Er,Cr:YSGG Laser for Root Caries Removal: Microleakage and Morphometric Evaluation

Objectives: To analyze the influence of Er,Cr:YSGG laser for root caries removal on the cavity characteristics and microleakage of a resin composite restoration. Methods: One hundred and fifty-four dental root samples from seventy two extracted human carious-free molars and premolars were used. After the in vitro root caries induction using S. mutans, the carious lesions were removed either by the conventional technique using burs (control), or by the Er,Cr:YSGG laser (l =2.78 µm, 20 Hz, pulse duration @ 150 µs, energy per pulse of 0 to 300 mJ, non-contact mode using a 600 µm tip and powers between 1 and 4.0 W with 0.25 W-intervals). During caries removal, preparation time was recorded for all groups. One sample of each group was observed in scanning electron microscopy (MEV). For the 14 groups (n=10/group) the samples were conditioned with Clearfil SE Bond and restored with a flowable composite. They were then thermal cycled (1000 Cycles) and immersed into a 2 % methylene blue solution for microleakage analysis. The data were statistically compared (ANOVA, Kruskall-Wallis and Spearman correlation tests; p = 0.05). Results: The lased groups showed significant higher microleakage index, cavity depth, presence of residual caries and time for caries removal procedure than control. There was a strong positive correlation between residual caries and microleakage. Powers higher than 3W lead to undesirable results. Conclusion: Er,Cr:YSGG laser irradiation is not a valid alternative to burs for root caries removal since it may cause a significant loss of marginal sealing of a resin composite restoration.