I went to a local dentist and they took x-rays and stayed that I had decay on several of my back teeth. I had 5 crowns placed on the left side of my mouth, two of which hurt a few days after the operation. I returned to the dentist several times to get the bite adjusted and nothing seemed to work. I they paid to see a endodontist and they did a cold test and verified that I needed two root canals. Now the dentist says after the root canals they will replace the crowns for free but is that right that 2/5 or 40% of the teeth that were fixed now need root canals? I had 0 pain before ever seeing the dentist. What should I do in this case? Do I have any options?

Sometimes it does happen that in removing enough decay to prepare the tooth for a crown, enough is removed to make the nerve be unprotected. In that case you do need a root canal if you want to end the pain and keep the tooth. Your other alternative is to have an extraction (which is cheap) and get fake teeth in a bridge or an implant (which is expensive). It sounds like your dentist wants to help you keep the teeth. A root canal is around $1000 per tooth. If they'll replace the crowns for free, this is really cheaper than implants and less hassle than living with fake teeth. But yes, it is entirely possible that the work of preparing the teeth for crowns caused the pain. It happened to me once; I found out while I still had a temporary crown in place, so the porcelain crown didn't have to be destroyed or even repaired which was good.

Your dentist has been very generous by offering to replace the crowns at no charge.

Nerves in teeth die and need root canals when they have been heavily restored with large fillings and/or crowns. There is no definite time frame for this to happen but it IS unfortunate when it happens after crowns are placed.

Having a crown on a tooth does not mean that tooth can never get a cavity, which is what some people believe. You actually have to be even more thorough when brushing and flossing around crowns because you have to remove plaque from the margins (where the crown and tooth meet).

After having your new crowns placed, you may want to talk to your dental hygienist about home care. Perhaps using a power toothbrush and a daily fluoride rinse or using a special toothpaste that contains NovaMin or daily use of xylitol mints. These are all things that can control bacteria levels in your mouth and protect your investment.

Good luck.