Changes in the degree of bacterial contamination of different areas of a dental unit chair used in the clinical practice of dental hygiene after disinfection

This study was conducted to determine the importance of infection prevention and to promote effective disinfection through a comparison of the degrees of bacterial contamination before and after disinfection in the clinical laboratory of a dental hygiene department. The subjects were five infectionprone parts of a dental unit chair, including the back of the chair, the spitting bowl, the bracket button, the light handle, and the bracket handle, of the clinical laboratory of the dental hygiene department of K University in Gangwon Province. To compare the degree of bacterial contamination before disinfection with that after disinfection, a sterilized cotton swab was used to swipe a 1x1cm area on the surface of a dental unit chair before disinfection, after which the cotton swab was promptly put into a sterilized saline solution. Safe Clean Spray (Associated Dental Products Ltd. Kemdent Works, Swindon, UK) was then applied to the same 1 × 1 cm surface of the dental unit chair, and after 1 min, another sterilized cotton swab was used to swipe the area, after which the cotton swab was promptly put into a sterilized saline solution. The bacteria on the cotton swab were smeared onto a Lysogeny broth (LB) agar medium and were cultured for 48 h at 37°C. The colony-forming unit (CFU) results showed less bacteria after surface disinfection, and all the five areas of the dental unit chair showed significant results (p<0.05). The bacterial identification results showed the highest rate of enterococcus in the pre-disinfected spitting bowl, followed by the bracket handle, and the distribution of the gram-positive bacteria was high. Although most of the bacteria were eliminated after surface disinfection, there were some remaining bacteria. Therefore, the frequency of surface disinfection in clinical laboratories is increased to prevent human cross-contamination from bacteria, using a more potent and biostable disinfectant.