# Biomimetic Surface Modification of Dental Zirconia via UV Irradiation for Enhanced Aesthetics and Wettability

## TL;DR

This paper shows that UV light can change the color and wettability of dental zirconia, which could improve the appearance of dental crowns.

## Contribution

The study introduces UV-C irradiation as a novel method to modify dental zirconia's aesthetics and wettability without altering its crystal structure.

## Key findings

- UV-C irradiation at 222 and 254 nm caused clinically perceptible color changes in zirconia.
- 222 nm UV irradiation reduced water contact angle more effectively than 254 nm.
- UV treatments increased the Zr/O ratio and did not damage the zirconia crystal structure.

## Abstract

Zirconia is a material that mimics human teeth and has been extensively studied and applied. This study investigated the surface modifications of dental zirconia induced by two UV-C wavelengths (222 and 254 nm). A total of 72 zirconia specimens were prepared and divided into groups for irradiation at varying distances (1, 6, 12 cm) and durations (40, 120, 480 and 1440 min), with three specimens retained as untreated controls. Surface changes were assessed by measuring colour difference (ΔE) and water contact angle, and by analyzing surface morphology and elemental composition using SEM and EDX, and XRD was employed to determine the crystalline structure. The results showed that both wavelengths induced clinically perceptible colour changes (ΔE > 2.0), with the most pronounced effect at 6 cm for 222 nm and 1 cm for 254 nm. WCA decreased significantly with irradiation time, showing a linear correlation with log(time), and 222 nm irradiation yielded lower WCA than 254 nm. While SEM revealed no morphological changes, both UV treatments significantly increased the Zr/O ratio compared to the control. XRD tests confirmed that UV-C irradiation does not damage the zirconium oxide crystal structure. It is concluded that both UV-C wavelengths can alter the colour and enhance the wettability of zirconia; these modifications are particularly relevant for dental restorative applications, specifically in the fabrication of anterior tooth crowns, where achieving a natural tooth-like appearance is desired.