En-masse Retraction Research Articles

Finite Element Analysis of Stress in Maxillary Dentition during En-masse Retraction with Implant Anchorage.

The goal of this study was to investigate how the height of the archwire hook and implant anchor affect tooth movement, stress in the teeth and alveolar bone, and the center of resistance during retraction of the entire maxillary dentition using a multibracket system. Computed tomography was used to scan a dried adult human skull with normal occlusion. Three-dimensional models of the maxillary bone, teeth, brackets, archwire, hook, and implant anchor were created and used for finite element analysis. The heights of the hook and the implant anchor were set at 0, 5, or 10 mm from the archwire. Orthodontic force of 4.9 N was systematically applied between the hook and the implant anchor and differential stress distributions and tooth movements observed for each traction condition. With horizontal traction, the archwire showed deformation in the superior direction anterior to the hook and in the inferior direction posterior to the hook. Differences in traction height and direction resulted in different degrees of deformation, with biphasic movement clearly evident both in front of and behind the hook. With horizontal traction of the hook at a height of 0 mm, all the teeth moved distally, but not with any other type of traction. At a height of 5 mm or 10 mm, deformation showed an increase. The central incisor showed extrusion under all traction conditions, with the amount showing a reduction as the height of horizontal or posterosuperior traction increased. The center of resistance was located at the root of the 6 anterior teeth and entire maxillary dentition. The present results suggest that it is necessary to consider deformation of the wire and the center of resistance during en-masse retraction with implant anchorage.

Effects of piezocision in orthodontic tooth movement: A systematic review of comparative studies.

BackgroundThe aim of this systematic review was to evaluate the effects of piezocision in accelerating orthodontic tooth movement (OTM) and its possible adverse effects.Material and MethodsThe Databases Medline, Embase, CENTRAL and LILACS were searched until March 2019, for randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that used piezocision associated with orthodontic treatment. A manual search was also performed. The search, studies selection, assessment of risk of bias and data collection were carried out by two independent reviewers.ResultsEleven publications were included in this review (4 CCTs and 7 RCTs). No study presented low risk of bias. Different types of tooth movement were evaluated: lower anterior alignment, en-masse retraction, overall orthodontic treatment and canine distalization. A total of 240 participants were analyzed in the included studies. Seven studies found significant acceleration in the piezocision group, while two studies found no differences. Adverse effects regarding patient’s satisfaction, pain perception, or worsening of periodontal parameters were not observed. There was no consensus concerning anchorage loss and root resorption.ConclusionsThe literature does not provide high-quality evidence to confirm that Piezocision results in significant OTM acceleration. Therefore, high-quality RCTs should be conducted to allow reliable conclusions about the effects of piezocision in orthodontics. Key words:Piezosurgery, tooth movement techniques, orthodontics.

Changes in the alveolar bone thickness of maxillary incisors after orthodontic treatment involving extractions - A systematic review and meta-analysis.

BackgroundOrthodontic treatment involving en-masse retraction of incisors following premolar extractions, may induce morphological alterations of the alveolar bone surrounding the anterior teeth.ObjectiveTo assess changes in alveolar bone thickness around the incisors of extraction patients measured with CBCT.Material and MethodsAn electronic search was conducted in PubMed, Scopus, Embase and Cochrane Library, using search terms, with no limitation on publication date, up to April 2018. The articles selected for analysis included randomized controlled trials, case-control studies and cohort studies of patients treated with fixed appliances and premolar extractions, which had measured alveolar bone thickness with CBCT before and after treatment. Changes in bone thickness were calculated and the heterogeneity of the studies was assessed using the I2 and Cochran’s Q tests.ResultsOf the 136 articles identified in the initial search, 19 were related to the review subject. After removing a further 14 that did not meet the inclusion criteria, 5 articles were selected for analysis. All five were retrospective studies of medium quality. The main changes in alveolar bone thickness were found in the labial cervical third of the central incisor, presenting increases of 0.4-0.64 mm. On the palatal side the results varied considerably.ConclusionsA significant increase in alveolar bone thickness occurs in the labial cervical third of the central incisor. These changes may be influenced by incisor position and inclination, the orthodontic technique and mechanics employed, the timing of the final CBCT scan and the bone remodeling capacity during en-masse retraction. Key words:Cone-beam computed tomography, alveolar bone, orthodontics.

