For the second time in just the past few days, the staff of a Vallejo dental office came to work to find their nitrous oxide cylinder missing, an employee said.

Theft of the large, typically 100-pound containers of a state-regulated substance often called "laughing gas," is an ongoing problem for some local dentists, registered dental assistant Stacy Tolman-Cordero of Vallejo Children's Dentistry said. Nitrous oxide, which causes giddiness and a sense of euphoria, is often used to calm dental patients, particularly young ones, she said.

"It happens every year, they come along and try to steal our nitrous," Tolman-Cordero said. "This is the third time this year."

The office's alarm sounded just before 3 a.m. Oct. 18, when thieves broke into the special outdoor boxes in which the practice's oxygen and nitrous oxide tanks are kept, in the first in a string of such break-ins, she said. The second happened about 4:20 a.m. Tuesday, she said.

Vallejo Police Detective Jason Potts said he knows of at least one local dentist who stopped using nitrous oxide because he tired of being burglarized.

For more on the story, see the Vallejo Times-Herald at http://www.timesheraldonline.com/news/ci_21851498