Effect of Low Intensity Pulsed Ultrasound (LIPUS) on Tooth Movement and Root Resorption: A Prospective Multi-Center Randomized Controlled Trial

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.

Low-intensity pulsed ultrasound promotes the osteogenesis of mechanical force-treated periodontal ligament cells via Piezo1

Background

Low-intensity pulsed ultrasound (LIPUS) can accelerate tooth movement and preserve tooth and bone integrity during orthodontic treatment. However, the mechanisms by which LIPUS affects tissue remodeling during orthodontic tooth movement (OTM) remain unclear. Periodontal ligament cells (PDLCs) are pivotal in maintaining periodontal tissue equilibrium when subjected to mechanical stimuli. One notable mechano-sensitive ion channel, Piezo1, can modulate cellular function in response to mechanical cues. This study aimed to elucidate the involvement of Piezo1 in the osteogenic response of force-treated PDLCs when stimulated by LIPUS.

Method

After establishing rat OTM models, LIPUS was used to stimulate rats locally. OTM distance and alveolar bone density were assessed using micro-computed tomography, and histological analyses included hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining and immunohistochemical staining. GsMTx4 and Yoda1 were respectively utilized for Piezo1 functional inhibition and activation experiments in rats. We isolated human PDLCs (hPDLCs) in vitro and evaluated the effects of LIPUS on the osteogenic differentiation of force-treated hPDLCs using real-time quantitative PCR, Western blot, alkaline phosphatase and alizarin red staining. Small interfering RNA and Yoda1 were employed to validate the role of Piezo1 in this process.

Results

LIPUS promoted osteoclast differentiation and accelerated OTM in rats. Furthermore, LIPUS alleviated alveolar bone resorption under pressure and enhanced osteogenesis of force-treated PDLCs both in vivo and in vitro by downregulating Piezo1 expression. Subsequent administration of GsMTx4 in rats and siPIEZO1 transfection in hPDLCs attenuated the inhibitory effect on osteogenic differentiation under pressure, whereas LIPUS efficacy was partially mitigated. Yoda1 treatment inhibited osteogenic differentiation of hPDLCs, resulting in reduced expression of Collagen Ⅰα1 and osteocalcin in the periodontal ligament. However, LIPUS administration was able to counteract these effects.

Conclusion

This research unveils that LIPUS promotes the osteogenesis of force-treated PDLCs via downregulating Piezo1.

Bibliometric and visualized analysis of randomized controlled trials in orthodontics between 1991 and 2022

INTRODUCTION

In many evidence-based approaches to orthodontic research, randomized controlled trials (RCTs) represent authoritative evidence to identify rational therapeutics. This study aimed to perform mappings of bibliometric networks on orthodontic RCTs and summarize visual characteristics between 1991 and 2022.

METHODS

The articles were retrieved from the Web of Science Core Collection in October 2022 without an initial time limit. Only orthodontic RCTs were eligible. Some bibliometric tools (HistCite, VOSviewer, SCImago Graphica, and CiteSpace) were applied for visualized analysis. Data such as geography, productive institutions, hot articles, journals, authors, references, and keywords were extracted and summarized for analysis.

RESULTS

A total of 1122 orthodontic RCTs were searched. A total of 3841 authors from 1157 institutions in 65 countries published orthodontic RCTs. The United States (149) was the most prolific country, and the University of Sao Paulo (35) was the most productive institution. The American Journal of Orthodontics and Dentofacial Orthopedics (206) was the most popular journal for scholars. The visualization results of keyword co-occurrence identified 5 clusters: (1) tooth movement and auxiliary measures, (2) appliances and oral health, (3) orthodontic discomfort and symptomatic therapy, (4) periodontal disease in orthodontics and health maintenance, and (5) retention and relapse.

CONCLUSIONS

Over the past 31 years, publications and citations on orthodontic RCTs from the Web of Science Core Collection have increased notably across many countries, authors, and institutions. Recently, there has been a significant increase in the attention to orthodontic RCTs that focus on accelerating tooth movement.

Low-intensity pulsed ultrasound reduces alveolar bone resorption during orthodontic treatment via Lamin A/C-Yes-associated protein axis in stem cells

BACKGROUND

The bone remodeling during orthodontic treatment for malocclusion often requires a long duration of around two to three years, which also may lead to some complications such as alveolar bone resorption or tooth root resorption. Low-intensity pulsed ultrasound (LIPUS), a noninvasive physical therapy, has been shown to promote bone fracture healing. It is also reported that LIPUS could reduce the duration of orthodontic treatment; however, how LIPUS regulates the bone metabolism during the orthodontic treatment process is still unclear.

AIM

To investigate the effects of LIPUS on bone remodeling in an orthodontic tooth movement (OTM) model and explore the underlying mechanisms.

