@smileys,
I have a relative who feared going to the dentist until years of unattended problems forced her to go. She had multiple sessions of sedation dentistry and everything went well for her - of course, not as well as it would have gone if she'd had regular dental check-ups, but pretty well under the circumstances.
Sedation is helpful for those who wouldn't undergo dental procedures without it. Your mother may be anxious, but I wouldn't suggest sedation unless she is truly terrified.