Would it be bad to get pregnant a month after getting a root canal? Are there any negative effects from the anesthesia, etc.? If so, how long should we wait after the root canal before trying?
The anesthetics used for the root canal are not very long lasting. An example of the longer-acting local anesthetics is Bupivacaine. The average half-life of Bupivacaine Hydrochloride in adults is 2.7 hours (that is, within 2.7 hours, half of the total dose absorbed is metabolized. In people with liver or renal failure, it may be longer, as it is metabolized by the liver.
While various factors may increase or decrease the half-life of bupivacaine, it is exceedingly unlikely that there will be any bupivicaine left in her system a week from having a root canal, let alone a month.
Of course, the exact drug(s) used by her dentist may differ.