METHODS

A rat model of OTM was established, and alveolar bone remodeling and tooth movement rate were evaluated via micro-computed tomography and staining of tissue sections. In vitro, human bone marrow mesenchymal stem cells (hBMSCs) were isolated to detect their osteogenic differentiation potential under compression and LIPUS stimulation by quantitative reverse transcription-polymerase chain reaction, Western blot, alkaline phosphatase (ALP) staining, and Alizarin red staining. The expression of Yes-associated protein (YAP1), the actin cytoskeleton, and the Lamin A/C nucleoskeleton were detected with or without YAP1 small interfering RNA (siRNA) application via immunofluorescence.

RESULTS

The force treatment inhibited the osteogenic differentiation potential of hBMSCs; moreover, the expression of osteogenesis markers, such as type 1 collagen (COL1), runt-related transcription factor 2, ALP, and osteocalcin (OCN), decreased. LIPUS could rescue the osteogenic differentiation of hBMSCs with increased expression of osteogenic marker inhibited by force. Mechanically, the expression of LaminA/C, F-actin, and YAP1 was downregulated after force treatment, which could be rescued by LIPUS. Moreover, the osteogenic differentiation of hBMSCs increased by LIPUS could be attenuated by YAP siRNA treatment. Consistently, LIPUS increased alveolar bone density and decreased vertical bone absorption in vivo. The decreased expression of COL1, OCN, and YAP1 on the compression side of the alveolar bone was partially rescued by LIPUS.

CONCLUSION

LIPUS can accelerate tooth movement and reduce alveolar bone resorption by modulating the cytoskeleton-Lamin A/C-YAP axis, which may be a promising strategy to reduce the orthodontic treatment process.

[Experimental study of subcutaneous adipose-derived stem cells inhibiting orthodontic root resorption]

Objective

To investigate the effect of human subcutaneous adipose-derived stem cells (hADSCs) local transplantation on orthodontically induced root resorption (OIRR) and provide theoretical and experimental basis for the clinical application of hADSCs to inhibit OIRR.

Methods

Forty 8-week-old male Sprague Dawley rats were randomly divided into experimental group and control group, with 20 rats in each group, to establish the first molar mesial orthodontic tooth movement (OTM) model of rat right maxillary. The rats in the experimental group were injected with 25 μL of cell suspension containing 2.5×10 5 hADSCs on the 1st, 4th, 8th, and 12th day of modeling, while the rats in the control group were injected with 25 μL of PBS. The rat maxillary models were obtained before and after 7 and 14 days of force application, and 10 rats in each group were killed and sampled after 7 and 14 days of force application. The OTM distance was measured by stereomicroscope, the root morphology of the pressure side was observed by scanning electron microscope and the root resorption area ratio was measured. The root resorption and periodontal tissue remodeling of the pressure side were observed by HE staining and the root resorption index was calculated. The number of cementoclast and osteoclast in the periodontal tissue on the pressure side was counted by tartrate resistant acid phosphatase staining.

Results

The TOM distance of both groups increased with the extension of the force application time, and there was no significant difference ( P<0.05). There was no significant difference in OTM distance between the experimental group and the control group after 7 and 14 days of force application ( P>0.05). Scanning electron microscope observation showed that small and shallow scattered resorption lacunae were observed on the root surface of the experimental group and the control group after 7 days of force application, and there was no significant difference in the root resorption area ratio between the two groups ( P>0.05); after 14 days of application, the root resorption lacunae deepened and became larger in both groups, and the root resorption area ratio in the experimental group was significantly lower than that in the control group ( P<0.05). The range and depth of root absorption in the experimental group were smaller and shallower than those in the control group, and the root absorption index in the experimental group was significantly lower than that in the control group after 14 days of force application ( P<0.05). The number of cementoclast in the experimental group was significantly lower than that in the control group after 7 and 14 days of force application ( P<0.05); the number of osteoclasts in the experimental group was significantly lower than that in the control group after 14 days of force application ( P<0.05).

Conclusion

Local transplantation of hADSCs may reduce the area and depth of root resorption by reducing the number of cementoclasts and osteoclasts during OTM in rats, thereby inhibiting orthodontic-derived root resorption.

The effect of low-frequency high-intensity ultrasound combined with aspirin on tooth movement in rats

BACKGROUND

Given the difficulties or incapacity of teeth movement in orthodontic treatment, the ways to speed tooth movement must be investigated. Besides, nonsteroidal anti-inflammatory drugs (NSAIDs) were utilized to treat pain caused by tooth movement during orthodontic treatment. The purpose of this study is to examine the impact of aspirin and low-frequency high-intensity ultrasound (LFHIU) on rat orthodontic tooth movement in rats.

METHODS

Thirty-six male Sprague-Dawley rats were divided into three groups: orthodontic (O), ultrasound-treated orthodontic (OU), and ultrasound-treated orthodontic with aspirin gavage (OUA) group. In the OU and OUA group, LFHIU (44 W/cm2, 28 kHz) was applied to the buccal side of the maxillary first molar alveolar bone for 10 s every day. In the OUA group, aspirin was given by gavage every day. The rats were sacrificed on days 1, 3, 7, and 14.

