3D Retraction Force Vector Indicator for Anterior en masse Retraction with Miniscrew Anchorage

In severely protrusive patients, skeletal anchorage from miniscrew is often used to avoid anchorage loss with preferred miniscrew location near centre of resistance (Cres) of posterior teeth. Biomechanical requirement for directing retraction force towards Cres of posterior teeth demands the insertion of miniscrew in loose mucosa, where risk of infection and failure increases. In addition, undesirable biomechanical side effects on anterior and posterior segments may be possible in all three planes, when continuous arch sliding mechanics are installed with miniscrew anchorage. This paper describes technique of molar-stabilizing power arm (MSPA) for simultaneous intrusion and retraction of anteriors with miniscrew placement at attached gingiva between 1st molar and 2nd premolar. Advantages of this technique include (i) the need of miniscrews placement in loose mucosa apically near the Cres of the posterior teeth is eliminated, (ii) the risk of infection and miniscrew failure is lowered since the miniscrew is placed in attached gingiva rather than the loose mucosa, and (iii) by adjusting vertical length or replacing MSPA, alteration of the retraction force vector is possible in all three planes; thus, need of removal and repositioning of the miniscrew (e.g., in correction of occlusal cant) can be eliminated.

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Dual-section versus conventional archwire for en-masse retraction of anterior teeth with direct skeletal anchorage: a finite element analysis

BMC Oral Health ◽

10.1186/s12903-021-01443-0 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Ryo Hamanaka ◽

Daniele Cantarella ◽

Luca Lombardo ◽

Lorena Karanxha ◽

Massimo Del Fabbro ◽

...

Keyword(s):

Finite Element ◽

Tooth Movement ◽

Occlusal Plane ◽

Skeletal Anchorage ◽

Element Analysis ◽

Posterior Teeth ◽

Posterior Portion ◽

Anterior Teeth ◽

Retraction Force ◽

En Masse Retraction

Abstract Background The aim of this study is to compare the biomechanical effects of the conventional 0.019 × 0.025-in stainless steel archwire with the dual-section archwire when en-masse retraction is performed with sliding mechanics and skeletal anchorage. Methods Models of maxillary dentition equipped with the 0.019 × 0.025-in archwire and the dual-section archwire, whose anterior portion is 0.021 × 0.025-in and posterior portion is 0.018 × 0.025-in were constructed. Then, long-term tooth movement during en-masse retraction was simulated using the finite element method. Power arms of 8, 10, 12 and 14 mm length were employed to control anterior torque, and retraction forces of 2 N were applied with a direct skeletal anchorage. Results For achieving bodily movement of the incisors, power arms longer than 14 mm were required for the 0.019 × 0.025-in archwire, while between 8 and 10 mm for the dual-section archwire. The longer the power arms, the greater the counter-clockwise rotation of the occlusal plane was produced. Frictional resistance generated between the archwire and brackets and tubes on the posterior teeth was smaller than 5% of the retraction force of 2 N. Conclusions The use of dual-section archwire might bring some biomechanical advantages as it allows to apply retraction force at a considerable lower height, and with a reduced occlusal plane rotation, compared to the conventional archwire. Clinical studies are needed to confirm the present results.

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

Dental Press Journal of Orthodontics ◽

10.1590/2177-6709.22.5.047-055.oar ◽

2017 ◽

Vol 22 (5) ◽

pp. 47-55 ◽

Cited By ~ 2

Author(s):

A. Sumathi Felicita

Keyword(s):

Clinical Outcomes ◽

Anterior Segment ◽

Applied Force ◽

Occlusal Plane ◽

Conceptual Approach ◽

Mini Implants ◽

Anterior Teeth ◽

Clinical Scenarios ◽

Retraction Force ◽

En Masse Retraction

ABSTRACT Objective: 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.

