Should I get a second opinion?

A little over a year ago I went to the dentist and had some spots where a cavity could form well I went again today and she said I have 13 cavities. Last time I went I was given a special toothpaste but never really used it (I know my fault) the dental aide said I have perfect teeth besides these spots... should I get a second opinion or just get them fixed?
Should I get a second opinion?
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