Inability to form a biofilm of Streptococcus mutans on silver fluoride– and potassium iodide–treated demineralized dentin
Geoffry M. Knight, BDSc, MSc, PhD1/ John M. McIntyre, AM, BDSc, PhD1/ Graham G. Craig, AM, MDS, PhD2/Mulyani, BDS, MDS, PhD1/ Peter S. Zilm, BSc (Hons), PhD1/Neville J. Gully, BSc (Hons), PhD1
Objective: The presence of abiofilm is necessary for both initiation and progression of dental caries. Silver-based preparations incorporated into, or applied onto, various materials designed for medical use have been shown to be effective in inhibiting biofilm formation. The purpose of this in vitro study was to measure whether a topical application of diamine silver fluoride (AgF) followed by potassium iodide (KI) onpartially demineralized dentin affected the formation of a Streptococcus mutans biofilm. Method and Materials: Forty partially demineralized dentin disks were divided into 4 groups as follows: 10 disks as a control, 10 disks treated with AgF followed by KI, 10 disks treated with KI, and 10 disks treated with AgF. The outer surfaces of the disks were examined with a scanning electron microscope. Crosssections of the disks were subjected to electron probe microanalysis (EPMA) to determine the levels of calcium, phosphorous, silver, and fluoride in the dentin. Results: An S mutans biofilm covered the entire exposed surfaces of all control and KI-treated disks. No discernible bacterial biofilm was detected on disks treated with AgF or AgF/KI. Detectable amounts of silver and fluoride were found upto 450 µm in the AgF and AgF/KI sections. Conclusions: Demineralized dentin disks treated with AgF and AgF/KI prevented the formation of an S mutans biofilm and were significantly more resistant to further demineralization than the control and KI-treated disks over the experimental period. The presence of silver and fluoride in the outer layers of the disks treated with AgF and AgF/KI was thelikely cause of the prevention of biofilm formation. Additional studies are required before any clinical recommendations can be made. (Quintessence Int 2009;40:155–161)
Key words: biofilm, demineralized dentin, potassium iodide, silver fluoride, Streptococcus mutans
The arrestment of early dentin caries using chemotherapeutic procedures is a desirable goal, especially on root surfaces and inareas where access for restorative proce-
Dental School, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia.
formerly, Associate Professor, Preventive Dentistry, University of Sydney, Sydney, Australia; currently, Editor, Dental Outlook Publications.
Correspondence: Dr Geoffrey M. Knight, 20 Carpenter St, Brighton, Victoria, 3186, Australia. Fax: 613 95925866. E-mail: email@example.com
dures is limited. To date, the main chemotherapeutic approaches to the problem have involved the use of fluorides1 and, more recently, ozone.2 A metal-based topical fluoride preparation, diamine silver fluoride (referred to as AgF in this article), has been used to arrest dentin caries in the primary dentition3,4 and reduce caries formation in deciduousteeth and permanent first molars.5 However, its potential in arresting early dentin caries in sites such as root surfaces of the permanent dentition is not known.
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Q U I N T E S S E N C E I N T E R N AT I O N A L
Knight et al
Following the application of silver salts to a treatment site, excess free silver ions have traditionally been reduced by application of either eugenol or stannous fluoride, resulting in the formation of a black precipitate.6–8 To circumvent this problem, another approach is...