Theresa Ferritto, 87, had a family dentist who said she needed two teeth pulled. Surviving on $1,300 a month, she feared an oral surgeon would cost too much. So Ferritto went to Aspen Dental instead, assuming from its ads that it would be cheaper. The office outside Cleveland signed her up for a treatment plan four pages long, charging her $7,835 on a credit card. They later reduced her charges to $2,540.