A randomized, placebo-controlled clinical trial on the effects of recombinant human relaxin on tooth movement and short-term stability

Exploring biological mechanisms in orthodontic tooth movement: Bridging the gap between basic research experiments and clinical applications - A comprehensive review

OBJECTIVES

The molecular mechanisms behind orthodontic tooth movements (OTM) were investigated by clarifying the role of chemical messengers released by cells.

METHODS

Using the Cochrane library, Google scholar, and PubMed databases, a literature search was conducted, and studies published from 1984 to 2024 were considered.

RESULTS

Both bone growth and remodeling may occur when a tooth is subjected to mechanical stress. These chemicals have a significant effect on the stimulation and regulation of osteoblasts, osteoclasts, and osteocytes during alveolar bone remodeling. This regulation can take place in pathological conditions, such as periodontal diseases, or during OTM alone. This comprehensive review outlines key molecular mechanisms underlying OTM and explores various clinical assumptions associated with specific molecules and their functional domains during this process. Furthermore, clinical applications of certain molecules such as relaxin, prostaglandin E (PGE), and interleukin-1β (IL-1β) in accelerating OTM have been reported. Our findings underscore the existing gap between OTM clinical applications and basic research investigations.

CONCLUSION

A comprehensive understanding of orthodontic treatment is enriched by insights into biological systems. We reported the activation of osteoblasts, osteoclast precursor cells, osteoclasts, and osteocytes in response to mechanical stress, leading to targeted cellular and molecular interventions and facilitating rapid and regulated alveolar bone remodeling during tooth movement. Despite the shortcomings of clinical studies in accelerating OTM, this review highlights the crucial role of biological agents in this process and advocates for prioritizing high-quality human studies in future research to gain further insights from clinical trials.

The tooth movement efficiency of different orthodontic thermoplastics for clear aligners: study protocol for a randomized controlled clinical trial

INTRODUCTION

With regard to the esthetics and comfort of orthodontic treatment, the requirement for removable clear aligners (CAs) is increasing. Unlike conventional fixed orthodontic appliances, CAs were made of thermoplastic film by thermoforming on the personalized dental models. The construction of orthodontic thermoplastic is a critical factor for orthodontic tooth movement (OTM). Polyethylene terephthalate glycol-modified (PETG) and thermoplastic polyurethane (TPU) are the most commonly orthodontic thermoplastics; however, the evidence of the differences between different orthodontic thermoplastic are limited to vitro environment and the evidence in vivo environment is not available. Therefore, this trial aims to provide reliable evidence for orthodontists' personalized treatment plans whether the two most commonly used orthodontic thermoplastics of PETG and TPU have differences in the efficiency of OTM.

METHODS AND ANALYSIS

This randomized controlled clinical study will recruit 44 orthodontic patients for orthodontic treatment. All the subjects will be randomized into two groups (PETG and TPU, n = 22 for each group). In the first stage (M0 to M1), clear aligners will be made of two orthodontic thermoplastics and move the maxillary first or second premolars 2 mm. In the second stage, patients will take the standard orthodontic treatments. The primary outcome will be the efficiency of clear aligners made of different materials on the digital models. The secondary outcome will be the efficiency of clear aligners made of different materials on the cone-beam computed tomography (CBCT). The efficiency will be calculated through the superimposition of the digital models and CBCT.

DISCUSSION

The results from this trial will serve as evidence for orthodontists and manufacturers and clarify whether the difference in orthodontic thermoplastics significantly impacts the efficiency of OTM.

TRIAL REGISTRATION NUMBER

ChiCTR2300070980. Registered on 27 April 2023. https://www.chictr.org.cn/showproj.html?proj=186253.

Relaxin treatment stimulates the differentiation of mesenchymal stem cells into osteoblasts

Background/purpose

Several studies have determined that relaxin stimulates differentiation and regulates the activity of mature osteoclasts, but little is known about its effect on the differentiation of mesenchymal cells towards the osteogenic lineage. Therefore, this study aimed to determine the effect of relaxin on the proliferation and differentiation of the osteoblastic lineage of mesenchymal cells derived from human dental pulp (hDPSC).

Materials and methods

In this in vitro study, hDPSC were characterized and treated with relaxin at different doses (10-80 ng/ml) and times (1-21 days). Morphology was assessed by microscopy, and proliferation was assessed using a resazurin assay. Osteoblastic differentiation was evaluated by Alizarin Red staining, alkaline phosphatase (ALP) labeling, and changes in the expression of the osteoblastic differentiation genes RUNX2 and BMP2.

Results

Relaxin treatment did not induce changes in the proliferation or viability of hDPSCs; however, larger cells and increased cytoplasmic prolongation were observed. Relaxin treatment (20 and 80 ng/ml) significantly increased calcified nodule formation on days 14 and 21. The cytochemical signals for ALP, RUNX2, and BMP2 gene expression were significantly (P < 0.05) increased by the relaxin treatment.

Conclusion

Relaxin treatment does not induce changes in hDPSC proliferation but induces morphological changes, increases ALP detection, calcified nodule formation, and increases expression of RUNX2 and BMP2, suggesting the induction of osteoblastic differentiation of hDPSC.

Effect of leukocyte-platelet-rich fibrin (L-PRF) on the rate of orthodontic tooth movement and expression of various biomarkers in gingival crevicular fluid

OBJECTIVES

To assess the outcome of leukocyte-platelet-rich fibrin (L-PRF) on the rate of maxillary canine retraction and its correlation with the levels of Receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), and RANKL:OPG in the gingival crevicular fluid (GCF) during comprehensive orthodontic treatment.

SUBJECTS AND METHODS

Eighteen females who required all 1st premolars extraction for the correction of their class I bimaxillary protrusion malocclusions were included. The L-PRF plugs were placed in the experimental side 1st premolar extraction sockets. Canine retraction was performed by sliding mechanics. Canine retraction was assessed from the maxillary study models prepared just before the extraction (T₀) and then at 1 week (T₁), 2 weeks (T₂), 4 weeks (T₃), and 8 weeks (T₄) after the 1st premolar extraction and placement of L-PRF plugs. The concentrations of RANKL and OPG in the GCF were evaluated at T₀, T₁, T₂, T₃, and T₄.

