Treatment effects of mini-implants for en-masse retraction of anterior teeth in bialveolar dental protrusion patients: A randomized controlled trial

Friction versus frictionless mechanics during maxillary en-masse retraction in adult patients with Class I bimaxillary dentoalveolar protrusion: a randomized clinical trial

BACKGROUND

Extraction space closure is a challenging phase during orthodontic treatment that affects not only the total treatment duration but also the whole treatment outcome.

OBJECTIVE

To compare the efficiency of friction and frictionless mechanics during en-masse retraction of maxillary anterior teeth in adult patients with bimaxillary dentoalveolar protrusion.

TRIAL DESIGN

Two-arm parallel group, single-center randomized clinical trial.

MATERIALS AND METHODS

Thirty-two adult patients with bimaxillary protrusion were recruited and randomly allocated to two different retraction mechanics. A friction group, using NiTi coil springs and a frictionless group using closing T-loops for en-masse retraction. Randomization in a 1:1 ratio was generated by Microsoft Excel. The randomization numbers were secured in opaque sealed envelopes for allocation concealment. Retraction started in all patients following first premolars extraction using miniscrews as a source of indirect anchorage. Activation was done on a monthly basis until complete retraction of anterior segment. The rate of retraction, amount of anchorage loss, the dental, and soft tissue changes were analyzed on digital models and lateral cephalograms taken before retraction and after space closure.

BLINDING

The outcome assessor was blinded through data concealment during assessment.

RESULTS

Two patients were lost to follow up, so 30 patients completed the trial. The rate of anterior segment retraction was 0.88 ± 0.66 mm/month in the frictionless group compared to 0.72 ± 0.36 mm/month in the friction group which was statistically significant. Anchorage loss of 1.18 ± 0.72 mm in the friction group compared to 1.29 ± 0.55 mm in the frictionless group with no significant difference. Comparable dental and soft tissue changes following en-masse retraction were reported in both groups, with no statistically significant difference.

HARM

one patient complained of soft tissue swelling following miniscrew insertion, but the swelling disappeared after one week of using mouth wash.

LIMITATION

The study focused only on the maxillary arch.

CONCLUSION

Both mechanics have successfully achieved the required treatment objectives in patients with bimaxillary dentoalveolar protrusion. Frictionless group showed a faster rate of retraction than the friction group, which was statistically but not clinically significant.

TRIAL REGISTRATION

Clinicaltrials.gov with the identifier NCT03261024.

Effect of low-level laser therapy on en masse retraction in females with bimaxillary dentoalveolar protrusion : A single-center randomized clinical trial

BACKGROUND

Acceleration of tooth movement has gained remarkable attention during the last decade. The aim of this study was to evaluate the effect of low-level laser therapy (LLLT) on en masse retraction of upper anterior teeth in adult women with bimaxillary dentoalveolar protrusion.

MATERIALS AND METHODS

In this two-arm parallel trial, 36 women with bimaxillary dentoalveolar protrusion were randomly divided into two equal groups. Eligibility criteria included class I Angle molar relationship, good general and oral health as well as no systemic disease or syndrome. Four temporary anchorage devices (TADs) were used in the upper and lower arches for anchorage purposes. A 0.019×0.025-inch stainless steel wire with crimped hooks just distal to the maxillary canines was inserted. Nickle titanium (NiTi) closed coil springs (200 g/side) were employed for en masse retraction following extraction of the first premolars. In the laser group (LG), retraction of the upper anterior teeth was done along with the application of LLLT on days 0, 3, 7, and 14 after extraction and then repeated biweekly until the end of retraction. Retraction was completed without LLLT application in the nonlaser group (NLG). Data concerning the rate of retraction as well as first molars and anterior positional changes were gained from digitized models and cone beam computed tomography (CBCT) scans taken just before extraction and at the end of retraction. Treatment-associated pain and root resorption were evaluated using visual analogue scale (VAS) and CBCT scans, respectively.

RESULTS

Four patients dropped out prior to follow-up. The duration of retraction was 10.125 ± 2.876 and 13.643 ± 3.455 months in the LG and NLG, respectively. The LG showed a statistically significant faster rate of en masse retraction (0.833 ± 0.371 mm/month) compared to the NLG (0.526 ± 0.268 mm/month; P ≤ 0.035). The observed root resorption was significantly less in the LG (P ≤ 0.05) with comparable pain scores in both groups.

CONCLUSIONS

Within the constraints of the parameters of the LLLT used in the current study and despite the statistically significant results on the rate of en masse retraction and the associated root resorption, LLLT did not demonstrate a clinically relevant effect that justifies its use to enhance en masse retraction.

NAME OF THE REGISTRY

Clinicaltrials.gov TRIAL REGISTRATION NUMBER: NCT05183451 DATE OF REGISTRATION: January 10, 2022, "Retrospectively registered" URL OF TRIAL REGISTRY RECORD: https://www.

CLINICALTRIALS

gov/study/NCT05183451.

Treatment outcome comparison of Invisalign vs fixed appliance treatment in first premolar extraction patients

INTRODUCTION

In this study, we compared the dentitional changes after Invisalign and conventional orthodontic treatment with 4 first premolar extractions.

METHODS

This retrospective study included 57 patients whose orthodontic treatment involved the extraction of 4 first premolars because of bialveolar protrusion. A total of 27 patients were treated with Invisalign (mean age, 25.5 ± 5.2 years) and 30 patients with the fixed appliance (mean age, 24.4 ± 5.8 years). The angular and linear changes of the maxillary and mandibular central incisors, second premolars, first molars, and second molars were measured from the recordings on the basis of the lateral cephalograms taken before and after treatment. The angular changes of the canines and second premolars were measured using panoramic radiographs.

RESULTS

The overbite and interincisal angle increased significantly in the Invisalign group compared with in the conventional fixed appliance group (P <0.05). The maxillary central incisors showed increased lingual tipping in the Invisalign group (P <0.05), whereas there was no statistically significant difference in the angular change of the mandibular incisors between groups (P >0.05). The maxillary first and second molars showed mesial tipping in the Invisalign group (P <0.05). The maxillary second premolars, first and second molars, and the mandibular second molars showed mesial movement in the Invisalign group (P <0.05).

CONCLUSIONS

The Invisalign group showed more statistically significant lingual tipping of the maxillary central incisors, distal tipping of the maxillary canines, and mesial tipping of the maxillary first and second molars after maximum retraction of the anterior teeth compared with the fixed appliance group.

Soft tissue changes with skeletal anchorage in comparison to conventional anchorage protocols in the treatment of bimaxillary proclination patients treated with premolar extraction : A systematic review

PURPOSE

This review systematically evaluates the evidence related to comparisons between skeletal and conventional anchorage protocols in the treatment of bimaxillary proclination patients who underwent premolars extraction with respect to soft tissue profile changes, treatment duration and three-dimensional (3D) soft tissue changes.

METHODS

Electronic database search and hand search with no language limitations were conducted in the Cochrane Library, PubMed, Ovid, Web of Science, Scopus and ClinicalTrials.gov. The selection criteria were set to include studies with patients aged 13 years and above requiring extractions of upper and lower first premolars to treat bimaxillary proclination with high anchorage demand. Risk of bias assessment was undertaken with Cochrane's Risk Of Bias tool 2.0 (ROB 2.0) for randomised controlled trials (RCTs) and ROBINS‑I tool for nonrandomised prospective studies. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach was used for quality assessment. Results were summarised qualitatively; no meta-analysis was conducted.

RESULTS

Two RCTs and two nonrandomised prospective studies were included. According to the GRADE approach, there is low to very low quality of evidence that treatment using mini-implant anchorage may significantly change nasolabial angle, upper and lower lip procumbence, and facial convexity angle compared to treatment with conventional anchorage. Similarly, very low quality evidence exists showing no differences in treatment duration between treatments with skeletal or conventional anchorage.

CONCLUSIONS

The overall existing evidence regarding the effect of anchorage protocols on soft tissue changes in patients with bimaxillary protrusion and premolar extraction treatment plans is of low quality.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42020216684.

Comparison of treatment effects during en-masse retraction of upper anterior teeth placed using mini-implants placed at infrazygomatic crest and interradicular sites: A randomized controlled trial

INTRODUCTION

The objective of this prospective study was to examine the efficacy of posterior interradicular and infrazygomatic crest mini-implants for en-masse anterior retraction.

METHODS

The 22 patients were divided into two groups. In group 1 (IZC n = 11), mini-implants were placed in the infrazygomatic crests and in group 2 (IR, n = 11), mini-implants were placed in the molar-premolar interradicular sites. Soft tissue, skeletal, and dental treatment effects between two groups were compared using lateral cephalometric measurements.

RESULTS

The average angle between the cranial base and A point was 1.01 degrees (P = .004), and the linear distance between the upper incisor and A point was 2.67 to 5.2 millimetres (P = .00). In IZC group the maxillary incisor to the palatal plane moved upward by a mean of -5.20 mm (P = .059), whereas in IR group the incisor movement changed by -2.67 mm (P = .068). There was no significant difference between groups IZC and IR while comparing overall treatment changes on upper incisor position change, angle, and overjet.

CONCLUSIONS

Mini-implants placed in between the molar and premolar as well as the infrazygomatic crest can withstand the deepening of the bite during retraction. Mini-implants in IZC are capable of causing intrusion of the anterior teeth and preventing intrusion of the molars, thereby providing absolute anchoring in all planes. Placement of the mini-implants in the infrazygomatic crest resulted in more linear retraction.

