Korean J Orthod.  2015 Jan;45(1):29-37. 10.4041/kjod.2015.45.1.29.

Comparison of the frictional characteristics of aesthetic orthodontic brackets measured using a modified in vitro technique

• Arici N
• Akdeniz BS
• Arici S

• KMID: 2074820
• DOI: http://doi.org/10.4041/kjod.2015.45.1.29

Abstract

OBJECTIVE
The coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined.
METHODS
Four types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a 0.017 x 0.025-in wire in the 0.018-in slots and a 0.019 x 0.025-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukey's post-hoc test at the 95% confidence level (alpha = 0.05) were also used for statistical analyses.
RESULTS
There were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (micro = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (micro = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (micro = 0.85).
CONCLUSIONS
Brackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases.

Keyword

Brackets; Archwires; Coefficient of friction; Tribometer

MeSH Terms

Aluminum Oxide
Ceramics
Friction*
Orthodontic Brackets*
Stainless Steel
Aluminum Oxide
Ceramics
Stainless Steel

Figure

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  Figure 1 Modified CSM tribometer test equipment (A), schematic drawing of the bracket holder part (B), and close-up view of bracket (upper) and archwire (lower) holding parts (C).

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  Figure 2 Mean coefficient of friction (COF) values of the brackets tested. Refer to Table 1 for the explanation about each product.

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  Figure 3 Profile plot showing no interaction between slot size (0.018 inches [in] and 0.022 in) and bracket material from the two-way analysis of variance. COF, Coefficient of friction; G, Gemini metal; C, Clarity metal-slot ceramic; I, InVu ceramic; P, Pure ceramic; T, Transcend ceramic brackets. Refer to Table 1 for the explanation about each product.

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  Figure 4 Post-experiment light microscope images of the tested brackets (left) and the archwires coupled with them (right). Arrows show the wear areas on the archwires. Letters indicate the group labels (G, Gemini metal; C, Clarity metal-slot ceramic; I, InVu ceramic; P, Pure ceramic; T, Transcend ceramic brackets). Refer to Table 1 for the explanation about each product.

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