RESULTS

After ultrasonic treatment, the speed of tooth movement was increased by about 1.5 times. And the number of osteoclasts considerably increased by about 2 times. However, they decreased slightly after aspirin gavage. By Applying ultrasound therapy, Receptor Activator for Nuclear Factor-κ B Ligand (RANKL) levels in periodontal tissue were elevated. Aspirin was able to reduce these increases. Results from Micro Computed Tomography (Micro-CT) revealed that bone mineral density decreased by about 1/5 after ultrasound treatment on the compression side. The rate of bone mineral apposition indicated that bone was forming under tension, and that of the OU group increased by about 1.3 times that O group.

CONCLUSIONS

Although aspirin slowed this trend, LFHIU still enhanced overall tooth mobility in orthodontic treatment.

Knowledge mapping and global trends in the field of low-intensity pulsed ultrasound and endocrine and metabolic diseases: a bibliometric and visual analysis from 2012 to 2022

Background

Low-intensity pulsed ultrasound (LIPUS) is a highly promising therapeutic method that has been widely used in rehabilitation, orthopedics, dentistry, urology, gynecology, and other multidisciplinary disease diagnoses and treatments. It has attracted extensive attention worldwide. However, there is currently a lack of comprehensive and systematic research on the current status and future development direction of the LIPUS field. Therefore, this study comprehensively analyzed LIPUS-related reports from the past decade using bibliometrics methods, and further conducted research specifically focusing on its application in endocrine and metabolic diseases.

Methods

We downloaded LIPUS literature from 2012 to 2022 reported in the Web of Science Core Collection Science Citation Index-Expanded and Social Sciences Citation Index, and used bibliometric analysis software such as VOSviewer and CiteSpace to execute the analysis and visualize the results.

Results

We searched for 655 English articles published on LIPUS from 2012 to 2022. China had the highest number of published articles and collaborations between China and the United States were the closest in this field. Chongqing Medical University was the institution with the highest output, and ULTRASOUND IN MEDICINE AND BIOLOGY was the journal with the most related publications. In recent years, research on the molecular mechanisms of LIPUS has continued to deepen, and its clinical applications have also continued to expand. The application of LIPUS in major diseases such as oxidative stress, regeneration mechanism, and cancer is considered to be a future research direction, especially in the field of endocrinology and metabolism, where it has broad application value.

Conclusion

Global research on LIPUS is expected to continue to increase, and future research will focus on its mechanisms of action and clinical applications. This study comprehensively summarizes the current development status and global trends in the field of LIPUS, and its research progress in the field of endocrine and metabolic diseases, providing valuable reference for future research in this field.

Evaluation of Efficacy of Low-Intensity Pulsed Ultrasound on Comorbidities Following Mandibular Impacted Third Molar Surgery: A Prospective Study

Introduction

Despite several in vitro and in vivo applications of low-intensity pulsed ultrasound (LIPUS), it remains an under-studied feature of the oral and maxillofacial region. The goal of this in vivo study was to objectively investigate the efficacy of low-intensity pulsed ultrasound on wound healing and related morbidities following surgical removal of an impacted third molar.

Materials and Methods

The following in vivo prospective, comparative, randomised controlled clinical study was carried out amongst 56 patients who reported to the Department of Oral and Maxillofacial Surgery fulfilling the inclusion criteria. Group A received sham ultrasound, whereas Group B received LIPUS therapy. Based on the group allocated LIPUS 1 MHz, pulsed 20% and dose 1.0 watts/square centimetre (W/cm2)/sham, ultrasound therapy was given on 1st, 2nd and 3rd post-operative days. The assessment of post-operative pain, oedema, trismus and wound healing on preoperative, first, third and seventh postoperative days.

Results

The quantitative variables of the study were assessed using independent sample t-test, and qualitative variables were assessed using the Chi-square test. The P < 0.05 on third and seventh post-op days for pain, trismus and wound healing in the LIPUS group compared to control group making it statistically significant. There was no statistically significant difference in the reduction of oedema amongst the two groups.

Discussion

Post-LIPUS application in the patients, postoperative pain was significantly reduced, trismus was noticeably improved and wound healing was satisfactory and can be employed as a complementary technique.

