Age-dependent biologic response to orthodontic forces

Predictability of maxillary dentoalveolar expansion with clear aligners in patients with mixed dentition

Objective

This prospective study evaluated the effectiveness of clear aligner treatment (CAT) in achieving dentoalveolar upper arch expansion in patients with mixed dentition and transverse maxillary deficiency.

Methods

Forty patients with mixed dentition and a transverse discrepancy of ≤ 5 mm were treated using clear aligners. Pre- and post-treatment digital dental models were measured using specific landmarks and compared with the programmed expansion in the virtual treatment plan. Statistical analyses included the inter-class correlation coefficient to evaluate inter-rater reliability. A paired t test was employed to compare pre- and post-treatment values and to examine the significance of the changes. Multiple regression analysis was conducted to estimate the relationship between the prescribed and observed measurements, stratified by inter-dental measurements (deciduous canines, first deciduous molars, and permanent molars, at cusp and gingival levels).

Results

Excellent measurement reproducibility was observed. The accuracy of dentoalveolar maxillary arch expansion varied among different tooth regions. The inter-canine accuracy was 87.7% at the cusp level and 82.7% at the gingival level. The inter-first deciduous molars exhibited accuracies of 84.9% (cusp level) and 80.5% (gingival level). The inter-first molars showed accuracies of 77.8% (cusp level) and 67.9% (gingival level). Significant differences were observed between the planned and obtained measurements for specific tooth regions.

Conclusions

CAT demonstrated reliable predictability in achieving dentoalveolar expansion of the maxillary arch in patients with mixed dentition. A higher accuracy was observed in the anterior region than in the posterior region. These findings suggest that CAT could be an effective option for treating transverse maxillary deficiencies in patients with mixed dentition with moderate inter-arch transverse discrepancies, considering tooth-specific predictability differences.

Comparative Assessment of Relapse Following Fixed Orthodontic Treatment in Patients Treated With and Without Extraction: A Systematic Review and Meta-Analysis

The present systematic review aimed to evaluate and compare the post-treatment relapse of overjet, overbite, and mandibular incisor crowding in patients treated with extraction and non-extraction orthodontic approaches and to assess the influence of treatment modality on long-term stability. The review was conducted following PRISMA guidelines. Data were extracted from 10 studies, including retrospective and longitudinal designs, with a total of 720 participants. The primary outcome measures included overjet, overbite, and Little's Irregularity Index. Standardized mean difference (SMD) was used as the summary statistic to compare extraction and non-extraction groups. The risk of bias was assessed using the ROBINS-I tool. The meta-analysis revealed no statistically significant differences in relapse between extraction and non-extraction groups for overjet (SMD: 0.52, 95% CI: -0.18 to 1.23, p>0.05), overbite (SMD: 0.41, 95% CI: -0.11 to 0.93, p>0.05), and incisor irregularity index (SMD: 0.71, 95% CI: -0 to 1.23, p>0.05). Funnel plots indicated no significant publication bias. Risk of bias assessment showed moderate concerns in confounding and participant selection across several studies, while bias due to missing data was notable in longer follow-up studies. The findings suggest that both extraction and non-extraction treatment approaches exhibit similar post-treatment relapse rates for overjet, overbite, and incisor irregularity. The choice of treatment should be based on clinical considerations along with concerns of long-term stability. Further high-quality randomized controlled trials are required to strengthen the evidence.

The effect of micro-osteoperforation (MOP) in molar distalization treatments: an exploratory systematic review and meta-analysis of RCTs

OBJECTIVE

Molar distalization is a therapeutic approach commonly used for treating Class II malocclusions. However, the extended duration of this treatment often leads to its replacement with alternative methods that offer shorter treatment times. Micro-osteoperforation (MOP) has been introduced as a technique aimed at accelerating tooth movement and reducing treatment duration. The purpose of this study is to evaluate the impact of MOP on molar distalization outcomes to provide evidence for its effective and safe use.

SEARCH METHODS

A comprehensive search was conducted across multiple databases, including MEDLINE, Web of Science, EMBASE, Scopus, and Cochrane's CENTRAL, up to April 2024, without any language or date restrictions.

SELECTION CRITERIA

Only randomized clinical trials (RCTs) that addressed the defined PICO question were included in the analysis. The risk of bias in the included studies was assessed using the Cochrane Risk of Bias 2.0 (RoB 2) tool.

DATA COLLECTION AND ANALYSIS

Relevant data were extracted using custom-designed forms, and a random-effects inverse variance meta-analysis was performed to synthesize the results. The primary outcomes analyzed were the rate and amount of molar distalization, while secondary outcomes included pain levels, root resorption, and periodontal health.

RESULTS

Four RCTs, involving a total of 71 participants, were included in this exploratory review. Most studies were at low or some concerns risk of bias. The meta-analysis revealed no significant differences in the rate or amount of molar distalization between the MOP and control groups (mean difference [MD] = 0.1 mm/month and 0.01 mm, respectively, P > .05). However, the MOP group reported significantly higher pain levels on the day of the procedure (MD = 2, P = .01) on a 10-point visual analog scale (VAS) compared to the control group. This difference in pain perception was no longer significant seven days after the procedure (MD = 0.52, P = .52).

CONCLUSION

While MOP is associated with increased immediate postoperative pain, it does not significantly enhance the efficiency of molar distalization. Therefore, the use of MOP for distalization should be judiciously considered and reserved for cases that involve particularly challenging or prolonged movements, based on the specific needs and characteristics of each patient. Limitations of this review include the small number of available RCTs and variability in MOP protocols, which may limit the generalizability of the findings.

REGISTRATION

The protocol for this systematic review was registered at PROSPERO with the ID CRD42024589482.

Efficacy and Comfort Level with the Non-Sliding Lingual Orthodontic Technique (BRIUS™) Versus Labial Full Fixed Appliances: A Pilot Randomized Controlled Clinical Trial

Introduction: This pilot two-arm, parallel group, randomized clinical trial aimed to compare the efficacy of tooth movement and patient comfort during orthodontic leveling and alignment with the BRIUS™ lingual system (BR) versus labial full fixed appliances (LFFAs). Methods: Patients in the permanent dentition with mild to moderate crowding were recruited at the University at Buffalo and randomly assigned into the BR group (seven patients) or LFFAs group (six patients). The patients' dental arches were scanned before bonding (T1) and after 18 weeks (T2). Digital dental model superimpositions were performed to three-dimensionally evaluate tooth movement. Changes between T1 and T2 were measured in the x, y, and z planes. Little's Irregularity Index (LII) was also assessed at T1 and T2. An electronic questionnaire was completed daily for 7 days after T1 to evaluate the patients' comfort levels. Results: After 18 weeks, similar displacements were observed for all teeth in both groups except for the lower left second premolar (LL5) in the x-axis which showed greater displacement in the BR group (p = 0.016). Groups showed similar changes in LII. Discomfort during the first week after bonding was greater on the tongue in the BR group and on the lips and cheeks in the LFFAs group. Tongue discomfort caused by the BR lasted for around 3 days. Conclusion: The BR and LFFAs showed similar teeth displacements and therefore were equally effective at leveling and aligning teeth. LFFAs caused cheek- and lip-borne discomfort while the BR caused tongue-borne discomfort during the first week after bonding. Larger studies with longer follow-ups are needed to obtain more definitive results.

