In vitro evaluation of disinfection efficacy and physical properties of polyether impression material after ultraviolet-C radiation with different exposure times and distances

Statement of problem

Polyether impression material may be susceptible to water absorption when exposed to chemical disinfectants, and ultraviolet-C (UV-C) radiation could serve as an alternative disinfection method. However, studies on the disinfection efficacy and physical properties of polyether material after UV-C radiation are lacking.

Purpose

The purpose of this in vitro study was to evaluate the disinfection efficacy, contact angle, and linear dimensional change of polyether impression material after exposure to UV-C radiation at varying times and distances.

Material and methods

Disk-shaped polyether specimens were fabricated and divided into 12 groups based on 2 distances (8 cm and 16 cm) and 6 disinfection methods: no UV (UV0), UV radiation for 2.5, 5, 10, or 30 minutes (UV2.5, UV5, UV10, and UV30), and a 10-minute immersion in 0.5% sodium hypochlorite (NaOCl). Disinfection efficacy against Streptococcus mutans and Candida albicans, contact angle, and linear dimensional change were evaluated. Data were analyzed using the 2-way ANOVA with exposure times and distances as main factors, followed by the Tukey honestly significant difference test (α=.05).

Results

For both microbes, the UV2.5, UV5, and UV10 groups at 8 cm exhibited a significant reduction in the number of residual microbial cells compared with those at 16 cm (P<.001). Conversely, the UV0, UV30, and NaOCl groups showed no significant differences (P>.05). Complete microbial eradication was achieved after 10 minutes of UV-C radiation at 8 cm and 30 minutes at 16 cm. Comparing exposure times, the number of residual Streptococcus mutans and Candida albicans cells significantly decreased as UV-C exposure time increased for both distances (P<.001). All groups exhibited no significant differences in contact angle compared with the UV0 group at either distance (P>.05), except for the UV30 group at 8 cm and the UV5, UV10, and UV30 groups at 16 cm. The percentage of dimensional change in all groups ranged from 0.11% to 0.31%, all of which were below the International Organization for Standardization specification limit of 1.5%.

Conclusions

A 10-minute UV-C radiation at 8 cm effectively disinfected polyether impression material, comparable with a 10-minute immersion in 0.5% NaOCl. A 30-minute UV-C radiation at either 8 or 16 cm effectively disinfected polyether impression material, enhanced surface wettability, and maintained dimensional stability.