title: Effect of gallium on growth of Streptococcus mutans NCTC 10449 and dental tissues.
abstract: Gallium-doped phosphate-based glasses (Ga-PBG) were assessed for their impact on Streptococcus mutans and dental mineralisation, firstly by disc diffusion assays followed by biofilms grown on nitrocellulose filter membrane (NFM) and constant-depth film fermentor (CDFF). Short-time exposure (10 min) effects of Ga-PBG on S. mutans biofilm were compared with that of 0.2% chlorhexidine. The effects of Ga-PBG on bovine enamel (which was investigated under pH-cycling condition) and dentine were analysed using transverse microradiography (TMR), profilometry and inductively coupled plasma optical-emission spectrometry (ICP-OES). The disc diffusion assays showed inhibition zones of 24.5 ± 0.5 mm for Ga-PBG compared with controls (C-PBG). Ga-PBG showed statistically significant growth inhibition of S. mutans biofilms on NFM (p = 0.001) and CDFF (p < 0.046) compared with hydroxyapatite (HA) and C-PBG. The CDFF assay revealed a maximum of 2.11 log colony-forming unit (CFU) reduction at 48 h, but short-time exposure effects were comparable with that of 0.2% chlorhexidine only on older biofilms (maximum of 0.59 vs. 0.69 log CFU reduction at 120 h). TMR analyses of the enamel revealed non-significant mineral loss (p = 0.37) only in the case of Ga-PBG samples compared with controls including sodium fluoride. ICP-OES analyses indicated transient gallium adsorption into dentine by calcium displacement. The results confirmed that gallium inhibited S. mutans growth and appears to have the potential to protect the enamel surface under conditions representative of the oral environment. Further work is needed to establish whether it has an application in daily oral hygiene procedures to prevent or reduce caries.
authors: Department of Health Services Research and School of Dentistry, University of Liverpool, Liverpool.
authors: S P
authors: SP
authors: Valappil
authors: G J
authors: GJ
authors: Owens
authors: E J
authors: EJ
authors: Miles
authors: N L
authors: NL
authors: Farmer
authors: L
authors: L
authors: Cooper
authors: G
authors: G
authors: Miller
authors: R
authors: R
authors: Clowes
authors: R J M
authors: RJ
authors: Lynch
authors: S M
authors: SM
authors: Higham
mesh_terms: D000327:Adsorption; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002130:Calcium Phosphates / Q000737:chemistry; D002327:Cariostatic Agents / Q000494:pharmacology; D002417:Cattle; D002710:Chlorhexidine / Q000494:pharmacology; D003101:Collodion / Q000737:chemistry; D003743:Dental Enamel / Q000187:drug effects*; D003804:Dentin / Q000187:drug effects; D005708:Gallium / Q000494:pharmacology*; D005898:Glass / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D050296:Microbial Viability / Q000187:drug effects; D008852:Microradiography / Q000379:methods; D012969:Sodium Fluoride / Q000494:pharmacology; D013054:Spectrophotometry, Atomic / Q000379:methods; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D000891:Anti-Infective Agents, Local; D002130:Calcium Phosphates; D002327:Cariostatic Agents; D008567:Membranes, Artificial; C076375:rhenanite; D012969:Sodium Fluoride; D003101:Collodion; D005708:Gallium; D002710:Chlorhexidine