Palatal en-masse retraction of segmented maxillary anterior teeth: A finite element study

ObjectiveThe aim of this finite element study was to clarify the mechanics of tooth movement in palatal en-masse retraction of segmented maxillary anterior teeth by using anchor screws and lever arms.MethodsA three-dimensional finite element method was used to simulate overall orthodontic tooth movements. The line of action of the force was varied by changing both the lever arm height and anchor screw position.ResultsWhen the line of action of the force passed through the center of resistance (CR), the anterior teeth showed translation. However, when the line of action was not perpendicular to the long axis of the anterior teeth, the anterior teeth moved bodily with an unexpected intrusion even though the force was transmitted horizontally. To move the anterior teeth bodily without intrusion and extrusion, a downward force passing through the CR was necessary. When the line of action of the force passed apical to the CR, the anterior teeth tipped counterclockwise during retraction, and when the line of action of the force passed coronal to the CR, the anterior teeth tipped clockwise during retraction.ConclusionsThe movement pattern of the anterior teeth changed depending on the combination of lever arm height and anchor screw position. However, this pattern may be unpredictable in clinical settings because the movement direction is not always equal to the force direction.

TADs assisted Camouflage Orthodontic Treatment of Class II Division 1 Malocclusion in a Non Growing Patient: A case report

Class II, Division I malocclusion has been described as the most frequent treatment problem in orthodontic practice. Aim & objectives of the present case report was to evaluate the management of skeletal Class II division 1 malocclusion in non growing patient with extraction of upper first premolars. Clinical and cephalometric evaluation revealed skeletal Class II with Angles Class II division 1 malocclusion with mild mandibular anterior crowding and increased overjet, severe maxillary incisor proclination, mild mandibular crowding, exaggerated curve of spee, convex profile, incompetent lips, increased overjet and overbite. Maxillary first premolars were extracted followed by en-masse retraction of anteriors with the help of temporary anchorage devices (TADs) to avoid anchorage loss. Mandibular incisor was extracted to correct curve of spee. Following treatment marked improvement in patient’s smile, facial profile and lip competence were achieved and there was a remarkable increase in the patient’s confidence and quality of life.

Comparative study of the rate of tooth movement between corticotomy and piezocision to facilitate en masse retraction in bimaxillary protrusion

Objective: The aim of this study was to evaluate the rate of orthodontic tooth movement and the time needed for extraction space closure when corticotomy and piezocision were used to facilitate en-masse retraction in bimaxillary protrusion cases. Subjects and Methods: The sample of this study consisted of twenty subjects having Class I malocclusion with bimaxillary protrusion and requiring extraction of four first premolars and en-masse retraction of the anterior segments on both arches. The sample was randomly divided into two equal groups; group I:corticotomy was performed by using piezosurgery through flap reflection and group II: corticotomy was performed by using piezocision (flapless corticotomy). Study models were obtained just before surgery and in every month for 6 months after surgery to measure the rate of orthodontic tooth movement in both groups. After completing the en-masse retraction, the retraction time in months was recorded for the right and left sides and averaged. Results: Group I showed a statistically significant shorter retraction time than group II. Group I showed a statistically significant increase in the rate of tooth movement from the 2nd to the 5th month in the upper arch. For the lower arch, group I exhibited a significant increase in the rate of tooth movement in the 4th month. Conclusion: Corticotomy involving flap reflection showed a shorter retraction time and higher rates of tooth movement than piezocision during en-masse retraction.

Comparative Study of the Rate of Tooth Movement Between Corticotomy and Piezocision to Facilitate En-Masse Retraction in Bimaxillary Protrusion.

Comparative Study of the Rate of Tooth Movement Between Corticotomy and Piezocision to Facilitate En-Masse Retraction in Bimaxillary Protrusion.

