The importance of biofilm contamination control for dental unit waterlines: a multicenter assessment of the microbiota diversity of biofilm in dental unit waterlines

Figures & data

Table 1. Characteristics of sampling dental chair units.

	Biofilm samples (n = 29)
	n	%
Origin
Stomatological hospitals	14	48
General hospitals	10	34
dental clinics	5	17
Sample
Biofilm of Water tubes	22	76
Biofilm of air tubes	7	24
Departments
General Dentistry	11	38
Orthodontics	7	24
Endodontics	4	14
Oral surgery	3	10
Prosthodontic	2	7
Implant	2	7
water supply
purified water	19	66
Municipal water system	10	34
Age
1 year	5	17
2 years	5	17
3 years	1	3
5 years	3	10
6 years	11	38
9 years	2	7
11 years	2	7
Treatment of incoming water
Filter	29	100
Treatment of DUWL
Chemical disinfection	29	100
Disinfection cycle
All the time/cycle	10	34
Once Every day	12	41
Once every two days	3	10
Once a week	4	14
Handpieces sterilization
After each patient	29	100

Table 2. Alpha-diversity indices and good coverage for microbial community among biofilm samples.

Microbial community	sample	Observed outs	chao1	Shannon	Simpson	Goods coverage	p
bacteria	Water tubes	203.86$\pm$28.40	203.94$\pm$28.43	4.34$\pm$0.13	0.86$\pm$0.01	1.000.00	>0.05
	Air tubes	186.4314.92	186.44$\pm$19.92	4.27$\pm$0.12	0.85$\pm$0.01	1.000.00
fungi	Water tubes	18.23$\pm$10.81	19.65$\pm$11.10	1.76$\pm$1.02	0.56$\pm$0.26	1.000.00	>0.05
	Air tubes	14.43$\pm$5.50	15.86$\pm$5.85	1.23$\pm$0.87	0.43$\pm$0.28	1.000.00

Figure 1. Relative abundance of bacterial and fungal community at genus level (Re: samples from air tubes for 16SrRNA, Rf: samples from air tubes for ITS2, Wa: sample from water tubes for 16SrRNA, Wb: sample from water tubes for ITS2, the Arabic numbers indicate the corresponding DCUs).

Table 3. The overall relative abundance (%) of potential pathogenic microorganism at genus level.

Pathogen	Biofilm samples from water tubes	Biofilm samples from air tubes	overall relative abundance
Bacteria
Pseudomonas	12.30$\pm$1.30	12.34$\pm$0.92	35.00$\pm$2.40
Stenotrophomonas	5.78$\pm$0.77	5.63$\pm$0.64	5.70$\pm$0.70
Hafnia-Obesumbacterium	4.80$\pm$0.85	4.71$\pm$0.64	4.80$\pm$0.80
Burkholderia-Caballeronia-Paraburkholderia	2.87$\pm$0.39	3.33$\pm$0.54	3.00$\pm$0.50
Ralstonia	2.59$\pm$0.67	2.15$\pm$0.39	2.50$\pm$0.60
Enterobacter	1.86$\pm$0.40	1.80$\pm$0.32	1.80$\pm$0.40
Klebsiella	1.65$\pm$0.37	1.53$\pm$0.21	1.60$\pm$0.30
Fungi
Malassezia	35.11$\pm$40.61	41.66$\pm$40.52	36.70$\pm$40.20
Candida	6.50$\pm$12.50	7.96$\pm$21.05	6.90$\pm$14.20
Alternaria	7.39$\pm$15.16	0.00$\pm$0.01	5.60$\pm$17.00
Cryptococcus	3.96$\pm$7.32	2.11$\pm$5.57	3.50$\pm$1.70
Rhodotorula	1.10$\pm$4.67	6.57$\pm$17.38	2.40$\pm$9.30
Rhinocladiella	1.71$\pm$5.05	0.36$\pm$0.96	1.40$\pm$4.40