Visualize the time dynamics and research trends of macrophage associated periodontitis research from 2004 to 2023: Bibliometrix analysis

BACKGROUND

Macrophages play an important role in the symptoms and structural progression of periodontitis, and are receiving increasing attention. In recent years, research has shown significant progress in macrophage associated periodontitis. However, there is still lack of comprehensive and methodical bibliometric analysis in this domain. Therefore, this research aims to describe the state of the research and current research hotspots of macrophage associated periodontitis from the perspective of bibliometrics.

METHODS

This study collected and screened a total of 1424 articles on macrophage associated periodontitis retrieved between 2004 and 2023 from Web of Science Core Collection database. Use Citespace (6.1. R6), Bibliometrix-R (4.1.3), VOSviewer (1.6.19), and Graphpad Prism8 software to analyze and plot countries/regions, institutions, journals, authors, literature, and keywords to explore the research hotspots and development trends of macrophage associated periodontitis.

RESULT

After analysis, the amount of macrophage associated periodontitis publications has been rising consistently over time, with China having the most publications (29.32%). 3 countries accounted for 65.57% of the total publications: the United States, China, and Japan, occupying a dominant position in this research field. China publications have the fastest growth rate and played a driving role. The most productive institution is the Sichuan University in China. Journal of Periodontal Research is highly popular in the field of macrophage associated periodontitis, with the highest number of publications. Grenier, Daniel is the most prolific author. Inflammation and Bone Loss in Periodontal Disease are the most cited literature. "Biological pathogenic factors," "immune regulation," "mechanism research," "susceptibility factor research," "pathological processes and molecular correlation," "pathological characteristics," "inflammatory response" are the main keyword groups in this field.

CONCLUSION

This study systematically analyzes and describes the development process, direction, and hotspots of macrophage associated periodontitis using bibliometric methods, providing a reference for future researchers who continue to study macrophage associated periodontitis.

Effect of Two Different Penetration Depths of Micro-osteoperforation on the Rate of Orthodontic Tooth Movement: A Prospective Clinical Study

Objective

The objective is to evaluate the effectiveness of two different penetration depths of micro-osteoperforations (MOPs) on the rate of orthodontic tooth movement over 60 days. In addition, the amount of pain and discomfort caused by the MOP was evaluated.

Materials and Methods

A total of 22 patients (18-30 years) who need fixed orthodontic treatment were recruited and randomly assigned into two groups. Randomization for determination of the experimental side and depth of perforations was done using sealed envelopes. On each patient, the other side of the mouth worked as control side with no MOPs. Patients in group 1 (MOP-5) received 3MOPs on the buccal surface of the alveolar bone each at 5 mm depth, whereas patients in group 2 (MOP-7) received 3MOPs on the buccal surface of the alveolar bone each at 7 mm depth. The amount of canine retraction was measured every 30 days at two intervals on both sides of the mouth. Pain perception was measured after 1 h, 24 h, 72 h, 7 days, and 28 days of procedure. MOP-related pain was measured using a visual analog scale. The level of statistical significance was P ≤ 0.05.

Results

The result of the intra-examiner reliability using intraclass correlation coefficient more than 0.97 (P < 0.001), indicating excellent repeatability and reliability of the measurements. The baseline characteristics between groups were similar (P > 0.05). Both the groups demonstrated a significantly higher canine movement than the control group. No significant difference was seen between the MOP-5 and MOP-7 groups (P > 0.05) in terms of canine retraction. Mild-to-moderate pain was experienced only in the first 24 h of the procedure.

Conclusion

Three MOPs with a depth of 5 mm can be performed as an effective method to increase the rate of tooth movement. However, increasing the depth of perforation beyond 5 mm does not additionally enhance tooth movement.

The age-related effects on orthodontic tooth movement and the surrounding periodontal environment

Orthodontic treatment in adults is often related to longer treatment time as well as higher periodontal risks compared to adolescents. The aim of this review is to explore the influence of age-related chages on orthodontic tooth movement (OTM) from macro and micro perspectives. Adults tend to show slower tooth movement speed compared to adolescence, especially during the early phase. Under orthodontic forces, the biological responses of the periodontal ligament (PDL) and alveolar bone is different between adult and adolescents. The adult PDL shows extended disorganization time, increased cell senescence, less cell signaling and a more inflammatory microenvironment than the adolescent PDL. In addition, the blood vessel surface area is reduced during the late movement phase, and fiber elasticity decreases. At the same time, adult alveolar bone shows a higher density, as well as a reduced osteoblast and osteoclast activation, under orthodontic forces. The local cytokine expression also differs between adults and adolescents. Side-effects, such as excessive root resorption, greater orthodontic pain, and reduced pulpal blood flow, also occur more frequently in adults than in adolescents.

Age-related alveolar bone maladaptation in adult orthodontics: finding new ways out

Compared with teenage patients, adult patients generally show a slower rate of tooth movement and more pronounced alveolar bone loss during orthodontic treatment, indicating the maladaptation of alveolar bone homeostasis under orthodontic force. However, this phenomenon is not well-elucidated to date, leading to increased treatment difficulties and unsatisfactory treatment outcomes in adult orthodontics. Aiming to provide a comprehensive knowledge and further inspire insightful understanding towards this issue, this review summarizes the current evidence and underlying mechanisms. The age-related abatements in mechanosensing and mechanotransduction in adult cells and periodontal tissue may contribute to retarded and unbalanced bone metabolism, thus hindering alveolar bone reconstruction during orthodontic treatment. To this end, periodontal surgery, physical and chemical cues are being developed to reactivate or rejuvenate the aging periodontium and restore the dynamic equilibrium of orthodontic-mediated alveolar bone metabolism. We anticipate that this review will present a general overview of the role that aging plays in orthodontic alveolar bone metabolism and shed new light on the prospective ways out of the impasse.