Influence of the Curve of Spee on Tooth Displacement Patterns: A Finite Element Analysis at Varying Implant Heights

Background Monocortical mini-screw-type temporary anchorage devices (TADs), or mini-screws, have significantly impacted orthodontic treatment strategies, especially in severe crowding and protrusion cases. These devices offer flexibility in placement sites, but the chosen location can considerably influence tooth displacement patterns. Key factors include the 'line of force' and the biomechanical properties of orthodontic tools. By analyzing tension distribution and three-dimensional displacements, the finite element method (FEM) provides a thorough means to comprehend these patterns. The Curve of Spee (COS) is a crucial factor potentially affecting displacement. Objective This study aimed to leverage finite element analysis (FEA) to understand the impact of varying mini-implant heights (10 mm, 13 mm, and 16 mm) on the displacements of different tooth types under a consistent force of 150 gm and compare these displacements both in the presence and absence of the COS. Materials and methods A CAD model of the jaw and teeth was developed using CT scan data and a Rexcan III 3D White Light Scanner. This model was meshed in Altair HyperMesh using tetrahedral elements, resulting in a Finite Element Model. The model incorporated various components, including teeth, the periodontal ligament (PDL), alveolar bone, brackets, a titanium mini-screw, and an archwire measuring 0.019 x 0.025 inches. Unique material properties were assigned to the PDL, and the assembly accurately replicated the clinical alignment of the archwire and brackets. Subsequently, stress and strain analyses were conducted on the model using the FEM. Results The displacement patterns of various teeth at implant heights of 10 mm, 13 mm, and 16 mm under a 150-gm force were analyzed in relation to the COS. Notably, for the central incisor, the COS significantly affected displacements in the Y and Z directions. Similarly, the Lateral Incisor and Canine exhibited marked changes in the Z direction with the presence of the COS. The Second Premolar's apex displacement showed significant variation due to the COS, while the First Molar displayed notable changes in the X direction. Generally, the presence of the COS either maintained or slightly increased Z-directional displacements across teeth, particularly at the apices. Conclusion The presence of COS significantly influences tooth displacement patterns when using mini-screws at different implant heights. Central incisors, lateral incisors, and canines are particularly sensitive to changes in the Z direction with the COS. The biomechanical analysis emphasizes the importance of considering COS in treatment planning for optimal results with mini-implants in orthodontics.

Comparison of two treatment protocols for intrusion and retraction of maxillary anterior teeth using mini-implants : A prospective clinical trial

OBJECTIVE

The primary objective of this study was to compare the magnitude of incisor intrusion and retraction between two different treatment protocols and the secondary objective was to evaluate overall treatment effects.

MATERIALS AND METHODS

Thirty-four patients with proclined upper anterior teeth, increased overbite, and incisal show were randomly assigned to two treatment groups (G1 and G2). Upper first premolar extractions were performed in all cases. In G1, space closure was performed with conventional straight-wire friction mechanics with NiTi (nickel titanium) coil springs placed on 0.019″ × 0.025″ stainless steel wires in a 0.022 slot system with an additional intrusive force via a midline mini-implant. In G2, NiTi coil springs were placed from buccal mini-implants placed onto 0.016″ × 0.022″ SS wires in a 0.022 slot system bilaterally. Lateral cephalograms and study models taken at the beginning and at the end of 6 months of treatment were assessed.

RESULTS

Both groups showed a statistically significant mild maxillary incisor intrusion, reduction in overjet, overbite, incisal show and a reduction in lower anterior facial height. There was a mild intrusion of the maxillary first permanent molar in G2 (not significant). Mesial movement of the maxillary first permanent molar was noted in G1 but distal movement occurred in G2. Constriction of the entire maxillary arch was noted in G1, whereas constriction was seen in the molar region only in G2. Root resorption was noticed in both groups.

CONCLUSION

Both groups produced comparable results. Except for molar control, all the results obtained were comparable between the two mechanics. Application of an intrusive force in the midline may be beneficial in patients treated with conventional straight-wire mechanics to treat increased overbite when anchorage requirement is not high.

Vertical changes in the hard tissues after space closure by miniscrew sliding mechanics: a three-dimensional modality analysis

OBJECTIVES

This study aimed to investigate vertical changes in the maxillary central incisor and the maxillary first molar, along with alterations in the mandibular plane angle during space closure using miniscrew sliding mechanics.

METHODS

Twenty adult patients treated at Peking University Hospital of Stomatology between 2008 and 2013 were included. Digital dental models and craniofacial cone-beam computed tomography (CBCT) scans were obtained at the start of treatment (T0) and immediately after space closure (T1). Stable miniscrews were used for superimposing maxillary digital dental models (T0 and T1), and vertical changes in the maxillary first molar and the maxillary central incisor were measured. Three-dimensional changes in the mandibular plane were assessed through CBCT superimposition.

RESULTS

The maxillary central incisor exhibited an average extrusion of 2.56 ± 0.18 mm, while the maxillary first molar showed an average intrusion of 1.25 ± 1.11 mm with a distal movement of 0.97 ± 0.99 mm. Additionally, the mandibular plane angle decreased by an average of 0.83 ± 1.65°. All three indices exhibited statistically significant differences.

CONCLUSION

During space closure using the miniscrew sliding technique, significant changes occurred in both the sagittal and vertical dimensions of the upper dentition. This included extrusion of the maxillary central incisors, intrusion of the maxillary first molars, and a slight counterclockwise rotation of the mandibular plane.

Rate and anchorage loss during en-masse retraction between friction and frictionless mechanics: A randomized clinical trial

OBJECTIVE

To compare rate and anchorage loss during en-masse retraction of anterior maxillary teeth between friction mechanics (FM) and frictionless mechanics (FLM).

SETTING AND SAMPLE POPULATION

Thirty-eight patients requiring en-masse retraction of protruded anterior maxillary teeth were randomly allocated into FM and FLM groups.

METHODS

En-masse retraction with sliding mechanics (FM) using an elastomeric chain was compared with continuous mushroom loop archwire mechanics (FLM). Study models and lateral cephalograms were taken before (T1) and immediately after retraction (T2). The primary outcome was the rate of en-masse retraction. Anchorage loss was the secondary outcome. Intergroup comparison was performed using an independent t test (P < .05).

RESULTS

Baseline characteristics were similar between groups. Thirty-six patients completed the trial. Two patients were lost to follow-up in the FLM group. The rate of en-masse retraction did not differ significantly (P = .625) between FM (0.7 mm/mo) and FLM (0.8 mm/mo) groups. The intragroup comparison showed significant anchorage loss in FM (2.28 mm) and FLM (1.13 mm) groups; however, the intergroup comparison showed no statistically significant difference (P = .093). Maxillary first molar showed a statistically significant change in angulation between the two mechanic groups (P < .001). Vertical movement of the maxillary incisor and first molar showed no significant difference between FM and FLM groups (P = .143, P = .546, respectively).

CONCLUSIONS

The rate of en-masse retraction and anchorage loss was comparable between the FM and FLM groups. Significant anchorage loss was seen with both mechanics. The result suggests that both the mechanic group require external reinforcement to prevent anchorage loss.

Dentoalveolar and Soft Tissue Changes Following en-Masse Anterior Retraction With Different Force Vectors in Subjects With Bidental Protrusion: A Retrospective Evaluation

Introduction The aim of the study is to determine the effects of different vertical force vectors acting on dentoalveolar and soft tissues while applying a retraction force using various anchorage sources and their effects on these tissues. Material and methods Based on the selection criteria, a total of 35 patient case records with Angle's Class I bidental malocclusion and incompetent lips treated with four premolar extractions were included. Retraction was achieved using a NiTi coil spring with two different force vectors. The anchorage in group 1 was enhanced by a transpalatal arch (TPA) and Lower Stabilizing Arch (LSA) in the upper and lower arch, respectively, with a force vector parallel to the occlusal plane, whereas in group 2, the force vector using Temporary Anchorage Devices (TADs) was 15 - 20 degrees to the occlusal plane. The skeletal, dental, and soft tissue were obtained using 40 parameters. Intra-group comparisons between pre- and post-treatment records were conducted using a paired t-test, while inter-group comparisons were conducted using an independent t-test. Result Significant anchor loss was observed in group 1, indicated by mesial movement of molar crowns by (-2.10±0.50) in the maxillary arch and (-1.75±0.38) in the mandibular arch. Distal movement of incisors following premolar extractions with both studied force vectors resulted in an improvement in lip procumbency and incisor inclinations, without any significant skeletal changes. Molar mesial movement was observed in subjects treated with conventional anchorage. Conclusion En masse anterior retraction did lead to anchorage loss when carried out without TADs. Altering the force vector did not produce significant changes in tooth movement along the vertical plane.

Relative anchorage loss under reciprocal anchorage in mandibular premolar extraction cases treated with clear aligners

OBJECTIVES

To compare mandibular relative anchorage loss (RAL) under reciprocal anchorage between first and second premolar extraction cases in bimaxillary protrusion mild crowding cases treated using clear aligner therapy (CAT).

MATERIALS AND METHODS

Adult patients who met the following criteria were included: treated using CAT with bilateral mandibular premolar extractions and space closure using intra-arch reciprocal anchorage. RAL was defined as the percent molar mesial movement relative to the sum of molar mesial plus canine distal movement. Movements of the mandibular central incisor (L1), canine (L3), and first molar (L6) were measured based on superimposition of the pre- and post-treatment dentition and jaw models.

RESULTS

Among the 60 mandibular extraction quadrants, 38 had lower first premolar (L4) and 22 had lower second premolar (L5) extracted. L6 mesial movement was 2.01 ± 1.11 mm with RAL of 25% in the L4 extraction group vs 3.25 ± 1.19 mm with RAL of 40% in the L5 extraction group (P < .001). Tooth movement efficacy was 43% for L1 occlusogingival movement, 75% for L1 buccolingual inclination, 60% for L3 occlusogingival movement, and 53% for L3 mesiodistal angulation. L1 had unwanted extrusion and lingual crown torquing whereas L3 had unwanted extrusion and distal crown tipping, on which the power ridges or attachments had little preventive effect.

CONCLUSIONS

The average mandibular reciprocal RAL is 25% or 40% for extraction of L4 or L5, respectively, in CAT cases. A RAL-based treatment planning workflow is proposed for CAT extraction cases.

