Optimal force magnitude loaded to orthodontic microimplants: A finite element analysis

Abstract

Objective: To find an optimal force that can be loaded onto an orthodontic microimplant to fulfill the biomechanical demands of orthodontic treatment without diminishing the stability of the microimplant. Materials and Methods: Using the finite element analysis method, 3-D computer-aided design models of a microimplant and four cylindrical bone pieces (incorporating cortical bone thicknesses of 0.5, 1.2, 2.0, and 3.0 mm) into which the microimplant was inserted were used. Various force magnitudes of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 N were then horizontally and separately applied to the microimplant head as inserted into the different bone assemblies. For each bone/ force assembly tested, peak stresses developed at areas of intimate contact with the microimplant along the force direction were then calculated using regression analysis and compared with a threshold value at which pathologic bone resorption might develop. Results: The resulting peak stresses showed that bone pieces with thicker cortical bone tolerated higher force magnitudes better than did thinner ones. For cortical bone thicknesses of 0.5, 1.2, 2.0, and 3.0 mm, the maximum force magnitudes that could be applied safely were 3.75, 4.1, 4.3, and 4.45 N, respectively. Conclusions: For the purpose of diminishing orthodontic microimplant failure, an optimal force that can be safely loaded onto a microimplant should not exceed a value of around 3. 75-4.5 N. (Angle Orthod. 2016;86:221-226.)

Evaluation of factors influencing the success rate of orthodontic microimplants using panoramic radiographs

“…OMIs were inserted into the attached gingiva just adjacent to the mucogingival junction, at the midpoint between the roots of the adjacent teeth, and immediately loaded with orthodontic forces of approximately 50 to 200 g using elastic chains. 25 All OMIs were directly placed by two right-handed operators (K.I.M. and J.M.C.)…”

Clinical applicability of IZC’s in orthodontics - A review

“…As von mises stress is directly proportional to force magnitude-220 to 340g (8 to 12 oz) of force is required for mechanics with mini-implants in the IZC area but in cases where two step retraction is required i.e., individual retraction of canines and premolars followed by anterior retraction or single tooth retraction then force must be adjusted between 150 and 200 g. So, an optimal force that can be safely loaded onto a micro-implant should not exceed a value of around 3.75-4.5 N as recommended by Alrbata. 6,22 However, according to a recent study by Paul P. (2021) 21 both in the MI and the bone maximum and minimum stresses was recorded when load was 12 oz at 8 oz respectively. Hence, the loading force should be between 8 -12 oz.…”

Maxillary total arch distalization with infra-zygomatic crest (IZC) bone screws for the correction of skeletal class II malocclusion: A case report

“…So, an optimal angulation and force that are required for the effective biomechanics of the IZC implants and can be safely loaded, should not exceed these values. 28,29…”