You, my friend, have the most interesting posts on SDN. 🙂
And, I don't think it's a rare occurrence to find your spouse in dental school. She might be a dental student, or a hygiene student, or a med student, or a nursing student, or a working professional, or someone you might meet at a friend's kickback! But I'd say there's a pretty good shot of your meeting your spouse in the upcoming 4 years! Just make sure you're on the lookout, but not the stalker-ish kind. ;-)
I wish you the best of luck in this search 🙂
P.S. I've heard of a lot of couples meeting in dental school (both being students, some even in the same year). It's common enough, but not so common that it's even 50% of the class...if I wanted to guesstimate, I'd prob say 5-15%? But it's all situational