RESULTS

In experimental sides, the amount of canine retraction was statistically more during the T₀-T₁, T₁-T₂, and T₂-T₃ periods. The mean concentration of RANKL at T₁, T₂, and T₃ was significantly more in the experimental sides. The mean concentration of OPG was significantly less in the experimental sides at T₂, T₃, and T₄. The RANKL:OPG was significantly more in the experimental sides at T₁, T₂, T₃, and T₄. No significant correlation was found between amount of canine retraction and concentration of RANKL and OPG and RANKL to OPG ratio in GCF.

CONCLUSIONS

The L-PRF accelerated the rate of maxillary canine retraction by 0.28 mm over an 8-week period. The L-PRF favored the local osteoclastogenesis by enhancing the RANKL and suppressing the OPG concentrations. There was no significant correlation between the rate of maxillary canine retraction and expression of RANKL, OPG, and RANKL:OPG in GCF.

TRIAL REGISTRATION

The Clinical Trials Registry of India (Reg. No. CTRI/2020/10/028390, Date-13.10.2020).

The single-chain relaxin mimetic, B7-33, maintains the cardioprotective effects of relaxin and more rapidly reduces left ventricular fibrosis compared to perindopril in an experimental model of cardiomyopathy

The hormone, relaxin (RLX), exerts various organ-protective effects independently of etiology. However, its complex two-chain and three disulphide bonded structure is a limitation to its preparation and affordability. Hence, a single chain-derivative of RLX, B7-33, was developed and shown to retain the anti-fibrotic effects of RLX in vitro and in vivo. Here, we determined whether B7-33 could retain the other cardioprotective effects of RLX, and also compared its therapeutic efficacy to the ACE inhibitor, perindopril. Adult male 129sv mice were subjected to isoprenaline (ISO; 25 mg/kg/day, s.c)-induced cardiomyopathy, then s.c-treated with either RLX (0.5 mg/kg/day), B7-33 (0.25 mg/kg/day; equivalent dose corrected for MW) or perindopril (1 mg/kg/day) from days 7-14 post-injury. Control mice received saline instead of ISO. Changes in animal body weight (BW) and systolic blood pressure (SBP) were measured weekly, whilst cardiomyocyte hypertrophy and measures of vascular dysfunction and rarefaction, left ventricular (LV) inflammation and fibrosis were assessed at day 14 post-injury. ISO-injured mice had significantly increased LV inflammation, cardiomyocyte hypertrophy, fibrosis, vascular rarefaction and aortic contractility in the absence of any changes in BW or SBP at day 14 post-injury. Both B7-33 and RLX equivalently reduced LV fibrosis and normalised the ISO-induced LV inflammation and cardiomyocyte hypertrophy, whilst restoring blood vessel density and aortic contractility. Comparatively, perindopril lowered SBP and the ISO-induced LV inflammation and vascular rarefaction, but not fibrosis or hypertrophy. As B7-33 retained the cardioprotective effects of RLX and provided rapid-occurring anti-fibrotic effects compared to perindopril, it could be considered as a cost-effective cardioprotective therapy.

Adverse Effects of Surgically Accelerated Orthodontic Techniques: A Systematic Review

Evidence on the potential adverse effects of surgically accelerated orthodontic techniques is scarce. The aim of this review was to evaluate the available scientific evidence regarding the adverse effects on periodontium, tooth vitality, and root resorption, associated with these surgical procedures in children, adolescents, and adults. The reporting of this review was based on the PRISMA2020 guidelines. Seven databases and three registers were searched for randomized clinical trials (RCTs) and controlled clinical trials (CCTs) published up to 22 June 2022. Hand searching of the reference lists of the included studies was also performed. The quality of the evidence was assessed with the Cochrane risk of bias and ROBINS-I tools. A total of 887 records were initially screened. Finally, 33 RCTs (713 patients), six CCTs (103 patients), and six ongoing protocols were eligible for this systematic review. The current review indicated that there are no significant adverse effects of surgically accelerated orthodontic techniques on periodontium, root length, or tooth vitality. High-quality clinical trials with less risk of bias should be conducted to allow reliable conclusions regarding the adverse effects of the surgical procedures associated with the acceleration of orthodontic treatment on children, adolescents, and adults.

Clinical expression of programmed mandibular canine rotation using various attachment protocols and 1- vs 2-week wear protocols with Invisalign SmartTrack aligners: A retrospective cohort study

INTRODUCTION

Rotation of rounded teeth, particularly canines, is reported as one of the most difficult and inaccurate tooth movements with aligners. This retrospective study aimed to assess the accuracy and reliability of prescribed mandibular canine rotation with Invisalign aligners and the influence of attachment type and wear schedule on accuracy.

METHODS

A sample of 75 subjects with mandibular canines requiring rotation was collected from an existing database. The initial, predicted finish, and achieved finish, were measured using metrology software, and the differences between predicted and achieved mandibular canine rotations were calculated. The sample was divided into 3 groups: optimized rotation attachments using 1-week wear, optimized rotation attachments using 2-week wear, and conventional rectangular attachments using 2-week wear.

RESULTS

Rotation was an underexpressed movement, with an overall median sample efficiency of 75.4%. For all groups, predicted rotation was not equivalent to achieved rotation at a ± 5° equivalence margin. This indicates that none of the Invisalign SmartTrack aligner attachment configurations display clinical accuracy in their predicted rotation. By attachment type, median efficiencies of 81.5%, 76.5%, and 63.1% were found for groups 1-week wear, 2-week wear, and 2-week wear, respectively. By wear schedule, there was no significant difference in efficiency for optimized rotation attachments.

CONCLUSIONS

The clinical expression of canine rotation with SmartTrack aligners is less than the prescribed rotation for all attachment configurations. Vertical rectangular attachments were associated with the least accurate expression of prescribed movement. There was no difference in rotation efficiency between 1- or 2-week aligner wear.

The Effectiveness of Repetition or Multiplicity of Different Surgical and Non-Surgical Procedures Compared to a Single Procedure Application in Accelerating Orthodontic Tooth Movement: A Systematic Review and Meta-Analysis

In this study, we aimed to assess the current scientific evidence concerning the effectiveness of combining two acceleration techniques or repeating an acceleration procedure in comparison with the single application in terms of the speed of the orthodontic tooth movement (OTM).