Effectiveness of Clear Aligners on Sequential Maxillary Molar Distalization: Discrepancy between Treatment Goal and Outcome

Objectives: The purpose of this preliminary study was to determine the differences between planned and actual maxillary molar movements after the completion of treatment with an initial set of clear aligners including sequential maxillary molar distalization. Methods: The data records of 14 non-growing patients who completed orthodontic treatment with sequential maxillary molar distalization using clear aligners were retrospectively evaluated (n= 14, 4 males and 10 females, 33.61 ± 8.57 years). Data on planned tooth movements were obtained from ClinCheck software (ClinCheck Pro version 5.3). The amounts of actual tooth movements were obtained by performing superimposition of lateral cephalograms taken before and after treatment. The amounts of distal translation and tipping between planned and actual maxillary molar movements were compared with the paired Student's t-test. Results: The statistically significant differences between planned and actual translation movements of maxillary first and second molars were shown after completing treatment with the first series of aligners (p < 0.05). The average actual amount of molar distalization on maxillary first molars was less than the planned amount by 1.32 ± 0.42 mm. Similarly, the average actual amount of molar distalization on maxillary second molars was less than the planned amount by 1.57 ± 0.45 mm. The accuracy for molar distalization, namely, the percentage of actual distal translation to planned movement, was 40.11% for maxillary first molars and 35.39% for maxillary second molars. However, the difference between the planned and actual angulation movements was not significant (p > 0.05). Conslusions: In conclusion, the amounts of actual distal translation of maxillary molars through the utilization of clear aligners were significantly lower than planned. However, there were no statistically significant differences between the degrees of actual and planned molar angulation movement.

The effectiveness of the total-maxillary-arch-distalization approach in treating class II division 1 malocclusion: A systematic review

OBJECTIVE

The objective of this review is to assess the effect of total maxillary arch distalization (TMAD) treatment on the dental, skeletal, soft tissues, and airways during non-extraction camouflage treatment of class II division 1 patients.

METHODS

We performed a systematic review of the published data in four electronic databases up to April 2023. We considered studies for inclusion if they were examining the effects of TMAD during treatment of class II division 1 malocclusion in the permanent dentition. Study selection, data extraction, risk of bias assessment, and assessment of the strength of the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool were performed in duplicate.

RESULTS

Out of the 27 articles that met the initial eligibility criteria, 19 studies were finally selected. Fair to relatively good quality evidence was identified after the risk of bias assessment of the included studies. Out of the 19 selected studies, 5 studies used inter-radicular TADs, 10 studies used modified C- palatal plate (MCPP), 3 studies used infra zygomatic crest (IZC) TADs, 1 study compared buccal TADs versus MCPP, and 1 study compared between cervical headgear and MCPP. The maximum amount of maxillary arch distalization using buccal TADs, MCPP, IZC TADs, and headgear was 4.2mm, 5.4mm, 5mm, and 2.5mm respectively. Different results regarding the amount of dental, skeletal, and soft tissue changes were observed.

CONCLUSIONS

The current low to very low certainty level of evidence suggests that TMAD is effective in camouflaging class II division 1 malocclusion. Future well-conducted and clearly reported randomized controlled trials that include a control group are needed to make robust recommendations regarding the effect of TMAD with different appliances on dental, skeletal, and soft tissue structures.

CLINICAL RELEVANCE

TMAD should be given priority with caution in class II patients who refuse the extraction of premolars. TMAD may be considered an adjunctive approach to solve cases associated with high anchorage need or anchorage loss.

Effect of age on orthodontic tooth movement in mice

Background/purpose

The number of middle-aged and elderly orthodontic patients is increasing due to changes in age composition. It is important to investigate the detailed mechanisms of bone remodeling in orthodontic tooth movement (OTM) in the elderly. However, there are few reports on the mechanism of tooth movement in the elderly. The purpose of the present study was to analyze OTM and osteoclastogenesis in aged mice and to elucidate the mechanism.

Materials and methods

It has been reported that tumor necrosis factor (TNF)-α plays an important role in osteoclast formation and OTM. First, 8-week-old and 78-week-old male C57BL/6J mice were subcutaneously injected with TNF-α into the calvaiae, and micro-CT, tartrate-resistant acid phosphatase (TRAP) staining, and real-time PCR were performed to evaluate osteoclast formation and bone resorption. Furthermore, osteoclastogenesis by TNF-α and receptor activator of nuclear factor-kappa B ligand (RANKL) using bone marrow cells was evaluated in vitro. Finally, a nickel-titanium closed-coil spring was attached, mesial movement of the maxillary left first molar was performed, and tooth movement distance and osteoclast formation were evaluated.

Results

Compared to 8-week-old mice, 78-week-old mice had decreased TNF-α-induced bone resorption, osteoclastogenesis, and TRAP and cathepsin K expression in the calvariae. In vitro osteoclast formation also decreased in 78-week-old mice. Furthermore, tooth movement distance and osteoclastogenesis were reduced.

Conclusion

OTM decreased in aged mice, which was shown to be caused by a decrease in osteoclastogenesis. Therefore, it was suggested that it is necessary to keep in mind that tooth movement may be suppressed when treating elderly patients.

Tensile forces in the neurovascular bundle: A contributor to orthodontic relapse?

OBJECTIVES

The aim of this study is to investigate the neurovascular bundle (NVB) as a potential orthodontic relapse factor. The mechanical properties and the forces generated in the NVB after orthodontic extrusion are explored.

MATERIALS AND METHODS

Six NVBs branching from the inferior alveolar nerve to the apices of the mandibular canines and premolars of mature pigs were harvested. Stress relaxation tests were conducted. A standard linear solid model (SLS) was utilized to simulate the orthodontic extrusion of a single rooted tooth with NVB length and cross-sectional diameter of 3.6 and 0.5 mm, respectively, so the NVB was stretched 10% and 20% of its original length. The maximum force within the NVB was then calculated.

RESULTS

Based on our data, the average Young's modulus before relaxation (E 0 ), after relaxation (E P ) and the difference between Young's moduli before and after relaxation (E S ) were 324 ± 123, 173 ± 73 and 151 ± 52 kPa, respectively. The theoretical force within the NVB stretched to 10% and 20% strain was 3 and 5 mN, respectively.

CONCLUSION

The data from our study indicate that the NVB exhibits stress relaxation, a characteristic trait of viscoelastic materials. SLS model simulation predicted residual forces around 5 mN for elongation up to 20%. We observed strain hardening with additional elongation, which has the potential to cause forces to increase exponentially. Therefore, tensile forces in the NVB should not be ruled out as a contributor to orthodontic relapse, especially in adult patients who may have decreased adaptability of their NVB. Further preclinical and clinical models should be developed to further clarify what is the contribution of the NVB to orthodontic relapse.

Effectiveness of dental monitoring system in orthodontics: A systematic review

BACKGROUND

Dental monitoring (DM) constitutes a recent technological advance for the remote monitoring of patients undergoing an orthodontic therapy. Especially in times of health emergency crisis, the possibility of relying on remote monitoring could be particularly useful.

OBJECTIVES

To assess the effectiveness of DM in orthodontic care.

ELIGIBILITY

Studies conducted on healthy patients undergoing orthodontic care where DM was applied, assessing a change in treatment duration, emergency appointments, in-office visits, orthodontic relapse, early detection of orthodontic emergencies and improvement of oral health status.

INFORMATION SOURCES

PubMed, Web of Science and Scopus were searched for publications until November 2022.

RISK OF BIAS

Quality assessment was performed with the STROBE Checklist.

DATA EXTRACTION

Data were extracted independently by two reviewers, and discrepancies were resolved with a third reviewer.

