This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'A 24 year old male presents to OPD with sensitivity to cold water. On intraoral examination, 46 is carious and dentist decides to restore the teeth with amalgam restorative material with zinc phosphate base. Which of the following is NOT a modification of this cement? \nSelect and explain. \nA. Copper phosphate cement, B. Silver phosphate cement, C. Resin modified cements, D. Fluorophosphate cement', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Copper cements are basically modified zinc phosphate cements. Silver salts or copper\xa0oxide are sometimes added to the powders of the zinc phosphate cements to increase their\xa0‘antibacterial’ properties. Copper cements gradually fell out of favor because of their poor\xa0biological properties. It was highly acidic and the copper was considered toxic to the cell.\xa0\nThis may have been due to the extremely high copper content (97%) in certain cements\xa0(Ames). There has been a renewed interest in copper cements recently. New formulations\xa0have come out with lower copper content (2%). It is claimed that these new generation\xa0copper cements are safe and is especially recommended for indirect pulp capping and\xa0where there is active caries.\xa0\nCOMPOSITION\n\n\xa0Copper oxide (if cuprous oxide is used—cement is red, if cupric oxide is used, the cement is black)\n\xa0Zinc oxide\n\xa0Liquid used is clear phosphoric acid\n\nKey Concept\xa0 \xa0\nCopper phosphate and silver phosphate cements were developed to impart antibacterial properties and fluorophosphate cements to impart anticariogenic properties to the zinc phosphate cements. However, these materials are not in use now as they possess\xa0many disadvantages compared to conventional zinc phosphate cements.\nReference: Mannapallil p; 98', 'role': 'assistant'}]