We performed a comprehensive electronic search to retrieve relevant studies on 10 databases. Randomized controlled trials (RCTs) on fixed orthodontic treatment patients who received multiple types of acceleration techniques or underwent a repeated acceleration procedure compared to a single application were included. Version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2) was used for assessing the risk of bias of retrieved studies.

A total of six RCTs were included in this review. Regarding multiple acceleration methods, it seems that the combination of low-level laser therapy (LLLT) with a surgical technique outperforms the single application of each technique separately. Additionally, the combination of two surgical interventions may have a synergistic effect leading to reduced treatment time compared to the application of a single intervention. Regarding acceleration method repetition, it seems that the re-application of surgical procedures twice is more efficient than the single application. The meta-analysis showed a non-significant difference in the canine retraction rate between the four-weekly micro-osteoperforations (MOPs) (three times of applications) and both the eight-weekly MOPs (two times of applications) [mean difference (MD) = 0.24; 95% CI: -0.2-0.77; p = 0.36], as well as 12-weekly MOPs (two times of applications) (MD = 0.06; 95% CI: -0.14-0.27; p = 0.55).

Based on very low evidence, combining two acceleration techniques is superior over a single application in accelerating tooth movement. Again, very low evidence suggests that the efficacy of repetition of surgical procedures twice and three times is similar. Further high-quality RCTs are required to assess the benefit of repeating an acceleration procedure or combining two different methods. In addition, more insight is needed into the possible side effects associated with the repetition or multiplicity of procedures.

Effect of vibration on orthodontic tooth movement in a double blind prospective randomized controlled trial

The purpose of the present study was to investigate the effect of vibration on orthodontic tooth movement and safety assessment based on our previous basic research in animal experiments. A double-blind prospective randomized controlled trial using split-mouth design was conducted in patients with malocclusion. The left and right sides of maxillary arch were randomly assigned to vibration (TM + V) and non-vibration (TM) groups. After leveling, vibrations (5.2 ± 0.5 g-forces (gf), 102.2 ± 2.6 Hertz (Hz)) were supplementary applied to the canine retracted with 100 gf in TM + V group for 3 min at the monthly visit under double-blind fashion, and the canine on the other side without vibration was used as TM group. The amount of tooth movement was measured blindly using a constructed three-dimensional dentition model. The amount of canine movement per visit was 0.89 ± 0.55 mm in TM group (n = 23) and 1.21 ± 0.60 mm in TM + V group (n = 23), respectively. There was no significant difference of pain and discomfort, and root resorption between the two groups. This study indicates that static orthodontic force with supplementary vibration significantly accelerated tooth movement in canine retraction and reduced the number of visits without causing side effects.

Do Relaxin Levels Impact Hip Injury Incidence in Women? A Scoping Review

PURPOSE

The aim of this review is to assess the current evidence regarding the impact of relaxin on incidence of soft tissue hip injuries in women.

METHODS

A trained research librarian assisted with searches of PubMed, Embase, CINAHL, and SPORTDiscus, with a preset English language filter. The review was completed per the Joanna Briggs Institute (JBI) Manual for Evidence Synthesis methodology. Included studies required assessment of relaxin effects on musculoskeletal health, pelvic girdle stability, or hip joint structures in human subjects. Letters, texts, and opinion papers were excluded.

RESULTS

Our screen yielded 82 studies. Molecularly, relaxin activates matrix metalloproteinases (MMPs) including collagenases MMP-1/-13 and gelatinases MMP-2/-9 to loosen pelvic ligaments for parturition. However, relaxin receptors have also been detected in female periarticular tissues, such as the anterior cruciate ligament, which tears significantly more often during the menstrual cycle peak of relaxin. Recently, high concentrations of relaxin-activated MMP-9 receptors have been found on the acetabular labrum; their expression upregulated by estrogen.

CONCLUSIONS

Menstrual cycle peaks of relaxin activate MMPs, which locally degrade collagen and gelatine. Women have relaxin receptors in multiple joints including the hip and knee, and increased relaxin correlates with increased musculoskeletal injuries. Relaxin has paracrine effects in the female pelvis on ligaments adjacent to hip structures, such as acetabular labral cells which express high levels of relaxin-targeted MMPs. Therefore, it is imperative to investigate the effect of relaxin on the hip to determine if increased levels of relaxin are associated with an increased risk of acetabular labral tears.

The rationale for orthodontic retention: piecing together the jigsaw

Retaining teeth in their corrected positions following orthodontic treatment is one of the most challenging aspects of orthodontic practice. Despite much research, the rationale for retention is not entirely clear. Teeth tend to revert to their pre-treatment positions due to periodontal and gingival, soft tissue, occlusal and growth factors. Changes may also follow normal dentofacial ageing and are unpredictable with great variability. In this overview, each of these factors are discussed with their implications for retention, along with adjunctive procedures to minimise relapse. The state of current knowledge, methods used to assess relapse, factors regarded as predictive of or associated with stability as well as overcorrection are outlined. Potential areas requiring further investigation are suggested. The way in which the clinician may manage current retention practice, with a need for individualised retention plans and selective retainer wear, is also considered.

Evaluation of the efficacy of laser-assisted flapless corticotomy in accelerating canine retraction: a split-mouth randomized controlled clinical trial

OBJECTIVE

To evaluate the efficacy of laser-assisted flapless corticotomy in the acceleration of canine retraction compared with the conventional technique and to evaluate patients' pain and discomfort levels after corticotomy.

MATERIALS AND METHODS

A single-center randomized controlled trial was conducted on 18 class II division 1 patients (7 males, 11 females; age range: 16 to 24 years) who required the first-upper-premolar extraction followed by canine retraction. A split-mouth design was used in which the Er:YAG laser-assisted flapless corticotomy was randomly allocated to one side, whereas the other side served as the control side. The primary outcome measure was the canine retraction rate which was assessed immediately after laser application, 1, 2, 4, 8, and 12 weeks after laser application. Also, the levels of pain and discomfort during the first week following laser application were assessed. Paired t-tests or Wilcoxon matched-pairs signed-rank tests were used to detect significant differences.