INCLUDED STUDIES

Out of 6887 records screened, 11 studies were included.

SYNTHESIS OF RESULTS

DM implemented to the standard orthodontic care was found to significantly decrease the number of in-office visits by 1.68-3.5 visits and showed a possible trend towards improvement of aligner fit. Conversely, evidence does not support a reduction of treatment duration and emergency appointments. The assessment of the remaining variables did not allow any qualitative synthesis.

CONCLUSIONS

This review highlighted that DM implemented to standard orthodontic care can significantly decrease the number of in-office visits and may potentially result in an improved aligner fit. Due to the low quality of most of the included studies and the heterogeneity of the orthodontic system where DM was applied, studies with different investigation team and rigorous methodology are advocated.

Changes in alveolar bone structure during orthodontic tooth movement in adolescent and adult rats: A microcomputed tomography study

BACKGROUND

Increasing number of adults are willing to seek orthodontic treatment, but treatment duration for them is commonly longer. Although there have been studies on molecular biological changes during tooth movement, few have focused on microstructural changes in alveolar bone.

OBJECTIVE

This study aims to compare the microstructural changes in alveolar bone during orthodontic tooth movement in adolescent and adult rats.

METHODS

25 6-week-old and 25 8-month-old male Sprague-Dawley (SD) rats were used to build orthodontic tooth-movement models. On Days 0, 1, 3, 7 and 14, the rats were sacrificed. Microcomputed tomography was used to evaluate tooth movement, alveolar crest height loss and microstructural parameters of alveolar bone (bone volume fraction, trabecular thickness, trabecular separation and trabecular number).

RESULTS

Tooth movement in the adult group was slower than in the adolescent group. Alveolar bone crest height in adults was lower than it was in adolescents on Day 0. Under orthodontic force, the alveolar crest in both groups decreased and the degree of decrease are higher at early stage in adolescents. The microstructural parameters indicated that the alveolar bone was originally denser in the adult rats. With orthodontic force, it tended to be looser.

CONCLUSIONS

Under orthodontic force, changes in alveolar bone differ between adolescent and adult rats. Tooth movements in adults are slower, and the decrease in alveolar bone density are more severe.

Effects of Flapless Laser Corticotomy in Upper and Lower Canine Retraction: A Split-mouth, Randomized Controlled Trial

Aim One of the major difficulties in orthodontic treatment is the lengthy course of therapy, particularly in situations involving extractions. Hence, various methods for accelerating tooth movement rate had been devised. Flapless corticotomy is one of those methods. This study aimed to evaluate the effects of flapless laser corticotomy (FLC) compared to the conventional retraction (CR) method on the rate of canine retraction. Methods A split-mouth, randomized controlled trial included 56 canines from 14 patients (12 females and two males) with a mean age of 20.4 ± 2.5 years, who were complaining of bimaxillary protrusion requiring extraction of four premolars. All canines were randomly assigned to four groups (maxillary FLC, maxillary control CR, mandibular FLC, and mandibular control CR). Randomization was performed by creating two equal, random computer-generated lists with a 1:1 allocation ratio-one list for the right side and one for the left. The allocation concealment was achieved using opaque sealed envelopes until the time of intervention. FLC was applied on the experimental sides before canine retraction by drilling six holes penetrating 3 mm into the bone on the mesial and distal sides of the canines. Subsequently, all canines were retracted employing closed coil springs to deliver a force of 150 g using indirect anchorage from temporary anchorage devices (TADs). All canines were assessed at T0 (before retraction), T1 (one month after retraction), T2 (two months), and T3 (three months) using three-dimensional (3D) digital models. Additionally, canine rotation, molar anchorage loss assessed using 3D digital models, root resorption assessed using cone beam computed tomography (CBCT), probing depth, plaque, gingival indices, and pulp vitality were all evaluated as secondary outcomes. It was possible to blind only the outcome analysis expert (single-blinded). Results The measurements of canine retraction during the follow-up period from T0 to T3 were 2.46 ± 0.80 mm and 2.55 ± 0.79 mm in maxillary FLC and control groups, respectively, and 2.44 ± 0.96 mm and 2.31 ± 0.95 mm in mandibular FLC and control groups, respectively. The results demonstrated a statistically non-significant difference in the distance of canine retraction between the FLC and control groups at all time points. Moreover, no differences were observed between groups in canine rotation, molar anchorage loss, root resorption, probing depth, plaque, gingival indices, and pulp vitality (p > 0.05). Conclusion In the FLC procedure performed in this study, the rate of upper and lower canine retraction could not be accelerated and no significant differences were observed between FLC and control groups in canine rotation, molar anchorage loss, root resorption, periodontal condition, and pulp vitality.

When (and when not) to use the Dahl Concept

The Dahl Concept describes the re-establishment of occlusal contacts after the provision of a planned localised appliance or restoration in supraocclusion. Initially developed to create space for prosthetic rehabilitation of anterior teeth suffering from localised wear, the principle has later been successfully applied to a variety of situations, including the Hall technique and resin-bonded bridges cemented in supraocclusion. Despite high levels of success seen in the relevant literature and widespread adoption in specialist care, the wider profession appears to be far more cautious in its use. This article aims to provide a brief summary of the Dahl Concept and discuss the local and general factors that influence its successful implementation in the hope of promoting its increased adoption by the broader dental profession.

Matrix Metalloproteinases in Dental and Periodontal Tissues and Their Current Inhibitors: Developmental, Degradational and Pathological Aspects

Objectives: This review article aims to describe some of the roles of Matrix metalloproteinases (MMPs) in enamel, dentine, dental caries, hybrid layer degradation, pulp and periodontal tissues, throwing light on their current inhibitors. The article addresses the potential of MMPs to serve as biomarkers with diagnostic and therapeutic value. Design: The sections of this review discuss MMPs’ involvement in developmental, remodeling, degradational and turnover aspects of dental and periodontal tissues as well as their signals in the pathogenesis, progress of different lesions and wound healing of these tissues. The literature was searched for original research articles, review articles and theses. The literature search was conducted in PubMed and MEDLINE for articles published in the last 20 years. Results: 119 published papers, two textbooks and two doctoral theses were selected for preparing the current review. Conclusions: MMPs are significant proteases, of evident contribution in dental and periapical tissue development, health and disease processes, with promising potential for use as diagnostic and prognostic disease biomarkers. Continuing understanding of their role in pathogenesis and progress of different dental, periapical and periodontal lesions, as well as in dentine-pulp wound healing could be a keystone to future diagnostic and therapeutic regimens.