A Novel Method to Accelerate Orthodontic Tooth Movement Using Low-Intensity Direct Electrical Current in Patients Requiring en-Masse Retraction of the Upper Anterior Teeth: A Preliminary Clinical Report

BACKGROUND

Shortening the duration of orthodontic treatment by speeding up the rate of tooth movement has become an essential goal for both orthodontists and patients. This preliminary report aimed to investigate the safety and effectiveness of a new intraoral removable electrical device in accelerating the en-masse retraction of the upper anterior teeth using low-intensity direct electrical current.

METHODS

This prospective preliminary interventional clinical study was conducted at the Department of Orthodontics, Faculty of Dentistry, Damascus University, Syria, between March 2019 and February 2020. The sample consisted of six patients (four females and two males; mean age: 19.55 ± 0.89 years) whose initial diagnosis was class II division I malocclusion, and their treatment plan suggested the extraction of upper first premolars followed by en-masse retraction. The electrical stimulation was applied on the maxillary anterior region during the en-masse retraction phase using a specially fabricated removable device that was designed by two coauthors of this manuscript (RIS, MYH). Patients were asked to wear their own electrical devices inside their mouths for five hours daily. The primary outcomes were the en-masse retraction rate and duration. The secondary outcomes were safety and patient acceptance.

RESULTS

The average total retraction rate during the treatment period was 0.97±0.06 mm/month. The total amount of retraction achieved during follow-up was 5.65 ± 0.85 mm, which was about 91.86% of the space resulting from the extraction of the upper first premolars. The mean treatment duration to complete the en-masse retraction was 5.66±0.81 months. No side effects of the electrical stimulation were found during the follow-up.

CONCLUSIONS

Low-intensity direct electrical current could be an effective method to accelerate orthodontic movement. The electrical accelerating device used in this study effectively increased the en-masse retraction rate of the upper anterior teeth without any side effects and with high patient acceptance.

Stability of vertical dimension following total arch intrusion

BACKGROUND

The purpose of this study is to evaluate stability of vertical dimension following total arch intrusion using miniscrews by measuring the change during treatment and relapse amount after more than one year of retention.

METHODS

Thirty patients (6 men, 24 women) were included in this study. Lateral cephalographs were taken with conventional radiography at the start of treatment (T0), after treatment (T1), and at least one year after treatment (T2). The evaluation was performed by measuring changes of selected parameters during treatment and the extent of relapse after more than one year.

RESULTS

During total arch intrusion treatment (T1-T0), anterior and posterior teeth intruded significantly. The mean vertical distance between the maxillary posterior teeth and palatal plane was reduced by 2.30 mm (P < 0.001). The mean vertical distance between the maxillary anterior teeth and palatal plane was reduced by 2.04 mm (P < 0.001). The anterior facial height was also reduced by 2.70 mm (P < 0.001). During retention period (T2-T1), the vertical distance between the maxillary anterior teeth and the palatal plane significantly increased by 0.92 mm (P < 0.001). The anterior facial height increased by 0.81 mm (P < 0.01).

CONCLUSIONS

Anterior facial height significantly decreases after treatment. During retention period, relapse of AFH and maxillary anterior teeth observed. There was no correlation between initial amount of AFH, mandibular plane angle, or SNPog and posttreatment AFH relapse. However, there was a significant correlation between the amount of intrusion of anterior and posterior teeth achieved by the treatment and the extent of relapse.

Evaluation of stress distribution values at the temporomandibular joint and distalization of teeth during en-masse retraction of the mandibular dentition using buccal shelf bone screws: A FEM study

INTRODUCTION

Present Finite-element-method (FEM) study evaluates the stress distribution values at the Temporomandibular-Joint (TMJ) during en-masse retraction of the mandibular dentition using buccal shelf bone screws with varying magnitudes of forces.

MATERIAL AND METHODS

Nine replicas of a pre-existing three-dimensional finite element model of the craniofacial skeleton and articular disc from Cone-Beam-Computed-Tomography (CBCT) data and Magnetic-Resonance-Imaging (MRI) data of a patient were used. Buccal shelf (BS) bone screws were inserted buccal to the mandibular second molar region. Forces of magnitudes 250 gm, 350 gm and 450 gm were applied through NiTi coil springs along with stainless-steel archwires of sizes 0.016 × 0.022-inch, 0.017 × 0.025-inch and 0.019 × 0.025-inch.

RESULTS

On the articular disc, the maximum stress was observed at the inferior region and the inferior part of the anterior and posterior zone at all force levels. The stress on the articular disc and displacement of teeth increased with increase in force levels in all the 3 archwires. The maximum stress at the articular disc and displacement of teeth was observed for 450 gm force and the least for 250 gm force. No significant difference in the amount of displacement of teeth or the stresses produced at the articular disc was seen with increasing the size of the archwire.

CONCLUSION

With the present FEM study, we can deduce that it is better to use forces of lower levels on patients with temporomandibular-disorders (TMD) so as to reduce the stresses produced at the TMJ to avoid worsening of the TMD condition.

Temporary anchorage devices and the forces and effects on the dentition and surrounding structures during orthodontic treatment: a scoping review

BACKGROUND

Temporary anchorage devices (TADs) offer the clinician an immediate temporary source of skeletal anchorage for a range of orthodontic interventions. It is important to understand forces involved in using TADs and the effects on the dentition and surrounding structures, to improve clinical outcomes.

OBJECTIVE

To examine and qualitatively synthesize literature on the forces involved with the use of TADs and the effects on the dentition and surrounding structures in orthodontic tooth movement, to provide better understanding of the complex interactions and the clinical implications.

SEARCH METHODS

Electronic databases searched included: Cochrane Library [including Central Register of Controlled Trials (CENTRAL)], Embase via OVID, Pubmed, and Scopus. Study screening and selection were conducted in duplicate.

SELECTION CRITERIA

Studies selected were clinical studies, simulation studies (computer or laboratory-based), or animal studies with no restriction over gender, age, study type (excluding case reports), or setting. Studies focusing on the forces involved with the use of TADs in orthodontic treatment and their effects on the dentition and surrounding structures were included.

DATA COLLECTION AND ANALYSIS

A data charting form was piloted and refined. Data charting was performed independently and in duplicate. This consisted of key fields with predetermined options and free text. The extracted data were collated, and a narrative synthesis conducted.

RESULTS

The results from 203 included studies were grouped into seven TAD based interventions combining the clinical, simulation, and animal studies. They were: En masse retraction of anterior teeth, intrusion, movement of a single tooth, orthopaedic interventions, distalisation, maxillary expansion and other types. The forces involved with the use of TADs, and their effects on the dentition and surrounding structures, were presented in descriptive and tabular formats.

LIMITATIONS

This review restricted study language to English. Formal appraisal of the quality of evidence is not a required feature of scoping reviews, as per the PRISMA-ScR guidelines, however it was evident that a proportion of clinical studies were of high risk of bias and low quality and therefore any proposed changes the reader may consider to their clinical practice should be contextualized in light of this.

CONCLUSIONS

Across the seven types of TAD based interventions the effects on the dentition and surrounding structures are described providing a better understanding of the complex interactions. A guide to the level and direction of forces in each type of intervention is provided to aid clinicians in achieving high quality outcomes.

IMPLICATIONS

There is a need to validate future FEA simulation studies by comparing to clinical data. It is also recommended that future scoping reviews incorporate a formal critical appraisal of studies to facilitate the translation of the results into clinical practice. Development of a standard set of terms for TADs is recommended to facilitate future research.

REGISTRATION

Registration of a scoping review is not possible with PROSPERO.

FUNDING

None to declare.

Three-dimensional evaluation of maxillary tooth movement in extraction patients with three different miniscrew anchorage systems: a randomized controlled trial

OBJECTIVE

To compare the three-dimensional (3-D) movement of maxillary teeth in response to three common miniscrew anchorage systems in extraction patients with maxillary dentoalveolar protrusion.

MATERIALS AND METHODS

The study employed a randomized controlled single-blinded design with three arms. Thirty extraction patients who required maximum anchorage to retract maxillary anterior teeth were included and randomly allocated into three treatment groups: space closure with direct miniscrew anchorage and low crimpable hooks (DL group), indirect miniscrew anchorage and low crimpable hooks (IL group), and direct miniscrew anchorage and high crimpable hooks (DH group). Cone beam computed tomography (CBCT) images of all included patients were obtained immediately before (T0) and after (T1) space closure. The outcomes were 3-D positional changes of maxillary central incisor, lateral incisor, canine, second premolar, and first molar. The repeated measures analysis of variance with post hoc LSD test was used to evaluate differences among groups.

RESULTS

A significant intrusion (- 1.34 mm; 95% CI, - 1.60 mm, 1.08 mm) and buccal (- 6.92°; 95% CI, - 8.67°, - 5.13°) and distal (4.90°; 95% CI, 3.75°, 6.04°) inclination of the maxillary first molars were observed in the DL group, compared to the other two groups. The mesial movement (- 0.40 mm; 95% CI, - 0.83 mm, - 0.03 mm) of the maxillary first molars was found in the IL group, while the DL (0.44 mm; 95% CI, 0.15 mm, 0.73 mm) and IL (0.62 mm; 95% CI, 0.28 mm, 0.96 mm) groups exhibited distal movement. In the DH group, the lingual inclination changes of maxillary central incisor (5.04°; 95% CI, 2.82°, 7.26°) were significantly lower, which is indicative of good lingual root torque control of the maxillary anterior teeth.

CONCLUSION

Three miniscrew anchorage systems produced significantly different 3-D maxillary tooth movement. The maxillary first molars were significantly buccally and distally inclined and intruded in patients using direct miniscrew anchorages with low crimpable hooks. Direct miniscrew anchorages with high crimpable hooks could help to achieve better lingual root torque control of the maxillary incisors. Trial registration The trial was registered at www.chictr.org.cn (ChiCTR1900026960). Registered 27 October 2019.

