American Dental Partners Announces the Accreditation of Riverside Dental Group.

WAKEFIELD, Mass. -- American Dental Partners, Inc. (NASDAQ: ADPI) announced today that Riverside Dental Group has achieved accreditation status with the Accreditation Association for Ambulatory Health Care ("AAAHC").

The AAAHC is a peer-based, not-for-profit organization that is nationally recognized for conducting extensive evaluations of ambulatory health care organizations to ensure the highest quality standards. More than 1,800 ambulatory health care organizations across the United States are accredited by the AAAHC. With the accreditation of Riverside Dental Group, eight of American Dental Partners' affiliated dental groups are accredited by the AAAHC. Riverside Dental Group is the only accredited dental group in the state of California.

Riverside Dental Group, founded in 1974, is a multi-specialty dental group with five practices located in southern California's Inland Empire region. "Riverside Dental Group's accreditation is well-deserved and is recognition of their commitment to high quality standards and clinical excellence." said Gregory A. Serrao, Chief Executive Officer.

American Dental Partners encourages its affiliated dental groups to pursue AAAHC accreditation as a means to set and maintain measurable quality benchmarks and achieve the highest possible standard of patient care. Dr. Jesley C. Ruff, Senior Vice President and Chief Professional Officer of American Dental Partners, works with the Company's affiliates in the pursuit of accreditation. "We hope that by having our affiliated dental groups be part of a select group of dental practices accredited by the AAAHC, American Dental Partners will be at the forefront of promoting clinical excellence in the dental profession," said Dr. Ruff. "While AAAHC accreditation is a rigorous and demanding process, we believe it will help our affiliated dental groups continue to recruit high quality professionals and enhance relationships with patients and local dental communities," Dr. Ruff added.

American Dental Partners is one of the nation's leading business partners to dental groups. The Company is affiliated with 20 dental groups which have 182 dental facilities with approximately 1,636 operatories located in 18 states.

Note: Some of the information in this press release contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. The words "believe," "expect," "anticipate," "project,'' and similar expressions, among others, identify forward-looking statements. Forward-looking statements speak only as of the date the statement was made. Such forward-looking statements are subject to uncertainties and other factors that could cause actual results to differ materially from those projected, anticipated or implied. Certain factors that might cause such a difference include, among others, the Company's risks associated with overall or regional economic conditions, contracts its affiliated dental group practices have with third party payors and the impact of any terminations or potential terminations of such contracts, the cost of and access to capital, the fluctuations in labor markets, the Company's acquisition and affiliation strategy, management of rapid growth, dependence upon affiliated dental group practices, dependence upon service agreements and government regulation of the dental industry. Additional risks, uncertainties and other factors are set forth in the "Risk Factors" section of the Company's Annual Report on Form 10-K for the year ended December 31, 2004.