Difference in the alveolar bone remodeling between the adolescents and adults during upper incisor retraction: a retrospective study

The purpose of this study was to compare the difference of alveolar bone remodeling between the adolescents and adults in the maxillary incisor area during retraction. This retrospective study included 72 female patients who needed moderate anchorage to correct the bimaxillary protrusion. Subjects were further divided into the minor group (n = 36, 11-16 years old) and adult group (n = 36, 18-35 years old). Digital lateral cephalography and cone beam CT scanning were taken in each patient before (T0) and after treatment (T1). Cephalometry was conducted to assess incisor retraction, while alveolar bone thickness (ABT), alveolar bone distance (ABD), and alveolar bone area (ABA) were detected to assess changes in the alveolar bone. No difference in the inclination of upper incisors was observed at both T0 and T1 between two groups. Changes in the alveolar bone showed a similar tendency with bone apposition on the labial side and bone resorption on the palatal side in both groups. Less increase in the labial ABT (T1-T0) and more decrease in the palatal ABT (T1-T0) was found in the adult group, leading to less total ABT in the adult group. Higher reduction in ABD (T1-T0) was found in the adult group. Moreover, more decrease in the ABA (T1-T0) was found in the adult group. Adult patients have less alveolar bone support after treatment when compared with young adolescents. Orthodontists should take the age into consideration to reduce the potential periodontal risks during the treatment planning.

Accuracy of 3D Tooth Movements in the Fabrication of Manual Setup Models for Aligner Therapy

Background: The clinical outcome of aligner therapy is closely related to the precision of its setup, which can be manually or digitally fabricated. The aim of the study is to investigate the suitability of manual setups made for aligner therapy in terms of the precision of tooth movements. Methods: Six dental technicians were instructed to adjust each of eleven duplicate plaster casts of a patient models as follows: a 1 mm pure vestibular translation of tooth 11 and a 15° pure mesial rotation of tooth 23. The processed setup models were 3D scanned and matched with the reference model. The one-sample Wilcoxon signed-rank test (p < 0.05) was used for evaluation. Results: The overall precision of the translational movement covers a wide range of values from 0.25 to 2.26 mm (median: 1.09 mm). The target value for the rotation of tooth 23 was achieved with a median rotation of 9.76° in the apical-occlusal direction. Unwanted movements in the other planes also accompanied the rotation. Conclusions: A manual setup can only be fabricated with limited precision. Besides the very high variability between technicians, additional unwanted movements in other spatial planes occurred. Manually fabricated setups should not be favored for aligner therapy due to limited precision.

Comparison of the friction forces delivered by different elastomeric patterns and metal ligature on conventional metal brackets with a NiTi arch wire versus a self-ligating system: An in vitro study

OBJECTIVES

The aim of this study was to measure the frictional resistance of different types of ligatures used on conventional and self-ligating brackets.

MATERIALS AND METHODS

Monoblock (conventional) and Portia (self-ligating) brackets were used and the archwire used was nickel-titanium. On conventional brackets the ligatures tested were the Elastomeric type and steel 0.30 tie-wire. The groups were divided according to the ligature types (n=8): (1) conventional elastomeric ligature; (2) relaxed conventional elastomeric ligature; (3) elastomeric ligature in shape-8; (4) double vertical elastomeric ligatures; (5) double-crossed elastomeric ligatures; (6) crossed ligature; (7) steel wire ligature; and (8) self-ligating ligature (self-ligating bracket). A segment of five brackets, each ligature types, was mounted. The archwire, between the bracket and the ligature, was connected on Instron® Universal test machine to simulate the frictional resistance. The maximum frictional resistance was obtained, and the mean values were submitted to the analysis of variance (ANOVA) and the Tukey's post-hoc test (α=0.05).

RESULTS

The elastomeric ligature in shape-8 showed the highest value compared with other groups (P<0.05). Although the crossed elastomeric ligature presented the lowest mean value and it was not statistically different regarding relaxed conventional elastomeric ligature, steel wire ligature and self-ligating (P≥0.05).

CONCLUSIONS

The frictional resistance was influenced by ligature types. Elastomeric Ligature in shape-8 showed the highest frictional force. Crossed Elastomeric Ligature had the lowest frictional force value.

Orthodontic space closure in sliding mechanics: a systematic review and meta-analysis

BACKGROUND/OBJECTIVES

The aim of this systematic review was to compare the different force delivery systems for orthodontic space closure by sliding mechanics.

SEARCH METHODS

Multiple sources including Cochrane Central, Ovid Medline, Embase etc. were used to identify all relevant studies.

SELECTION CRITERIA

Randomized controlled trials (RCT) of parallel-group and split-mouth designs were included.

PARTICIPANTS

Orthodontic patients of any age treated with fixed orthodontic appliances and requiring space closure.

DATA COLLECTION AND ANALYSIS

Search result screening, data extraction and quality assessment were performed independently and in duplicate by 2 reviewers. The included studies were grouped into parallel-arm and split-mouth studies and subgroup analysis was then performed for the type of retraction subsets; en-masse and individual canine retraction. A traditional meta-analysis, and network meta-analysis (NMA) for direct and indirect comparisons for the rate of space closure were performed.

RESULTS

Thirteen studies, six parallel-arm and seven split-mouth were included. The traditional meta-analysis comparing Nickel-titanium (NiTi) closed coil springs and elastomeric power chain for the rate of tooth movement showed statistically significant difference favouring NiTi springs (MD: 0.24; 95% CI, 0.03-0.45; I2 0%, P = 0.02) and the comparison between NiTi springs and active ligatures also showed statistically significant result favouring NiTi springs (MD: 0.53; 95% CI, 0.44-0.63; I2 0%, P ˂ 0.00001) for the rate of tooth movement. NMA for the rate of space closure showed fairly confident evidence for NiTi coil springs when compared with elastomeric chain and active ligatures. The NiTi coil spring ranked best between all methods of space closure.

CONCLUSIONS

There is moderate quality evidence in favour of NiTi coil springs for the rate of space closure when compared with active ligature and low quality of evidence favouring NiTi springs when compared with elastomeric chain. The ranking from NMA showed NiTi coil springs to be the best method for space closure with 99% chance. An urgent need for standardization of study designs and the need for development of an agreed core outcome sets and core outcome instrument measurement sets is evident.

REGISTRATION

PROSPERO CRD42020157811.

Chemokines and Pain in the Trigeminal System

Chemotactic cytokines or chemokines are a large family of secreted proteins able to induce chemotaxis. Chemokines are categorized according to their primary amino acid sequence, and in particular their cysteine residues that form disulphide bonds to maintain the structure: CC, CXC, CX3C, and XC, in which X represents variable amino acids. Among their many roles, chemokines are known to be key players in pain modulation in the peripheral and central nervous systems. Thus, they are promising candidates for novel therapeutics that could replace current, often ineffective treatments. The spinal and trigeminal systems are intrinsically different beyond their anatomical location, and it has been suggested that there are also differences in their sensory mechanisms. Hence, understanding the different mechanisms involved in pain modulation for each system could aid in developing appropriate pharmacological alternatives. Here, we aim to describe the current landscape of chemokines that have been studied specifically with regard to trigeminal pain. Searching PubMed and Google Scholar, we identified 30 reports describing chemokines in animal models of trigeminal pain, and 15 reports describing chemokines involved in human pain associated with the trigeminal system. This review highlights the chemokines studied to date at different levels of the trigeminal system, their cellular localization and, where available, their role in a variety of animal pain models.

