When the nerves of the tooth is damaged either by trauma or cavities/caries/decay it will initially begin to swell. Because it is encased within a hard tissue [the tooth itself] as it swells the pressure will cause cell death within the nerve. Once this begins to occur the only option is to either remove the nerve [root canal treatment] or remove the tooth.
Many people ask why we cannot simply treat this infection with antibiotics. The reasons are that firstly once the nerve dies there is no blood flow to the inside of the tooth and so the antibiotics do not reach the infection. Secondly as the infection continues within the toothy continues to leak bacteria of the end of the tooth and so without removing the cause [the dead and dying nerve tissue] you will never completely eradicate the infection. That is why patients initially get better with antibiotic treatment and then the pain comes back.
Although there has been some recent literature to the contrary the dental profession’s experience with Rick Nancy is that these are terminal procedures for the tooth which will buy you somewhere between five and 15 years of continued service from the tooth prior to it needing to be extracted. Having said this is still a worthwhile first step in that nothing that we can provide as a replacement will work as well as your natural tooth. This is because we were a cavity is a complex environment which gains feedback information not only from your tongue and John muscles but also from the fibers [periodontal ligament fibers] which hold the tooth into the bone. All of these feedback loops work together to allow you to produce the appropriate job pressure and jaw motions when eating. Implants will approximate many of the functions of the teeth are replacing but will not allow or provide feedback loops as far as biting pressure and jaw motion.