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The Effect of Varied Positioning of Mini-screw, Anterior Retraction Hook, and Resultant Force Vector on Efficient En-Masse Retraction Using Finite Element Method: A Systematic Review

The Journal of Indian Orthodontic Society ◽

10.1177/0301574220982098 ◽

2021 ◽

Vol 55 (1) ◽

pp. 11-21

Author(s):

Ashish Agrawal ◽

P Subash

Keyword(s):

Systematic Review ◽

Finite Element Method ◽

Finite Element ◽

Risk Of Bias ◽

Resistance Force ◽

Cochrane Central Register ◽

Force Vector ◽

En Masse Retraction ◽

Element Method ◽

Center Of Resistance

Objective: The objective of this systematic review was to assess the available evidence to evaluate the effectiveness of en-masse retraction design with mini-screw with respect to the retraction hook and mini-implant position and height. Methods: The following electronic databases were searched till July 31, 2020: Pro-Quest Dissertation Abstracts and Thesis database Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Google Scholar, US National Library of Medicine, and National Research Register. En-masse retractions with anterior retraction hooks assisted by mini-implant three-dimensional finite element method (3D FEM) models were included in the study. The selected studies were assessed for the risk of bias using the Cochrane Collaboration risk of bias tool. The “traffic plot” and “weighted plot” risk of bias distribution were designed using the ROBVIS tool. The authors extracted and analyzed the data. Results: Twelve studies fulfilled the inclusion criteria. The risks of biases were low for 9 studies and high for 3 studies. Data on mini-implant, retraction hook, and the center of resistance/force vectors were extracted. The outcomes of the included studies were heterogeneous. Conclusions: According to the currently available literature review for successful bodily en-masse tooth movement, the force vector should pass through the center of resistance, which can be achieved by the clinical judgment of placing a mini-screw and an anterior retraction hook. The force from an implant placed at a higher level from the anterior retraction hook will cause intrusion; an implant placed at the medium level shows bodily movement; and an implant placed at a lower level shows tipping forces in consolidated arches.

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Effects of Skeletally Supported Anterior en Masse Retraction with Varied Lever Arm Lengths and Locations in Lingual Orthodontic Treatment: A 3D Finite Element Study

BioMed Research International ◽

10.1155/2021/9975428 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Mohammad Ghannam ◽

Beste Kamiloğlu

Keyword(s):

Finite Element ◽

Orthodontic Treatment ◽

Three Dimensional ◽

Torque Control ◽

Finite Element Models ◽

3D Finite Element ◽

Force Application ◽

Lever Arm ◽

Retraction Force ◽

En Masse Retraction

Objective. This study is aimed at analyzing different points of force application during miniscrew supported en masse retraction of the anterior maxillary teeth to identify the best line of action of force in lingual orthodontic treatment. Materials and Methods. Three-dimensional (3D) finite element models were created to stimulate en masse retraction with different heights and positions of the miniscrew and lever arm to change the force application points; a 150 g retraction force was applied from the miniscrew to the lever arms, and the initial tooth displacements were analyzed. Results. Lingual crown tipping and occlusal crown extrusion were seen at all heights and positions of the miniscrew and lever arm, but when the miniscrew height was at 8 mm and the power arm was located between the lateral incisors and canines, these tipping patterns were less than those obtained with a 4.5 mm high miniscrew and a lever arm located distal to the canines. Conclusion. All miniscrew heights and lever arm positions showed initial lingual crown tipping and labial root tipping with occlusal crown extrusion. However, the 8 mm miniscrew height and the lever arm located between the lateral incisor and canine showed fewer amounts of these tipping patterns than a 4.5 mm miniscrew height and lever arm located distal to the canines. Therefore, this could be the preferred point of force application during en masse retraction in lingual treatment with additional torque control methods.

