A SIDE NOTE AND IT IS IMPORTANT
If you have any cardiac issues whatsoever, check with your USA medical doctor. Regular Novocaine contains epinephrine, which enhances its longevity and strength. All standard Novocaine contains the additive.
And it can be hazardous or even deadly to folks who suffer from heart rhythm or other cardiac issues. Epinephrine-free Novocaine is extremely rare in Mexico. It is only available in the largest cities. Border dentists may or may not have it. I have been lied to several times by idiots who claim to have epinephrine-free Novocaine but turned out it was regular Novocaine*. The best away around this is to visit a medical doctor in the town you plan to have the dental work done in, explain the issue to him and have him telephone the dentist and explain clearly the life and death importance of not using epinephrine.
*They fessed-up when a doctor telephoned them.