CD4 and periapical periodontitis: The current study also identified skewed distribution of Th17/Treg cells as reflected by increased CD4+IL‐17A+ Th17 cells and decreased CD4+CD25+Foxp3+ Treg cells in the bone marrow of OVX rats, and intragastric administration of probiotics can effectively rescue this CD4+ T‐cell abnormality, consequently attenuating the alveolar bone loss as observed in either periodontitis or periapical periodontitis.