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OPTIMUM FORCE SYSTEM FOR EN-MASSE RETRACTION OF SIX MAXILLARY ANTERIOR TEETH IN LABIAL ORTHODONTICS

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519419500660 ◽

2020 ◽

Vol 20 (02) ◽

pp. 1950066

Author(s):

ABHISHEK M. THOTE ◽

RASHMI V. UDDANWADIKER ◽

KRISHNA SHARMA ◽

SUNITA SHRIVASTAVA ◽

VENKATESWAR REDDY

Keyword(s):

Theoretical Model ◽

Research Study ◽

Sagittal Plane ◽

Optimum Combination ◽

Force System ◽

Anterior Teeth ◽

Slot Size ◽

Retraction Force ◽

En Masse Retraction

The orthodontists generally do not recommend application of force system above the archwire level owing to additional attachments and patient’s discomfort. Hence, the present research study focusses on application of retraction force system at the archwire level. The objective of this study is to specify an optimum combination of archwire and bracket slot size for en-masse (simultaneous) parallel retraction of six maxillary anterior teeth in labial orthodontics (LaO). In this research study, the concept (theoretical) model has been developed based on simple principles of mechanics to estimate the torque generated by different sizes of archwire in bracket slots. Based on torque value, retraction force developed by each combination of archwire and slot size was determined and compared with required retraction force of 150 gram-force on each side of sagittal plane. For combination of [Formula: see text] inch stalinless steel SS archwire and 0.022 inch SS bracket slot, magnitude of computed retraction force matched closely with aforementioned required force than other combinations and hence, it is recommended in the present research study. The validation of selected combination of archwire and bracket slot size was done successfully by in vivo (clinical) experimentation on three patients. Thus, it proves that the aforementioned combination of archwire and bracket slot size is more suitable than others for retraction force system applied at archwire level.

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

The Angle Orthodontist ◽

10.2319/080916-616.1 ◽

2016 ◽

Vol 87 (4) ◽

pp. 549-555 ◽

Cited By ~ 3

Author(s):

David Lee ◽

Giseon Heo ◽

Tarek El-Bialy ◽

Jason P. Carey ◽

Paul W. Major ◽

...

Keyword(s):

Anterior Segment ◽

Nickel Titanium ◽

Skeletal Anchorage ◽

Posterior Teeth ◽

Treatment Groups ◽

Anterior Teeth ◽

Retraction Force ◽

En Masse Retraction ◽

Maxillary Arch

ABSTRACT 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.

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The effect of varied force vector on type of tooth movement of maxillary anterior teeth during en masse retraction; randomized clinical trial

Egyptian Orthodontic Journal ◽

10.21608/eos.2021.78005.1017 ◽

2021 ◽

Vol 59 (6) ◽

pp. 26-38

Author(s):

Tarek Yousry ◽

Sherief Abdel-Haffiez ◽

Mohamed Mowafy

Keyword(s):

Clinical Trial ◽

Randomized Clinical Trial ◽

Tooth Movement ◽

Force Vector ◽

Anterior Teeth ◽

En Masse Retraction

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Finite Deformation Stiffness of Sliding Elastomeric Bearings

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.374-377.1858 ◽

2011 ◽

Vol 374-377 ◽

pp. 1858-1862

Author(s):

Jian Chun Xiao ◽

Peng Liu ◽

Ke Jian Ma

Keyword(s):

Parametric Analysis ◽

Steel Plates ◽

Structural Behavior ◽

Analysis Method ◽

Force Vector ◽

Elastomeric Bearings ◽

Before And After ◽

Bearing Stiffness ◽

Vector Formula

Anchor bolts are set in some elastomeric bearings of large-span column-supported spatial steel roofs. Besides helping the bearing in-site assembly, the bolts play the roles of sliding position limitation and vertical anchorage. To analyze the effect of bearings on nonlinear structural behavior, the bearing stiffness change is studied just before and after the elastomer pad is in contact with the bolts. For the bearing that the pad is glued with the top/bottom steel plates, three kinds of relation of pad and bolts are discussed and an approximate horizontal stiffness formula is obtained with parametric analysis method. Based on the analysis results a stiffness expression for sliding elastomeric bearings is deduced. To solve the computational problem caused by the bearing stiffness changes, an improved imbalance force vector formula is proposed. Case study shows that the bolts have influence upon the computed results more significantly.

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