GGTLC1 and periodontitis: A linear multiple regression analysis was performed using data from these blood tests as independent variables, adjusted for age, smoking history, and oral hygiene; the results showed that serum aspartate aminotransferase, alanine aminotransferase, gamma‐glutamyl transpeptidase, cholinesterase, lactate dehydrogenase, and high‐density lipoprotein cholesterol (inversely proportional) were significantly correlated with the severity of periodontitis.