Is it reasonable for me to ask for ativan (lorazepam) for my endodontic treatment?

Yes. Yes, many people fear the dentist and need things like Ativan (lorazepam) to help calm them down. Some dentists will prescribe it, while others wont just based on their level of familiarity/experience with sedation/anxiolysis. If it is prescribed you need to make sure you have someone drive you to and from the appointment.
Maybe. Ativan (lorazepam) is an effective antianxiety drug that is often used to premed patients prio to surgery. Usually given im or IV for surgery but can be given orally to aid in relaxing nervous patients. I have used Valium (diazepam) in my office for years to effectively pre medicate nervous patients going into oral surgery or root canal treatment.
Maybe. Most patients do great getting root canal treatment. But if you are extremely nervous or have trouble opening os sitting still. Then Ativan (lorazepam) works great make sure you have someone drive you to and from the appt.
Maybe. Ativan (lorazepam) helps many people sit thru their root canal treatment. A medical history must be taken prior to giving this drug to ensure there is no contraindications. The patient cannot operate any machinery or do tasks of responsibility following their dental treatment if they have taken ativan (lorazepam).