MADRID (Reuters) - Spanish police have broken up a gang of Ecuadoreans posing as dentists who offered compatriots in Madrid cheap treatment but carried it out so badly that several of their patients needed emergency hospital treatment. The police arrested eight Ecuadoreans -- none of them qualified dentists -- in "Operation Filling", the Interior Ministry said on Friday. The gang carried out complicated operations such as root canal treatment with home-made equipment and no professional training, preying on illegal immigrants by undercutting regular Spanish dentists’ prices, the ministry said. They operated in their homes and used a microwave oven to...