Assessment of Myeloperoxidase Levels In Relation to the Nature and Duration of Orthodontic Forces – An In vivo, Split Mouth Study

To assess the change in the myeloperoxidase levels(MPO)in the gingival crevicular fluid(GCF) at different time intervals during the course of orthodontic treatment with the application of intermittent and continuous forces. It was an interventional, split mouth study done on twenty patients scheduled to undergo fixed orthodontic treatment with therapeutic extractions of the first premolars.Mini implant assisted enmasse retraction was done after leveling and aligning of the arch.Continuous force with the help of Niti coil spring was used in the first quadrant and intermittent force with an elastomeric chain was used in the second quadrant. MPO was collected from the GCF using What man’s paper at baseline,1 week and 2 weeks after the application of retraction forces.The levels were assessed using a commercially available ELISA kit. Mean MPO activity was increased in the GCF of all the patients at 1 and 2 weeks after retraction,in both quadrants.At 2 weeks, MPO levels at the intermittent force application site were found to be significantly higher than those at the site of continuous force application. Myeloperoxidase is a useful marker to assess inflammation associated with orthodontic tooth movement.Intermittent forces cause a higher degree of inflammation as compared to continuous forces.

Comparison of rate of tooth movement and pain perception during accelerated tooth movement associated with conventional fixed appliances with micro-osteoperforations - a randomised controlled trial.

To investigate the influence of micro-osteoperforation (MOP) on rate of orthodontic tooth movement and pain perception with fixed appliances. 2 arm parallel randomized controlled trial with an allocation ratio of 1:1. The outpatient department of a dental college. 105 patients were screened, out of which 60 met the inclusion criteria and consented to participate; consisting of 33 females and 27 males requiring en-masse retraction following first premolar extractions. The experimental group consisted of patients bonded with a fixed appliance (Gemini 3M) who received MOP distal to canines throughout the period of retraction every 28 days. These were compared with a control group treated with identical brackets without MOP and were assessed for rate of tooth movement (canine retraction) and pain perception using a Visual Analogue Scale (VAS) of 10 mm. Prior to commencement, all baseline parameters were matched between the two groups (p>0.05). A statistically significant increase in rate of tooth movement in the MOP group (p<0.05). MOP appears to enhance the rate of tooth movement with no differences in pain perception.

Assessment of Immediate Loading with Mini-Implant Anchorage in Critical Anchorage Cases Between Stainless Steel Versus Titanium Miniscrew Implants: A Controlled Clinical Trial

Anchorage in orthodontics is a decisive factor in progress and outcome of a case. With the advent of mini-implants, great advances have been achieved in terms of absolute anchorage. The following article compares the use of stainless steel and titanium implants in a split mouth, controlled clinical study, having direct in vivo comparison. 10 patients were selected for the same and carefully evaluated. The mini-implants were placed in the buccal mucosa, under local anaesthesia, after radiographic safe zone selection. The loading protocol was standardised with low immediate load, followed by incremental load up to 150g. For the study, the cases planned with en-masse retraction of the anteriors into the premolar space were selected for the uniformity in mechanics. The results are discussed with comparative analysis between the two materials and their success rate individually and in relation to upper and lower jaw respectively. In results, a significant success rate has been found with use of titanium implants, with higher implant failure in upper jaw compared to lower jaw.

Comparison of stress distribution on bone and mini-implants during en-masse retraction of maxillary anterior teeth in labial and lingual orthodontics: A three-dimensional finite element analysis

