Porcelain color alteration after orthodontic bonding using three different surface preparation methods

Mehrnaz Moradinezhad, Mina Moradi, Milad Shamohammadi, Elham Hormozi, Amir Ghorani


Background: By increasing the number of adults seeking orthodontic treatment bonding
orthodontic brackets to the surfaces other than intact enamel has become necessary. The purpose
of this study was to evaluate the effect of three different surface preparation methods associated
with orthodontic bonding on porcelain color alteration.
Materials and Methods: In this in vitro study forty‑five porcelain discs (6‑ mm diameter, 2‑ mm
thickness) were fabricated. The color of the specimens was evaluated by means of a Vita Easyshade.
Commision Internationale de I’Eclairage (CIE) L* a* b* system was used for color measurement.
Then, the specimens were randomly divided into three groups (n = 15) with respect to the
surface preparation methods including a 9.6% hydrofluoric acid (HF) + silane, sandblasting, and
sandblasting + 9.6% HF + silane. Metal orthodontic brackets were bonded. Samples were stored
in 37° c water for 24 hours. Afterward, the brackets were debonded with a debonding plier and
porcelain surfaces were polished with a tungsten‑carbide bur. The color assessment was done,
and ΔE values were measured. ΔE = 3.7 units were considered as an acceptability threshold. Data
were analyzed with Paired t‑test and one‑way ANOVA. Level of significance was set at P < 0.05.
Results: Orthodontic bonding changed the color parameters significantly. Mean L*, a* and b*
difference were 1.35 ± 2.41, 0.19 ± 0.80, 0.89 ± 1.27 units, respectively (P = 0.003 for L*, P < 0.001
for a* and b*). There was not any significant difference in ΔE units between the groups (P = 0.456).
In all the groups the mean ΔE values were below 3.7 units and within the clinically acceptable limit.
Conclusion: Orthodontic treatment changed the CIE color parameters of porcelain surface.
However, the color alteration is below the clinically acceptable threshold. With regard to color
alteration, there is no difference between different surface conditioning methods.
Key Words: Dental bonding, dental debonding, dental porcelain, orthodontic brackets

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