It varies dramatically each year. Sometimes there are several OCONUS options, other years it's all CONUS. Usually the list has somewhere in the 10-15 range.
The basic places like Ft. Hood, Ft. Benning, JBLM, Ft. Leonard Wood, Ft. Bragg... Have so many dentists that they will show up on the list every year.
The smaller and more specific locations that only have a handful of dentists only come available every few years.
Do you have questions about any specific locations?