A vet using hi-tech dental technology tried to clean the paint from an ancient stone circle on August 4 - but conservationists may have to resort to tooth picks.

Chipping Norton vet Peter Aylmer, front, with assistant Kate Ormston,

The 3,500-year-old Rollright Stones, near Chipping Norton, were daubed in yellow paint by vandals earlier this year. So far attempts to clean them without harming the stones have failed.

After a visit to the dentists last week, the wife of one of the stones' trustees suggested trying the ultra-sound drill used to clean teeth. Reasoning that animals have bigger teeth than humans, Chipping Norton vet Peter Aylmer was asked to bring along his portable equipment.

"The test was inconclusive," said site manager Don Prout. "There's a lot of water involved in the process so we'll have to wait and see if the stones have been harmed.

"It was very successful in one patch, allowing us to peel the paint off with dental picks, so I suspect we'll be using the technique for part of the clean-up."