MMPs and TIMPs Expression Levels in the Periodontal Ligament during Orthodontic Tooth Movement: A Systematic Review of In Vitro and In Vivo Studies

Background: During orthodontic tooth movement (OTM), applied orthodontic forces cause an extensive remodeling of the extracellular matrix (ECM) in the periodontal ligament (PDL). This is mainly orchestrated by different types of matrix metalloproteinases (MMPs) and their tissue inhibitors of matrix metalloproteinases (TIMPs), which are both secreted by periodontal ligament (PDL) fibroblasts. Multiple in vitro and in vivo studies already investigated the influence of applied orthodontic forces on the expression of MMPs and TIMPs. The aim of this systematic review was to explore the expression levels of MMPs and TIMPs during OTM and the influence of specific orthodontic force-related parameters. Methods: Electronic article search was performed on PubMed and Web of Science until 31 January 2021. Screenings of titles, abstracts and full texts were performed according to PRISMA, whereas eligibility criteria were defined for in vitro and in vivo studies, respectively, according to the PICO schema. Risk of bias assessment for in vitro studies was verified by specific methodological and reporting criteria. For in vivo studies, risk of bias assessment was adapted from the Joanna Briggs Institute Critical Appraisal Checklist for analytical cross-sectional study. Results: Electronic article search identified 3266 records, from which 28 in vitro and 12 in vivo studies were included. The studies showed that orthodontic forces mainly caused increased MMPs and TIMPs expression levels, whereas the exact effect may depend on various intervention and sample parameters and subject characteristics. Conclusion: This systematic review revealed that orthodontic forces induce a significant effect on MMPs and TIMPs in the PDL. This connection may contribute to the controlled depletion and formation of the PDLs' ECM at the compression and tension site, respectively, and finally to the highly regulated OTM.

Perception of pain in Class II malocclusion children treated with cervical headgear: a randomized controlled trial

OBJECTIVES

The aims of this study were: 1. to evaluate the experience of pain perceived by children during separator placement and headgear wear; 2. to find possible associations between the perceived intensity of pain and the levels of Substance P (SP) and interleukin-1 beta (IL-1β) in the gingival crevicular fluid (GCF) during these procedures; 3. to identify other factors, such as previous pain experience, which could be associated to the patients' perceived discomfort or pain during treatment.

TRIAL DESIGN

Nine-month parallel-group randomized controlled trial.

METHODS

Forty Class II malocclusion children (8-12 years) were included, half of which received a cervical headgear while the other half did not receive any treatment during the study period. Baseline pain data were recorded including previous experience to general and dental pain, Corah's Dental Anxiety Scale, and baseline pain using a visual analogue scale (VAS). Elastic separators were placed in children for 1 week, followed by molar band and cervical headgear placement. Children were seen at various time points throughout the 9-month period where at each appointment, a VAS assessment of pain as well as GCF sampling was carried out to quantify the levels of SP and IL-1β. Multiple regression analysis was performed to ascertain the influence of factors including sex, age, time, headgear wear, and baseline pain data on pain severity.

RESULTS

Pain severity and SP and IL-1β levels in the GCF follow a similar pattern, with peaks being observed 1 day after orthodontic elastic separator placement. Pain was more severe after the placement of orthodontic separators than following cervical headgear wear. With regard to pain predictors, pain is more severe in older children, those with a worse previous general pain experience, and those with higher levels of IL-1β, particularly after elastic separator placement.

CONCLUSIONS

Orthodontic pain and discomfort following orthodontic separator placement and cervical headgear wear depends on factors including age, previous pain experience, and the level of IL-1β in the GCF.

The effect of platelet-rich fibrin (PRF) on maxillary incisor retraction rate

OBJECTIVE

To investigate the efficiency of platelet-rich fibrin (PRF) injection on maxillary incisor retraction rate.

MATERIALS AND METHODS

The study included 40 patients (23 women and 17 men; mean age; 20.7 ± 1.45) with Class II Division 1 malocclusion. The treatment plan for all patients was extraction of the maxillary first premolars and canine distalization, followed by retraction of the maxillary incisors. Patients were randomly divided into two groups. The study group received injectable platelet-rich fibrin (i-PRF) two times with an interval of 2 weeks; the control group did not receive i-PRF. In both groups, the measurements were bilaterally assessed as the distances between the lateral and canine teeth on the plaster models at five time points. The rate of incisor movement was evaluated by Student's t-test, analysis of variance, and Tukey honestly significant difference tests. Statistical significance was set as P < .05.

RESULTS

The average movements of incisors were significantly higher in the study group than the control group at all time points (P < .05). According to the within-group comparison, none of the measurements showed any significant differences between the right and left sides in both groups at all time points (P > .05). While the movement of incisors was significantly higher in the study group in the week following the PRF injection compared to the other weeks (P < .05), there were no significant differences in the control group at all-time points (P > .05).

CONCLUSIONS

Applying i-PRF significantly increased the rate of maxillary incisor retraction at all time intervals. Platelet-rich fibrin injection can be an effective method for shortening treatment duration.

Using Salivary MMP-9 to Successfully Quantify Periodontal Inflammation during Orthodontic Treatment

Periodontitis is one of the most common immune-mediated inflammatory conditions resulting in progressive destruction of periodontium. Metalloproteinase-9 (MMP-9), an enzyme that is involved in the degradation of gelatin and collagen and present in the gingival crevicular fluid, is markedly increased in periodontitis. The aim of the study is to evaluate the effects of periodontal treatment either alone or in combination with orthodontic treatment on MMP-9 levels. In this study, 60 individuals were subjected to periodontal treatment (PD) or periodontal treatment combined with orthodontic treatment (POD). Both periodontal and periodontal plus orthodontic treatments significantly improved clinical parameters and lowered MMP-9 levels compared to control group. However, the combination of periodontal with orthodontic treatment further improved clinical parameters and enhanced the lowering effect on MMP-9 levels compared to periodontal or control groups alone. Finally, the degree of malocclusion significantly affected the effect of the treatment on MPP-9 levels with PD treatment having the most pronounced effect. We concluded that salivary MMP-9 can serve to accurately predict the level of inflammation in affected periodontal tissues during orthodontic treatment that is also associated with the type of malocclusion, making it a viable diagnosis tool in monitoring the progression of the periodontium during orthodontic treatment.

Predictors of treatment decisions made by adult orthodontic patients presenting with unerupted permanent teeth

OBJECTIVE

Unerupted permanent teeth are amongst the most commonly occurring dental anomalies in adults and present unique treatment challenges. The aim of this retrospective study was to (1) identify the prevalence of adult patients with unerupted teeth attending a multidisciplinary clinic and (2) to identify predictors (age, gender, incisor and skeletal classification) which influence the patients treatment decision.