Treatment outcome of class II malocclusion therapy including extraction of maxillary first molars: a cephalometric comparison between normodivergent and hyperdivergent facial types

Background

The dentoalveolar component of a Class II division 1 malocclusion can be orthodontically treated either with extractions or by distalization of the molars. This study aimed to compare skeletal, dentoalveolar and profile changes in normodivergent and hyperdivergent Class II Division I growing patients orthodontically treated with fixed appliances including maxillary first molar extraction.

Methods

Sixty-four patients treated orthodontically with full fixed appliances including maxillary first molar extractions were retrospectively analyzed. Patients were divided into a normodivergent group (Group N; 30° ≤ SN^GoGn < 36°) consisting of 38 patients (17M, 21F; mean age 13.2 ± 1.3 years) and a hyperdivergent (Group H; SN^GoGn ≥ 36°) including 26 patients (12M, 14F; mean age 13.7 ± 1.1 years). Lateral cephalograms were available before (T0) and after treatment (T1) and cephalometric changes were calculated for 10 linear and 13 angular variables. The Shapiro-Wilk test confirmed a normal distribution of data, hence parametric tests were employed. The Student t-test was used to compare groups at baseline. The paired t-test was used to analyze intragroup changes between timepoints, and the Student t-test for intergroup comparisons. The level of significance was set at 0.05.

Results

The Class II division 1 malocclusion was successfully corrected, and the facial profile improved both in normodivergent and hyperdivergent patients. Divergency increased by 0.76 ± 1.99° in Group N (p = 0.02) while it decreased -0.23 ± 2.25° (p = 0.60); These changes were not significant between groups after treatment (p = 0.680). Most dentoskeletal measurements changed significantly within groups but none of them showed statistically significant differences between groups after treatment. Dental and soft tissue changes were in accordance with the biomechanics used for this Class II orthodontic therapy.

Discussion

The effect of orthodontic treatment of Class II division 1 malocclusion including extraction of the maxillary first molars in growing patients can be considered clinically equivalent in normodivergent and hyperdivergent patients. For this reason, this orthodontic treatment can be considered a viable option in the armamentarium of the Class II Division I therapy for both facial types.

Displacement Pattern, Stress Distribution, and Archwire Play Dimensions during En-masse Retraction of Anterior Teeth using Sliding Mechanics: A FEM Study

Aims

This finite element study was undertaken to evaluate the pattern of stress distribution around the implant and anterior teeth during en-masse retraction in the premolar extraction case. Displacement of the teeth and play of wire in the bracket slot were also evaluated to determine the most favorable height of the power arm attached to the arch-wire.

Materials and methods

A three-dimensional (3D) finite element model of the maxilla was constructed using computed tomography (CT) scan. A total of 12 models were fabricated with different heights of power arms placed distal to the canine. A retraction force of 1.5 N was applied from the implant placed between the roots of the second premolar and first molar, and the response was predicted using Analysis of Systems (ANSYS) software.

Results

When power-arm height was near the center of resistance of the anterior segment, stability in the stress distribution around the implant site and anterior teeth was observed. Displacement of the teeth varied along the three planes of space with the change in power-arm height.

Conclusion

For en-masse retraction, power-arm height should be kept at a level of the center of resistance. Play in the bracket slot and the archwire show a negative role in the bodily movement of anterior teeth.

Clinical significance

For efficient en-masse retraction of anterior teeth, it is imperative to study the most effective site of application of force. Therefore, our study recommends certain key points to keep in mind during the attachment of the power arm and engaging wire in the bracket slot, which could benefit the orthodontist immensely.

How to cite this article

Singh H, Khanna M, Walia C, et al. Displacement Pattern, Stress Distribution, and Archwire Play Dimensions during En-masse Retraction of Anterior Teeth using Sliding Mechanics: A FEM Study. Int J Clin Pediatr Dent 2022;15(6):739-744.

Stainless steel vs. titanium miniscrew implants: Evaluation of stability during retraction of maxillary and mandibular anterior teeth

OBJECTIVES

This study was aimed to compare the stability of stainless steel and titanium miniscrew implants of the same diameter and length during en masse retraction of maxillary and mandibular anterior teeth.

MATERIALS AND METHODS

Forty miniscrew implants (1.3 mm diameter and 8 mm length) were placed in 10 patients (20 titanium and 20 stainless steel). Stability was checked at insertion (T0), at one month (T1), and at sixth months (T2) and the amount of retraction was recorded in millimeters.

RESULTS

Titanium and stainless steel implants were equally stable at the time of insertion. At T1, three titanium miniscrew implants showed grade 2 mobility, whereas seven stainless steel miniscrew implants showed grade 2 mobility. For T2, none of the titanium miniscrew implants had grade 2 mobility while four stainless steel miniscrew implants resulted in grade 2 mobility. Both had an equal frequency of grade 3 and grade 4 mobility. However, the difference in the stability was not statistically significant. No statistical significance was found when the amount of retraction achieved by titanium and stainless steel miniscrew implants was compared between the maxillary and mandibular arches.

CONCLUSION

Both titanium and stainless steel miniscrew implants provide good anchorage and remain stable during en masse retraction of maxillary and mandibular anterior teeth. Thus, both miniscrews are clinically effective.

Which anchorage device is the best during retraction of anterior teeth? An overview of systematic reviews

Objective

To evaluate the available evidence regarding the clinical effectiveness of different types of anchorage devices.

Methods

A comprehensive literature search of different electronic databases was conducted for systematic reviews investigating different anchorage methods published up to April 15, 2021. Any ongoing systematic reviews were searched using PROSPERO, and a grey literature search was undertaken using Google Scholar and OpenGrey. No language restriction was applied. Screening, quality assessment, and data extraction were performed independently by two authors. Information was categorized and narratively synthesized for the key findings from moderate- and high-quality reviews.

Results

Fourteen systematic reviews were included (11 were of moderate/high quality). Skeletal anchorage with miniscrews was associated with less anchorage loss (and sometimes with anchorage gain). Similarly, skeletal anchorage was more effective in retracting anterior teeth and intruding incisors and molars, resulting in minor vertical skeletal changes and improvements in the soft tissue profile. However, insufficient evidence was obtained for the preference of any anchorage method in terms of the duration of treatment, number of appointments, quality of treatment, patient perception, or adverse effects. The effectiveness of skeletal anchorage can be enhanced when directly loaded, used in the mandible rather than the maxilla, used buccally rather than palatally, using dual rather than single miniscrews, used for en-masse retraction, and in adults.

Conclusions

The level of evidence regarding anchorage effectiveness is moderate. Nevertheless, compared to conventional anchorage, skeletal anchorage can be used with more anchorage preservation. Further high-quality randomized clinical trials are required to confirm these findings.

Survival estimates and risk factors for failure of palatal and buccal mini-implants

OBJECTIVES

The primary objective was to compare the success and survival rates of palatal and buccal mini-implants for different locations and treatment requirements. The secondary objective was to evaluate risk factors influencing the survival of mini-implants.

MATERIALS AND METHODS

In this retrospective cohort, records of 127 orthodontic patients with 257 mini-implants were included after imposing inclusion/exclusion criteria. Along with the implant failure data, factors such as age, sex, transverse location, anteroposterior location, and purpose of mini-implants were recorded. Kaplan-Meier survival analysis was used to draw the curves and a Nathan Mantel-David Cox test to compare variables.

RESULTS

The failure rate of palatal mini-implants was 8.5%, whereas the failure rate for buccal shelf mini-implants was 68.7% (P < .0001). A significant difference was that the survival rates of palatal mini-implants were dependent on the purpose of the mini-implants and, for the buccal mini-implants, they were dependent on the skeletal malocclusion and location type of mini-implants (P < .05).

CONCLUSIONS

The overall survival rate of palatal mini-implants was high, at 91.5%. Of the buccal mini-implants, inter-radicular mini-implants had the highest survival rate for 12 (75.5%) and 24 (71.9%) months, while buccal shelf mini-implants had the lowest success and survival rates for 12 (31.3%) and 24 (20.8%) months. Class III malocclusion had the lowest survival rate for the buccal mini-implants (65.3% and 54.2%) for 12 and 24 months.

Stability of immediately loaded 3 mm long miniscrew implants: a feasibility study

Introduction:

Shorter miniscrew implants (MSIs) are needed to make orthodontics more effective and efficient.

Objective:

To evaluate the stability, insertion torque, removal torque and pain associated with 3 mm long MSIs placed in humans by a novice clinician.

Methods:

82 MSIs were placed in the buccal maxillae of 26 adults. Pairs of adjacent implants were immediately loaded with 100g. Subjects were recalled after 1, 3, 5, and 8 weeks to verify stability and complete questionnaires pertaining to MSI-related pain and discomfort.

Results:

The overall failure rate was 32.9%. The anterior and posterior MSIs failed 35.7% and 30.0% of the time, respectively. Excluding the 10 MSIs (12.2%) that were traumatically dislodged, the failure rates in the anterior and posterior sites were 30.1% and 15.2%, respectively; the overall primary failure rate was 23.6%. Failures were significantly (p= 0.010) greater (46.3% vs 19.5%) among the first 41 MSIs than the last 41 MSIs that were placed. Excluding the traumatically lost MSIs, the failures occurred on or before day 42. Subjects experienced very low pain (2.2% of maximum) and discomfort (5.5% of maximum) during the first week only.

Conclusions:

Shorter 3 mm MSIs placed by a novice operator are highly likely to fail. However, failure rates can be substantially decreased over time with the placement of more MSIs. Pain and discomfort experienced after placing 3 mm MSIs is minimal and temporary.