Low-intensity pulsed ultrasound regulates osteoblast-osteoclast crosstalk via EphrinB2/EphB4 signaling for orthodontic alveolar bone remodeling

Background: The limited regenerative potential of periodontal tissue remains a challenge in orthodontic treatment, especially with respect to alveolar bone remodeling. The dynamic balance between the bone formation of osteoblasts and the bone resorption of osteoclasts controls bone homeostasis. The osteogenic effect of low-intensity pulsed ultrasound (LIPUS) is widely accepted, so LIPUS is expected to be a promising method for alveolar bone regeneration. Osteogenesis is regulated by the acoustic mechanical effect of LIPUS, while the cellular perception, transduction mode and response regulation mechanism of LIPUS stimuli are still unclear. This study aimed to explore the effects of LIPUS on osteogenesis by osteoblast-osteoclast crosstalk and the underlying regulation mechanism. Methods: The effects of LIPUS on orthodontic tooth movement (OTM) and alveolar bone remodeling were investigated via rat model by histomorphological analysis. Mouse bone marrow mesenchymal stem cells (BMSCs) and bone marrow monocytes (BMMs) were purified and used as BMSC-derived osteoblasts and BMM-derived osteoclasts, respectively. The osteoblast-osteoclast co-culture system was used to evaluate the effect of LIPUS on cell differentiation and intercellular crosstalk by Alkaline phosphatase (ALP), Alizarin Red S (ARS), tartrate-resistant acid phosphatase (TRAP) staining, real-time quantitative PCR, western blotting and immunofluorescence. Results: LIPUS was found to improve OTM and alveolar bone remodeling in vivo, promote differentiation and EphB4 expression in BMSC-derived osteoblasts in vitro, particularly when cells were directly co-cultured with BMM-derived osteoclasts. LIPUS enhanced EphrinB2/EphB4 interaction between osteoblasts and osteoclasts in alveolar bone, activated the EphB4 receptor on osteoblasts membrane, transduced LIPUS-related mechanical signals to the intracellular cytoskeleton, and gave rise to the nuclear translocation of YAP in Hippo signaling pathway, thus regulating cell migration and osteogenic differentiation. Conclusions: This study shows that LIPUS modulates bone homeostasis by osteoblast-osteoclast crosstalk via EphrinB2/EphB4 signaling, which benefits the balance between OTM and alveolar bone remodeling.

Prevention and repair of orthodontically induced root resorption using ultrasound: a scoping review

INTRODUCTION

This review summarizes the available recent literature on different mechanisms and parameters of pulsed ultrasound (US) that have been used during orthodontic treatments to prevent and repair root resorption.

AREAS COVERED

A literature search was conducted between January (2002) and September (2022) in the following databases: PubMed, Google-Scholar, Embase and The-Cochrane-Library. After exclusions, a total of 19 papers were included in the present review. The most used US parameters with positive outcomes were frequency of 1.5 MHz, pulse repetition frequency of 1000 Hz, output intensity of 30 mW/cm2, duration of application of 20 mins and total number sessions were 14 with a repetition interval of 1day. The suggested mechanisms induced by US were alteration of cementoblasts, osteoblasts, osteoclasts, alkaline-phosphatase (ALP), runt-related-gene-2 (Runx2), osteoprotegerin (OPG), type-I-collagen (Col-I), C-telopeptide-type-I-collagen (CTX-I), hepatocyte-growth-factor (HGF), bone morphogenetic protein-2 (BMP-2), cyclooxygenase-2 (Cox-2), calcium (Ca2+), receptor activator of nuclear factor-kappa-B ligand (RANKL), and receptor activator of nuclear factor-kappa-B (RANK).

EXPERT OPINION

Understanding mechanisms and deciding which parameters of US that can be used during orthodontic treatment to prevent and repair root resorption is a great challenge. This work summarizes all the available data that can aid this process and suggest that US is an effective noninvasive method not only in prevention and repairing of orthodontic induced root resorption but also in accelerating teeth movement.

Impact of low intensity pulsed ultrasound on volumetric root resorption of maxillary incisors in patients treated with clear aligner therapy: A retrospective study

OBJECTIVE

The aim of this study was to evaluate the volumetric root resorption in maxillary incisors following clear aligner therapy (CAT) with low-intensity pulsed ultrasound (LIPUS), and compare the results to CAT alone.

MATERIAL AND METHODS

This retrospective study evaluated pretreatment (T0) and post-treatment (T1) cone-beam computed tomography imaging of 42 adult patients. Twenty-one patients (14 females, 7 males, mean age= 38.1±12.96 years) were treated using CAT with LIPUS device, whereas the other twenty-one matching controls patients (15 females, 6 males, mean age= 35.6±11.7 years) were treated using CAT alone. Images were analyzed and a segmentation protocol was applied on the maxillary incisors. Each segmented tooth volume was exported as a surface mesh in the Visualization Toolkit (VTK) file format. The VTK files for all maxillary incisors were coded and corresponding teeth volumes from T0 and T1 were superimposed. Clipping the crown of each tooth was done, then measurements of root volumes and differences between groups were performed. Changes in root volumes were assessed (p<0.05).

RESULTS

Root loss was evident in all teeth in both groups, but was significantly increased in all maxillary incisors of the control group (p<0.001) and in upper left central incisor of LIPUS group (p=0.009). When both groups were compared, there was statistically significant minimal volumetric root loss in LIPUS group (3.50-7.32 mm3), when compared to control group (11.48-12.95 mm3) (p<0.05).

CONCLUSION

LIPUS group showed less volumetric root resorption compared to control group during the studied treatment time using clear aligners.

