Ask most adults when they last worried about a cavity and you will get a laugh or a shrug. Cavities feel like a childhood problem, something that ended with the last baby tooth and the pediatric checkups. That assumption is costing grown-ups fillings, crowns, and sometimes whole teeth. Nearly 90% of adults aged 20 to 64 have had decay in their teeth, according to the National Institute of Dental and Craniofacial Research. If you are searching for adult cavities in St. John's,