Most people know a technique called PCR from flu or viral testing. In the context of the oral microbiome, PCR acts like a checklist: it only finds what you are already looking for. At high speed and ultra-low cost, it typically detects 1-20 predefined species, providing just a few „stones“ of a massive mosaic. It often focuses on the „bad bugs” making you sick but fully misses the „good cops” keeping you healthy and neglects the so important microbial „dark matter” (bacteria that have not been discovered and explored yet).