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Evaluation of frictional resistance between monocrystalline (ICE) brakcets and Stainless Steel, Beta TMA and NiTiarch wires
Meysam Mirzaie, Valiollah Arash, Mahmoud Rabiee, Iman Ramezani, Ali Bijani,
Volume 2, Issue 2 (9-2013)
Abstract

Introduction: When using sliding mechanics for space closure during orthodontic treatment, friction occurs at the bracket-wire interface. The aim of this study was to evaluate the frictional resistance between monocrystalline (ICE) brackets and Stainless Steel, Beta TMA and NiTi wires.

Methods: In this experimental study, we used 5 different types of orthodontic wires. Brackets and wires were divided in to 5 groups: 1-(monocrystalline+stainless steel 18) 2–(monocrystalline+stainless steel 19×25) 3-(monocrystalline+Beta-TMA) 4–(monocrystalline+Beta TMA 19×25) 5-(monocrystalline+NiTi 18). Instron Universal Testing Machine was used to investigate the static frictional resistance. The angulation between bracket and wire was 0 and the wires were pulled through the slots at a speed of 10 mm/min. Tests were performed 10 times for each group in artificial saliva. The average of 10 forces recorded was considered as static friction. One-way ANOVA and SPSS Version 18 and LSD post hoc test were used to evaluate the results of the study.

Results: The mean static frictional force for each group was: group1: 0.82 ± 0.14, group 2: 1.09 ± 0.30, group 3: 0.87 ± 0.53, group 4: 1.9 ± 1.16, group 5: 1.42 ± 0.30. There was a significant difference when comparing the two groups of similar wires in terms of shape (round or rectangular cross-section) as when comparing Beta TMA 18 and 19×25 arch wires with each other, the obtained p-value was 0.023, while the obtained p-value for the comparison of stainles steel arch wires was 0.034 .

Conclusions: The result of this study shows that Stainless Steel 18 wires generate the least amount of friction and round wires produce less friction than the rectangular wires. Beta TMA wires generate the highest amount of friction.


Effect of CO2 laser irradiation on the surface of the polycrystalline ceramic bracket and the rate of canine movement with sliding mechanic
Mostafa Ebrahimi, Reza Ghorbanipour, Tania Ghasemi, Ali Bijani, Maysam Mirzaie,
Volume 11, Issue 2 (9-2022)
Abstract
Introduction: Metal brackets are the most commonly used brackets in clinical orthodontics, but the sight of color of the metal bracket can be unpleasant for some patients. Ceramic brackets offer the desired beauty but they have higher frictional resistance.  Considering that in vitro studies suggest that CO2 laser reduces the friction between the wire and slot of the bracket in the sliding mechanics, the aim of this study was to evaluate the clinical effect of CO2 laser on the speed of tooth movement using the sliding mechanics.
Materials & Methods: This randomized double-blind clinical trial was performed on 7 patients and a total of 13 half jaws in each group. These patients were candidates for bilateral extraction of the first premolars due to lack of space or dentoalveolar protrusion. After alignment and leveling, the ceramic brackets were passively bonded. The ceramic brackets of the experimental group irradiated with the CO2 laser and the brackets of the control group were bonded unchanged. The brackets were examined with an atomic force microscope (AFM) before and after irradiation. Statistical data were analyzed paired t-test to compare the rate of gap closure between the two groups at one-month intervals. ANOVA was used to examine the reduction in spacing at three-month intervals. A value of p<0.05 was considered statistically significant.
Results: The rate of gap closure between the two groups was compared at one-month intervals, which was not statistically significant in either month. Furthermore, in the comparison between the study and control groups, the decrease in the distance between the canine and second premolars was not statistically significant after a total of three months (p=0.0918).
Conclusion: According to the results of this study, CO2 laser irradiation of the bracket surface has no effect on the speed of movement of the canine when sliding on the wire.

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