain perception, anxiety, and impacts on oral health-related quality of life (OHRQoL) between adult patients receiving clear aligners and fixed appliances during the initial stage of orthodontic treatments. MATERIAL AND METHODS: The two groups were well matched by ages, gender, and levels of malocclusion severity. Pain perception, anxiety, and OHRQoL were assessed through visual analogue scale, state-trait anxiety inventory, and oral health impact profile-14 (OHIP-14), respectively. And the comparison of above scores was performed by two-way analysis of variance. RESULTS: A total of 110 patients (55 pairs) were enrolled in this study. Orthodontic pain levels peaked on the first day and decreased gradually afterwards in both groups, which were significantly higher in the fixed group on the first, second, fourth, and fifth days. Likewise, anxiety levels peaked on the first day and decreased thereafter, with significant difference on the 1st, 3d, 5th, 7th, and 14th days. Moreover, the OHIP-14 scores increased and peaked on the first day and then gradually decreased for both groups, which were also significantly higher in the fixed group on the 1st, 7th, and 14th days. LIMITATIONS: More malocclusion types should be used for group matching. The effect of exclusion of small groups should be taken into consideration in sample size calculation. Income was significantly unbalanced between two groups due to higher cost of clear aligners, and random assignment of treatment modalities was unfeasible. CONCLUSIONS: Patients treated with clear aligners experienced lower pain levels, less anxiety, and higher OHRQoL as compared to those receiving fixed appliances.

Immune landscape of periodontitis unveils alterations of infiltrating immunocytes and molecular networks-aggregating into an interactive web-tool for periodontitis related immune analysis and visualization.

BACKGROUND: Immunity reaction plays an essential role in periodontitis progress and we aim to investigate the underlying regulatory network of immune reactions in periodontitis. METHODS: CIBERSORT was used to estimate immunocyte fractions in different clinical statuses. Logistic regression was used to assess the immunocyte weight in periodontitis. Immune-related periodontitis subtypes were identified by the Nonnegative Matrix Factorization algorithm. Gene-set enrichment analysis and Gene-set variation analysis were conducted to analyze pathway activities. Immunocytes related gene modules were identified by Weighted gene co-expression network analysis. RESULTS: Altered immunocytes in healthy versus periodontitis, aggressive versus chronic, male versus female and age were identified. Immunocytes enriched in periodontitis were calculated, and their correlation was also explored. Two distinct immune-related periodontitis subtypes were identified and one is characterized by B cell reactions and the other is IL-6 cytokine reactions. 463 statistically significant correlations between 22 immunocytes and pathways were revealed. Immunocytes and clinical phenotypes matched their gene modules, and their functions were annotated. Last, an easy-to-use and user-friendly interactive web-tool were developed for periodontitis related immune analysis and visualization ( https://118.24.100.193:3838/tool-PIA/ ). CONCLUSIONS: This study systematically investigated periodontitis immune atlas and caught a glimpse of the underlying mechanism of periodontitis from gene-pathway-immunocyte networks, which can not only inspire researchers but also help them in periodontitis related immune researches.

The dynamics of the oral microbiome and oral health among patients receiving clear aligner orthodontic treatment.

OBJECTIVES: This 6-month prospective clinical study assessed the impacts of Invisalign appliances on the oral bacterial community and oral health of patients. METHODS: Salivary samples were obtained from twenty-five adult patients receiving Invisalign aligner treatment before the treatment (Group B) and at a 6-month follow-up (Group P). The bacterial composition of each sample was determined using Illumina MiSeq sequencing of the bacterial 16S rRNA. Intra- and intergroup biodiversity was analyzed. Clinical periodontal parameters and daily oral hygiene habits were recorded. RESULTS: Reduction in plaque, increased daily brushing frequency, and decreased dessert intake were observed in Group P compared with that in Group B. A total of 1,853,952 valid reads were obtained from the 50 salivary samples, with 37,904 sequences per sample. No significant differences were detected in the intra- and intergroup biodiversity comparisons between the two groups. By clustering, 8,885 OTUs were identified and categorized into six major phyla: Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, Actinobacteria, and Candidate_division_TM7_norank. At the genus level, compared with Group B, Group P demonstrated significantly increased Bacillus abundance and decreased Prevotella abundance. CONCLUSIONS: Our results suggested that the general biodiversity and salivary microbial community structure did not change significantly and that patients had increased beneficial oral hygiene habits and awareness during the first six months of Invisalign treatment. Hence, on the basis of this study, it appears that Invisalign aligner treatment did not induce deterioration of oral health nor significant biodiversity changes in oral bacterial communities, assuming that detailed oral hygiene instructions for both teeth and aligners were provided.

Effectiveness of remineralizing agents in the prevention and reversal of orthodontically induced white spot lesions: a systematic review and network meta-analysis.

OBJECTIVES: To compare the effectiveness of remineralizing agents in the prevention and reversal of white spot lesions (WSLs), which occur during fixed orthodontic treatment, through a systematic review and network meta-analysis. MATERIALS AND METHODS: We reviewed controlled randomized clinical trial (RCT) data querying nine databases combined with a manual search (last search date: March 10, 2020). Of 2273 identified studies, 36 RCTs were finally included. After study selection and data extraction, pair-wise and network meta-analyses were performed to analyze the effectiveness of remineralizing agents in the prevention and reversal of WSLs in the short term (≤ 3 months) and long term (> 3 months). The risk of bias was assessed based on the Cochrane guidelines. Statistical heterogeneity, inconsistencies, and cumulative ranking were also evaluated. RESULTS: In terms of WSL prevention, sodium fluoride (NaF) varnish had the highest cumulative ranking for the short-term decalcification index (99.3%); acidulated phosphate fluoride (APF) foam ranked first for long-term incidence (96.9%), followed by difluorosilane (Dfs) varnish and high-concentration fluoride toothpaste (HFT) (79.4% and 77.4%, respectively). In the reversal of WSLs, no significant difference was found among different agents or their combinations for the two available outcomes (short-term integrated fluorescence loss and short-term percentage of fluorescence loss). CONCLUSIONS: In the prevention of WSLs, APF foam showed the best remineralizing effectiveness in the long term (after debonding), followed by Dfs varnish and HFT. It is unclear whether remineralizing agents can effectively reverse WSLs based on the existing evidence. CLINICAL RELEVANCE: APF foam may be recommended as a remineralizing agent for preventing orthodontically induced WSLs. PROSPERO REGISTRATION NUMBER: CRD42019116852.