Trust: Trust is always a big issue and you need to know whether or not you can trust your dentist and the advise on dental care you are receiving. Does your dentist answer your questions fully to where you understand the services he or she is suggesting to you.
When major dental care is required, sometimes you may want a second opinion to verify all the dental services be suggested. That is normally and is encouraged among dentist.
However not all dentist will advise the same exact treatment. So when comparing the two opinions, if you have questions about why the two do not match up inquire into it with your dentist before just thinking one is a bad dentist. Cost may also be a factor.
If you have dental insurance you may want to make sure that your dental insurance plan would cover for a second option. Some dental plans may not cover for additional services already done. If so you would want to know the cost ahead of time to make sure it is something you can afford to have done.