RESULTS

All of the selected eighteen patients entered the statistical analysis stage. Significant differences were observed (P < 0.001) in canine retraction rates between the experimental and control sides at the baseline to 1st-week, 1st- to 2nd-week, 2nd- to 4th-week, and 4th- to 8th-week intervals. No significant difference was found between the two sides at the 8th- to 12th-week interval. A significant reduction was seen in the mean score of pain during eating at all assessment times when compared to the baseline data (P = 0.002 at day 2, P < 0.001 at days 5 and 7).

CONCLUSION

Er:YAG laser-assisted flapless corticotomy appears to be an effective treatment method for accelerating canine retraction and was accompanied by a mild degree of pain and discomfort.

TRIAL REGISTRATION

ClinicalTrials.gov (No.: NCT04316403), retrospectively registered on the 20th of March 2020. URL: https://clinicaltrials.gov/ct2/show/NCT04316403.

PTH/PTHrP in controlled release hydrogel enhances orthodontic tooth movement by regulating periodontal bone remodaling

OBJECTIVE

This study aimed to evaluate the effects of local application of parathyroid hormone (PTH) or parathyroid hormone-related protein (PTHrP) on osteogenesis and osteoclastogenesis during orthodontic tooth movement (OTM).

BACKGROUND

Periodontal bone remodeling is the crucial biological process in the OTM that involves both bone resorption and formation, with the former more important as the initiator. PTH or PTHrP both play dual roles in bone remodeling regulation, and the balance may shift to the bone resorption side when they are given continuously, suggesting them as potential candidate medicine for OTM acceleration.

METHODS

A total of 40 rats underwent orthodontic mesialization of the maxillary first molars and received no micro-perforation (MOP), or MOP followed by injection of temperature-sensitive hydrogel containing PTH, PTHrP, or normal saline. The rats were sacrificed after 2-week OTM, except for the relapse groups, which had one more week of observation after removal of the force appliances. The amount of tooth movement, rate of relapse after OTM, and effects on the bone remodeling were assessed through micro-computed tomography (μCT) analysis, alkaline phosphatase (ALP) assay, alizarin red staining, tartrate-resistant acid phosphatase (TRAP) staining, immunohistochemistry (IHC) analysis, Western blot (WB), and quantitative real-time polymerase chain reaction (qRT-PCR). The effects of PTHrP on the osteogenic differentiation of human periodontal ligament cells (hPDLCs) were explored in vitro.

RESULTS

The cumulative release of PTH or PTHrP from PECE hydrogels was beyond 75% at 14 days in a sustained manner. After the intervention in vivo, the distance of OTM in the PTH (0.78 ± 0.06 mm) or PTHrP (0.81 ± 0.04 mm) group was significantly larger than that of the MOP only (0.51 ± 0.04 mm) or the no MOP (0.46 ± 0.05 mm) group. Moreover, PTH injection significantly reduced the rate of relapse after OTM (25.7 ± 4.3%) compared to the control (69.6 ± 6.1%). μCT analysis showed decreased BV/TV, BS/BV, and Tb.N, while increased Tb.Sp of alveolar bone in the PTH or PTHrP group. There were also more TRAP-positive osteoclasts in the PTH or PTHrP group with a significantly enhanced ratio of receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG). The protein expressions of PTH/PTHrP type 1 receptor (PTHR1), alkaline phosphatase (ALP), osteocalcin (OCN), runt-related transcription factor 2 (RUNX2), and β-catenin were significantly increased in the PTH or PTHrP group, as well as the gene expressions of Pth1r, Bglap, and Alpl. There was no significant difference between the effects of PTH and PTHrP. Nevertheless, inhibition of PTHrP on the osteogenic differentiation of hPDLCs was detected in vitro with decreased expression of OCN, RUNX2, COL-1, and ALP.

CONCLUSION

Local injection of either PTH or PTHrP carried by controlled release PECE hydrogel similarly enhances OTM in rats through regulating periodontal bone remodeling, which deserves further study for potential clinical application.

Is Inflammation a Friend or Foe for Orthodontic Treatment?: Inflammation in Orthodontically Induced Inflammatory Root Resorption and Accelerating Tooth Movement

The aim of this paper is to provide a review on the role of inflammation in orthodontically induced inflammatory root resorption (OIIRR) and accelerating orthodontic tooth movement (AOTM) in orthodontic treatment. Orthodontic tooth movement (OTM) is stimulated by remodeling of the periodontal ligament (PDL) and alveolar bone. These remodeling activities and tooth displacement are involved in the occurrence of an inflammatory process in the periodontium, in response to orthodontic forces. Inflammatory mediators such as prostaglandins (PGs), interleukins (Ils; IL-1, -6, -17), the tumor necrosis factor (TNF)-α superfamily, and receptor activator of nuclear factor (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) are increased in the PDL during OTM. OIIRR is one of the accidental symptoms, and inflammatory mediators have been detected in resorbed roots, PDL, and alveolar bone exposed to heavy orthodontic force. Therefore, these inflammatory mediators are involved with the occurrence of OIIRR during orthodontic tooth movement. On the contrary, regional accelerating phenomenon (RAP) occurs after fractures and surgery such as osteotomies or bone grafting, and bone healing is accelerated by increasing osteoclasts and osteoblasts. Recently, tooth movement after surgical procedures such as corticotomy, corticision, piezocision, and micro-osteoperforation might be accelerated by RAP, which increases the bone metabolism. Therefore, inflammation may be involved in accelerated OTM (AOTM). The knowledge of inflammation during orthodontic treatment could be used in preventing OIIRR and AOTM.

Do orthodontists aim to decrease the duration of fixed appliance treatment?

OBJECTIVES:

The aim of the present study was to investigate the trends in the use of fixed appliance and accelerated orthodontics to decrease the treatment duration. Further, this study aimed to assess the effect of demographic factors on the participant's choice of treatment modality.

METHODS:

This was a cross-sectional study in the form of questionnaire-based online survey especially designed and distributed to 265 orthodontists via email. The questions aimed to collect basic information about the participants and respondents’ choices for decreasing the treatment duration. The data were analyzed according to gender, level of academic education and years of clinical experience using Chi-square test.

