The Potential of Robusta Coffee Bean Extract (Coffea canephora) in Reducing Surface Roughness of Stainless-Steel and CuNiTi Orthodontic Wires

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Robusta Coffee Bean Extract Reduces Surface Roughness of Stainless-Steel and CuNiTi Orthodontic Wires

A laboratory study published in September 2026 demonstrates that Robusta coffee bean extract (Coffea canephora) acts as an effective natural corrosion inhibitor to reduce surface roughness on orthodontic archwires. The research was conducted by Leliana Sandra Devi, Herniyati, Dwi Prijatmoko, Lusi Hidayati, Agus Sumono, Swasthi Prasetyarini, Amalia Tri Utami, and Amara Intan Kayla from the Faculty of Dentistry at the University of Jember, Indonesia. Published in the International Journal of Contemporary Sciences (IJCS), the findings highlight an eco-friendly natural compound that helps prevent orthodontic wire degradation, lower friction during treatment, and improve patient comfort.

Background and Relevance

Orthodontic treatment for correcting malocclusion relies on archwires, such as stainless-steel and copper-nickel-titanium (CuNiTi), to exert continuous forces that move teeth into proper alignment. However, the human oral environment—characterized by fluctuating pH levels and acidic conditions—frequently triggers metallic corrosion. Corrosion increases the surface roughness of orthodontic wires, leading to higher friction between the wire and bracket slots. This increased friction impairs tooth movement, lengthens treatment duration, and can cause soft-tissue irritation or allergic reactions in patients. Controlling wire corrosion with organic inhibitors derived from local agricultural products, such as Robusta coffee beans cultivated in Jember, offers a sustainable bio-based solution for dental material development.

Simplified Methodology

The research team performed a laboratory posttest-control-group experiment using 16 stainless-steel and 16 CuNiTi orthodontic wires manufactured by American Orthodontics. Wire samples were assigned to a control group or one of three treatment groups. All samples were submerged in artificial saliva for seven days to replicate oral conditions, with the treatment groups receiving twice-daily immersion in Robusta coffee bean extract at concentrations of 1.5 g/L, 2.0 g/L, and 2.5 g/L. Surface roughness values (Roughness Average/Ra) were measured using a Kosaka SE800 Surface Roughness Tester, and data were statistically evaluated using one-way ANOVA and post-hoc LSD tests.

Key Findings

The experimental measurements revealed significant reductions in wire surface roughness following application of Robusta coffee bean extract:

• Optimal Concentration Identified: The 2.0 g/L Robusta coffee extract concentration (group T-2) produced the lowest average surface roughness values across both stainless-steel and CuNiTi orthodontic wires.
• Significant Smoothness Improvement: On stainless-steel wires, the mean surface roughness dropped from 0.0675 Ra in the control group to 0.0225 Ra in the 2.0 g/L group. For CuNiTi wires, roughness decreased from 0.1500 Ra in the control group to 0.0900 Ra in the 2.0 g/L group.
• Critical Saturation Threshold: Increasing the extract concentration to 2.5 g/L (group T-3) led to higher roughness values (0.0825 Ra for stainless-steel and 0.1800 Ra for CuNiTi). Exceeding the critical inhibitor concentration creates an uneven protective film and triggers layer decomposition, highlighting the necessity of precise dosing.

Implications and Real-World Impact

The bioactive compounds in Robusta coffee beans—specifically flavonoids, tannins, and alkaloids—contain hydroxyl and polar functional groups with free electron pairs that bind to metal ions. These chemical interactions form a thin protective passive layer (Ni(OH)2) over the wire surface, shielding it from corrosive environmental factors. This discovery opens opportunities for oral healthcare manufacturers to formulate natural dental care products, such as specialized mouthwashes or cleaning solutions containing Robusta coffee extracts. Utilizing natural organic inhibitors helps maintain smooth wire surfaces, reduces treatment friction, and optimizes orthodontic care outcomes.

Leliana Sandra Devi and her research team at the University of Jember emphasized, "Robusta coffee bean extract (Coffea canephora) at a concentration of 2 g/L is the most effective concentration in reducing the surface roughness of orthodontic wires made of stainless steel and CuNiTi through passive protective layer formation".

Author Profiles:

1. drg. Leliana Sandra Devi, M.Kes. is a researcher and lecturer at the Faculty of Dentistry, University of Jember, Indonesia, specializing in orthodontics and dental materials science.
2. Prof. Dr. drg. Herniyati, M.Kes. is a senior academic and researcher at the Faculty of Dentistry, University of Jember, Indonesia, with expertise in orthodontics and tooth movement mechanics.
3. Dr. drg. Dwi Prijatmoko, Ph.D. is a faculty member and researcher at the Faculty of Dentistry, University of Jember, Indonesia, specializing in dental materials and clinical orthodontics.
4. drg. Lusi Hidayati, M.Kes. is a lecturer and researcher at the Faculty of Dentistry, University of Jember, Indonesia, focusing on dental materials and biomaterials.
5. Ir. Agus Sumono, M.T. is an engineering academic and researcher at the University of Jember, Indonesia, specializing in materials engineering and metallic testing.
6. drg. Swasthi Prasetyarini, M.Kes. is a dental researcher at the Faculty of Dentistry, University of Jember, Indonesia, specializing in preventive dentistry and natural compounds.
7. drg. Amalia Tri Utami, M.Biomed. is a biomedical researcher at the Faculty of Dentistry, University of Jember, Indonesia, focusing on basic dental sciences.
8. Amara Intan Kayla, S.KG. is a dental researcher affiliated with the Faculty of Dentistry, University of Jember, Indonesia.

Source Information:

• Article Title: The Potential of Robusta Coffee Bean Extract (Coffea canephora) in Reducing Surface Roughness of Stainless-Steel and CuNiTi Orthodontic Wires
• Journal Name: International Journal of Contemporary Sciences (IJCS)
• Publication Year: 2026 (Vol. 4, No. 9, pp. 2353–2366)
• DOI: https://doi.org/10.55927/jrgf0245
• Official URL: https://journalijcs.my.id/index.php/ijcs