MATERIAL AND METHODS

Consecutive adult patients with unerupted permanent teeth attending the Joint Orthodontic-Restorative clinic were identified. Study variables were collected using a prespecified data collection form. Descriptive statistics were employed; Fisher's exact test was used to detect associations between variables and treatment decision outcome. Ordinal logistic regression derived multinomial regression relative risk ratios (RRR) and 95% confidence intervals (CI) were calculated for the effect of age, gender, incisor and skeletal classification on treatment decision/outcome.

RESULTS

Sixty-six patients with impacted teeth were identified from a sample of 483. The prevalence of adults with unerupted teeth was 13.7%. The mean age was 30.7 years (SD 11.2). The majority of the sample had a Class I incisor relationship (54.6%) or Class I skeletal base relationship (54.6%), and the most common distribution of impacted teeth was a single unerupted upper right canine (34.9%). Orthodontic treatment (non-extraction or extraction basis incorporating the alignment or removal of impacted teeth) and restorative treatment only were equally favoured. Factors including age, gender, incisor and skeletal classification did not appear to influence or predict the final treatment decision.

CONCLUSIONS

In this sample, adults presenting with impacted teeth favoured certain treatment modalities: orthodontic treatment only and restorative treatment only. Factors such as age, gender, incisor and skeletal classification did not influence the outcome.

Effect of clear aligners on oral health-related quality of life: A systematic review

Clear aligners have been frequently applied in orthodontic clinic practice. However, its effect on oral health-related quality of life (OHRQoL) compared with fixed appliance treatment (FAT) remains inconclusive. This systematic review aimed to compare the impacts of clear aligner treatment (CAT) with FAT on patients' OHRQoL. Electronic searches of databases (PubMed, Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, Embase, Medline, two Chinese databases and six grey literature databases) were conducted up to July 2019. Randomized controlled trials, controlled clinical trials, cohort studies and cross-sectional studies comparing the impact of CAT and FAT on OHRQoL with validated instruments were included. Extraction of data and assessment of the risk of bias were conducted using ROBINS-I-tool, Newcastle-Ottawa Scale and ROB 2.0 based on study design. Of the 1112 records initially identified, 2 studies were included in this review. One study evaluated OHRQoL at the last debonding appointment, while the other made evaluation at the early stage of treatment. In the aspect of functional dimensions, both studies reported less eating disturbance in CAT patients than FAT ones. Based on currently limited information, the effect of CAT on the overall OHRQoL compared to FTA was still inconclusive. In individual dimensions, however, weak evidence supported that CAT might cause less eating disturbance than FAT. More high-quality clinical trials using validated OHRQoL instruments are needed to draw more reliable conclusions in the effect of CAT and FAT on OHRQoL.

Duration of orthodontic treatment with fixed appliances in adolescents and adults: a systematic review with meta-analysis

OBJECTIVES

Adults with fixed orthodontic appliances are increasing nowadays. Compared with adolescents, adults present biological differences that might influence treatment duration. Therefore, the aim of the study was to compare duration of treatment with fixed appliances between adults and adolescents.

MATERIALS AND METHODS

Eight databases were searched up to September 2019 for randomized and non-randomized clinical studies comparing treatment duration with fixed appliances in adolescents and adult patients. After duplicate study selection, data extraction, and risk of bias assessment with the Cochrane ROBINS-I tool, random effects meta-analyses of mean differences (MD) and their 95% confidence intervals (CIs) were performed, followed by assessment of the quality of evidence with GRADE.

RESULTS

A total of 11 unique studies (one prospective and 10 retrospective non-randomized) with 2969 adolescents and 1380 adult patients were finally included. Meta-analysis of 7 studies found no significant difference in the duration of comprehensive treatment with fixed appliances (MD = - 0.8 month; 95% CI = - 4.2 to 2.6 months; P = 0.65; I2 = 92%) between adults and adolescents. Similarly, both distalization of upper first molars with skeletal anchorage for class II correction and the retraction of canines into the premolar extraction spaces lasted similarly long among adults and adolescents. On the other hand, alignment of palatally displaced canines lasted considerably longer in adults compared to adolescents (1 study; MD = 3.8 months; 95% CI = 1.4 to 6.2 months; P = 0.002). The quality of evidence for the meta-analysis was low due to the inclusion of non-randomized studies with considerable risk of bias.

CONCLUSIONS

While existing evidence does not indicate a difference in the overall duration of treatment with fixed appliances between adults and adolescents, the alignment of palatally displaced canines lasted significantly longer in adults. However, our confidence in these estimates is low due to the risk of bias in the included studies.

TRIAL REGISTRATION

PROSPERO: ( CRD42019148169 ).

Impact of clear aligner therapy on tooth pain and masticatory muscle soreness

BACKGROUND

Clinical findings suggest that orthodontic treatment with clear aligners (clear aligner therapy/CAT) may cause masticatory muscle soreness in some patients.

OBJECTIVE

This multi-site prospective study investigated tooth pain and masticatory muscle soreness and tenderness in patients undergoing CAT and explored whether psychological traits affected these outcomes.

METHODS

Twenty-seven adults (22F, 5M; mean age ± SD=35.3 ± 17.6 years) about to start CAT were recruited at three clinics. During CAT, they reported on 100-mm visual analogue scales their tooth pain, masticatory muscle soreness and stress three times per day over 4 weeks (week 1 = baseline; week 2 = dummy aligner; week 3 = first active aligner; week 4 = second active aligner). Pressure pain thresholds (PPTs) were measured at the masseter and temporalis at baseline and after week 4. Mixed models were used to evaluate the outcome measures over time.

RESULTS

Clear aligner therapy caused mild tooth pain, which was greater with the passive than the first and second active aligners (both P < .001). Mild and clinically not relevant masticatory muscle soreness was produced by all aligners (all P < .05), with the first active aligner producing less soreness than the dummy aligner (P < .001). PPTs did not change significantly after 4 weeks. Both tooth pain and masticatory muscle soreness were affected by stress and trait anxiety, whilst muscle soreness was affected also by oral behaviours.

CONCLUSIONS

In the short term, CAT produces tooth pain and masticatory muscle soreness of limited significance. Frequent oral behaviours are related to increased masticatory muscle soreness during CAT. The medium- and long-term effects of CAT should be further explored.

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.

Effect of mini-screw-facilitated micro-osteoperforation on the rate of orthodontic tooth movement: a single-center, split-mouth, randomized, controlled trial

Objective

The present study aimed to evaluate the effect of MOP over a 3-month period and to determine the influence of the number of perforations on the rate of canine retraction. In addition, the amount of pain and discomfort caused by the MOP method was evaluated.

Trial design

A single-center, split-mouth, triple-blind, randomized, controlled trial was conducted.

