Yu-Ying Zheng,1,2,* Yuan-Yuan Wang,1,3,* Qian Guo,1,4 Chan-Yuan Shen,1,5 Rong Huang,1,2 Li Wang,1,6 Huan Sun1,2 

1State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, People’s Republic of China; 2Department of Comprehensive Emergency, School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei Province, 430079, People’s Republic of China; 3Center for Oral and Maxillofacial Surgery, School & hospital of stomatology (Optics Valley Branch), Wuhan University, Wuhan, Hubei Province, 430075, People’s Republic of China; 4Center for Orthodontics and Pediatric Dentistry, School & hospital of stomatology (Optics Valley Branch), Wuhan University, Wuhan, Hubei Province, 430075, People’s Republic of China; 5Department of Center for Emergency and General Dentistry, School & hospital of stomatology (Optics Valley Branch), Wuhan University, Wuhan, Hubei Province, 430075, People’s Republic of China; 6Department of Nursing, School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei Province, 430079, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Huan Sun, Department of Comprehensive Emergency, School & Hospital of Stomatology, Wuhan University, No. 237 of Luoyu Road, Hongshan District, Wuhan, 430079, Hubei Province, People’s Republic of China, Tel +86 13986003844, Email sunhuansh01@163.com Li Wang, Department of Nursing Department, School & Hospital of Stomatology, Wuhan University, No. 237 of Luoyu Road, Hongshan District, Wuhan, 430079, Hubei Province, People’s Republic of China, Tel +86 027-87686387, Email liwangwlwl@126.com

Objective: This study aimed to evaluate the long-term efficacy of two disinfection methods for waterline systems in inactive dental chair units (DCUs).
Methods: On-site sampling and quantitative bacterial analysis were conducted to compare the effectiveness of chlorine-based disinfectants and a combination of multi-enzymatic detergent with hypochlorous acid in controlling microbial contamination in waterline systems of inactive DCUs.
Results: No statistically significant differences in disinfection efficacy were observed between the treatment and control groups immediately after disinfection or on the third day post-disinfection (p > 0.05). However, significant differences were observed on the fifth day and seventh day following disinfection (p < 0.001).
Conclusion: Both chlorine-based disinfectants and the combination of multi-enzymatic detergent with hypochlorous acid effectively controlled contamination in waterline systems for DCUs inactive for up to three days. For periods of inactivity exceeding five days, the combination of multi-enzymatic detergent with hypochlorous acid demonstrated superior efficacy by reducing biofilm adhesion over time.

Keywords: chlorine-containing disinfectant, dental chair unit, hypochlorous acid, inactive, multienzyme, waterline disinfection