Impact of Frontier Development of Alveolar Bone Grafting on Orthodontic Tooth Movement

Sufficient alveolar bone is a safeguard for achieving desired outcomes in orthodontic treatment. Moving a tooth into an alveolar bony defect may result in a periodontal defect or worse–tooth loss. Therefore, when facing a pathologic situation such as periodontal bone loss, alveolar clefts, long-term tooth loss, trauma, and thin phenotype, bone grafting is often necessary to augment bone for orthodontic treatment purposes. Currently, diverse bone grafts are used in clinical practice, but no single grafting material shows absolutely superior results over the others. All available materials demonstrate pros and cons, most notably donor morbidity and adverse effects on orthodontic treatment. Here, we review newly developed graft materials that are still in the pre-clinical stage, as well as new combinations of existing materials, by highlighting their effects on alveolar bone regeneration and orthodontic tooth movement. In addition, novel manufacturing techniques, such as bioprinting, will be discussed. This mini-review article will provide state-of-the-art information to assist clinicians in selecting grafting material(s) that enhance alveolar bone augmentation while avoiding unfavorable side effects during orthodontic treatment.

Effect of Low-Intensity Pulsed Ultrasound (LIPUS) on Alveolar Bone during Maxillary Expansion Using Clear Aligners

The present study evaluated the possible effect of low-intensity pulsed ultrasound (LIPUS) on buccal bone plate thickness and height after maxillary arch expansion using clear aligners. The cone beam computed tomography (CBCT) of before and immediately after maxillary arch expansion (3 mm per side) of 28 adult patients (18 in LIPUS group and 10 in control) (average age $36.2\pm 13.2$ years old) was analyzed. The wearing protocol of clear aligners in the LIPUS group was to change the aligners every 4 to 5 days, while the wearing protocol in the control group (without LIPUS) was to change the aligners every 7 to 10 days. Bone thickness at 3 mm and 6 mm from the buccal alveolar bone crests, along with the measurements of buccal alveolar bone heights, was measured in standardized sagittal sections. Data were analyzed through paired sample $t$ -test and the Wilcoxon test. The results were given as $\text{mean}\pm \text{standard}\text{deviation}$ and 95% confidence intervals. $p$ value < 0.05 was considered statistically significant. The results showed significant increase in bone height in both groups. However, comparison of both LIPUS and control groups showed no statistically significant difference in bone thickness or bone height. The results of this study showed that the use of LIPUS together with accelerated aligner tray change protocol did not affect alveolar bone integrity when compared to the control group.

The applications of ultrasound, and ultrasonography in dentistry: a scoping review of the literature

OBJECTIVES

This scoping review aims to summarize the available literature on the clinical applications of ultrasonography and ultrasound in diagnostic, therapeutic, and interventional dental applications.

MATERIALS AND METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, Extension for Scoping Reviews checklist and conducted a protocol-driven scoping review of randomized controlled trials, cohort studies, cross-sectional studies, case-control studies, and case series that assessed ultrasonography or ultrasound use as a stand-alone diagnostic, therapeutic, and interventional tool in dentistry. We included studies published after 1980, study samples ≥ 10, with diagnostic, concordance, or therapeutic outcomes. We searched Ovid MEDLINE, Embase, and others (up to April 2021) and extracted information regarding study level, patient level, test or treatment level, and outcome level data.

RESULTS

Five interventional studies (related to oral medicine, temporomandibular disorders, and dental anesthesia), eight therapeutic studies (related to surgery and orthodontics), and seventy-five diagnostic studies (related to orthodontics, surgery, endodontics, oral medicine, temporomandibular disorders, restorative dentistry, and periodontology) were identified and presented in this review.

CONCLUSION

Ultrasonography has a well-established niche in diagnostic dentistry, while therapeutic and interventional ultrasounds have a smaller, yet present, niche in dentistry. However, further research is needed to report the precise estimates of the diagnostic, therapeutic, and interventional effects.

CLINICAL SIGNIFICANCE

Dentists are mostly unfamiliar with ultrasonography and ultrasound and their potential uses. This review maps the diagnostic and therapeutic applications of ultrasonography and ultrasound technology in dentistry and highlights the current challenges, gaps of knowledge, and research status of ultrasound technology in this regard.

Orthodontically Induced External Apical Root Resorption in Class II Malocclusion

Orthodontic-induced external apical root resorption is one of the idiopathic phenomena as an effect, with force generated through mechanotherapy as the cause and the biological tissues with their diversified variations as witness. It is also classified as iatrogenic as a result of indeterminate application of orthodontic forces with subconscious appreciation of the existing underlying conditions. Numerous factors were identified to relate to this irreversible pathologic condition, but none were proven scientifically. Genetics and salivary markers have proved the reliability with time, but the application became insignificant limiting mostly to the research field. Different assessment methods were also identified to clinically diagnose it both subjectively and objectively. Mostly, it is identified through routine radiographic stage records like orthopantomogram or certain prediction radiographs for root resorption probability assessment like in this case. This case report discusses one such encounter which was experienced after stage 1 and 2 mechanics involving quite a few teeth. Considering the biotype of the individual and tooth morphology, the ongoing treatment was terminated and recovery measures were briefed to uplift the self-esteem of the individual. Furthermore, the prognosis is compromised to be very poor with unpredictability to any other treatment modalities.

