Stress distribution patterns at mini-implant site during retraction and intrusion—a three-dimensional finite element study

Abstract

BackgroundThe purpose of this study was to evaluate the stress patterns produced in mini-implant and alveolar bone, for various implant dimensions, under different directions of simulated orthodontic force, using a three-dimensional finite element method.MethodsEight finite element (FE) models of mini-implant and bone were generated with insertion angles of 30° and 60°, diameters of 1 and 1.3 mm, and lengths of 6 and 8 mm. A simulated constant orthodontic force of 2 N was applied to each of these FE models in three directions simulating anterior retraction, anterior intrusion and retraction, and molar intrusion.ResultsComparison of the maximum von Mises stress in the mini-implant showed that the 1-mm diameter produced significantly high stress, and the amount of stress produced was more for a mini-implant inserted at an angle of 60°. The cortical bone showed that high stresses were generated for the 1-mm-diameter mini-implant and on increasing the insertion angulation from 30° to 60°, the stress produced increased as well. The comparison of von Mises stress in the cancellous bone was insignificant as the amount of stress transmitted was very low.ConclusionsThe 1-mm-diameter mini-implants are not safe to be used clinically for orthodontic anchorage. The 1.3 × 6 mm dimension mini-implants are recommended for use during anterior segment retraction and during simultaneous intrusion and retraction, and the 1.3 × 8 mm dimension mini-implant is recommended for use during molar intrusion. All mini-implants should be inserted at a 30° angle into the bone for reduced stress and improved stability.

Dental Implant Length and Diameter: A Proposed Classification Scheme

“…Moreover, in a recent study by Romanos et al the term “narrow implant” was used to describe a 3.7 mm diameter implant; however, Ioannidis et al used the same term to define implants with a diameter of 3.3 mm. More interestingly, Christensen termed 3.3 mm diameter implants as “standard diameter implants.” Furthermore, Ertugrul and Pipko categorized dental implants with diameters of 2.2 mm as mini‐implants, whereas in Sivamurthy and Sundari's study, dental implants with diameters ranging between 1 and 1.3 mm were considered “mini‐implants.” As a result of this confusion, it is not unexpected to find in the literature an implant with known diameter (1.8 mm) that has four different classifications in four different studies (mini, small, narrow, and very small). Another example of unconformity would be when two different terms were used to describe the same implant size by the same author .…”

“…More interestingly, Christensen 6 termed 3.3 mm diameter implants as "standard diameter implants." Furthermore, Ertugrul and Pipko 10 categorized dental implants with diameters of 2.2 mm as mini-implants, whereas in Sivamurthy and Sundari's study, 11 dental implants with diameters ranging between 1 and 1.3 mm were considered "miniimplants." As a result of this confusion, it is not unexpected to find in the literature an implant with known diameter (1.8 mm) that has four different classifications in four different studies (mini, 12 small, 4 narrow, 13 and very small 14 ).…”

Miniscrew Composition, Transmucosal Profile, and Cortical Bone Thickness: A Three-dimensional Finite-element Analysis of Stress Fields

“…The stress fields over the FE models were assessed according to the maximum distortion energy theory, 14 and have been used previously in orthodontics by other researchers. [15][16][17][18] The stress field in the cortical bone was assessed and compared among the models. The simulations were divided into two length groups (1 and 2 mm) and subjected to various MS and transmucosal profile material combinations (Table 1).…”

Molar protraction using miniscrews (temporary anchorage device) with simultaneous correction of lateral crossbite: An orthodontic case report

“…This method allows more bone contact of implants due to the conical shape of dental roots and reduces stress and improve stability. [ 14 15 ] Protraction force was given by elastic chain because it provides constant and continuous force. Bondable button was placed in the palatal surface of 15 and 17 for the bilateral force to counteract the molar rotation [ Figure 7 ], and molar protraction was done on 0.019” × 0.025” stainless steel wire.…”