Evaluation of Orthodontic Mini-implant-anchored en masse Retraction of Maxillary Anterior Teeth with Reduced Bone Support: A Prospective Finite Element Analysis Study
Sonal Sahasrabudhe, M Sunil Kumar, Iram S Khan, Sindhu Naik, Ashok Kumar
Alveolar bone loss, Anterior retraction hook, Finite element analysis, Orthodontic mini-implant
Citation Information :
Sahasrabudhe S, Kumar MS, Khan IS, Naik S, Kumar A. Evaluation of Orthodontic Mini-implant-anchored en masse Retraction of Maxillary Anterior Teeth with Reduced Bone Support: A Prospective Finite Element Analysis Study. J Contemp Dent Pract 2021; 22 (7):833-839.
Aim: The purpose of this study was to evaluate force systems to bring about the en masse retraction of maxillary anterior teeth having reduced bone levels using finite element analysis.
Materials and methods: This is a prospective study. Three-dimensional finite element models of maxillary dentition having normal alveolar bone level and 2, 4, and 6 mm bone loss with first premolar extraction were constructed from a spiral CT scan of a skull. Archwire and brackets were modeled on the facial surfaces of teeth. Retraction force of 175 gm was applied from an orthodontic mini-implant placed bilaterally between the second premolar and first molar and 12 mm above plane of the archwire to anterior retraction hook (ARH) fixed at two heights of 6 and 10 mm above the archwire.
Results: Maximum displacement and periodontal ligament (PDL) stress were calculated for different combinations of bone levels and ARH. As the bone loss increased, the tipping tendency, amount of intrusion, and maximum von Mises stress in PDL also increased, showing a direct correlation.
Conclusion: To minimize tipping and PDL stress, the height of ARH should be increased in alveolar bone loss conditions to allow retraction force to pass through or even above the center of resistance of anterior teeth. Even then, pure bodily retraction may not be achieved, but tipping tendency can be reduced. Nevertheless, it may not be suitable to increase ARH beyond a limit owing to chances of irritation to the vestibular mucosa. Alternative methods should be contemplated to reduce the tipping behavior.
Clinical significance: The alternative is to apply a lighter retraction force to reduce lingual tipping. A higher counter-moment in the archwire or bracket can also be incorporated.
Artun J, Urbye K. The effect of orthodontic treatment on periodontal bone support in patients with advanced loss of marginal periodontium. Am J Orthod Dentofac Orthop 1988;93(2):143–148. DOI: 10.1016/0889-5406(88)90292-2.
Boyd RL, Leggott PJ, Quinn RS, et al. Periodontal implications of orthodontic treatment in adults with reduced or normal periodontal tissues versus those of adolescents. Am J Orthod Dentofac Orthop 1989;96(3):191–199. DOI: 10.1016/0889-5406(89)90455-1.
Melsen B, Agerbaek N, Markenstam G. Intrusion of incisors in adult patients with marginal bone loss. Am J Orthod Dentofac Orthop 1989;96(3):232–241. DOI: 10.1016/0889-5406(89)90460-5.
Yoshida N, Koga Y, Mimaki N, et al. In vivo determination of the centres of resistance of maxillary anterior teeth subjected to retraction forces. Eur J Orthod 2001;23(5):529–534. DOI: 10.1093/ejo/23.5.529.
Geramy A. Alveolar bone resorption and the center of resistance modification (3-D analysis by means of the finite element method). Am J Orthod Dentofac Orthop 2000;117(4):399–405. DOI: 10.1016/s0889-5406(00)70159-4.
Padmawar SS, Belludi A, Makhija PG, et al. Stress appraisal with simulation of en masse absolute intrusion of maxillary anteriors deploying strategic mini-implant locations: a finite element analysis. J Indian Orthod Soc 2012;46:77–81. DOI: 10.5005/jp-journals-10021-1064.
Tominaga JY, Tanaka M, Koga Y, et al. Optimal loading conditions for controlled movement of anterior teeth in sliding mechanics: a 3D finite element study. Angle orthod 2009;79(6):1102–1107. DOI: 10.2319/111608-587R.1.
Smith RJ, Burstone CJ. Mechanics of tooth movement. Am J Orthod 1984;85(4):294–307. DOI: 10.1016/0002-9416(84)90187-8.
Geramy A. Initial stress produced in the periodontal membrane by orthodontic loads in the presence of varying loss of alveolar bone: a three-dimensional finite element analysis. Eur J Orthod 2002;24(1):21–33. DOI: 10.1093/ejo/24.1.21.
Tanne K, Nagataki T, Inoue Y, et al. Patterns of initial tooth displacements associated with various root lengths and alveolar bone heights. Am J Orthod Dentofac Orthop 1991;100(1):66–71. DOI: 10.1016/0889-5406(91)70051-W.
Cobo J, Sicilia A, Argüelles J, et al. Initial stress induced in periodontal tissue with diverse degrees of bone loss by an orthodontic force: tridimensional analysis by means of the finite element method. Am J Orthod Dentofac Orthop 1993;104(5):448–454. DOI: 10.1016/0889-5406(93)70071-U.
Cobo J, Argfielles J, Puente M. Dentoalveolar stress from bodily tooth movement at different levels of bone loss. Am J Orthod Dentofac Orthop 1996;110(3):256–262. DOI: 10.1016/s0889-5406(96)80008-4.
Jeon PD, Turley PK, Ting K. Three-dimensional finite element analysis of stress in the periodontal ligament of the maxillary first molar with simulated bone loss. Am J Orthod Dentofacial Orthop 2001;119(5):498–504. DOI: 10.1067/mod.2001.112999.
Ona M, Wakabayashi N. Influence of alveolar support on stress in periodontal structures. J Dent Res 2006;85(12):1087–1091. DOI: 10.1177/154405910608501204.
Sung SJ, Jang GW, Chun YS, et al. Effective en-masse retraction design with orthodontic mini implant anchorage: a finite element study. Am J Orthod Dentofac Orthop 2010;137(5):648–657. DOI: 10.1016/j.ajodo.2008.06.036.
Ammar HH, Ngan P, Crout RJ, et al. Three-dimensional modeling and finite element analysis in treatment planning for orthodontic tooth movement. Am J Orthod Dentofac Orthop 2011;139(1):e59–e71. DOI: 10.1016/j.ajodo.2010.09.020.
Nanda R, Ghosh J. Biomechanical considerations in sliding mechanics. In: Nanda R, editor. Biomechanics in clinical orthodontics. Philadelphia: W. B. Saunders; 1997. p. 188–217.
Sia S, Shibazaki T, Koga Y, et al. Experimental determination of optimal force system required for control of anterior tooth movement in sliding mechanics. Am J Orthod Dentofac Orthop 2009;135(1):36–41. DOI: 10.1016/j.ajodo.2007.01.034.
Park HS, Kwon TG. Sliding mechanics with microscrew implant anchorage. Angle Orthod 2004;74(5):703–710. DOI: 10.1043/0003-3219(2004)074<0703:SMWMIA>2.0.CO;2.