Low-intensity pulsed ultrasound promotes angiogenesis via the AKT pathway and DNA methylation in human umbilical vein endothelial cells

Angiogenesis involves the activation of endothelial cells (ECs). Low-intensity pulsed ultrasound (LIPUS), which delivers ultrasound waves at a low intensity, can induce the angiogenic potential of ECs. However, the underlying cellular mechanisms remain to be elucidated. In this study, the LIPUS parameters were 1.5 MHz pulsed frequency, 200 us pulse duration, 1.0 kHz repetition rate, and 30 mW/cm² energy intensity. First, we evaluated the effects of LIPUS on the proliferation and angiogenic differentiation of the EC line EA.hy926. The results showed that LIPUS could induce cell proliferation, promote migration, and increase mRNA level inKDR and CD144.Also, the mRNA level and secretion of VEGF were enhanced. We then investigated the role of the AKT signaling pathway in this process. We observed that the expression of p-AKT was upregulated which means that the AKT signaling pathway could be activated by LIPUS, while inhibitor LY294002 of the AKT signaling pathway effectively blocked LIPUS-induced angiogenesis. Finally,we applied confocal Raman microscopy to track biomolecular changes in cells after LIPUS treatment. Spectral analysis showed DNA methylation changes. An Infinium Methylation assay suggested that399 sites were significantly different. After KEGG enrichment analysis, we found seven genes (IRS1, GNG7, COL4A1, FOXO3, COL4A2, CDK4 and EGF) which were closely related to AKT signaling pathway. We verified that AKT signaling pathway inhibition partially blocked LIPUS-induced DNA methylation changes. Ourstudy demonstrated that LIPUS couldpromote the proliferation and angiogenic differentiation of ECs via the AKT signaling pathway. LIPUS could also alter DNA methylation of ECs via the activation of AKT signal.

Effect of 970 nm low-level laser therapy on orthodontic tooth movement during Class II intermaxillary elastics treatment: a RCT

This prospective randomized clinical trial aimed to evaluate the effect of low-level laser therapy on tooth movement during Class II intermaxillary elastics treatment. Forty-two patients with Class II malocclusion were included, and their maxillary quadrants were allocated into two groups: treatment with an active diode laser and a placebo group. In each group, the time taken to obtain Class I occlusion after 6 months, rate of movement, total displacement of the maxillary canine to Class I occlusion and pain were recorded. The time to reach Class I occlusion in the active laser group (2.46 ± 2.1 months) was not significantly different from that in the placebo group (2.48 ± 2.0 months) (p = 0.938). Interestingly, the total distance of movement on the active laser side (2.27 ± 1.5 mm) was significantly greater than that on the placebo side (1.64 ± 1.3 mm) (p = 0.009). The pain levels on days 1, 2 and 3 were not significantly different between the laser and placebo sections. The rate of distance change toward Class I occlusion in the laser group (1.1 ± 0.7 mm/month) was significantly higher than that in the placebo group (0.74 ± 0.6 mm/month) (p = 0.037). Low-level laser therapy (970 nm) did not reduce the time needed to obtain Class I occlusion, but a significant acceleration in tooth movement was observed in the irradiated group.

Trial registration: NCT02181439. Registered 04 July 2014—https://www.clinicaltrials.gov/ct2/results?term=cinelaser.

Orthodontic root resorption

External apical root resorption (EARR) is one of the most frequently reported iatrogenic side effects of orthodontic movement. Nevertheless, no robust and unequivocal scientific evidence is yet available in the literature regarding the clinical and biological factors that trigger EARR. The purpose of the present position paper is to provide clinicians, residents, and investigators a summary of our current understanding about root resorption caused by orthodontic tooth movement, based on up-to-date available scientific evidence. Morphological, structural, biomechanical, and biological differences account for predisposing the apical third to EARR compared to other root surfaces during orthodontic treatment. In addition, a relevant number of patient and treatment-related factors increase risk of EARR. The main patient-related factors are reviewed and discussed: genetic factors, tooth anatomy, demographic factors, malocclusion factors, previous endodontic treatment, medical history, short root anomaly. Similarly, the influence of treatment-related factors are analyzed with regard to the effect of: biomechanical factors, type of orthodontic appliance, adjunctive therapies to accelerate tooth movement, early treatment, maxillary expansion, teeth extractions, the duration of treatment and the amount of apical displacement. Clinical management of EARR from pre-treatment records to the monitoring strategy as well as recommendations for the post orthodontic-treatment period are presented as a guide for the clinician. Despite years of studies, we still do not fully understand EARR, but the future is promising. True three-dimensional imaging with higher resolution and low radiation, and predictive tools towards an earlier detection without radiographs, will mark future developments in the field of EARR in orthodontics.

