How long do I have to bring suit in small claims court in Colorado?

The statute of limitations for negligence cases in CO (for any court in the state) is 2 years.

Agreed. The statute of limitations is two years. See CRS 13-80-102.

You have two years in which to file your claim in Colorado, but to file a medical malpractice claim requires more than simply filing a complaint in small claims court. To sue a medical care provider in Colorado you must have the case reviewed by a medical care provider in the same area of expertise - in your case, a dentist - and have your medical expert find that there is a good faith basis for pursuing the med mal claim. Unfortunately, this typically is very expensive and precludes claims such as yours being worthwhile to pursue in small claims court.