Alveolar cortical plate changes associated with incisor retraction and its influence on the limits of orthodontic tooth movement

OBJECTIVE

The extent to which the modelling behaviour of the anterior alveolus limits tooth movement remains unclear. Will the labial and lingual cortical plates model as incisors retract, or will they remain unchanged, therefore limiting the extent of possible tooth movement?

SETTING AND SAMPLE POPULATION

Pre- and post-treatment lateral cephalometric radiographs of 29 bimaxillary protrusive patients of South Korean descent were examined. Treatment consisted of two premolar extractions in one or both arches with en masse retraction of the incisors using miniscrew anchorage.

MATERIALS AND METHODS

Pre- and post-treatment measurements of both tooth and cortical plate position were made at various increments along the length of the root and then compared using paired t tests.

RESULTS

Despite the use of miniscrew anchorage, the incisors were retracted by controlled tipping. The labial cortical plates in both arches modelled to follow tooth movement. Following retraction of the incisors in the maxilla, the incisor root approached the lingual cortical plate, which remained unchanged. In the mandible, the lingual cortical plate position was unchanged except at the level closest to the cementoenamel junction.

CONCLUSIONS

The maxillary and mandibular lingual cortical plates did not model to follow the incisor movement while the labial cortical plates did. These findings suggest that lingual cortical plates may act as limitations to planned orthodontic tooth movement.

The effectiveness of traditional corticotomy vs flapless corticotomy in miniscrew-supported en-masse retraction of maxillary anterior teeth in patients with Class II Division 1 malocclusion: A single-centered, randomized controlled clinical trial

INTRODUCTION

This single-centered, parallel-groups trial aimed to evaluate the efficacy of traditional corticotomy vs flapless corticotomy in accelerating en-masse retraction. In addition, to assess the skeletal, dental, and soft-tissue variables, as well as the external apical root resorption (EARR) of the maxillary anterior teeth.

METHODS

Forty patients with Class II Division 1 malocclusion aged >18 years at the beginning of treatment, requiring maxillary first premolar extractions, were randomly distributed into 2 groups (n = 20 each): 1 group was treated using traditional corticotomy, and the other group was treated with flapless corticotomy in en-masse retraction with anchorage based on miniscrews placed between maxillary second premolars and first molars bilaterally. Randomization was implemented with a computer-generated list of random numbers; allocation was concealed in sequentially numbered, opaque, sealed envelopes. The study was single-blinded (outcomes' assessor). The primary outcome was the en-masse retraction duration. Secondary outcomes were the skeletal, dental, and soft-tissue changes on lateral cephalometric and the EARR of maxillary anterior teeth on digital panoramic radiographs.

RESULTS

The en-masse retraction duration in the flapless corticotomy group was longer than the traditional corticotomy group. The average retraction duration was 4.04 ± 1.10 months for the flapless corticotomy group and 3.75 ± 2.14 months for the traditional corticotomy group, with no significant difference between the 2 groups (95% confidence interval [CI], -0.81 to 1.39; P = 0.59). No significant differences were observed between the 2 groups regarding changes in several lateral cephalometric variables (eg, SNA angle [95% CI, -2.55° to 1.66°; P = 0.67], SN-U1 angle [95% CI, -1.70° to 1.32°; P = 0.80], and UL-E [95% CI: -1.33 to 1.00 mm; P = 0.78]) or in the amount of EARR in the maxillary anterior teeth (P = 0.31). The proportion of the observed EARR ranged from 1% to 6% of root length in both corticotomy groups. No serious harms were observed in both groups.

CONCLUSIONS

No significant differences between the flapless and traditional corticotomies were found in terms of the skeletal, dental, and soft-tissue variables as well as in the amount of EARR. Corticotomy-assisted en-masse retraction led to improvements in skeletal structures and facial profile and resulted in sufficient retraction of maxillary anterior teeth, slight distal movement of maxillary first molars, and an intrusion movement for both anterior and posterior teeth. Both corticotomy techniques did not cause significant EARR.

REGISTRATION

ClinicalTrials.gov (Identifier: NCT03279042).

PROTOCOL

The protocol was not published before the trial commencement.

Effectiveness of orthodontic temporary anchorage devices in canine retraction and anchorage preservation during the two-step technique: a systematic review and meta-analysis

Background

Temporary anchorage devices have been used for decades in orthodontic practice for many applications. The aim of this systematic review was to assess the effectiveness of orthodontic temporary anchorage devices in canine retraction during the two-step technique.

Methods

A search was systematically performed for articles published prior to June 30, 2019 in five electronic databases (PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, Scopus). The risk of bias was assessed using the Cochrane risk of bias tool for randomized controlled trials (RCTs) and the risk of bias in nonrandomized studies of interventions (ROBINS-I) tool for controlled clinical trials (CCTs). The Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach was used for the quality assessment. Data concerning the mean difference in mesial molar movement and extent of canine retraction were extracted for statistical analysis. The mean differences and 95% confidence intervals were analyzed for continuous data. A meta-analysis with a random-effects model for comparable outcomes was carried out.

Results

Three RCTs and five CCTs were finally included. Meta-analysis showed a significant increase not only in anchorage preservation in the implant anchorage group in both the maxilla (1.56 mm, 95% CI: 1.14 to 1.98, P < 0.00001) and the mandible (1.62 mm, 95% CI: 1.24 to 2.01, P < 0.00001) but also in canine retraction in the implant anchorage group in both the maxilla (0.43 mm, 95% CI: 0.16 to 0.69, P = 0.001) and the mandible (0.26 mm, 95% CI: 0.02 to 0.49, P = 0.03).

Conclusions

There is very low-quality evidence showing that implant anchorage is more efficient than conventional anchorage during canine retraction. Additional high-quality studies are needed.

Meta-analysis dataset comparing orthodontic mini-implants and conventional anchorage reinforcement for maximum orthodontic anchorage

The present article describes data from systematic review and meta-analysis investigating the efficacy and safety outcomes comparing mini-implants (MIs) and conventional anchorage reinforcement in patients with maximum dentoalveolar protrusion. All relevant RCTs and non-RCTs published up to 2018 were collected from PubMed, Embase and Cochrane database. Thirteen studies assessing the effect of mini-implants were included, of which 4 were randomized controlled trials (RCTs) and 9 observational studies. The efficacy parameters include mesiodistal movements of molars and incisors and vertical movements of molars and incisors. Whereas, the safety parameters were angular and linear measurement of soft tissue change. Subgroup analysis data was provided in terms of patients average age (<18 years and ≥18 years) at the initiation of treatment. This dataset is suitable for research purpose in the field of orthodontics and also helps dental doctors to determine their treatment preferences in the choice of anchorage reinforcement.

Three-Dimensional Finite Element Analysis on En-Masse Retraction of the Maxillary Anterior Teeth With Quantitative Combined Loading Control

This study aims to elucidate the biomechanical effects of combined loading of maxillary anterior and posterior implants using the sliding method on en-masse retraction of the anterior teeth and to quantify the loading ratio (LR) of anterior and posterior implants to achieve controlled retraction of the maxillary anterior teeth. A three-dimensional finite element model of the maxilla-upper dentition appliance was constructed. Implants were placed on the distal (A) and mesial (B) sides of the lateral incisors as well as on the mesial (C) side of the first molar and different amounts of force were loaded between the implants using 2- or 5-mm traction hooks. The labiolingual movement of the anterior teeth was recorded and the relationship between the LR of the implants and the movement of the central incisors was evaluated. With 2-mm traction hooks, the central incisors exhibited a translation tendency during retraction at lower A/C and B/C LR and labial or lingual crown inclination at higher values. With 5-mm traction hooks, the central incisors, lateral incisors, and canine teeth exhibited a labial crown inclination. The results of this study suggest that 2-mm traction hooks can cause labial crown inclination, translation tendency during retraction, or lingual crown inclination of the central incisors due to alterations in the LR of the anterior and posterior implants. The central incisors only exhibited labial crown inclination during combined loading of the anterior and posterior implants when 5-mm traction hooks were used.

Comparison of Anchorage Efficiency of Orthodontic Mini-implant and Conventional Anchorage Reinforcement in Patients Requiring Maximum Orthodontic Anchorage: A Systematic Review and Meta-analysis

OBJECTIVE

To compare the clinical effectiveness of mini-implants (MIs) and conventional anchorage appliances used for orthodontic anchorage reinforcement in patients with class I or II malocclusion with bimaxillary protrusion.

MATERIALS AND METHODS

Literature search was conducted through PubMed, Embase, and Cochrane from inception to July 2018. The following Medical Subject Heading terms were used for the search string: "skeletal anchorage", "temporary anchorage devices", "miniscrew implant", "mini-implant", "micro-implant". Standardized mean difference (SMD) and 95% confidence interval (CI) of horizontal and vertical movements of teeth from baseline were used for comparison.

RESULTS

A total of 12 studies were included in the final analysis. MI group significantly lowered mesial movement of molars compared to conventional anchorage group (SMD = -1.48, 95% CI = -2.25 to -0.72; P = .0002). There was significantly higher retraction of incisors in the MI group than in the conventional group (SMD = -0.47 mm, 95% CI = -0.87 to -0.07; P = .02). No significant difference was seen in vertical movement of molars (SMD = -0.21 mm, 95% CI = -0.87 to 0.45; P = .52) and incisors (SMD = -0.30, 95% CI = -1.18 to 0.58; P = .5).

CONCLUSION

MIs seem to be more effective than the conventional anchorage devices in terms of minimizing unintended mesial movement of molars with maximum retraction of anterior teeth.

Comparison of the Anchorage Value of the First Molars Supported with Implant and First Molars Supported with Second Molar during En Masse Retraction

Aims and Objectives:

The aim of this study was to determine the efficacy of mini-implants as adjuncts for intraoral anchorage units for en masse retraction of maxillary anterior teeth in bimaxillary dentoalveolar protrusion cases.

