After more than 10 years of substantial U.S. and state financing support of medical care for the poor, there still are significant differences in the frequency of visits, waiting time and travel time to a physician between low and high-income groups, according to a study released yesterday. The differences between medical care for low and high-income groups are even more pronounced when denstry, which less often is covered by insurance, is taken into account.

One of the study's most startling endings is that the percentage ofwhites and blacks who see a physician curing a 12-month period has narrowed dramatically from a difference of 25 per cent to about 2 or 3 per cent since 1963. The federal Medicaid program of subsidizedhealth care for the poor was launched in the mid-1960's.

Not surprisingly, the study found that as income rises, the access to and use of medical care rises. Although some of the findings of the study confirm expectations, the survey is believed to be the largest and most comprehensive of its kind performed in this country.

Although a gap still exists between the access of low- middle- and high-income persons to physicians. It appears to have narrowed since the pre-Medicaid days of 1963, when a previous survey was made. At that time the study found that about 72 per cent of high-income persons saw a physician at least once every 12 months, about 65 per cent of medium income persons did, and about 55 per cent of those with low income did.

By 1976, roughly 80 per cent of those with a high income saw a doctor at least once every 12 months while 75 per cent of those with medium income and about 72 per cent of persons with low income had such visits.

At the same time that access to medical care has improved in the last 13 years, a wide gap continues to exist between the dental care received by lower medium and high-income persons. About 62 per cent of high income persons saw a dentist at least once in 1976, compared to about 33 per cent of low-income persons. In 1963, about 23 per cent of low-income persons visited a dentist, compared to about 55 per cent of those with high incomes.

One explanation offered for the continuing disparity is that 88 per cent of the population has some kind of medical insurance coverage but only 18 per cent is covered by dental insurance.

The survey was conducted by the National Center for Health Services Besearch at the University of Chicago under a $1.2 million grant from the Robert Wood Johnson Foundation and $250,000 from the federal government. About 7,800persons in 5,400 households across the cuntry were picked at random and questioned for the survey.

Some of the findings include:

About 77 per cent of urban blacks reported seeing a physician compared to only 65 per cent of rural blacks.

About 43 per cent of low-income persons have to wait more than 30 minutes to see their physician, compared to 32 per cent of high-income persons.

About 12 per cent of the population - more than 24 million persons - reported that they had no regular source of medical care, either a physician or a clinic, when they need it.

Of all ethnic groups, Latinos had the lowest utilization rate of physicians - 65 per cent.

The report also documents someparadoxes in views Americans hold about medical care. For example, 88 per cent of those surveyed said they generally were satisfied with the care they received. But 61 per cent, including a substantial portion of the satisfied group, said there is a "crisis in health care today in the United States." The reason for the paradox, the report says, "is a mystery still to be probed."

The greatest source of dissatisfaction - 37 per cent - was recorded over out-of-pocket costs for medical care. Low-income persons,who are far less likely to have health insurance - about one-fourth did not - were more dissatisfied with costs than high-income persons of whom only 5 per cent did not have some form of health insurance.

More low-income persons - 33 per cent - said they were dissatisfied with the amount of time they had to wait in physician's offices than high-income persons - 25 per cent.

Seventy per cent of those surveyed agreed with the statement "If I have a medical question, I can reach someone for help without any problem." At the same time, 38 per cent agreed that it is hard to get medical care quickly in an emergency. Another 15 per cent were not sure and 47 per cent disagreed.