In vitro evaluation of marginal leakage at enamel and dentin treated by different laser densities

Rafael Zacatei Aveiro, Karen Cristina Kazue Yui, Tânia Mara da Silva, Lucélia Lemes Gonçalves, Stella Renata Machado Silva Esteves, Sérgio Eduardo de Paiva Gonçalves


Objectives: To evaluate “in vitro” the degree of marginal leakage in class V cavities irradiated with Nd:YAG laser onto enamel and dentin pretreated with bonding system (Single Bond, 3M ESPE) without light-curing. Material & Methods: Class V cavities were performed and standardized in 60 bovine incisors. After the acid etching, the teeth were divided into three groups: G1 – Application of bonding system, irradiation with Nd:YAG laser at 140 mJ/pulse without light-curing. G2 – Application of bonding system, irradiation with Nd:YAG laser at 200 mJ/pulse without light-curing. Group C - Application of bonding system and light-curing. Next, resin composite restorations were executed and thermocycled at alternated baths from 2 to 50 ºC (± 2 ºC), totalizing 500 cycles. To assess the microleakage, the teeth were submersed into 50% silver nitrate solution for 24 h, cut at 1 mm of thickness and analyzed through stereoscopy. The following leakage criterion scores were employed: 0 – none leakage; 1 – gingival or incisal wall; 2 – axial wall towards the pulp. Results : It was observed a high leakage frequency with score 1 among the experimental conditions. There was a higher predominance of score 2 leakage for control group at cementum. Concerning to enamel and cementum, Group C was similar to G1. By comparing control group with G2, and G1 with G2, it was verified statistically significant differences. Conclusion: The laser energy provided a reduction of the marginal leakage at enamel and dentin/ cementum; however, the energy density increase resulted in smaller marginal leakage at enamel and dentin/cementum.

Nd-YAG Laser; Energy; Marginal leakage; Enamel; Dentin.

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