Formation of carbon-added anatase-rich TiO2 layers on titanium and their antibacterial properties in visible light

Takatoshi Ueda; Naoki Sato; Ryusuke Koizumi; Kyosuke Ueda; Koyu Ito; Kouetsu Ogasawara; Takayuki Narushima

doi:10.1016/j.dental.2020.10.009

Formation of carbon-added anatase-rich TiO₂ layers on titanium and their antibacterial properties in visible light

Dent Mater. 2021 Feb;37(2):e37-e46. doi: 10.1016/j.dental.2020.10.009. Epub 2020 Nov 13.

Authors

Takatoshi Ueda¹, Naoki Sato¹, Ryusuke Koizumi¹, Kyosuke Ueda¹, Koyu Ito², Kouetsu Ogasawara², Takayuki Narushima³

Affiliations

¹ Department of Materials Processing, Tohoku University, 6-6-02 Aza Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
² Department of Immunobiology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.
³ Department of Materials Processing, Tohoku University, 6-6-02 Aza Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan; Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaragi 305-0047, Japan. Electronic address: narut@material.tohoku.ac.jp.

PMID: 33198964
DOI: 10.1016/j.dental.2020.10.009

Abstract

Objective: To avoid risk of infections associated with dental implants, thermal oxidation processes for practical dental Ti alloys were studied for both high bonding strength and antibacterial properties in visible light.

Methods: Two-step thermal oxidation, comprising carburization (first step of treatment: in Ar-1%CO gas) and subsequent oxidation (second step of treatment: in air), was conducted on commercially pure (CP) Ti, Ti-6Al-4V (Ti64), and Ti-6Al-7Nb (Ti67) alloys to form TiO₂ layers. Their bonding strengths and antibacterial properties against Escherichia coli (E. coli) in visible light (λ ≥ 400 nm) were evaluated.

Results: TiO₂ layers formed on each metal were composed of anatase and/or rutile. Anatase fraction and carbon concentration in the layers decreased with increasing temperature in the second step of treatment. Antibacterial properties of the TiO₂ layers were dependent on the temperature in the second step of treatment. An approximate antibacterial activity value of 2 (killing ∼99% bacteria) was obtained when the temperatures in the second step of treatment were 673 and 773 K for CP Ti, 773 K for Ti64, and 773 and 873 K for Ti67. It was found that the TiO₂ layer must contain carbon and be anatase-rich to exhibit excellent antibacterial properties. Bonding strength between the substrate and TiO₂ layers formed at 773 K in the second step of treatment exceeded 80 MPa and was independent of substrate type.

Significance: TiO₂ layers, possessing both high bonding strength and excellent antibacterial properties, were successfully formed on practical dental Ti alloys via two-step thermal oxidation.

Keywords: Antibacterial activity; Dental application; Titanium alloys; Two-step thermal oxidation; Visible-light responsive.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anti-Bacterial Agents / pharmacology
Carbon*
Escherichia coli
Light
Surface Properties
Titanium*

Substances

Anti-Bacterial Agents
titanium dioxide
Carbon
Titanium