Materials and Methods:

The study sample consisted of 15 patients (10 females and 5 males). The samples were compared for anchorage loss with the implant-supported molar and conventional molar contralaterally in both the maxilla and mandible after six months of retraction period. The mini-implants used were 1.5 mm in diameter and 8 mm in length and were inserted in the first and third quadrant between the roots of second premolar and first molar under local anesthesia at an angle of 45°. For en masse retraction, active tiebacks with ligating (100g) were used bilaterally extending from molar hooks to J-hook on a 0.019” × 0.025” stainless steel arch wire. Lateral cephalograms were taken before and after retraction for assessing the loss of anchorage in maxillary and mandibular first molars.

Results:

Anchorage loss of 1.46 mm in the maxilla and 1.36 mm in mandible was found with conventional molar anchorage, whereas no statistically significant anchorage loss was found in the implant-supported molar side.

Conclusion:

Implant-supported molar side showed better anchorage compared with the conventional molar side. Hence, implant-supported molar can be used as an absolute anchorage unit in the en masse retraction of anterior teeth.

Soft Tissue Changes in Patients With Dentoalveolar Protrusion Treated With Maximum Anchorage: A Systematic Review and Meta-analysis

OBJECTIVE

This meta-analysis aimed at comparing the angular and linear changes of soft tissue profile using conventional anchorage techniques and mini-implant (MI)-based space closure in patients with dentoalveolar protrusion.

MATERIALS AND METHODS

Electronic databases, viz. PubMed, Embase, and Cochrane Central Register of Controlled Trials, were searched for relevant literature from their inception to December 2017 according to the specific inclusion and exclusion criteria. The following Medical Subject Heading terms were used for searching: "skeletal anchorage", "temporary anchorage devices", "miniscrew implant", "mini-implant", "micro-implant". Selected randomized control trials (RCTs) were assessed for their quality using Cochrane's Risk of Bias Tool, whereas the Newcastle-Ottawa scale was used for non-RCTs. Standardized mean difference (SMD) and 95% confidence interval (CI) were obtained with either fixed- or random-effects models based on the heterogeneity of the included studies.

RESULTS

A total of 5 articles (2 RCTs with moderate risk of bias and 3 high-quality non-RCT studies) were included in the final analysis. The nasolabial angle had significantly greater changes in the MI group than in the conventional anchorage group (SMD = 0.68, 95% CI = 0.39 to 0.97, P < .0001). Significantly higher retraction of the upper lip was seen in the MI group than in the conventional group (SMD = -0.51, 95% CI = -0.84 to -0.18; P = .002). No significant difference was seen in the facial convexity (SMD = -0.34, 95% CI = -0.76 to 0.07, P = .106) and lower lip retraction (SMD = 0.28, 95% CI = -1.72 to 2.28, P = .784) between the groups.

CONCLUSION

It was seen that MIs facilitated favorable soft tissue profile than the conventional anchorage devices. However, more high-quality studies are warranted to confirm the clinical effectiveness of MIs.

Evaluation of Treatment Outcomes of En masse Retraction with Temporary Skeletal Anchorage Devices in Comparison with Two-step Retraction with Conventional Anchorage in Patients with Dentoalveolar Protrusion: A Systematic Review and Meta-analysis

Objective

The main objective is to evaluate the effectiveness of en masse retraction with temporary skeletal anchorage devices (TSADs) versus two-step retraction with conventional anchorage (CA) in terms of the skeletal, dental, and soft-tissue variables, as well as the duration of retraction or overall orthodontic treatment.

Materials and Methods

An electronic search of PubMed and nine other major databases for prospective, randomized controlled trials (RCTs) and clinical controlled trials (CCTs) was carried out between January 1990 and April 2018. The bibliography in each identified article was checked out. In addition, manual searching was performed in the same time frame in five major orthodontic journals. Adult patients undergoing fixed orthodontic treatment with extraction of maxillary premolars followed by an en masse retraction in the experimental group and two-step retraction of upper anterior teeth in the control group. Methodological index for nonrandomized studies for CCTs and Cochrane's risk of bias tool for RCTs were applied.

Results

Four articles (two RCTs and two CCTs) were included in this review and all articles were appropriate for the quantitative synthesis. There was no significant difference between the en masse retraction and two-step retraction groups in terms of SNA, SNB, ANB, and MP-SN angles. Using TSADs gave significantly better results in terms of posterior anchorage and incisors inclination, and greater anterior teeth retraction in comparison with CA (standardized mean difference [SMD] = -3.03 mm, P < 0.001; SMD = 0.74°, P = 0.003; SMD = -0.46 mm, P = 0.03, respectively). En masse/TSAD combination caused a significantly greater increase in nasolabial angle, higher decrease in facial convexity angle, and greater lower lip retraction in comparison with two-step/CA combination (weighted mean difference = 4.73°, P = 0.007; P = 0.0435; SMD = -0.95 mm, P = 0.01, respectively).

Conclusion

There is weak-to-moderate evidence that using either en masse/TSAD combination or two-step/CA combination would lead to similar skeletal improvement. There is a very weak-to-moderate evidence that using TSADs with en masse retraction would cause better posterior anchorage and incisors inclination, and greater anterior teeth retraction than using CA with two-step retraction. There is weak-to-moderate evidence that using en masse/TSAD combination would lead to a better improvement in the facial profile. According to the quality of evidence, we confirm the need for more well-conducted RCTs in the en masse retraction field.

Effect of archwire stiffness and friction on maxillary posterior segment displacement during anterior segment retraction: A three-dimensional finite element analysis

Objective

Sliding mechanics using orthodontic miniscrews is widely used to stabilize the anchorage during extraction space closure. However, previous studies have reported that both posterior segment displacement and anterior segment displacement are possible, depending on the mechanical properties of the archwire. The present study aimed to investigate the effect of archwire stiffness and friction change on the displacement pattern of the maxillary posterior segment during anterior segment retraction with orthodontic miniscrews in sliding mechanics.

Methods

A three-dimensional finite element model was constructed. The retraction point was set at the archwire level between the lateral incisor and canine, and the orthodontic miniscrew was located at a height of 8 mm from the archwire between the second premolar and first molar. Archwire stiffness was simulated with rectangular stainless steel wires and a rigid body was used as a control. Various friction levels were set for the surface contact model. Displacement patterns for the posterior and anterior segments were compared between the conditions.

Results

Both the anterior and posterior segments exhibited backward rotation, regardless of archwire stiffness or friction. Among the conditions tested in this study, the least undesirable rotation was found with low archwire stiffness and low friction.

Conclusions

Posterior segment displacement may be unavoidable but reducing the stiffness and friction of the main archwire may minimize unwanted rotations during extraction space closure.

Effectiveness of anchorage with temporary anchorage devices during anterior maxillary tooth retraction: A randomized clinical trial

Objective

This study evaluated the efficiency of anchorage provided by temporary anchorage devices (TADs) in maxillary bicuspid extraction cases during retraction of the anterior teeth using a fixed appliance.

Methods

Patients aged 12 to 50 years with malocclusion for which bilateral first or second maxillary bicuspid extractions were indicated were included in the study and randomly allocated to the TAD or control groups. Retraction of the anterior teeth was achieved using skeletal anchorage in the TAD group and conventional dental anchorage in the control group. A computed tomography (CT) scan was performed after alignment of teeth, and a second CT scan was performed at the end of extraction space closure in both groups. A three-dimensional superimposition was performed to visualize and quantify the maxillary first molar movement during the retraction phase, which was the primary outcome, and the stability of TAD movement, which served as the secondary outcome.

Results

Thirty-four patients (17 in each group) underwent the final analysis. The two groups showed a significant difference in the movement of the first maxillary molars, with less significant anchorage loss in the TAD group than that in the control group. In addition, TAD movement showed only a slight mesial movement on the labial side. On the palatal side, the mesial TAD movement was greater.

Conclusions

In comparison with conventional dental anchorage, TADs can be considered an efficient source of anchorage during retraction of maxillary anterior teeth. TADs remain stable when correctly placed in the bone during the anterior tooth retraction phase.

Which one closes extraction spaces faster: en masse retraction or two-step retraction? A randomized prospective clinical trial

OBJECTIVES

To compare the time to close extraction spaces between en masse (ER) and two-step retraction (TSR).

MATERIALS AND METHODS

Forty-eight patients with bimaxillary protrusion underwent treatment with extraction of four first premolars. All patients were randomly allocated to one of two groups: ER (n = 24) or TSR (n = 24). The main outcome was the time required to close spaces between ER and TSR; the closing time of spaces between females and males was a secondary outcome. The size of premolars was measured on the models and data were collected on clinical records at the following times: retraction start date (T1) and space closure completion date (T2). The total time to close the extraction spaces was calculated for each extracted premolar (T1 to T2). The Kaplan Meier method and the Log-Rank test were used to compare the groups.

RESULTS

The time to close extraction spaces showed significant differences between the ER and TSR groups. While ER took between 12.1 and 13.8 months, TSR took between 24.7 and 26.8 months. The TSR group showed a significant difference between sexes; male patients took 5.5 months longer than female patients for the extraction spaces to close.

CONCLUSIONS

TSR takes between 1.8 and 2.2 times longer than ER to close the extraction spaces and it took longer in males than females.

Anchorage effectiveness of orthodontic miniscrews compared to headgear and transpalatal arches: a systematic review and meta-analysis

BACKGROUND

Anchorage in orthodontics can be provided through several extra- and intra-oral sources including headgear, teeth, cortical bone and soft tissue.

OBJECTIVE

The aim of this review was to systematically review the effectiveness of miniscrews in reinforcing anchorage during en-masse retraction of anterior teeth in comparison to conventional anchorage appliances. Search method: Comprehensive searching of the electronic databases was undertaken up to March 2018 in the Cochrane Database of Systematic review, Cochrane Central Register of Controlled Trials, MEDLINE via PubMed and Scopus databases. Additional searching for on-going and unpublished data and hand search of relevant journals were also undertaken, authors were contacted, and reference lists screened. Eligibility criteria: Searches were restricted to randomized clinical trials (RCTs) published in English, which compared anchorage reinforcement using mechanically-retained miniscrews (diameter of 2 mm or less) to conventional anchorage appliances during en-masse retraction of anterior teeth in participants of any age treated with fixed appliances combined with extraction of maxillary premolars.