Impact of photobiomodulation and low-intensity pulsed ultrasound adjunctive interventions on orthodontic treatment duration during clear aligner therapy: A retrospective study

OBJECTIVE

To assess the efficiency of low-intensity pulsed ultrasound (LIPUS) and photobiomodulation (PBM) interventions in accelerating orthodontic tooth movement during clear aligner therapy (CAT).

MATERIALS AND METHODS

This retrospective study was carried out on the records of 84 subjects who were treated using CAT. Twenty-eight patients were treated using CAT with a daily use of LIPUS for 20 minutes, 28 patients were treated using CAT with a daily use of PBM for 10 minutes, and 28 patients were treated using CAT alone. The total duration of treatment was recorded for all patients. One-way analysis of variance and post hoc Tukey test were used to assess whether there was any significant difference in total treatment duration among the three groups (P < .05).

RESULTS

The mean treatment durations in days were 719 ± 220, 533 ± 242, and 528 ± 323 for the control, LIPUS, and PBM groups, respectively. The LIPUS group showed a 26% reduction, on average, in treatment duration when compared with the control group, whereas the PBM group showed an average 26.6% reduction in the treatment duration when compared with the control group. The results showed that there were statistically significant differences among the groups (P = .011). Treatment durations were significantly reduced in the LIPUS and PBM groups as compared with the control (P = .027 and P = .023, respectively), with no statistically significant differences between the LIPUS and PBM groups (P = .998).

CONCLUSIONS

Daily use of LIPUS or PBM as adjunctive interventions during CAT could reduce the duration of orthodontic treatment.

Impact of intraoral non-pharmacological non-surgical adjunctive interventions on orthodontically induced inflammatory root resorption in humans: A systematic review

BACKGROUND

The current systematic review aimed to assess the impact of intraoral non-surgical non-pharmacological adjunctive interventions on orthodontically induced inflammatory root resorption (OIIRR).

SEARCH METHODS

Search without restrictions was performed up to November 2020 in three electronic databases (Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE) for randomized controlled trials (RCTs), prospective and retrospective non-randomized studies. The ROB 2.0 tool was used to assess the quality of the included RCTs, and the ROBINS-I tool was applied to non-randomized clinical studies. The strength of evidence was ranked using GRADE.

RESULTS

Three hundred and sixteen records were initially retrieved. A total of 10 studies, with 236 patients, were finally considered. These studies assessed the effects of mechanical vibration (low-frequency and high-frequency), low-intensity pulsed ultrasound (LIPUS), low-level laser therapy (LLLT) and photobiomodulation (light-emitting devices (LED). While the low-frequency vibration and LED do not seem to affect OIIRR, OIIRR has been reported to be reduced in high-frequency vibration, and LIPUS-treated teeth (differences may not likely be considered clinically relevant). The potential positive effect of LLLT on OIIRR is still debatable. Overall, the existing evidence suggests that the amount of OIIRR observed while using these interventions with traditional orthodontic treatment was not more than that was observed without it.

CONCLUSIONS

Based on a very low level of confidence, it seems that intraoral non-pharmacological non-surgical adjunctive interventions do not affect the amount of OIIRR either positively or negatively to a clinically relevant degree when compared to what is seen with conventional orthodontic treatment alone.

The Effect of High-Frequency Vibration on Tooth Movement and Alveolar Bone in Non-Growing Skeletal Class II High Angle Orthodontic Patients: Case Series

This study presents a novel technique utilizing high-frequency vibration to shorten treatment time and preserve alveolar bone in challenging orthodontic cases that have been treated with Invisalign^® clear aligners. Four non-growing orthodontic patients (age range 14–47 years old) with Class II skeletal patterns (convex profiles with retrognathic mandibles) who sought correction of their crowded teeth and non-surgical correction of their convex profiles were included in this study. These patients were treated using Invisalign clear aligners together with high-frequency vibration (HFV) devices (120 Hz) (VPro5™) that were used by all patients for five minutes per day during active orthodontic treatment. Vertical control and forward rotation of the mandible for each patient was achieved through pre-programming the Invisalign to produce posterior teeth intrusion. Successful forward rotation of the mandibles achieved in all patients led to improvement of their facial convex profiles (apical base relationship (ANB) improved 2.1 ± 0.5 degrees; FMA (Frankfurt mandibular plane angle) improved 1.2 + 1.1 degrees). Dental decompensation was achieved by lingual tipping of the lower incisors and palatal root torque of upper incisors. The use of HFV together with Invisalign facilitated achieving these results within a 12 ± 6 months period. In addition, more bone labial to the lower incisors after their lingual movement was noted. In conclusion, the use of HFV concurrent with SmartTrack Invisalign aligners allowed complex tooth movement and forward mandibular projection without surgery in non-growing patients with skeletal Class II relationships. The clinical impact and implications of this case series are: (1) the use of HFV facilitates complex orthodontic tooth movement including posterior teeth intrusion and incisor decompensation; (2) forward mandibular projection of the mandible and increased bone formation labial to lower incisors can be achieved in non-growing patients that may minimize the need for surgical intervention in similar cases or gum recession due to lower incisors labial inclination.

