Aims: To show that Macular Degeneration, Alzheimer's Disease, Parkinson's Disease, and Multiple Sclerosis are caused by Human Herpesvirus-6, Chlamydia Pneumoniae, Porphyromonas Gingivalis, and Odontoblast cells. The key to these diseases is the virusbacteria interactions and how odontoblast cells affect the human body. Methods: I have examined my patients and kept records on their treatments. Results: I have stabilized my patients with these conditions. Conclusions: Macular Degeneration, Alzheimer's Disease, Parkinson's Disease, and Multiple Sclerosis are caused by a viral-bacterial infection and odontoblast cells. These diseases can be treated.