An In Vitro Spectroscopic Analysis to Determine the Chemical Composition of the Precipitate Formed by Mixing Sodium Hypochlorite and Chlorhexidine

Abstract

Introduction The purpose of this in vitro study was to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite (NaOCl) and Chlorhexidine (CHX), and relative molecular weight of the components. Methods Using commercially available chlorhexidine gluconate (CHXg), a 2% solution was formed and mixed in a 1:1 ratio with commercially available NaOCl producing a brown precipitate. The precipitate as well as a mixture of precipitate and pure chlorhexidine diacetate (CHXa) was then analyzed using 1D and 2D NMR spectroscopy. Results The 1D and 2D NMR spectra were fully assigned, in terms of chemical shifts of all proton and carbon atoms in intact CHX. This permitted identification of CHX breakdown products with and without the aliphatic linker present, including lower molecular weight components of CHX that contained a para-substituted benzene that was not para-chloroaniline (PCA). Conclusions Based on this in vitro study, the precipitate formed by NaOCl and CHX is composed of at least two separate molecules, all of which are smaller in size than CHX. Along with native CHX, the precipitate contains two chemical fragments derived from CHX, neither of which are PCA.

Corrected and republished article: Corrections of the root canal irrigation protocol: Primum non nocere (2013, vol. 29, no. 68, pg. 1289-1297)

“…Osim toga, ustanovljeno je da se ovaj talog sastoji od para-hloranilina (PCA), za koga je dokazano da deluje toksično u eksperimentima subkutane implantacije kod pacova 30 . Literaturni podaci ukazuju ne samo na toksičnost PCA, nego i na toksičnost njegovih degradacionih produkata 31,32,33 . Para-hloranilin se inače koristi kao pesticid i može imati kancerogeno dejstvo 34 .…”

“…Literature data indicate not only the toxicity of PCA, but also the toxicity of its degradation products 31,32,33 . Para-chloroaniline is used as a pesticide and can have carcinogenic effect 34 .…”

Effect of adding chlorhexidine to calcium enriched mixture (CEM) on its antimicrobial activity

“…Chlorhexidine has been initially introduced as an irrigation solution due to its broad-spectrum antibacterial activity (Barrios et al, 2013 (Ayhan et al, 1991;Nowicki and Sem, 2011).…”

Análise química do precipitado formado na reação entre hipoclorito de sódio e digluconato de clorexidina

“…Há uma grande discussão sobre a associação, pois estas substâncias reagem formando um precipitado de cor marrom, não solúvel em água (Siqueira Jr, 1997;Kuruvilla;Kamath, 1998;White et al, 1999;VivacquaGomes et al, 2002;Zenhder, 2006;Basrani et al, 2007;Marchesan et al, 2007;Bui et Krishnamurthy;Sudhakaran, 2010;Thomas;Sem, 2010;Nowicki;Sem, 2011).…”

“…Frente ao exposto, não é possível afirmar que apenas um ou dois compostos são formados quando da reação NaOCl/CLX, como relatado em trabalhos anteriores (Basrani et al, 2007;Basrani et al, 2010;Nowicki;Sem, 2011;Sodhi et al, 2011). Nos mesmos espectros é possível observar que a maior parte dos compostos presentes no precipitado apresentam pesos moleculares maiores que o da CLX, sugerindo que ocorra um reagrupamento de partes da molécula de CLX fragmentada ou dela inteira em sítios específicos de outra molécula de CLX.…”