RESULTS:

A response rate of 85.2% was reported. Most of the orthodontists aimed to reduce the treatment duration by the biomechanical (66.8%) and surgical approaches (27.4%). The use of sliding mechanics (69.4%) and one-step retraction was more common (66.3%). MBT bracket prescription was more prevalent (51.7%), followed by Roth (41.1%). Conventional brackets were used more than self-ligating brackets, and aesthetic brackets were avoided by one third of the respondents. NiTi wires were the most commonly used wires during the alignment stage (44.2%). However, the effect of gender, years of clinical experience and specialty level of education showed some effects on the use of certain techniques and clinical practice of the respondents.

CONCLUSIONS:

Most of the orthodontists aimed to decrease orthodontic treatment duration by using biomechanical and surgical approaches. Gender and clinical experience to a certain extent affected the participants’ choice during orthodontic treatment.

The effect of the local administration of biological substances on the rate of orthodontic tooth movement: a systematic review of human studies

Background

The influence of different biological agents on the rate of orthodontic tooth movement (OTM) has been extensively reviewed in animal studies with conflicting results. These findings cannot be extrapolated from animals to humans. Therefore, we aimed to systematically investigate the most up-to-date available evidence of human studies regarding the effect of the administration of different biological substances on the rate of orthodontic tooth movement.

Methods

A total of 8 databases were searched until the 16th of June 2020 without restrictions. Controlled randomized and non-randomized human clinical studies assessing the effect of biological substances on the rate of OTM were included. ROBINS-I and the Cochrane Risk of Bias tools were used. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Results

A total of 11 studies (6 randomized clinical trials and 5 prospective clinical trials) were identified for inclusion. Local injections of prostaglandin E1 and vitamin C exerted a positive influence on the rate of OTM; vitamin D showed variable effects. The use of platelet-rich plasma and its derivatives showed inconsistent results, while the local use of human relaxin hormone showed no significant effects on the rate of OTM.

Limitations

The limited and variable observation periods after the administration of the biological substances, the high and medium risk of bias assessment for some included studies, the variable concentrations of the assessed biological agents, the different experimental designs and teeth evaluated, and the variety of measurement tools have hampered the quantitative assessment of the results as originally planned.

Conclusions and implications

Despite the methodological limitations of the included studies, this systematic review provides an important overview of the effects of a variety of biological agents on the rate of tooth movement and elucidates the deficiencies in the clinical studies that have been conducted so far to evaluate the effectiveness of these agents in humans, providing some guidelines for future robust research.

Trial registration

PROSPERO (CRD42020168481, www.crd.york.ac.uk/prospero)

MicroRNA-125a-5p modulates macrophage polarization by targeting E26 transformation-specific variant 6 gene during orthodontic tooth movement

OBJECTIVE

The aim of this study was to investigate the role of microRNA-125a-5p (miR-125a-5p) in macrophages during orthodontic tooth movement (OTM).

DESIGN

Periodontal ligament tissues were collected from patients underwent OTM. Periodontal ligament cells were isolated from periodontal ligament tissues. Periodontal ligament stem cells were isolated from normal human impacted third molars. The miR-125-5p levels were measured by real-time quantitative polymerase chain reaction. The impact of miR-125-5p on macrophage polarization was tested by alizarin red staining assay. The effects of miR-125-5p and E26 transformation-specific variant 6 gene (ETV6) on M1/M2 macrophages phenotype markers were determined by real-time quantitative polymerase chain reaction, western blot, and flow cytometry analyses. The interaction between miR-125-5p and ETV6 was verified using luciferase reporter and RNA immunoprecipitation assays.

RESULTS

Periodontal miR-125a-5p was upregulated under the force. Macrophage polarization facilitated osteogenesis by cocultured system. Moreover, miR-125a-5p was upregulated in macrophages polarized with M2 conditions. MiR-125a-5p downregulation promoted the expression of M1 phenotype markers, while suppressed the expression of M2 markers. Mechanistically, ETV6 was confirmed to be a target of miR-125a-5p. ETV6 overexpression increased the expression of M1 polarized markers, while decreased the expression of M2 polarized markers. Furthermore, ETV6 knockdown reversed the effects of miR-125a-5p inhibitor on both M1 macrophages and M2 macrophages.

CONCLUSIONS

Overall, miR-125a-5p facilitates bone healing by targeting ETV6 to promote macrophage M2 polarization.

Surgically accelerated orthodontic techniques and periodontal response: a systematic review

BACKGROUND

Reduction in orthodontic treatment time is gaining popularity due to patient demands. Several new techniques of acceleratory orthodontic treatment have been introduced to effectively treat the malocclusion in a shorter time period with minimal adverse effects.

OBJECTIVE

The objective of this systematic review is to critically evaluate the potential effect of accelerated surgically assisted orthodontic techniques on periodontal tissues.

MATERIALS AND METHODS

Electronic databases used to perform the search were Medline (Ovid), EMBASE, PubMed, Scopus, Cochrane, Google Scholar, and hand searching of the literature was also performed.

SELECTION CRITERIA

Only randomized control trials (RCTs) that assessed the relationship between accelerated surgically assisted orthodontic techniques and its effects on periodontium were included.

DATA COLLECTION AND ANALYSIS

The Joanna Briggs Institute (JBI) critical appraisal checklist tool (2016) was used to assess the finally selected studies. Among these studies, five evaluated corticotomy-facilitated orthodontics, two tested accelerated tooth movement with piezocision, one compared corticotomy-facilitated orthodontics with piezocision, and one studied the effects of periodontally accelerated osteogenic orthodontics. The duration of these studies was relatively short and had moderate to high risk of bias.

RESULTS

Literature search identified 225 records from 5 databases and 50 articles from the partial grey literature (Google scholar) search. Finally, nine eligible RCTs were included in the review.

LIMITATIONS

Most of the included studies were of a high risk of bias due to high experimental heterogeneity and small sample size. Long-term follow-up of the periodontal response to these interventions was also lacking.

CONCLUSIONS

There is an absence of evidence considering the lack of long-term follow-up and small sample size therefore, the results of this review should be carefully interpreted.

