title: Immersion disinfection of irreversible hydrocolloid impression in pH-adjusted sodium hypochlorite. Part 1: Microbiology.
abstract: Sodium hypochlorite is one of the disinfectants recommended for impressions, usually in a 1:10 dilution to minimize the negative effects on the impression material and poured gypsum cast. Dilution causes a loss of antimicrobial properties, however. Sodium hypochlorite is known to have enhanced antimicrobial properties at lower pH levels. This study evaluated the antimicrobial activity of sodium hypochlorite at progressively lower pH levels. A metal model of a dental arch was contaminated, and irreversible hydrocolloid impressions were made, cultured, disinfected (by immersion), and cultured again. Predisinfection and postdisinfection bacterial counts were compared. It was found that a 10-minute immersion in solutions reduced to pHs 7 to 11 consistently produced a 4-log (99.99%) or greater reduction in viable organisms. A pH of 10 was the only level that was consistently effective at decreased immersion times. It was effective in times of 3 minutes or greater.
authors.affiliation: University of Texas Health Science Center, San Antonio 78284-7914, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Schwartz
authors.forename: D H
authors.initials: DH
authors.lastname: Hensley
authors.forename: D V
authors.initials: DV
authors.lastname: Bradley
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects; D003102:Colloids; D015169:Colony Count, Microbial; D019551:Dental Disinfectants / Q000737:chemistry / Q000494:pharmacology*; D003760:Dental Impression Materials; D003761:Dental Impression Technique / Q000295:instrumentation; D004203:Disinfection / Q000379:methods*; D004866:Equipment Contamination; D005069:Evaluation Studies as Topic; D006863:Hydrogen-Ion Concentration; D003765:Models, Dental; D009163:Mycobacterium bovis / Q000187:drug effects; D009930:Organic Chemicals; D012973:Sodium Hypochlorite / Q000737:chemistry / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects; D013997:Time Factors
chemical_list: D003102:Colloids; D019551:Dental Disinfectants; D003760:Dental Impression Materials; D009930:Organic Chemicals; C043594:Jeltrate; D012973:Sodium Hypochlorite