Efficacy of LED light curing units compared to QHT units in terms of microleakage in resin restorations

In recent years, LED curing units have become more popular among the dentists due to their overall superior attributes. Therefore, assessment of the leakage levels in resin restorations after curing with these nearly new devices is a priority. This study was conducted with the aim to compare the microleakage in class V restorations after being cured with LED and QTH light units. Microfilled composite Z100 (3M ESPE,USA)was used on 30 samples in this experimental study. Separate class V cavities (3mm× 2mm×2mm) were prepared on buccal surfaces of 30 sound freshly extracted premolars and then filled with Z100 composite resin. Samples were divided into two groups of 15 each. The first group was cured with a halogen light curing unit (Coltolux 2.5,USA) and the second with a LED unit (Apoza,Japan) for 40 seconds. Then, the specimens were subjected to thermo cycling (5-55º for 500 cycles). Afterwards, they were covered with a nail polish 1 mm away from cervical margin and they were kept in 50% aqueous silver nitrate solution by weight for 2 hours. The samples were then placed in developing solution for 6 hours, after which, the specimens were sectioned and observed under stereomicroscope at x40 magnification. The data was analyzed with Mann Whitney and Fisher tests. Microleakage levels in gingival and occlusal margins of resins restoration, in LED and QHT units were 1.13±0.35 and 1.6±1.05 and 0.2±0.43, 0.13±0.35 respectively. There was no significant difference between the efficacy of LED and QHT units in terms of microleakage levels found in the composite resin restorations (p<0.2), (p<0.4). Application of QTH or LED curing unit to cure Z100 composite leads to similar microleakage levels in enamel/dentin margins.