INTRODUCTION: In fixed orthodontic treatment, space closure is one of the most challenging aspects. The common method of en-masse retraction in sliding mechanics is the use of the elastomeric chain and power arm. Recently, titanium mini-implants are used as absolute sources of orthodontic anchorage. Lingual and labial bracket placement influences the pattern of tooth movement, but the stress that occurs around the teeth, the mini-implants, and the surrounding bone can be accurately mapped using a three-dimensional (3D) finite element method. AIM: The aim of this study was to evaluate the stress distribution on bone and mini-implants during en-masse retraction of maxillary anterior teeth in labial and lingual orthodontics with the help of finite element analysis. MATERIALS AND METHODS: Following the standard protocol for 3D finite element models, two models were created for en-masse retraction of the six anterior teeth: one model using the labial technique with the mini-implant placed at a height of 5 mm from the alveolar crest bucally and the second model using the lingual technique with the mini-implant placed at a height of 5 mm from the gingival margin palatally, and 200 g of retraction forces was given using a elastomeric chain. RESULTS AND CONCLUSIONS: The Von Mises stresses in the bone and mini-implant were significantly higher in the lingual technique as compared to the labial technique. The variations in stress patterns in the bone and the mini-implant in the labial and lingual technique could be the result of difference in the inter-bracket distance, point of force application, and its location to the center of resistance of the dentition.

Osseous outgrowth on the buccal maxilla associated with piezosurgery-assisted en-masse retraction: A case series

Piezoelectric surgery is a novel surgical approach used in orthodontic treatment for rapid tooth movement. This paper presents a case series wherein osseous outgrowths were observed in response to piezosurgery-assisted en-masse retraction. Sixteen patients requiring upper premolar extractions were treated with miniscrew-supported en-masse retraction and received minimally invasive decortication via piezosurgery. Computed tomography (CT) of the maxillary anterior region was performed to investigate the nature of the outgrowths. In 8 of the 16 patients, hemispheric or disc-shaped osseous outgrowths were observed on the sites where piezosurgery was performed during retraction. CT images revealed that these outgrowths were alveolar bone. This case series presents a previously unreported osseous response to piezosurgery-assisted tooth movement during orthodontic treatment. The response is mostly transient and is observed in 50% of the treated patients, suggesting a bone turnover that can be assessed clinically and radiographically.

EFFECT OF SURFACE TREATMENT OF ORTHODONTIC MINI-SCREW IMPLANTS ON THEIR STABILITY; IN VIVO STUDY

Purpose: To evaluate the effect of anodization surface treatment on the stability of minimplants ( MIs ) during en-masse retraction. Materials and Methods: The sample of this split mouth; clinical trial, consisted of 27 patients with an allocation ratio of 1:1. Forty five MIs (1.8 mm diameter and 8 mm length) were divided into: 27 MIs with surface treatment by anodization technique while the other 27 were with smooth surface (group B). Finishing, leveling and alignment, the surface treated MIs and the smooth ones were randomly inserted between the roots of maxillary 2nd bicuspid and 1st molar at the mucogingival junction on both sides of each patient. After two weeks healing period, bilateral extraction of maxillary 1st bicuspids were done. Closed coil spring was extended from the MI head to along hock secured onto the main arch wire between the maxillary lateral incisor and canine on both sides, delivering 200 g force per side to en-masse retract the upper anterior teeth. The average observation period lasted 9–12 months. Results: In total, 40 of 54 minimplants were able to achieve the treatment goals. In group A, 22 (81.5%) mini-screw implants presented long-term stability, while in group B, only 18 (66%) minimplants were stable throughout the treatment. This difference was statistically significant (P =.0311). The total success rate for all inserted miniscrew implants was 74%. Conclusion: Anodized surface treated orthodontic mini-screw implants are more stable than smooth surface one during en-mass retraction.

Treatment of Class II, Division 2 Malocclusion with Miniscrew Supported En-Masse Retraction: Is Deepbite Really an Obstacle for Extraction Treatment?

A 17-year-old female patient, whose chief complaint was her unpleasing smile, had skeletal and dental class II malocclusion, hypodivergent facial type with a severely increased overbite. Among the treatment options, upper-first-premolar extractions followed by miniscrew-supported en-masse retraction was the treatment of choice. After the initial levelling and alignment, miniscrews with 1.5- to 1.4-mm diameter and 7-mm lenght, were installed between the roots of the second premolars and the first molars, bilaterally. En-masse retraction was achieved on a 0.016×0.022-inch stainless steel archwire with 7-mm long power hooks placed distal to the lateral incisors, and with nickel-titanium (NiTi) closed coil springs exerting 250-gr of force per side. At the end of the treatment, deepbite, incisor inclinations and interincisal angle were corrected, and Class II molar relationship with good intercuspation was achieved. Upper 2-2, lower 3-3 retainers were bonded for retention. As a result, deepbite and Class II canine relationship was successfully corrected with simultaneous incisor intrusion and retraction using miniscrew-supported en-masse retraction.