The effect of low intensity pulsed ultrasound on dentoalveolar structures during orthodontic force application in diabetic ex-vivo model

OBJECTIVE

This study aimed to investigate the effect of the low intensity pulsed ultrasound (LIPUS) on the dentoalveolar structures during orthodontic force application in ex-vivo model using mandible slice organ culture (MSOC) of diabetic rats.

DESIGN

18 male Wistar rats with a mean weight (275 g) were randomly divided into three main groups: 1) normal rats, 2) Insulin treated diabetic rats, and 3) diabetic rats. Diabetes mellitus (DM) was induced by streptozotocin. Four weeks later, rats were euthanized, mandibles were dissected, divided into 1.5-mm slices creating mandible slice organ cultures (MSOCs). MSOCs were cultured at 37 °C in air with 5 % CO₂. The following day, orthodontic spring delivering a 50-g of force was applied to each slice. In each group, rats were randomly assigned to 2 subgroups; one received 10 min of LIPUS daily and the other was the control. Culture continued for 7 days, and then the sections were prepared for histological and histomorphometric analysis.

RESULTS

For all study groups (Normal, Insulin Treated Diabetic and Diabetic), LIPUS treatment significantly increased the thickness of predentin, cementum, and improved bone remodeling on the tension side and increased odontoblast, sub-odontoblast, and periodontal ligaments cell counts and bone resorption lacunae number on the compression side.

CONCLUSIONS

Application of LIPUS treatment for 10 min daily for a week enhanced bone remodeling and repair of cementum and dentin in normal as well as diabetic MSOCs.

Shortening of Overall Orthodontic Treatment Duration with Low-Intensity Pulsed Ultrasound (LIPUS)

The aim of this retrospective clinical study was to determine if there is a reduction in the overall treatment duration in orthodontic patients using low-intensity pulsed ultrasound (LIPUS) and Invisalign SmartTrack® clear aligners. Data were collected from the first thirty-four patients (9 males, 25 females; average age 41.37 ± 15.02) who finished their orthodontic treatment using an intraoral LIPUS device and Invisalign clear aligners in a private clinic. The LIPUS parameters used by patients at home for 20 min/day were: ultrasonic frequency 1.5 MHz, pulse duration 200µs, pulse repetition rate 1 kHz, and spatial average-temporal average intensity 30mW/cm². A control group (11 males, 23 females; average age 31.36 ± 14.41) matching for the same malocclusions was randomly selected from finished treatment cases of the same clinician. The date of first Invisalign attachment placement and first use of LIPUS application was recorded as T0, and the date of retainer delivery was recorded as T1. The treatment duration (T1–T0) and treatment reduction percentage with LIPUS device were collected and analyzed using two-sample t-test in Microsoft Excel. Treatment duration was significantly reduced in the LIPUS group (541.44 ± 192.23 days) compared to control group (1061.05 ± 455.64 days) (p < 0.05). The LIPUS group showed on average 49% reduction in the overall treatment time as compared to the control group. The average compliance of the patients using LIPUS was 66.02%. Patients who used LIPUS showed a clinically significant reduction in the overall orthodontic treatment duration compared to the control group who used Invisalign clear aligners only.

Influence of photobiomodulation on pain perception during initial orthodontic tooth movement

Abstract Introduction Laser in low intensity (LLI) has been used to reduce the discomfort and pain that is triggered by the forces applied during orthodontic treatment. Objective To evaluate the effect of LLI application in the pain perception of periodontal ligament initial compression, during orthodontic tooth movement; and to compare the effect of this therapy between men and women. Material and method The sample consisted of 30 volunteers, who needed orthodontic band placement on mandibular first molars. After insertion of the elastic separators, LLI was applied to the mesial and distal apical region (wavelength 808nm, energy 2J, time 20s and fluency of 8.32J/cm2) and at three points on the root region (wavelength 808nm, energy 1J, time 10s and fluency of 4.16J/cm2) of the first molar (irradiated side) and compared to the contralateral first molar (non-irradiated side), in three time intervals: 0hs, 24hs and 48hs. Pain perception was evaluated by the Visual Analog Scale (VAS), at 0hs, 24hs and 48hs after insertion, with significance of 5%. Result The pain level was observed to be significantly lower (p<0.05) on the irradiated side, irrespective of gender and time. Women presented a significantly higher pain level (p<0.05) than men, irrespective of time and side. There were no significant differences between the time intervals (p>0.05). Conclusion It was concluded that LLI reduced the perception of initial pain in patients in whom compression of the periodontal ligament was promoted by elastic separation, and that women had a greater perception of pain sensitivity in the time intervals studied.