By Francesca Infante PUBLISHED: 10:09 EST, 29 April 2013 | UPDATED: 19:41 EST, 29 April 2013 Dental nurse Ravinder Kaur, 34, is facing charges relating to accusations that she poisoned two colleagues with mercury while working at a dental practice in Bedfordshire A dental nurse took revenge on her boss by  poisoning her coffee with the mercury used in fillings, a court was told. Ravinder Kaur, 34, was in danger of being dismissed from her job after a string of formal warnings about her behaviour when she allegedly poured a capsule of mercury amalgam into a cup of coffee and served it to her boss Laura Knowles in March last year.
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Ravinder Kaur, 34, accused of lacing drink in act of 'spite and revenge'
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She denies administering a poisonous or noxious substance with intent to cause harm
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Practice manager Laura Knowles rushed to hospital with cramps
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Kaur had twice been warned by bosses at Bedfordshire practice
@placeholder was hired as an assistant dental nurse in November 2011, and had been given training in the safe handling and storage of mercury.