Dentin decontamination using chloramine T prior to experiments involving bacteria

Objectives This study aims to investigate the importance of ISO11405 recommended storage regime for extracted teeth in surface disinfectant chloramine T (chlT) prior to use in biofilm or in vitro caries studies involving microorganisms. ChlT may be absorbed into dentin and undergoes breakdown with organic material. Methods Extracted roots were stored in chlT (2 days), rinsed and transferred to distilled deionised water. HPLC at regular intervals determined chlT elution. At 4 weeks roots were boiled in water and eluent assessed with HPLC. ChlT breakdown (±organic material) over time was monitored with HPLC. ChlT minimum inhibitory/bactericidal concentration (MIC/MBC) against Lactobacillus acidophilus was evaluated using L. acidophilus broth and chlT serial dilutions. Results No significant increase in chlT elution was detected between 2 h and 4 weeks (ANOVA, Tukeys, p > 0.05), although levels tended to increase with time. ChlT detected in water was 0.005%, corresponding to 0.05% in dentin. After boiling (4 weeks) chlT breakdown products in water corresponded to 0.015% in dentin. MIC/MBC of chlT against L. acidophilus was 0.031%. Significance ChlT breakdown is accelerated by organic material. L. acidophilus is highly sensitive to chlT. ChlT readily leaches from dentin but rinsing does not reduce chlT concentration below MIC/MBC. Low levels of chlT may remain but will probably be in a less active form. Teeth disinfected in chlT for use in research involving bacteria must be stored in distilled water for at least 2 h to reduce chlT concentration below MBC, although longer will give greater elution and breakdown.