LONDON — Layla Waters pulled out five of her own teeth after not being able to get an appointment with a National Health Service dentist.

       This kind of do-it-yourself dentistry has become increasingly common in the United Kingdom. There are reports of people yanking out their teeth with pliers from the garden shed, fixing crowns with superglue and traveling abroad for dental care. Local politicians’ inboxes are filled with complaints from constituents upset with their lack of access to affordable dentistry.