[lacrimacida]

I never had any issues with local anesthesia and usually get some novocaine gel as a local anesthetic prior to the local anesthetic. Maybe it is effective for some while not for others, I have no other explaination. I’d let a dentist drill anything, no matter how small without anesthesia.

[projektfu]

Infiltration techniques depend on the patient and, to some extent, the skill of the dentist. They're most common for single extractions and cavity prep, sometimes endodontics.

Nerve block techniques are more effective but also difficult for dentists to do properly, and some dentists have low success rates. There's no way to know a given dentist's success rate, but an oral surgeon has a lot more practice with nerve blocks.

Finally, some drugs have a very slow onset and patients aren't given enough time for the effect. You also don't usually get to choose the drug as a patient.