The results of the univariate regression analysis showed that the IGF-1 level (OR = 0.976, 95% confidence interval [CI] = 0.958–0.994; p = 0.0308) and osteoporosis status (OR = 2.423, 95% CI = 1.060–5.537; p = 0.02086) were significantly associated with a “decline in masticatory function”. The gene discussed is IGF1; the disease is osteoporosis.