Effective en-masse retraction design with orthodontic mini-implant anchorage: A finite element analysis

Factors controlling anterior torque during C-implant-dependent en-masse retraction without posterior appliances

“…However, using full fixed appliances with conventional mini-implants has some associated drawbacks that are related to the position of the CR and friction in the system. 12,13 A recent study showed the CR position to be located 13.5 mm posteriorly and 9 mm superiorly from the center of the archwire, similar to the estimations of Sung et al 13 and Melsen et al 32 In the finite element analysis study of Sung et al, 13 even though the vector of the retraction force was applied close to the CR for the 6 anterior teeth with an 8-mm ARH, the central and lateral incisors were not bodily retracted. They suggested that the compensating curves and the additional mini-implant placed between the incisors to add vertical forces would overcome the limitations of the ARH.…”

“…[2][3][4][5] When using mini-implants to retract the anterior teeth, it is most important to consider the location of the center of resistance (CR) relative to the location of the mini-implants. [6][7][8][9][10][11][12][13] Successful bodily translation of the anterior teeth might require additional complicated archwires or a supplementary mini-implant in the anterior segment. 13 If bilateral mini-implants are not in the same horizontal plane, as sometimes required by the anatomy of the maxilla, the clinician could see unwanted canting of the occlusal plane because of the different vectors of forces during retraction.…”

“…[6][7][8][9][10][11][12][13] Successful bodily translation of the anterior teeth might require additional complicated archwires or a supplementary mini-implant in the anterior segment. 13 If bilateral mini-implants are not in the same horizontal plane, as sometimes required by the anatomy of the maxilla, the clinician could see unwanted canting of the occlusal plane because of the different vectors of forces during retraction. 14 A final concern is that sliding mechanics in a full-arch appliance with mini-implant-assisted anterior retraction might be adversely affected by friction in the bracket slots and tubes.…”

Mechanical stability and clinical applicability assessment of novel orthodontic mini-implant design

“…As a result of efficient mechanics, mini-implants have been successfully used in treating complex cases that would not have been treatable with conventional orthodontics alone. [3][4][5][6] Currently, the scope of mini-implants has expanded to encompass both orthodontic and orthopedic movements. 7 For orthodontic tooth movements, a light force of 20-200g is ideal for various clinical treatments, including retraction, molar intrusion, extrusion, and openbite correction.…”

Torque Loss in En-Masse Retraction of Maxillary Anterior Teeth Using Miniimplants with Force Vectors at Different Levels: 3D FEM Study

“…The force application close to the centre of resistance (CR) can be achieved by modifying the heights of force application source (mini-implants at different heights) and the position of anteriorretraction hook (Chang Y et al, [11]). The finite element analysis was selected for this study because of its advantages like, it is a non-invasive technique, the object of interest can be studied in three dimensions, the actual physical properties of the materials involved can be simulated and the tooth, alveolar bone and the PDL can be simulated when the material properties of these structures are assigned, it is nearest that one possibly can get in simulating the oral environment in-vitro, the actual displacement of the tooth can be visualized, the actual stress experienced at any given point can be measured, the model can be magnified infinitely [12,14]. .…”