IMPLICATIONS

Due to the need for more studies with less risk of bias, these techniques should be implemented in dental practice with caution. With stronger evidence, the study may be confirmed to provide quicker desired results for orthodontic patients.

REGISTRATION

This study protocol was not registered.

FUNDING

No funding was obtained for this systematic review.

Could medications and biologic factors affect post-orthodontic tooth movement changes? A systematic review of animal studies

Immediately after the removal of orthodontic appliances, the teeth might start to drift away from their corrected position in an attempt to reach a new equilibrium. Medications and biologic factors could potentially modulate these processes. The objective of the present systematic review is to systematically investigate and appraise the quality of the evidence regarding the effect of various medications and biologic factors on the rate of relapse following active tooth movement. Search without restrictions in eight databases and hand searching until April 2020 were conducted. Studies performed on animal models investigating the effects of medication and biologic factors on the rate of relapse following orthodontic tooth movement were considered. Following study retrieval and selection, relevant data were extracted and the risk of bias was assessed. Seventeen studies were finally identified, mostly at either high or unclear risk of bias. Ketorolac did not show any significant effects on relapse, while the administration of tetracycline, atorvastatin, psoralen and raloxifene decreased it. Overall, the same result was observed with bisphosphonates with the exception of low dosage of risedronate, which did not have an effect. Osteoprotegerin and strontium resulted in reduced relapse, but not in the immediate post-administration period. Inconsistent or conflicting effects were noted after the use of simvastatin and relaxin. The quality of the available evidence was considered at best as low. It can be concluded that specific medications and biologic factors may have an effect on the rate of relapse following tooth movement. The orthodontist should be knowledgeable about the substances potentially affecting retention.

Effect of platelet-rich plasma on the rate of orthodontic tooth movement

OBJECTIVE

To investigate the effect of local injection of platelet-rich plasma (PRP) on the rate of orthodontic tooth movement.

MATERIALS AND METHODS

Sixteen female patients were randomly allocated in a split-mouth study design to receive PRP injections with CaCl2 activating solution on one side (intervention side) while the other side received CaCl2 injection only (control side). Canine retraction was performed on 0.017 × 0.025-inch stainless steel archwire applying 1.5 N retraction force. PRP and CaCl2 injections were done at 0, 3, and 6 weeks. The duration of the study was 4 months. Data were collected from digitized models. Assessment of pain accompanying the procedure was done using a visual analogue scale.

RESULTS

The rate of canine retraction was faster on the intervention side in the first 2 months, with a statistically significant difference in the first month (P = .049). On the other hand, the rate was statistically significantly slower on the intervention side in the third month following cessation of PRP injections (P = .02). Pain increased following injections on both sides.

CONCLUSIONS

PRP showed a positive potential to accelerate the rate of tooth movement when injected in the first 2 months. Repeated injections of PRP to maintain a steady rate of accelerated tooth movement warrant further investigation.

Relaxin and fibrosis: Emerging targets, challenges, and future directions

The peptide hormone relaxin is well-known for its anti-fibrotic actions in several organs, particularly from numerous studies conducted in animals. Acting through its cognate G protein-coupled receptor, relaxin family peptide receptor 1 (RXFP1), serelaxin (recombinant human relaxin) has been shown to consistently inhibit the excessive extracellular matrix production (fibrosis) that results from the aberrant wound-healing response to tissue injury and/or chronic inflammation, and at multiple levels. Furthermore, it can reduce established scarring by promoting the degradation of aberrant extracellular matrix components. Following on from the review that describes the mechanisms and signaling pathways associated with the extracellular matrix remodeling effects of serelaxin (Ng et al., 2019), this review focuses on newly identified tissue targets of serelaxin therapy in fibrosis, and the limitations associated with (se)relaxin research.

The Effect of Local Pharmacological Agents in Acceleration of Orthodontic Tooth Movement: A Systematic Review

AIM:

Acceleration of orthodontic tooth movement has gained a massive interest to decrease the total treatment time. Local pharmacological agents might be used for that purpose as a practical, effective and inexpensive alternative. A systematic review was achieved to evaluate the evidence in that topic.

METHODS:

A search was conducted on electronic databases including PubMed, Lilacs, Web of Science (Thompson Reuters), EMBASE (OvidSP), and Cochrane Database of Systematic Reviews (Wiley) in addition to hand searching of relevant journals till June 2018. Only studies written in English were utilised. Publications were selected, assessed systematically and graded by two observers according to Bondemark grading system.

RESULTS:

Only two human studies were found investigating the effect of Relaxin and Prostaglandins in the rate of orthodontic tooth movement. No obvious side effects were reported. Relaxin showed no increase in the rate of tooth movement while prostaglandin showed a marked increase in the rate of orthodontic tooth movement.

CONCLUSION:

There is below moderate evidence showing no effect of relaxin on orthodontic tooth movement, while inconclusive evidence was found regarding Prostaglandin in the acceleration of orthodontic tooth movement. More prospective well-conducted clinical trials are needed to reach a proper conclusion regarding the local pharmacological agents which can be safely used to accelerate orthodontic tooth movement.

Effect of Drugs on Orthodontic Tooth Movement in Human Beings: A Systematic Review of Randomized Clinical Trials

Background:

Orthodontic tooth movement represents a series of events at both cellular and molecular levels which in turn stimulates inflammatory pathway to induce tooth movement. Some drugs taken by patients have a negative effect which can block this pathway, on the other hand, others may influence these events and reduce treatment time.

Search Methods:

A search strategy was implemented using both manual hand search and electronic databases, including Cochrane database of clinical trials, PubMed, ScienceDirect and Scopus. The risk of biased eligible studies to be included in the final analysis was assessed independently by two authors using Cochrane risk of bias tool.

Results:

A total of 491 articles were identified in both manual and electronic searches as well as by checking the reference lists of articles to be included in the study. After reviewing the titles, abstracts and full-text articles, only 8 RCTs met the inclusion criteria, and thus, were included in the final analysis. Six out of the 8 RCTs were assessed as of low quality. No statistical methods were employed to combine the studies due to the heterogeneities of the studies and the low level of evidence.

