First lady Nancy Reagan is getting her first major checkup since she had her cancerous left breast removed six months ago. While his wife was being examined, President Reagan planned to have a full-mouth X-ray and routine dental checkup at Bethesda Naval Medical Center. White House spokesman Marlin Fitzwater described the procedures as "routine checkups not associated with any current physical findings or problems." Reagan last visited the hospital in January, undergoing an annual checkup for colon cancer.