Why can’t I get DNA tests for bacteria?

A.
Gum disease is not caused by one single type of bacteria, the current thinking is that there is an “ecosystem” with different types of bacteria (“good and bad bugs”) living together within the biofilm of plaque that gets attached to the teeth and can colonise the pockets under the gums resulting in bone loss in certain individuals. We know that individual genetic susceptibility is the critical factor but we also know that some bacteria are much more aggressive than others and not all individuals have the same bacterial profile under the gums. The gold standard of gum treatment is the mechanical removal of plaque (disturb the biofilm) both above and below the gum margins so that the body can cope with the remaining bacteria that is neither possible not necessary to completely eliminate. However there are specific individuals (aggressive cases, extremely susceptible people or non-responsive to conventional treatment) that benefit from antibiotic therapy. When and how to use antibiotics is a controversial issue and you will not find a complete consensus among the dentists. The potential benefit of DNA test for bacteria is the possibility of identifying the specific bacterial profile in order to select the most effective course of antibiotics in selected cases. I agree that its practicality and cost-benefit is arguable and again controversial. I use it only in very selective cases, more commonly in situations with gum disease around implants that are more resistant to conventional therapy.