Conclusion:

Acetylsalicylic acid and ibuprofen reduced orthodontic tooth movement whereas paracetamol, Rofecoxib and tenoxicam had no impact on orthodontic tooth movement. Due to the low quality of the studies included, therefore to base our practice on scientific evidence, better-controlled RCTs are needed to investigate the impact of common medications on orthodontic tooth movement.

Periodontal Accelerated Osteogenic Orthodontics Technique for Rapid Orthodontic Tooth Movement: A Systematic Review

Aim:

The aim of this review was to analyze the data in the available literature regarding aspects of periodontally accelerated orthodontic therapy such as reduction in treatment time, variation in surgical techniques, and patient satisfaction.

Materials and Methods:

An internet-based search was performed for the articles published between January 2008 and August 2018 using keywords periodontal accelerated orthodontic tooth movement, corticotomy, bone grafting, tooth movement, and treatment duration. A total of 84 articles were obtained from MEDLINE and Embase search engines, of which 31 articles were eligible to be included for the systematic review.

Results:

On analysis, it was observed that the earlier studies were predominantly pertaining to case reports. In the later part of the decade considered in this review, it was observed that the emphasis was given to clinical and animal studies.

Conclusions:

Most of the studies included in the review concluded that there was a significant reduction in orthodontic treatment duration using periodontal accelerated techniques compared to conventional orthodontic treatment.

A preliminary investigation of the effect of relaxin on bone remodelling in suture expansion

Background and objectives

Relaxin (RLN) is an insulin-like hormone associated with extracellular matrix degradation, osteoclastogenesis, and osteoblast differentiation. This study aimed to assess the effect of RLN during and after lateral expansion of murine calvarial sagittal sutures.

Materials and methods

RLN was injected topically using a nano-sized liposome carrier into the sagittal sutures of 8- to 10-week-old wild type mice just before lateral expansion. Suture morphology, bone mineral density (BMD), and bone volume were analysed by micro-computed tomography. Collagen deposition and osteoclast differentiation were observed by Verhoeff-Van Gieson (VVG) and tartrate-resistant acid phosphatase (TRAP) staining, respectively.

Results

Less collagen staining and higher tissue-specific relaxin/insulin-like family peptide receptor (Rxfp)-1 and -2 expression were observed in the RLN-treated samples after 48 hours. Increased BMD and volume, and thick well-organised osteoid tissue, with multinucleated TRAP-positive cells, were observed in RLN-treated samples after 1 week. Increased Rxfp-1 expression was observed in the sagittal sutures in the mid-suture fibrous tissue following RLN treatment. Rxfp-2 was only expressed in the calvarial bone under tensile stimulation and RLN treatment further increased its expression.

Limitations

RLN-liposomes were not detected at any instance under the current experimental conditions. This is a preliminary study and the sample number limits the power of its results. VVG staining cannot quantify collagen contents but can provide preliminary information on the presence of collagen fibres.

Conclusions

RLN treatment may modify bone remodelling and collagen metabolism during and after suture expansion.

Anti-fibrotic actions of relaxin

Fibrosis refers to the hardening or scarring of tissues that usually results from aberrant wound healing in response to organ injury, and its manifestations in various organs have collectively been estimated to contribute to around 45-50% of deaths in the Western world. Despite this, there is currently no effective cure for the tissue structural and functional damage induced by fibrosis-related disorders. Relaxin meets several criteria of an effective anti-fibrotic based on its specific ability to inhibit pro-fibrotic cytokine and/or growth factor-mediated, but not normal/unstimulated, fibroblast proliferation, differentiation and matrix production. Furthermore, relaxin augments matrix degradation through its ability to up-regulate the release and activation of various matrix-degrading matrix metalloproteinases and/or being able to down-regulate tissue inhibitor of metalloproteinase activity. Relaxin can also indirectly suppress fibrosis through its other well-known (anti-inflammatory, antioxidant, anti-hypertrophic, anti-apoptotic, angiogenic, wound healing and vasodilator) properties. This review will outline the organ-specific and general anti-fibrotic significance of exogenously administered relaxin and its mechanisms of action that have been documented in various non-reproductive organs such as the cardiovascular system, kidney, lung, liver, skin and tendons. In addition, it will outline the influence of sex on relaxin's anti-fibrotic actions, highlighting its potential as an emerging anti-fibrotic therapeutic.

LINKED ARTICLES

This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.

The Potential Use of Pharmacological Agents to Modulate Orthodontic Tooth Movement (OTM)

The biological processes that come into play during orthodontic tooth movement (OTM) have been shown to be influenced by a variety of pharmacological agents. The effects of such agents are of particular relevance to the clinician as the rate of tooth movement can be accelerated or reduced as a result. This review aims to provide an overview of recent insights into drug-mediated effects and the potential use of drugs to influence the rate of tooth movement during orthodontic treatment. The limitations of current experimental models and the need for well-designed clinical and pre-clinical studies are also discussed.

Effectiveness of minimally invasive surgical procedures in the acceleration of tooth movement: a systematic review and meta-analysis

OBJECTIVE

The objective of this study was to assess systematically the available scientific evidence relating the efficiency of minimally invasive surgical procedures in accelerating orthodontic tooth movement and the adverse effects associated with these procedures.

METHODS

Electronic search of these databases CENTRAL, EMBASE, Scopus, PubMed, Web of Science, Google Scholar Beta, Trip, OpenGrey and PQDT OPEN was performed (last updated January 2016). The reference lists of the included studies were hand searched. Unpublished literature and ongoing studies were also checked electronically through ClinicalTrials.gov and (ICTRP). Randomized controlled trials (RCTs) with patients who received minimally invasive surgical procedures combined with fixed orthodontic appliances compared with conventional treatment were included. Cochrane's risk of bias tool was used to assess risk of bias.

RESULTS

Four RCTs (61 patients) and nine ongoing protocols were included in this review. Only three RCTs were suitable for quantitative synthesis. Higher tooth movement rate was found with the minimally invasive surgical procedures by a weighted mean difference of 0.65 mm for 1 month of canine retraction (WMD = 0.65: 95 % CI (0.54, 0.76), p < 0.001) and by a weighted mean difference 1.41 mm for 2 months (WMD = 1.41: 95 % CI (0.81, 2.01), p < 0.001). No adverse effects associated with these procedures were reported.

