Longtime Mill Valley dentist Gabriela Garcia-Rojas had long considered herself environmentally conscious. But until she attended a recent lecture on greening the dental industry at a fellow dentist's office in San Leandro, she thought her business had no place on a list of green businesses, particularly given her industry's reliance on things like chemicals, X-rays and plastic molds.

"I said to myself, 'I do way more than him," Garcia-Rojas said of the East Bay dentist, who was certified in Alameda County. "I never thought I would never be able to be a green business. But I called the county and, sure enough, we were doing way more than other dentists that have been qualified as green."

Garcia-Rojas' family and cosmetic dental practice, located on Willow Street, was certified as a green business by the Marin County Board of Supervisors this week, along with fellow Mill Valley businesses Piatti's Ristorante, Acqua Hotel and Mill Valley Inn.

While many of the upgrades needed to attain green business certification are well known, from energy efficient lighting to sustainable waste management, the dental industry presents its own challenges.

For instance, Garcia-Rojas installed an amalgam separator that separates the mercury-laden residue from removed old fillings before it goes down the drain. Her office uses porcelain fillings to replace old ones, a more natural looking and less chemically enhanced substitute.

Instead of the traditional method of making plastic molds of teeth for crowns, Garcia-Rojas does so using a Cerec machine, which makes a digital scan of the tooth. The same is true for traditional X-rays, which are also done digitally and avoids the use of X-ray processing chemicals.

County supervisors hailed 21 green businesses in all this week, bringing the number of Marin's certified green businesses to 406. Garcia-Rojas' practice is the second certified green dentist in Marin, and a third, Haney Orthodontics in San Anselmo, was also certified this week.

The Marin green business program, part of a Bay Area regional project now involving 2,200 businesses, agencies and organizations, was launched in 2002 to encourage recycling, energy efficiency, conservation and related opportunities to boost both economic and environmental resources.

The other Marin green businesses certified this week:

Aah Haa! Inc., San Rafael

Blue Skies Janitorial Services, Novato

C2e LLC, Novato

Greenfire Strategies, Novato

Haney Orthodontics, San Anselmo

High Definition Home, San Rafael

Jessie et Laurent, San Rafael

Marin Mac Tech, Novato

Marin Primary & Middle School, Larkspur

My Alibi Clothing, Inverness

MyEco LLC, Greenbrae

Nick & Laura Photography, San Rafael

Noble Builders, Corte Madera

Simmonds & Associates, San Anselmo

Stella's, San Anselmo

Suzanne Halladay Tax Services, San Rafael

Unity in Marin, Novato