Temporary anchorage device insertion variables: effects on retention

Abstract

Increasing penetration depth of TADs results in greater retention. Increased abutment head distance from cortical plate leads to decreased retention. Placement of TADs at 90 degrees to the cortical plate is the most retentive insertion angle. Insertion at an oblique angle from the line of force reduces retention of TADs.

Effects of placement angle and direction of orthopedic force application on the stability of orthodontic miniscrews

“…20,26,27 In contrast, others have recommended placing miniscrews at 90u to the bone surface for optimum retention, while indicating that placement angles less than 90u potentially create longer lever arms, reducing anchorage resistance so that failure can occur even within orthodontic force levels. 14,28 Based on our results and those of previous studies, we recommend placement of the miniscrew perpendicular to the cortical bone (P90u) as long as root damage can be avoided to take advantage of improved biological and biomechanical stability when applying heavy orthopedic forces.…”

“…29 Thin cortical bone can cause stability issues because the stresses are localized mainly to the cortical bone region. Although we were only able to test the effects of force direction with our pull-out model, the test results using miniscrews at various insertion angles also advocate perpendicular insertion, 14 as do our FEM results. In general, TADs are not loaded vertically in clinical situations, since orthodontic retraction forces usually induce stable horizontal/lateral forces to the TAD parallel to the occlusal plane.…”

“…12 But, as seen in clinical situations, different placement angles or loading orientations can induce changes in the maximum force that a miniscrew can withstand, leading to instability. 14,15 Therefore, the aim of this study was to examine the possibilities and risks of applying orthopedic forces to miniscrews in various clinical settings. The effect of applying heavy orthopedic forces at different placement angles and loading orientations was compared using FEA in combination with pull-out tests.…”

Estudo in vitro da perfuração radicular por diferentes diâmetros de mini-implantes

“…Este material tem sido usado em ensaios biomecânicos com mini-implantes (BRINLEY et al, 2009;HWANG, 2008;PETREY et al, 2010;SONG; et al, 2010). Todo o processo de substituição do silicone pela espuma de poliuretano foi realizado pela empresa Nacional Ossos (Jaú, SP).…”

“…Assim, optou-se pela utilização de osso artificial para servir de suporte aos dentes e também como meio de inserção de miniimplantes para comparação com os dentes humanos. Trata-se de um material à base de espuma sólida rígida de poliuretano, disponível em diversas densidades e empregado em testes experimentais com mini-implantes (BRINLEY et al, 2009;HWANG, 2008;PETREY et al, 2010;SONG;. O uso de osso artificial em ensaios mecânicos pode apresentar resultados diferentes do que os obtidos em humanos, porém ter uma uniformidade da densidade e da espessura da cortical óssea pode ser uma vantagem (CIARELLI et al, 1991).…”