CONCLUSIONS

There is limited available evidence about the effectiveness of minimally invasive surgically accelerated orthodontics (MISAO). Although the current review indicated that MISAO can help in accelerating canine retraction, further research in this domain should be performed before it can be recommended in everyday clinical practice.

Evaluation of the effects of subgingival injection of Simvastatin on space re-opening after orthodontic space closure in adults

Background. This clinical trial evaluated the effect of Simvastatin on space re-opening after orthodontic space closure and its effect on the gingival index (GI) and clinical attachment loss (CAL). Methods. 16 females, 25-40 years old, with spaces between anterior mandibular teeth due to chronic periodontitis were participated in this study. The patients were randomly divided into control and experimental groups. In the experimental group, 1.2% Simvastatin gel and in the control group, 0.9% sodium chloride as a placebo was injected into the pocket depth of the six anterior teeth. The amount of space reopening, GI and CAL were measured. Results. No serious complications were observed during interventions and follow-up periods. Space re-opening was significantly reduced in patients receiving Simvastatin (P < 0.001). Moreover, GI reduction was significantly greater in Sim-vastatin group compared to the control group (P < 0.001). However, CAL did not demonstrate a significant difference between the groups. Conclusion. Simvastatin may decrease space re-opening after orthodontic space closure in human anterior teeth.

Variables affecting orthodontic tooth movement with clear aligners

INTRODUCTION

In this study, we examined the impacts of age, sex, root length, bone levels, and bone quality on orthodontic tooth movement.

METHODS

Clear aligners were programmed to move 1 central incisor 1 mm over the course of 8 weeks. Thirty subjects, ages 19 to 64, were enrolled, and measurements were made on digital models (percentage of tooth movement goal achieved). Morphometric features and bone quality were assessed with cone-beam computed tomography. Data from this study were combined with data from 2 similar studies to increase the power for some analyses.

RESULTS

The mean percentage of tooth movement goal achieved was 57% overall. Linear regression modeling indicated a cubic relationship between age and tooth movement, with a decreasing rate of movement from ages 18 to 35 years, a slightly increasing rate from ages 35 to 50, and a decreasing rate from ages 50 to 70. The final decreasing trend was not apparent for women. As would be expected, the correlation was significant between the percentage of the goal achieved and the cone-beam computed tomography superimposed linear measures of tooth movement. A significant negative correlation was found between tooth movement and the measurement apex to the center of rotation, but bone quality, as measured by fractal dimension, was not correlated with movement.

CONCLUSIONS

The relationship between age and tooth movement is complex and might differ for male and female patients. Limited correlations with cone-beam computed tomography morphology and rate of tooth movement were detected.

Acceleration of tooth movement during orthodontic treatment--a frontier in orthodontics

Nowadays, there is an increased tendency for researches to focus on accelerating methods for tooth movement due to the huge demand for adults for a shorter orthodontic treatment time. Unfortunately, long orthodontic treatment time poses several disadvantages like higher predisposition to caries, gingival recession, and root resorption. This increases the demand to find the best method to increase tooth movement with the least possible disadvantages. The purpose of this study is to view the successful approaches in tooth movement and to highlight the newest technique in tooth movement. A total of 74 articles were reviewed in tooth movement and related discipline from 1959 to 2013. There is a high amount of researches done on the biological method for tooth movement; unfortunately, the majority of them were done on animals. Cytokine, PTH, vitamin D, and RANKL/RANK/OPG show promising results; on the other hand, relaxin does not accelerate tooth movement, but increases the tooth mobility. Low-level laser therapy has shown positive outcome, but further investigation should be done for the best energy and duration to achieve the highest success rate. Surgical approach has the most predictable outcomes but with limited application due to its aggressiveness. Piezocision technique is considered one of the best surgical approaches because it poses good periodontal tissue response and excellent aesthetic outcome. Due to the advantages and disadvantages of each approach, further investigations should be done to determine the best method to accelerate tooth movement.

Relaxin: new pathophysiological aspects and pharmacological perspectives for an old protein

Human relaxin-2 (hereafter simply defined as "relaxin") is a 6-kDa peptidic hormone best known for the physiological role played during pregnancy in the growth and differentiation of the reproductive tract and in the renal and systemic hemodynamic changes. This factor can also be involved in the pathophysiology of arterial hypertension and heart failure, in the molecular pathways of fibrosis and cancer, and in angiogenesis and bone remodeling. It belongs to the relaxin peptide family, whose members comprehensively exert numerous effects through interaction with different types of receptors, classified as relaxin family peptide (RXFP) receptors (RXFP1, RXFP2, RXFP3, RXFP4). Research looks toward the in-depth examination and complete understanding of relaxin in its various pleiotropic actions. The intent is to evaluate the likelihood of employing this substance for therapeutic purposes, for instance in diseases where a deficit could be part of the underlying pathophysiological mechanisms, also avoiding any adverse effect. Relaxin is already being considered as a promising drug, especially in acute heart failure. A careful study of the different RXFPs and their receptors and the comprehension of all biological activities of these hormones will probably provide new drugs with a potential wide range of therapeutic applications in the near future.

Orthodontic tooth movement with clear aligners

Clear aligners provide a convenient model to measure orthodontic tooth movement (OTM). We examined the role of in vivo aligner material fatigue and subject-specific factors in tooth movement. Fifteen subjects seeking orthodontic treatment at the University of Florida were enrolled. Results were compared with data previously collected from 37 subjects enrolled in a similar protocol. Subjects were followed prospectively for eight weeks. An upper central incisor was programmed to move 0.5 mm. every two weeks using clear aligners. A duplicate aligner was provided for the second week of each cycle. Weekly polyvinyl siloxane (PVS) impressions were taken, and digital models were fabricated to measure OTM. Initial and final cone beam computed tomography (CBCT) images were obtained to characterize OTM. Results were compared to data from a similar protocol, where subjects received a new aligner biweekly. No significant difference was found in the amount of OTM between the two groups, with mean total OTM of 1.11 mm. (standard deviation (SD) 0.30) and 1.07 mm. (SD 0.33) for the weekly aligner and biweekly control groups, respectively (P = 0.72). Over eight weeks, in two-week intervals, material fatigue does not play a significant role in the rate or amount of tooth movement.