Mechanical influence of thread pitch on orthodontic mini-implant stability

Abstract

The aim of this study was to evaluate the effect of pitch distance on the primary stability (PS) of orthodontic mini-implants (MIs) in artificial bone. Twenty experimental MIs were allocated to two groups, according to their geometric design: G 1 (30 o X 0.6 mm) and G 2 (45 o X 0.8 mm), and inserted into artificial bone of different densities: D 1 (0.32 g/cm ). The maximum insertion torque (IT) and removal torque (RT) values were recorded in N.cm. Loss of torque (LT) values were obtained by calculating the difference between the IT and RT. MI mobility was measured by means of a Periotest assessment. Normality and homogeneity were determined by means of the Kolmogorov-Smirnov and Shapiro-Wilk tests, respectively. A two-way ANOVA was used to detect differences between the mini-implant design and density factors. The ANOVA/ Tukey tests were used to determine the intergroup difference. Higher IT values were observed for G 2 (p ≤ 0.05) in D 2 . No statistical difference for RT was observed between the groups, whereas G 2 presented higher values only for LT (p ≤ 0.05). The Periotest values (PTV) were higher for G 1 , in comparison with G 2 , in D 1 . G 1 presented better PS in D 2 (IT, RT and LT), whereas G 2 was found to be more stable in D 1 , after evaluation with Periotest.

Effects of a hydroxyapatite coating on the stability of endosseous implants in rabbit tibiae

“…The Periotest has been thoroughly studied and advocated as a reliable method for determining implant stability. [13][14][15][16] The Periotest measures implant mobility by percussing an abutment attached to the implant with an electromagnetically driven and electronically controlled rod fitted to the instrument. The contact time between the test object and tapping rod was measured with an accelerometer.…”

Bone quality affects stability of orthodontic miniscrews

“…In previous studies examining orthodontic miniscrews, various bone specimens have been used, including human cadaver bones 40 , 41 , artificial bones 15 , 29 , and animal bones 42 – 44 . Fresh human cadaver bones are costly and difficult to obtain.…”

“…In previous studies, porcine ribs, porcine femoral heads, and bovine pelvises were used as bone specimen materials 45 – 47 . Some studies have indicated that bovine pelvis bone is closest to that of human maxilla and mandible bones 42 . Therefore, bovine pelvis bones were selected as the bone specimen in this study.…”

Échecs des ancrages osseux

“…Les paramètres pouvant varier sont la profondeur des encoches, leur nombre ou encore l'angle qu'elles forment avec le corps. En cas de densité osseuse forte, un pas de petite taille associé à des angles d'arête faible favorise la tenue des vis [12]. Le contraire est vérifié.…”