Periodontosis
Periodontosis is an older periodontal term; modern periodontal diagnosis uses defined disease categories and consistent terminology.
[1][2]The short answer
Periodontosis is an older periodontal term whose meaning is clarified by modern disease classification.
[2]
What the change looks like

What might you notice?
What does the term refer to?
Periodontal disease is a group of diseases affecting the tissues that support teeth; the exact category matters because terminology can change diagnosis and treatment communication.
[2]How is periodontal disease classified now?
Why can the label cause confusion?
How is the problem clarified?
What treatment follows a clear diagnosis?
Treatment is selected for the identified gum disease. Periodontal treatment is directed at controlling the disease and its effects on supporting tissues.
[3]What determines the cost?
The cost follows the periodontal treatment required for the defined disease, rather than the historical word used to describe it.
[3]What is the risk of leaving the disease unclear?
How can periodontal health be protected?
Ongoing periodontal care is used to maintain control of gum disease after the specific condition has been identified.
[3]