A comparison of the rate of en-masse space closure using conventional and passive self-ligating brackets with closed-coil springs

Malocclusion prevalence is high, and an orthodontist needs to be effective and efficient in treating malocclusion. Self-ligating brackets are claimed to be more effective and efficient, and to have less friction in ortodontic movement than do conventional brackets. The objective of this study is to compare the rate of mandibular en-masse space closure retraction and loss of anchorage between passive self-ligating brackets and conventional brackets using closed-coil springs. The study design was a prospective randomized controlled clinical trial with split-mouth technique. Twenty two mandibular quadrants in patients that were ready for en-masse space closure retraction were placed with conventional brackets MBT Agile 3M slot.022” in a whole quadrant, while the contra lateral was placed with passive self-ligating brackets Damon Q standar torque Ormco. The en-masse space closure retraction rate and loss of anchorage were measured in study models at 4 and 8 weeks. The results indicated there was significant difference between passive self-ligating brackets and conventional brackets regarding the en-masse space closure retraction rate and loss of anchorage rate. Self-ligating brackets were faster in en-masse space closure with a mean rate 0.58mm in 4 weeks and 0.74mm in 8 weeks and they were more resistant to loss of anchorage. The split-mouth technique was effective for comparison of the rate of mandibular en-masse retraction and loss of anchorage between self-ligating brackets and conventional brackets using closed-coil springs, where individual variability was minimized.

Efficiency of piezosurgery technique in miniscrew supported en-masse retraction: a single-centre, randomized controlled trial.

Piezoelectric surgery is a newly introduced technique for rapid tooth movement. However, the efficiency of this technique has not been investigated on en-masse retraction cases yet. To investigate the efficiency of piezosurgery technique in accelerating miniscrew supported en-masse retraction and study the biological tissue response. In addition, to show if this technique induces a difference in dental, skeletal and soft tissue changes on lateral cephalograms, and in canine and molar rotations, besides intercanine and intermolar widths on dental casts. We conducted a randomized, single-centred, parallel-group, controlled trial, requiring upper right and left first premolar extractions on 30 patients above the minimum age of 14 years at the beginning of retraction. Piezosurgery-assisted versus conventional en-masse retraction anchored from miniscrews placed between second premolars and first molars, bilaterally. The main outcome was the en-masse retraction rate. Secondary outcomes were gingival crevicular fluid (GCF) volume and GCF content of receptor activator of nuclear factor κβ ligand (RANKL), changes regarding cephalometric and dental cast variables, and miniscrew success rates. Accomplished with opaque, sealed envelopes. Applicable for data assessment only. Commenced in February 2013 and ended in October 2014. Thirty-one patients were included in the study and divided into 2 groups of piezosurgery (n = 16) and control (n = 15). After 9.3 months of follow-up, no statistically significant difference was observed between groups for neither retraction rates (P = 0.958) nor GCF parameters (P > 0.05). Changes in lateral cephalometric and dental cast variables, and miniscrew success rates did not show significant differences either. Based on the results of this study, piezosurgery technique was found to be ineffective in accelerating en-masse retraction, and promoting a difference in the studied GCF parameters, skeletal and dental variables. The trial was not registered. The full protocol of this PhD thesis study can be accessed from tez.yok.gov.tr. This work was supported by Başkent University Research Fund. No conflict of interest was declared.

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

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. 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. 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 1.86mm more anchorage preservation than did conventional methods (P<0.001). The results of the meta-analysis showed that TISADs are more effective than conventional methods of anchorage reinforcement. The average difference of 2mm 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.

