My snake may have lost teeth

[Sinthed]

So we normally go to Pets Plus and buy my snake which is approximately 4foot long a medium size rat, and she eats them easily. It has been 2 weeks (the normal time we wait to feed again) since we fed her and she is only eating one of the rats. The second she will attack and she will bite it, but she will not actually constrict and eat it. I have tried holding it by the tail for her to keep it from moving to much and letting her eat it that way, but she can not get the rat. She is about 4 years old and ive had her close to 8 months.