The effects of endodontic irrigants and calcium hydroxide on lipopolysaccharide (LPS; endotoxin) were analyzed using the highly selective technique of mass spectrometry/gas chromatography with selected ion monitoring. An aqueous solution of LPS was mixed with one of a variety of endodontic irrigants for 30 min. Because it is a commonly used interappointment dressing, calcium hydroxide was also applied to LPS for 1, 2, or 5 days. LPS inactivation was measured by quantitation of free fatty acid release. Water, EDTA, ethanol, 0.12% chlorhexidine, chlorhexidine + sodium hypochlorite, and sodium hypochlorite alone showed little breakdown of LPS. Long-term calcium hydroxide--as well as 30-min exposure to an alkaline mixture of chlorhexidine, ethanol, and sodium hypochlorite--did detoxify LPS molecules by hydrolysis of ester bonds in the fatty acid chains of the lipid A moiety.
Bacteria from infected root canals can invade dentinal tubules, thus dentin disinfection is an important aspect of endodontic therapy. This study compares three endodontic irrigants for efficiency in killing bacteria established within human dentinal tubules. Root canals in extracted teeth were prepared and sterilized. Broth cultures of Enterococcus faecalis were allowed to grow within the canals to penetrate dentinal tubules. The infected canals were exposed individually to each of the irrigants for 1 min. Irrigants were 0.525% sodium hypochlorite, Tubulicid (0.2% EDTA), and 0.12% chlorhexidine (Peridex). Sterile water was the control. Viable bacteria were analyzed by drilling incrementally into dentin from the cementum toward the canal. Smaller diameter drills were used for each depth. Shavings were cultured at three depths, for each of three root levels: coronal, midroot, and apical. Although considerable variation occurred between roots, sodium hypochlorite seemed to be superior. Tubulicid and Peridex were better than water. More bacteria remained viable at greater distances from the pulp. These observations apparently apply to all levels in the canal.
In the COVID-19 pandemic, treatment of the virus, prevention of its spread, and dealing with its secondary effects on the economy and society have been left to the states and local governments, businesses and other public and private institutions, with the federal government furnishing only feeble support to the primary responders. I argue that COVID-19 is a national disaster, and as such, the federal government should have mounted a massive response under the auspices of the National Response Framework and the Robert T. Stafford Disaster Relief and Emergency Assistance Act. During my 30-year career administering federal disaster assistance, I worked throughout the United States and its territories in the Pacific and the Caribbean. I participated in many imaginative uses of the federal disaster authorities and programs to address serious and unique problems faced by people and their local, state, or territorial governments. During my disaster relief career, the nation never faced a disaster impacting every geographic area and segment of society as COVID-19 has. While the 9/11 attacks shocked the nation, the destruction was restricted to small areas of two cities, and the nation-wide cessation of air travel and other business and social disruptions were short-lived. More than ever before, the extent and severity of the disastrous effects of COVID-19 called for maximal engagement of the National Response Framework to mobilize the combined resources of the country to overcome multiple problems of astounding complexity.
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