All diagnostic X-ray equipments in dental clinics must undergo a radiation safety inspection upon initial installation and every three years thereafter. The objective of this study was to propose an appropriate inspection cycle based on the results of safety management inspection for dental diagnostic X-ray equipment.The subject of this study was the radiation safety management inspection results of 774 X-ray equipments at 88 dental clinics. The period of use of the X-ray equipment was analyzed using the device type, inspection date, installation date, manufacturing date, approval date, date of discontinuation of use, transfer date, and disposal date. The X-ray equipment composition comprised 477 intraoral units, 143 panoramic units, 134 CBCT units,and 20 other radiographic units. In equipment suitability classification, out of 774 devices, 98.7% (764 devices) were deemed suitable, and 1.3% (10 devices) were deemed unsuitable. Among the 10 unfit devices, one (0.8%) had a lifespan of 9 years, two (1.8%) had 12 years, three (5.4%) had 15 years, one (4.3%) had 18 years, two (18.2%) had 21 years, and one (100%) had 27 years.