Chlorhexidine hexametaphosphate as a coating for elastomeric ligatures with sustained antimicrobial properties: laboratory study

Yasmin Kamarudin, Matthew K Skeats, Anthony J Ireland*, Michele E Barbour

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

9 Citations (Scopus)
84 Downloads (Pure)


White spot lesions are a common side effect of orthodontic treatment. This laboratory study aimed to explore the suitability of chlorhexidine hexametaphosphate (CHX-HMP) as a coating for orthodontic elastomeric ligatures to provide sustained chlorhexidine (CHX) release.

Dissolution kinetics of CHX-HMP were firstly explored using spectroscopy and a colorimetric phosphate assay. Elastomeric ligatures were categorized into 3 groups—acetone-conditioned, ethanol-conditioned, and as received—and were then immersed in 5 mM CHX-HMP suspension or 5 mM chlorhexidine digluconate solution and rinsed. CHX release was measured over 8 weeks, and the effects of conditioning and immersion on elastomeric force and extension at rupture and surface topography were investigated.

CHX-HMP exhibited a gradual equilibration that had not reached equilibrium within 8 weeks, releasing soluble CHX and a mixture of polyphosphate and orthophosphate. CHX digluconate–treated ligatures showed no CHX release, whereas CHX-HMP–treated ligatures showed varying degrees of release. As received, CHX-HMP–treated ligatures showed a modest release of CHX up to 7 days. Acetone conditioning did not enhance CHX-HMP uptake or subsequent CHX release and caused a deterioration in mechanical properties. Ethanol conditioning enhanced CHX-HMP uptake (6×) and led to a sustained CHX release over 8 weeks without affecting mechanical properties.

Within the inherent limitations of this in-vitro study, CHX-HMP led to a sustained release of CHX from orthodontic elastomeric ligatures after ethanol conditioning. Conditioned and coated elastomeric ligatures may ultimately find application in the prevention of white spot lesions in orthodontic patients.
Original languageEnglish
Pages (from-to)e73-e82
Number of pages10
JournalAmerican Journal of Orthodontics and Dentofacial Orthopedics
Issue number5
Early online date29 Sept 2020
Publication statusPublished - 1 Nov 2020


  • chlorhexidine
  • chlorhexidine hexametaphosphate
  • fixed appliances
  • elastomeric ligatures
  • orthodontic ligatures


Dive into the research topics of 'Chlorhexidine hexametaphosphate as a coating for elastomeric ligatures with sustained antimicrobial properties: laboratory study'. Together they form a unique fingerprint.

Cite this