CLOCK and metabolic disease: The key circadian clock genes (CCGs) are closely intertwined with metabolism, immune function, cell proliferation, and signal transduction.30 Hence, disruptions in circadian rhythms or mutations in circadian clock genes are linked to the onset and progression of a diverse variety of diseases, including metabolic disorders,31 liver diseases, heart diseases,32 kidney diseases33 and cancer.34 Although some studies have shown that the circadian clock influences tooth enamel mineralization, the regulatory mechanisms still need to be elucidated.19