Methods

The clinical trial was conducted from December 2018 to July 2019 in the Orthodontic Clinic, Shiraz Dental School. Twenty-eight patients (range from16.3 to 35.2 years) who need fixed orthodontic treatment were recruited and randomly assigned to MOP1 and MOP2 groups. In each patient one side of the mouth worked as a control side which received no MOPs. Four months after first premolars extraction, patients in MOP1 group received 3 MOPs on the buccal surface of alveolar bone in the experimental side to accelerate canine retraction whereas patients in MOP2 group received 3 buccal MOPs and 3 palatal MOPs in the experimental side. The amount of canine retraction was measured every 28 days at three intervals on both sides of the mouth. Pain perception was also measured on the day of MOP procedure and subsequently at 24 h. Randomization was performed using online software RANDOM.ORG; the recruited patients were divided into two parallel groups with a 1:1 allocation ratio then the side of MOPs intervention in each subject was randomly determined with coin tossing. Triple blinding design was employed.

Results

The result of the intra-examiner reliability using ICC was 0.97 (P <  0.001), indicating excellent repeatability and reliability of the measurements. The baseline characteristics between the groups were similar (P > 0.05). There was a significant difference in the rate of canine retraction between the MOP groups and the contralateral control sides, as well as between the MOP1 and MOP2 groups (P <  0.05).

Conclusion

The MOP procedure was effective in accelerating orthodontic tooth movement, although the amount of acceleration was not clinically significant in the case of canine retraction. An increase in the number of MOPs resulted in a significant acceleration of the canine retraction.

Trial registration

The trial was registered 30 November 2018 at the Iranian Registry of Clinical Trials (IRCT20181121041713N1).

Different effects of soybean isoflavone genistein on transforming growth factor levels during orthodontic tooth movement among young and old rabbits

Background: Orthodontic treatment to improve aesthetics and for health reasons is performed in children and adults. Elderly individuals have low levels of estrogen, this results in alveolar bone resorption being greater than alveolar bone apposition. Isoflavones present in soybeans may be able to improve the remodeling process through the induction of osteoblastogenesis by increasing transforming growth factor-β1 (TGF-β1) levels. This study aimed to assess the comparative effect of soybean genistein isoflavone to TGF-β1 during orthodontic tooth movement among juvenile and adult rabbits. Methods: In this study, 12 healthy female rabbits were used. Subjects were divided into four groups (n=3); YG group (young rabbits), YGI group (young rabbits + isoflavones genistein), OG group (old rabbits), and OGI group (old rabbits + isoflavones genistein). Two lower incisors of the rabbit were moved distally using an orthodontic force (50 grams force) delivered by an open coil spring, which was inserted between two brackets. During active movements, the genistein isoflavones were given from the initial installation of the device until days 21, at a dose of 1.2 mg/kg BW once a day. Measurement of TGF-β levels were performed on days 1, 7, 14, 21 after appliance installation. TGF-β1 expression was analyzed using enzyme-linked immunosorbent assay (ELISA) and the optical density (OD) of the sample quantifed using a standard curve. The data obtained were analyzed using one-way Anova followed by Tukey HSD test. Results: The TGF-β1 levels were found to highest in the YGI group, and the TGF-β levels were significantly lower in the OG group ( p<0.05). ELISA analysis also revealed that TGF-β1 levels of the OGI group were significantly higher when compared with the OG group ( p<0.05). Conclusion: The administration of soybean genistein isoflavones could improve TGF-β1 levels in old rabbit's during active orthodontic tooth movement.

Different effects of soybean isoflavone genistein on transforming growth factor levels during orthodontic tooth movement among young and old rabbits

Background: Orthodontic treatment to improve aesthetics and for health reasons is performed in children and adults. Elderly individuals have low levels of estrogen, this results in alveolar bone resorption being greater than alveolar bone apposition. Isoflavones present in soybeans may be able to improve the remodeling process through the induction of osteoblastogenesis by increasing transforming growth factor-β1 (TGF-β1) levels. This study aimed to assess the comparative effect of soybean genistein isoflavone to TGF-β1 during orthodontic tooth movement among juvenile and adult rabbits. Methods: In this study, 12 healthy female rabbits were used. Subjects were divided into four groups (n=3); YG group (young rabbits), YGI group (young rabbits + isoflavones genistein), OG group (old rabbits), and OGI group (old rabbits + isoflavones genistein). Two lower incisors of the rabbit were moved distally using an orthodontic force (50 grams force) delivered by an open coil spring, which was inserted between two brackets. During active movements, the genistein isoflavones were given from the initial installation of the device until days 21, at a dose of 1.2 mg/kg BW once a day. Measurement of TGF-β levels were performed on days 1, 7, 14, 21 after appliance installation. TGF-β1 expression was analyzed using enzyme-linked immunosorbent assay (ELISA) and the optical density (OD) of the sample quantifed using a standard curve. The data obtained were analyzed using one-way Anova followed by Tukey HSD test. Results: The TGF-β1 levels were found to highest in the YGI group, and the TGF-β levels were significantly lower in the OG group ( p<0.05). ELISA analysis also revealed that TGF-β1 levels of the OGI group were significantly higher when compared with the OG group ( p<0.05). Conclusion: The administration of soybean genistein isoflavones could improve TGF-β1 levels in old rabbit's during active orthodontic tooth movement.

Effect of micro-osteoperforation on the rate of orthodontic tooth movement—a systematic review and a meta-analysis

Background

The micro-osteoperforation can be used to increase the rate of tooth movement, simplify complex orthodontic movements, and also help adjust the anchorage but there are conflicting reports on the effectiveness and adverse effects of this intervention.

Objectives

The aim of our systematic review and meta-analysis was to evaluate the effects of micro-osteoperforation on the rate of tooth movement in patients undergoing orthodontic treatment.

Search methods

A comprehensive search of MEDLINE, ISI web of science, EMBASE, Scopus, and CENTRAL online databases for studies measuring the effects of micro-osteoperforation on the rate of orthodontic tooth movement from inception to February 2019 was performed.

Selection criteria

Based on the PICO model, human studies which evaluated the effects of MOP on the rate of tooth movement in patients undergoing orthodontic treatment were selected for this review.

Data collection and analysis

The relevant data from the eligible studies were extracted using piloted custom extraction forms. The data were combined and analysed using inverse-variance random-effect meta-analysis and the mean difference was used for comparing the outcome measures.

Results

Six randomized clinical trials were finally included in this meta-analysis. The rate of canine retraction per month was significantly higher in the MOP group [mean difference (MD) = 0.45 mm, 95% CI = 0.17–0.74]. These results were similar with regard to different malocclusions, the jaw on which it was performed, and MOP methods. The patients did not report any significant differences in terms of pain severity levels after MOP. With regard to the adverse effects, one study reported higher amounts of root resorption among patients undergoing MOP.

Conclusions

The rate of tooth movement was increased after performing MOP but in at least one study higher root resorption was observed. Therefore, the use of MOP can be recommended after weighing the benefits and disadvantages this intervention can bring for each patient.

Registration

The protocol for this review was registered via crd.york.ac.uk/prospero with the ID CRD42019115499.