ABSTRACT
INTRODUCTION: Chlorhexidine (CHX) is likely to decompose into reactive by-products. This study evaluated the generation of 4-chloroaniline (pCA), reactive oxygen species (ROS), and 1-chloro-4-nitrobenzene in high concentrations of CHX and in a mixture of CHX and calcium hydroxide at different time points. METHODS: A gas chromatography method was developed to detect pCA and CHX by-products. Mass spectroscopy was used to elucidate the structure of compounds. The samples, which were kept at 36.5°C and 95% relative humidity during the study, were analyzed immediately and 7 days after preparation. RESULTS: pCA was detected in the 2% CHX solution and in the mixture of CHX and calcium hydroxide at all time points. pCA concentrations increased after storing under those conditions. The 2% CHX solution alone and the mixture of CHX and calcium hydroxide released ROS at all time points, but 1-chloro-4-nitrobenzene was not found. CONCLUSIONS: pCA and ROS were identified as by-products of the 2% CHX aqueous solution alone and as ointment base of calcium hydroxide paste.
Subject(s)
Aniline Compounds/analysis , Anti-Infective Agents, Local/chemistry , Calcium Hydroxide/chemistry , Chlorhexidine/analogs & derivatives , Nitrobenzenes/analysis , Reactive Oxygen Species/analysis , Tryptophan Hydroxylase/antagonists & inhibitors , Anti-Infective Agents, Local/analysis , Calcium Hydroxide/analysis , Chlorhexidine/analysis , Chlorhexidine/chemistry , Gas Chromatography-Mass Spectrometry , Humans , Humidity , Materials Testing , Temperature , Time FactorsABSTRACT
The aim of this study was to determine whether para-chloroaniline (PCA) and/or reactive oxygen species (ROS) are generated by chlorhexidine (CHX) alone or after CHX is mixed with calcium hydroxide at different time points. Mass spectrometry was performed to detect PCA in samples of 0.2% CHX and Ca(OH)2 mixed with 0.2% CHX. High-performance liquid chromatography was used to confirm the presence of CHX in the mixture with Ca(OH)2. The samples were analyzed immediately after mixing and after 7 and 14 days. During the intervals of the experiment, the samples were maintained at 36.5 degrees C and 95% relative humidity. PCA was detected in the 0.2% CHX solution after 14 days. The mixture of CHX with Ca(OH)2 liberated ROS at all time points, but no traces of CHX were present in the mixture as a result of immediate degradation of the CHX.
Subject(s)
Aniline Compounds/chemistry , Calcium Hydroxide/chemistry , Chlorhexidine/chemistry , Reactive Oxygen Species/chemistry , Root Canal Irrigants/chemistry , Aniline Compounds/analysis , Chromatography, High Pressure Liquid , Humans , Humidity , Mass Spectrometry , Materials Testing , Reactive Oxygen Species/analysis , Spectrometry, Mass, Electrospray Ionization , Temperature , Time FactorsABSTRACT
Neste trabalho foi estudado in-vitro o aumento de temperatura intra-pulpar de um grupo de 15 dentes (três passagens cada), geradas pela técnica de clareamento dental utilizando-se um aparelho Fotopolimerizador e dois sistemas conjugados de LEDs com Laser de marcas comerciais distintas, com um mesmo agente clareador. Um dos principais fatores limitantes para os procedimentos de clareamento dental fotoassistido é o aumento de temperatura gerado no elemento dental em decorrência da técnica. Em virtude disso foram avaliados os equipamentos e submetidos a uma comparação sob o aspecto de aumento de temperatura intra-pulpar in vitro. Os resultados foram compilados e mostraram que o equipamento denominado LEDs B, foi o maior gerador de aumento de temperatura, apresentando uma média aritmética de 5,98°C, inclusive ultrapassando os limites propostos por ZACH e COHEN em 1965. O equipamento Fotopolimerizador foi o segundo maior gerador de aumento de temperatura, com um aumento médio de 5,19°C, apresetando-se em uma posição limítrofe, aos limites propostos. O equipamento denominado LEDs A apresentou o menor aumento de temperatura gerado em decorrência da técnica, com uma média aritmética de 0,54°C, podendo ser considerada como desprezível