Determination of Optimal Loading Conditions Using Lever Arm and Mini- Implant System for En-masse Retraction in Lingual Orthodontics – A FEM Study

  • Shalini Mishra
  • Mukesh Kumar
  • Manish Goyal
  • Ashish Kushwah Dr.ashishdgr8
Keywords: Anterior En-masse Retraction, Lever arm, Lingual orthodontics, Mini-implants, Stress, Displacement, von Mises and principle stress, Finite element method.


Aim: To evaluate the stress distribution along the periodontal ligament and alveolar bone by various combinations of mini-implants and lever arm used during en-masse retraction of anterior teeth using finite element method.Materialsand Methods: Four three-dimensional finite element models of the bilateral maxillary first premolar extraction casewas constructed. Lingual brackets were (0.018” slot) positioned over the center of the clinical crown. In all four models 150 g of retraction force with the help of the NiTi closed coil springs was applied with different combinations of mini-implants and lever arm. A finite element analysis was then performed to evaluate stress distribution, the principle stress, von Mises stress and displacement of the anterior teeth using ANSYS 12.1 software.Result: In this study the constructed models along with the load application were imported into ANSYS (version 12.1) software for analyzing the displacement and stress distribution corresponding to the force application. The maximum tensile stress of periodontal ligament were observed at distal root apex area of canine in all four models. Variable amount of displacements like lingual crown tipping, lingual root tipping and extrusion were observed in all the models suggesting different combinations of lever arm and mini-implants affect the direction of the tooth displacements in lingual mechanics.Conclusion: In lingual orthodontics tipping movement of crown decreases as the height of lever arm increases. It was also found that when mini-implants were placed at higher position the amount of tipping movement decreases with minimum amount of extrusion seen in central incisor and lateral incisor.


Liang W, Rong Q, Lin J and XB. Torque Control of the Maxillary Incisors in Lingual and Labial Orthodontics: A 3-Dimentional Finite Analysis. Am J OrthodDentofacOrthop. 2009;135(3): 316-22.

Mehrotra R, Jaiswal KR, Mehrotra P, Kapoor S, Jain A. Evaluation of The Torque Control of the Maxillary Incisors In Lingual Orthodontics During Retraction. Int J Dent Sci and Res. 2015; 49(4):183-87.

Linkow LI. Implanto-Orthodontics. J Clin.Orthod 1970; 4(12): 685-705.

Rudolf DJ, Willies MG, Sameshima GT. Finite Element Model of Apical Force Distribution from Orthodontic Tooth Movement. Angle Orthod 2001; 71(2): 127-31.

Sia SS, Koga Y, Yoshida N. Determining The Center Of Resistance Of Maxillary Anterior Teeth Subjected To Retraction Forces In Sliding Mechanics. Angle Orthod 2007; 77(6):999-1003.

Burstone CJ. The Mechanics of the Segmented Arch Techniques. Angle Orthod 1966; 36(2):99-120.

Bohara P, Kumar M, Sharma H, Jayprakash PK, Mishra V, Savana K. Stress Distribution and Displacement of Maxillary Anterior Teeth During En-masse Intrusion and Retraction: A FEM Study. J Ind Orthod Soc; 51(3):152-159.

Creekmore TD, Eklund MK. The Possibility of Skeletal Anchorage. J Clin Orthod ;1983; 17:266-9.

Kang S, Shin-jae A, Ahn S.J, Heo MS, Kimd TW. Bone Thickness of the Palate for Orthodontic Mini Implant Anchorage in Adults. Am J OrthodDentofacialOrthop. 2007; 131:00.

Kim T, Suh J, Naksoo K, Lee M.Optimum. Conditions For Parallel Translation of Maxillary Anterior Teeth Under Retraction Force Determined With The Finite Element Method. Am J OrthodDentofacOrthop 2010; 137:639-47.

Sung SJ, Jang SW, Chun YS, Moon YS. Effective En-Masse Retraction Design with Orthodontic Mini-Implant Anchorage: A Finite Element Analysis. Am J OrthodDentofacOrthop. 2010; 137:648-57.

Ricketts RM, Bench RW, Gugino CF, Hilgers JJ, Schulhof RJ. Bioprogressive Therapy. Denver: Rocky Mountain Orthodontics and JPO Inc. 1979.

Shroff B, Lindauer SJ, Burstone CJ, Leiss JB. Segmented Approach to Simultaneous Intrusion and Space Closure: Biomechanics of the Three-Piece Base Arch Appliance Am J OrthodDentofacOrthop 1995; 107:136-43.

Zhang DQ, Su JH, Xu LY, Zhong PP. 3D Finite Element Study of En-Masse Retraction of Maxillary Anterior Teeth in Two Typical Force Directions. Chin J Dent Res 2008; 11(2): 101-7.

Tominaga JY, Tanaka M,Koga Y, Gonzales C, Kobayashi M, Yoshida N. Optimal Loading Conditions For Controlled Movement of Anterior Teeth In Sliding Mechanics. Angle Orthod. 2009; 79:1102–7.

Hong KR, Heo MJ, Ha KY. Lever-Arm and Mini Implant System for Anterior Torque Control during Retraction in Lingual Orthodontic Treatment. Angle Orthod 2005; 75(1):129-40.

Rex S, Balasubramanian, Ravi K, Krishna Raj P, Dilip S. Evaluation of Apical Force Distribution for Orthodontic Tooth Movements – A Finite Element Analysis. J IndOrthodSoc 2010; 44(1):38-42.

Mo Seo S et al. Torque control during anterior lingual retraction without posterior appliances. Korean J Orthod 2013;43(1):3-14.

How to Cite
Mishra, S., Kumar, M., Goyal, M., & Kushwah, A. (2021). Determination of Optimal Loading Conditions Using Lever Arm and Mini- Implant System for En-masse Retraction in Lingual Orthodontics – A FEM Study. UNIVERSITY JOURNAL OF DENTAL SCIENCES, 7(1).

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