This document discusses the diagnosis and classification of periodontal disease, as well as factors that affect treatment options. It describes Glickman's four-grade classification system for periodontal disease and details treatment approaches for each grade. Surgical procedures like root resection, hemisection, and extraction are discussed as options for managing multi-rooted teeth with furcation involvement, depending on factors like root morphology, bone loss pattern, and oral hygiene. Maintaining a clean, maintainable architecture and preventing further attachment loss are the goals of treating furcation defects.