DATA COLLECTION AND ANALYSIS

Blind and induplicate study selection, data extraction and risk of bias assessment were undertaken. The primary outcome was the amount of mesial movement of the upper first permanent molar (anchorage loss) while secondary outcomes included treatment duration, number of visits, adverse effects and patient-centered outcomes. The risk of bias was assessed using Cochrane risk of bias tool. A random-effects model with its corresponding 95% confidence interval (CI) were generated for comparable outcomes. Statistical heterogeneity across the studies were assessed using the I² and Chi² test. Additional sensitivity tests were implemented.

RESULTS

Seven RCTs met the inclusion criteria, however, data of 241 participants from 6 RCTs (250 miniscrews and 134 conventional anchorage appliances) were meta-analyzed. Qualities of the included RCTs varied from low to high. The standardized mean difference (SMD) of the anchrage loss between the two intervention groups was 2.07 mm ((95% CI (-3.05) to (-1.08), p < .001, I² = 88%, 6 RCTs)) in favour of miniscrews, which was also preserved after excluding the high risk of bias studies (SMD 1.94 mm, 95% CI (-2.46) to (-0.42) p < .001, I² = 93%, 3 RCTs)). Information on overall treatment duration, space closure duration, quality of treatment, patient-reported outcomes, adverse effects and number of visit were limited.

CONCLUSION

The result of the meta-analysis suggested that there is moderate quality of evidence that miniscrews are clinically and statistically more effective in preserving orthodontic anchorage than conventional appliances. However, this conclusion is supported by a small number of studies with variable qualities. High-quality RCTs would give a better understanding of miniscrews effectiveness in providing orthodontic anchorage.

Miniscrews failure rate in orthodontics: systematic review and meta-analysis

Background

Miniscrews in orthodontics have been mainly used for anchorage without patient compliance in orthodontic treatment. The literature has reported changing failure rates.

Objective

The aim of this review was to provide a precise estimation of miniscrew failure rate and the possible risk factors of the mechanically-retained miniscrews.

Search method

Electronic search in database was undertaken up to July 2017 through the Cochrane Database of Systematic Reviews, MEDLINE, Scopus, and Ovid. Additional searching for on-going and unpublished data, hand search of relevant journals and grey lietraure were also undertaken, authors were contacted, and reference lists screened.

Eligibility criteria

Randomised controlled trials (RCTs) and prospective cohort studies (PCSs), published in English were obtained, which reported the failure rate of miniscrews, as orthodontic anchorage, with less than 2 mm diameter.

Data collection and analysis

Blind and induplicate study selection, data extraction, and risk of bias assessment were undertaken in this research. Failure rates and relevant risk factors of miniscrews with the corresponding 95 per cent confidence intervals (CIs) were calculated by using the random-effects model. The heterogeneity across the studies was assessed using the I2 and Chi2 test. The risk of bias was assessed using Cochrane risk of bias and Newcastle-Ottawa Scale. Subgroup and sensitivity analyses were performed in order to test the robustness of the results in meta-analysis.

Results

The 16 RCTs and 30 PCSs were included in this research. Five studies were not included in the meta-analysis due to a lack of the statistical information needed to compute the effect sizes. About 3250 miniscrews from 41 studies were pooled in a random-effect model. The overall failure rate of miniscrews was 13.5 per cent (95% CI 11.5-15.9). Subgroup analysis showed that miniscrews 'diameter, length and design, patient age, and jaw of insertion had minimal effect on rate of miniscrews failure while the type of the gingivae and smoking had statistically significant effect.

Conclusion

Miniscrews have an acceptably low failure rate. The findings should be interpreted with caution due to high-level of heterogeneity and unbalanced groups in the included studies. High quality randomized clinical trial with large sample sizes are required to support the findings of this review.

Efficacy of orthodontic mini implants for en masse retraction in the maxilla: a systematic review and meta-analysis

Background/aim

Retraction of the upper incisors/canines requires maximum anchorage. The aim of the present study was to analyze the efficacy of mini implants in comparison to conventional devices in patients with need for en masse retraction of the front teeth in the upper jaw.

Material and methods

An electronic search of PubMed, Web of Science, and EMBASE and hand searching were performed. Relevant articles were assessed, and data were extracted for statistical analysis. A random effects model, weighted mean differences (WMD), and 95% confidence intervals (CI) were computed for horizontal and vertical anchorage loss at the first molars in the analyzed patient treatments.

Results

A total of seven RCTs employing direct anchorage through implants in the alveolar ridge were finally considered for qualitative and quantitative analysis, and further five publications were considered for the qualitative analysis only (three studies: indirect anchorage through implant in the mid-palate, two studies: direct/indirect anchorage in the alveolar ridge). In the control groups, anchorage was achieved through transpalatal arches, headgear, Nance buttons, intrusion arches, and differential moments.

WMD [95% CI, p] in anchorage loss between test and control groups amounted to − 2.79 mm [− 3.56 to − 2.03 mm, p < 0.001] in the horizontal and − 1.76 mm [− 2.56 to − 0.97, p < 0.001] favoring skeletal anchorage over control measures. The qualitative analysis revealed that minor anchorage loss can be associated with indirect anchorage, whereas anchorage gain was commonly associated with direct anchorage. Implant failures were comparable for both anchorage modalities (direct 9.9%, indirect 8.6%).

Conclusion

Within its limitations, the meta-analysis revealed that maximum anchorage en masse retraction can be achieved by orthodontic mini implants and direct anchorage; however, the ideal implant location (palate versus alveolar ridge) and the beneficial effect of direct over indirect anchorage needs to be further evaluated.

Electronic supplementary material

The online version of this article (10.1186/s40729-018-0144-4) contains supplementary material, which is available to authorized users.

Comparison of orthodontic tooth movement between adolescents and adults based on implant superimposition

OBJECTIVE

We compared tooth movement under maximum anchorage control with mini-screw implants in growing and non-growing patients.

METHODS

In total, 15 adolescent (G1) and 19 adult (G2) patients with prognathic profiles were selected. All patients underwent first premolar extraction treatment with mini-screw implants for maximum anchorage control. Cone-beam computed tomography (CBCT) data were obtained immediately after implant placement (T1) and at the end of anterior tooth retraction (T2). Tooth movement and root length changes of the maxillary first molar, canine, and incisors were evaluated with three-dimensional models constructed using CBCT data obtained before and after orthodontic retraction through the superimposition of stable implants.

RESULTS

Distal movement of the molar crown was observed in G2, but mesial movement was observed in G1. Mesial tipping of the first molar (1.82 ± 6.76°) was seen in G1 and distal tipping (4.44 ± 3.77°) was observed in G2. For the canines, mesial crown tipping (0.33 ± 4.99°) was noted in G1 and distal crown tipping (8.00 ± 5.57°) was observed in G2. In adults, the lingual inclinations of the lateral and central incisors were 11.91 ± 7.01° and 11.47 ± 6.70°, with 0.99 ± 1.22 mm and 1.08 ± 1.20 mm root retraction, respectively. In adolescents, the torque changes were smaller (lateral incisors, 8.25 ± 10.15°; central incisors, 9.82 ± 8.97°) and the root retractions were 0.31 ± 1.81 mm and 0.77 ± 1.59 mm, respectively. Less shortening of the central incisor roots occurred in adolescents than in adults.

CONCLUSIONS

Tooth movements, such as anchor molar angular change, the canine tipping pattern, and the amount of incisor retraction, differed between adolescents and adults treated using the same anchorage with mini-screw implants, bracket prescription, and en masse retraction method. Anchorage strength of the first molars, canine movement patterns, and incisor retraction ranges are not determined by the anchorage device alone; growth and alveolar limitations also play roles.

Cone-beam computed tomography-based diagnosis and treatment simulation for a patient with a protrusive profile and a gummy smile

For patients with bimaxillary protrusion, significant retraction and intrusion of the anterior teeth are sometimes essential to improve the facial profile. However, severe root resorption of the maxillary incisors occasionally occurs after treatment because of various factors. For instance, it has been reported that approximation or invasion of the incisive canal by the anterior tooth roots during retraction may cause apical root damage. Thus, determination of the position of the maxillary incisors is key for orthodontic diagnosis and treatment planning in such cases. Cone-beam computed tomography (CBCT) may be useful for simulating the post-treatment position of the maxillary incisors and surrounding structures in order to ensure safe teeth movement. Here, we present a case of Class II malocclusion with bimaxillary protrusion, wherein apical root damage due to treatment was minimized by pretreatment evaluation of the anatomical structures and simulation of the maxillary central incisor movement using CBCT. Considerable retraction and intrusion of the maxillary incisors, which resulted in a significant improvement in the facial profile and smile, were achieved without severe root resorption. Our findings suggest that CBCT-based diagnosis and treatment simulation may facilitate safe and dynamic orthodontic tooth movement, particularly in patients requiring maximum anterior tooth retraction.

Effectiveness of en masse versus two-step retraction: a systematic review and meta-analysis

Background

This review aims to compare the effectiveness of en masse and two-step retraction methods during orthodontic space closure regarding anchorage preservation and anterior segment retraction and to assess their effect on the duration of treatment and root resorption.

Methods

An electronic search for potentially eligible randomized controlled trials and prospective controlled trials was performed in five electronic databases up to July 2017. The process of study selection, data extraction, and quality assessment was performed by two reviewers independently. A narrative review is presented in addition to a quantitative synthesis of the pooled results where possible. The Cochrane risk of bias tool and the Newcastle-Ottawa Scale were used for the methodological quality assessment of the included studies.

