Rotational Resistance of Surface-Treated Mini-Implants

Abstract

Objective: To test the hypothesis that there is no difference in the stability and resistance to rotational moments of early loaded sandblasted and acid-etched (SLA) mini-implants and those of machined-surface implants of the same size and shape. Materials and Methods: A randomized complete block design was used in 12 skeletally mature male beagle dogs. Ninety-six orthodontic mini-implants were tested. Two types of implants were used: some had SLA surface treatment and some had machined surfaces without coating. After 3 weeks of healing, rotational moments of 150 g were applied. The success rates, maximum torque values, angular momentum, and total energy absorbed by the bone were compared. All values were subjected to mixed-model analysis to evaluate the influence of surface treatment, rotational force direction, and site of implantation. Results:The maximum insertion torque and angular momentum of SLA implants were significantly lower than those of machined implants (P ϭ .034, P ϭ .039). The SLA implants had a significantly higher value for total removal energy than the machined implants (P ϭ .046). However, there were no significant differences in total insertion energy, maximum removal torque, and removal angular momentum between the 2 groups. There was no significant difference between clockwise and counterclockwise rotation in all measurements. Conclusion: SLA mini-implants showed relatively lower insertion torque value and angular momentum and higher total energy during removal than the machined implants, suggesting osseointegration of the SLA mini-implant after insertion. (Angle Orthod. 2009;79:899-907.)

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

“…[17][18][19]21 However, this does not mean that the mini-implant will be difficult to remove. 19,33 The mini-implant used in this study, the C-implant, was a sand-blasted, large-grit, acid-etched, surface-treated mini-implant.…”

“…The retention portion of the C-implant has a higher osseointegration potential when compared with smooth titanium mini-implants and is better able to resist the rotational tendency during heavy dynamic loads. [19][20][21]33,34 Seo et al, 33 in a study of the histologic and histomorphometric findings of retrieved sandblasted, large grit, acid-etched C-implants that were functionally loaded, showed 52.6% of mean boneimplant contact (%) (excluding the upper smoothsurfaced 2-mm portion of the mini-implant). These authors described the C-implant as a "partially osseointegrated mini-implant."…”

“…2,[15][16][17][18] This concept developed because partially osseointegrated mini-implants or plates can easily endure multidirectional heavy forces even when they support orthodontic archwires. [19][20][21] In C-therapy, it is possible to retract the anterior segment independently by directly placing the wire into the hole of the mini-implant. 2,15,22 This mini-implant system allows light continuous forces, the ability to control complex tooth movements, minimum friction, and no need for patient compliance.…”

Root and Bone Response to the Proximity of a Mini-Implant under Orthodontic Loading

“…To enhance the stability of the small mini-implant, it is helpful to improve the shape, thread, surface treatment, and insertion method. 14,25,26 The use of 3-D CT or an appliance to avoid root contact can be useful for safe insertion of the mini-implant. 6 Future studies should investigate how to enhance mini-implant stability and decrease damage during insertion.…”

Three-dimensional finite element analysis for determining the stress distribution after loading the bone surface with two-component mini-implants of varying length

“…The screw part of the mini-implant is also surface treated for better osseointegration, which allows the application of dynamic or rotational forces. [9][10][11][12] The head part of the mini-implant, from the top of the screw part to the hole in the head part, is available in 3 sizes: 1 mm, 2 mm, and 3 mm (Fig 2). The mini-implant has also been used as a provisional or final prosthetic implant in children or patients who have insufficient space for holding a conventional dental implant.…”