To identify gender- and age-related associations between adult dental checkups and unmet dental care needs, we analyzed data of 14,000 participants, ages ≥ 19, from the 7th Korea National Health and Nutrition Examination Survey (2016–2018) (KNHANES VII). Data was collected via self-report questionnaires and interviews. Complex sample chi-square test and multiple logistic regression analysis indicated 31.7% of participants had unmet dental care needs; in the prior 12months, 67.1% had not utilized dental services, and 43.3% had not received dental checkups. Odds ratios (ORs) for dental checkups and unmet dental needs were 8.87 (CI:7.80–10.09, p < 0.001) for those who used dental services and 1.28 (CI: 1.13–1.44, p < 0.001) for those who had not. Significant age-dependent associations between those not receiving dental checkups and the rate of unmet dental care include men and women aged 50–59 years (OR: 1.77; CI = 1.22–2.58 and OR: 1.43; CI: 1.02–2.02; p = 0.040, respectively) and women ≥ 70 years (OR = 1.79, CI = 1.20–2.66, p = 0.004). Reducing unmet dental care needs requires greater public health promotion and education regarding regular dental checkups; additional practical strategies could enhance dental checkup compliance.