BackgroundThe aims of the study were measuring the light intensity of light curing units used in Qazvin’s dental offices, determining the relationship between the clinical age of these units and their light intensity, and identifying the reasons for repairing them.Material and MethodsIn this cross-sectional study, the output intensity of 95 light curing devices was evaluated using a radiometer. The average output intensity was divided up into four categories (less than 200, 200-299, 300-500, and more than 500 mW/cm2). In addition, a questionnaire was designed to obtain information mainly about the type, clinical age, and frequency of maintenance of the units and the reasons for fixing them. Data were analyzed using Kolmogorov-Smirnov, chi-squared, and t-tests (p< 0.05) on SPSS 24.ResultsA total of 95 light curing units were examined, with 61 (64.2%) of them being of the LED type and 34 (35.8%) of the QTH type. While average light intensity in LED units was significantly higher than in QTH devices, the two device types were not significantly different regarding desirable light intensity (i.e., ≥ 300 mw/cm2). A negative correlation was observed between clinical age and light intensity. In addition, bulb replacement in QTH devices was over three times as much as in LED units. Also, repairing QTHs was more than twice as much frequent as fixing LEDs. The most common reason for repair was the breakage of the tip of the device.ConclusionsThe light intensity of LED units is significantly higher than that of QTH devices, and the frequency of repairing in QTHs was significantly more than in LEDs. Furthermore, light intensity decreases with aging, and dentists should regularly monitor the conditions of light units. Key words:Light curing unit, radiometer, light intensity, dental equipment, dental offices.

BackgroundThe present study was performed with the following aims: (1) to assess the relationship between skeletal age, measured using the cervical vertebral maturity (CVM) method, and chronological age; (2) to determine the correlation of skeletal and chronological age to the cortical thickness of the lower border of the mandible using the linear radiomorphometric; and (3) to explore the relationship between these indices and skeletal malocclusion type.Material and MethodsThe data were collected from the records of 180 patients, including 57 males (31.7%) and 123 females (68.3%). The data were based on the panoramic and lateral cephalograms of each patient. The CVM stages were determined on the basis of the patients’ lateral cephalograms. Three radiomorphometric indices were measured: AI, MI and GI. The patients were divided up into three groups of skeletal malocclusion: Class I, II, and III. For all the tests, statistical significance was set at P<0.05.ResultsThe relationship between chronological age and skeletal age was 0.496. Furthermore, with an increase in chronological and skeletal age, the cortical thickness of the lower border of the mandible and consequently the radiomorphometric indices increase, except for the GI (P > 0.05). Lastly, the relationship between GI and skeletal malocclusion type proved significant.ConclusionsAI and MI were found to increase significantly with increasing age, so the assessment of mandibular radiomorphometric indices could be clinically useful in estimating of the growth and maturation of the mandible. Key words:Orthodontics, Radiomorphometric indices, Skeletal age, Skeletal malocclusion.