Results

Eight studies were included in the qualitative synthesis in this review. Four studies were included in the quantitative synthesis. En masse/miniscrew combination showed a statistically significant standard mean difference regarding anchorage preservation − 2.55 mm (95% CI − 2.99 to − 2.11) and the amount of upper incisor retraction − 0.38 mm (95% CI − 0.70 to − 0.06) when compared to a two-step/conventional anchorage combination. Qualitative synthesis suggested that en masse retraction requires less time than two-step retraction with no difference in the amount of root resorption.

Conclusions

Both en masse and two-step retraction methods are effective during the space closure phase. The en masse/miniscrew combination is superior to the two-step/conventional anchorage combination with regard to anchorage preservation and amount of retraction. Limited evidence suggests that anchorage reinforcement with a headgear produces similar results with both retraction methods. Limited evidence also suggests that en masse retraction may require less time and that no significant differences exist in the amount of root resorption between the two methods.

Electronic supplementary material

The online version of this article (10.1186/s40510-017-0196-7) contains supplementary material, which is available to authorized users.

Maxillary incisors changes during space closure with conventional and skeletal anchorage methods: a systematic review

PURPOSE

The objective of this systematic review was to compare the antero-posterior, vertical and angular changes of maxillary incisors with conventional anchorage control techniques and mini-implant based space closure methods.

MATERIALS AND METHODS

The electronic databases Pubmed, Scopus, ISI Web of knowledge, Cochrane Library and Open Grey were searched for potentially eligible studies using a set of predetermined keywords. Full texts meeting the inclusion criteria as well as their references were manually searched. The primary outcome data (linear, angular, and vertical maxillary incisor changes) and secondary outcome data (overbite changes, soft tissue changes, biomechanical factors, root resorption and treatment duration) were extracted from the selected articles and entered into spreadsheets based on the type of anchorage used. The methodological quality of each study was assessed.

RESULTS

Six studies met the inclusion criteria. The amount of incisor retraction was greater with buccally placed mini-implants than conventional anchorage techniques. The incisor retraction with indirect anchorage from palatal mini-implants was less when compared with buccally placed mini-implants. Incisor intrusion occurred with buccal mini-implants, whereas extrusion was seen with conventional anchorage. Limited data on the biomechanical variables or adverse effects such as root resorption were reported in these studies.

CONCLUSION

More RCT's that take in to account relevant biomechanical variables and employ three-dimensional quantification of tooth movements are required to provide information on incisor changes during space closure.

Diagnostic efficacy of a modified low-dose acquisition protocol for the preoperative evaluation of mini-implant sites

Purpose

The objective of this study was to compare the outcomes of surgical mini-implant placement when potential mini-implant sites were scanned using a lower-dose 180° acquisition protocol versus a conventional 360° acquisition protocol.

Materials and Methods

Ten dentate human skulls were used to provide sites for potential mini-implant placement. The sites were randomly divided into 2 groups: 360° and 180° cone-beam computed tomography (CBCT) acquisition protocols. A small-volume 180° CBCT scan and a 360° CBCT scan of each site were acquired using a Morita Accuitomo-170 CBCT machine and then a mini-implant was placed. A follow-up 360° CBCT scan was done as a gold standard to evaluate the location of the mini-implant and root perforation. Two raters evaluated the scans.

Results

Ninety-eight percent of the mini-implants placed did not perforate any root structure. Two percent of the sites had an appearance suggestive of perforation. On a Likert scale, both raters agreed that their subjective evaluation of the diagnostic quality of the protocols, ability to make and read measurements of the sites, and preferences for the specified diagnostic task were comparable. The Cohen kappa showed high inter-rater and intra-rater agreement.

Conclusion

In this ex vivo study, we found that the 180° rotational acquisition was as effective as the conventional 360° rotational acquisition for the preoperative evaluation of potential mini-implant sites.

Quantitative analysis of the relationship between maxillary incisors and the incisive canal by cone-beam computed tomography in an adult Japanese population

Background

In setting goals for orthodontic treatment, determining the morphologies of the alveolar bone and maxillary incisor root is important for avoiding root resorption, dehiscence, and fenestration. This study aimed to analyze the configurational relationships among maxillary incisors, the alveolar border, and the incisive canal by cone-beam computed tomography (CBCT).

Methods

Cone-beam CT images of 93 orthodontic patients were evaluated for length of the incisive canal (L); angles between the palatal plane and the maxillary alveolar border (θ1), the incisive canal (θ2), and maxillary incisor (θ3); distance from the left maxillary incisor to the incisive canal (D); and cross-sectional areas of the incisive canal (CSAs) at three vertical levels. Comparison of variables between male and female patients was performed with the two-sample t test. Correlations between parameters were examined by Pearson’s correlation analysis and Bonferroni correction for multiple comparisons.

Results

Male patients exhibited significantly greater values of L than female patients. There were significant positive correlations between θ1 and θ2, θ2 and θ3, and θ3 and θ1. While the value of D was the lowest at the oral opening, that of the cross-sectional area of the incisive canal (CSA) was the greatest at the incisal root apex.

Conclusions

This study demonstrated that the incisive canal had large inter-individual variability, and the proximity between the incisive canal and the incisal root could not be precisely predicted by the conventional cephalograms. Therefore, pre-treatment CBCT examination should be recommended when a large amount of maxillary anterior retraction and/or intrusion is planned in orthodontic diagnosis.

Effectiveness of orthodontic miniscrew implants in anchorage reinforcement during en-masse retraction: A systematic review and meta-analysis

INTRODUCTION

The aim of this systematic review was to compare the effectiveness of orthodontic miniscrew implants-temporary intraoral skeletal anchorage devices (TISADs)-in anchorage reinforcement during en-masse retraction in relation to conventional methods of anchorage.

METHODS

A search of PubMed, Embase, Cochrane Central Register of Controlled Trials, and Web of Science was performed. The keywords were orthodontic, mini-implants, miniscrews, miniplates, and temporary anchorage device. Relevant articles were assessed for quality according to Cochrane guidelines and the data extracted for statistical analysis. A meta-analysis of raw mean differences concerning anchorage loss, tipping of molars, retraction of incisors, tipping of incisors, and treatment duration was carried out.

RESULTS

Initially, we retrieved 10,038 articles. The selection process finally resulted in 14 articles including 616 patients (451 female, 165 male) for detailed analysis. Quality of the included studies was assessed as moderate. Meta-analysis showed that use of TISADs facilitates better anchorage reinforcement compared with conventional methods. On average, TISADs enabled 1.86 mm more anchorage preservation than did conventional methods (P <0.001).

CONCLUSIONS

The results of the meta-analysis showed that TISADs are more effective than conventional methods of anchorage reinforcement. The average difference of 2 mm seems not only statistically but also clinically significant. However, the results should be interpreted with caution because of the moderate quality of the included studies. More high-quality studies on this issue are necessary to enable drawing more reliable conclusions.

Initial forces experienced by the anterior and posterior teeth during dental-anchored or skeletal-anchored en masse retraction in vitro

OBJECTIVE

To investigate initial forces acting on teeth around the arch during en masse retraction using an in vitro Orthodontic SIMulator (OSIM).

MATERIALS AND METHODS

The OSIM was used to represent the full maxillary arch in a case wherein both first premolars had been extracted. Dental and skeletal anchorage to a posted archwire and skeletal anchorage to a 10-mm power arm were all simulated. A 0.019 × 0.025-inch stainless steel archwire was used in all cases, and 15-mm light nickel-titanium springs were activated to approximately 150 g on both sides of the arch. A sample size of n = 40 springs were tested for each of the three groups. Multivariate analysis of variance (α = 0.05) was used to determine differences between treatment groups.

RESULTS

In the anterior segment, it was found that skeletal anchorage with power arms generated the largest retraction force (P < .001). The largest vertical forces on the unit were generated using skeletal anchorage, followed by skeletal anchorage with power arms, and finally dental anchorage. Power arms were found to generate larger intrusive forces on the lateral incisors and extrusive forces on the canines than on other groups. For the posterior anchorage unit, dental anchorage generated the largest protraction and palatal forces. Negligible forces were measured for both skeletal anchorage groups. Vertical forces on the posterior unit were minimal in all cases (<0.1 N).

CONCLUSIONS

All retraction methods produced sufficient forces to retract the anterior teeth during en masse retraction. Skeletal anchorage reduced forces on the posterior teeth but introduced greater vertical forces on the anterior teeth.

Maxillary anterior en masse retraction using different antero-posterior position of mini screw: a 3D finite element study

Background

Nowadays, mini screws are used in orthodontic tooth movement to obtain maximum or absolute anchorage. They have gained popularity among orthodontists for en masse retraction of anterior teeth after first premolar extraction in maximum anchorage cases. The purpose of this study was to determine the type of anterior tooth movement during the time when force was applied from different mini screw placements to the anterior power arm with various heights.

Methods

A finite element method was used for modeling maxillary teeth and bone structure. Brackets, wire, and hooks were also designed for modeling. Two appropriate positions for mini screw in the mesial and distal of the second premolar were designed as fixed nodes. Forces were applied from the mini screw to four different levels of anterior hook height: 0, 3, 6, and 9 mm. Initial tooth movement in eight different conditions was analyzed and calculated with ANSYS software.

Results

Rotation of anterior dentition was decreased with a longer anterior power arm and the mesial placement of the mini screw. Bodily movements occurred with the 9-mm height of the power arm in both mini screw positions. Intrusion or extrusion of the anterior teeth segment depended on the level of the mini screw and the edge of the power arm on the Z axis.

Conclusions

According to the findings of this study, the best control in the sagittal plane during anterior en masse retraction was achieved by mesial placement of the mini screw and the 9-mm height of the anterior power arm. Where control in the vertical plane was concerned, distal placement of the mini screw with the 6-mm power arm height had minimum adverse effect on anterior dentition.