With less than six months remaining in his second term, President Clinton made appointments Monday for dental and optometry check-ups that are covered by his Physicians Plus presidential health plan. 'My teeth are fine, but I figured I should take advantage and get a cleaning before I get dropped next January,' Clinton said. 'And if I get new glasses before then, Physicians Plus will cover the lenses and 60 percent of the cost of frames, so I'd be crazy not to.' Clinton said he was worried he was already too late to get in for an eye exam before leaving office, but Dr. Heitman, his designated optometrist, had an opening on Dec. 17 at 8:15 a.m. 