BOSTON (AP) – The state must improve its system for providing dental care for the children of low-income families, a federal judge ruled.

U.S. District Judge Rya W. Zobel on Friday ordered the state and legal representatives of the families to come up with ways to change the system by Aug. 31.

The advocacy group Health Care for All argued in court that the state had violated the civil rights of children by creating a system that sometimes forced them to wait months or even years for dental appointments.

Critics say the delays are the result of a system that reimburses dentists too little, requires too much paperwork and demands that if dentists accept one low-income patient seeking dental care they must take every such patient.

Among 5,000 practicing dentists statewide, fewer than 800 treat patients enrolled in MassHealth, the state’s Medicaid program for low-income residents.

The ruling could affect as many as 500,000 MassHealth enrollees.

Zobel said in her ruling that evidence presented by health care advocates “persuasively demonstrates MassHealth established reimbursement levels so low that private dentists could not afford to treat enrollees who, thus, either received dental care only after much delay or not at all.”

The judge also found that Gov. Mitt Romney’s administration “violated sections of the Medicaid Act that require prompt provision of services, adequate notice, and treatment at reasonable intervals.”

“We’re pleased that Judge Zobel recognized that dental care received by children in MassHealth is inadequate and violated federal law,” said John McDonough, executive director of Health Care for All. “The Commonwealth now has an obligation to fix the mess.”

Administration lawyers are still reviewing the ruling, said Dick Powers, a Romney spokesman for health affairs. The administration will sit down with health care advocates, he said.

One concern of the ruling has already been addressed, Powers said. A measure in the state budget approved for the next fiscal year eliminates the rule that prevented dentists from capping how many MassHealth patients they accept.