One-Time Gain Boosts National Healthcare Net

National Healthcare Systems Inc. said it had net earnings of $40,026 for the third quarter--including a one-time gain of $61,000 from the sale of an asset--contrasted with a year-earlier loss of $8,592.

Without the one-time gain from the sale of an orthodontic practice it operated, the Irvine-based prepaid dental plan would have lost $20,974 on operations for the third quarter.

Revenues during the period ended Sept. 30 increased 6% to $1 million from $943,000 a year earlier.

For the first nine months of 1986, National Healthcare Systems said it had net earnings of $95,627, contrasted with a loss of $59,013 during the like period of 1985. Operating earnings for the nine months totaled $34,627. Nine-month revenues increased 14% to $3.2 million from $2.8 million a year earlier.