Comparison of stress distribution in bone and miniscrew and displacement pattern of maxillary anterior teeth by two methods of en-masse retraction: A 3-D finite element analysis

Introduction: To move the teeth in a desired pattern, the appropriate direction of the force must be selected. An inappropriate force delivers unfavourable stresses in the supporting tissues resulting in poor prognosis. It is very difficult to measure stresses accurately in vivo. Finite element analysis provides a definitive solution. Aim: To compare the stress distribution in bone and miniscrew and displacement pattern of maxillary anterior teeth with two methods of en-masse retraction i.e. NiTi coil spring and elastomeric chain, with miniscrews placed at various heights using finite element analysis. Materials and Methods: Total of four models were created i.e. two models with retraction by elastomeric chain and two models with retraction by NiTi coil spring with the help of implant placed at 3 mm and 5 mm height from alveolar crest. Results were represented in the form of stress diagrams. Results and Conclusions: Retraction with elastomeric chain produces lesser amount of von Mises stress on the bone as well as mini-implant as compared to that with NiTi coil spring. Retraction with elastomeric chain produced more sagittal and vertical displacement of canines as compared to its effect on incisors. The overall displacement of anterior teeth in both vertical as well as in sagittal direction was found to be more with elastomeric chain as compared with NiTi coil spring. Both the methods for retraction resulted in same amount of palatal root movement irrespective of the force vector. Keywords: Miniscrew; Stress; En-masse retraction; Finite Element Method

Effects of bracket slot size during en-masse retraction of the six maxillary anterior teeth using an induction-heating typodont simulation system.

ObjectiveTo investigate how bracket slot size affects the direction of maxillary anterior tooth movement when en-masse retraction is performed in sliding mechanics using an induction-heating typodont simulation system.MethodsAn induction-heating typodont simulation system was designed based on the Calorific Machine system. The typodont included metal anterior and resin posterior teeth embedded in a sticky wax arch. Three bracket slot groups (0.018, 0.020, and 0.022 inch [in]) were tested. A retraction force of 250 g was applied in the posterior-superior direction.ResultsIn the anteroposterior direction, the cusp tip of the canine in the 0.020-in slot group moved more distally than in the 0.018-in slot group. In the vertical direction, all six anterior teeth were intruded in the 0.018-in slot group and extruded in the 0.020- and 0.022-in slot groups. The lateral incisor was significantly extruded in the 0.020- and 0.022-in slot groups. Significant differences in the crown linguoversion were found between the 0.018- and 0.020-in slot groups and 0.018- and 0.022-in slot groups for the central incisor and between the 0.018- and 0.022-in slot groups and 0.020- and 0.022-in slot groups for the canine. In the 0.018-in slot group, all anterior teeth showed crown mesial angulation. Significant differences were found between the 0.018- and 0.022-in slot groups for the lateral incisor and between the 0.018- and 0.020-in slot groups and 0.018- and 0.022-in slot groups for the canine.ConclusionsUse of 0.018-in slot brackets was effective for preventing extrusion and crown linguoversion of anterior teeth in sliding mechanics.

Quantification of intrusive/retraction force and moment generated during en-masse retraction of maxillary anterior teeth using mini-implants: A conceptual approach.

ABSTRACTObjective: The aim of the present study was to clarify the biomechanics of en-masse retraction of the upper anterior teeth and attempt to quantify the different forces and moments generated using mini-implants and to calculate the amount of applied force optimal for en-masse intrusion and retraction using mini-implants. Methods: The optimum force required for en-masse intrusion and retraction can be calculated by using simple mathematical formulae. Depending on the position of the mini-implant and the relationship of the attachment to the center of resistance of the anterior segment, different clinical outcomes are encountered. Using certain mathematical formulae, accurate measurements of the magnitude of force and moment generated on the teeth can be calculated for each clinical outcome. Results: Optimum force for en-masse intrusion and retraction of maxillary anterior teeth is 212 grams per side. Force applied at an angle of 5o to 16o from the occlusal plane produce intrusive and retraction force components that are within the physiologic limit. Conclusion: Different clinical outcomes are encountered depending on the position of the mini-implant and the length of the attachment. It is possible to calculate the forces and moments generated for any given magnitude of applied force. The orthodontist can apply the basic biomechanical principles mentioned in this study to calculate the forces and moments for different hypothetical clinical scenarios.