Investigation of coronal leakage of root fillings after smear-layer removal with EDTA or Nd:YAG lasing through capillary-flow porometry.

OBJECTIVE: This study investigates the effects of Nd:YAG laser irradiation combined with different irrigation protocols on the marginal seal of root fillings. BACKGROUND DATA: Limited information exists regarding the effects of morphologic changes to root canal (RC) walls after Nd:YAG laser irradiation after smear-layer removal with EDTA on the sealing ability of root fillings. METHODS: The 75 root-filled teeth (5 × 15 teeth) were analyzed for through-and-through leakage by using capillary flow porometry (CFP). The RC cleaning procedure determined the assignment to a group: (1) irrigation with NaOCl 2.5% and EDTA 17% or standard protocol (SP), (2) SP + Nd:YAG lasing (dried RC), (3) NaOCl 2.5% + Nd:YAG lasing (dried RC), (4) SP + Nd:YAG lasing (wet RC), or (5) NaOCl 2.5% + Nd:YAG lasing (wet RC). Groups 1r to 5r consisted of the same filled teeth with resected apices up to the most apical point of the preparation length. Resection was performed after the first CFP measurement. Roots were filled with cold lateral condensation. CFP was used to assess minimum, mean flow and maximum pore diameters after 48 h, and immediately after these measurements, including root resection. Statistics were performed by using nonparametric tests (p > 0.05). An additional three roots per group were submitted to SEM of the RC wall. RESULTS: Through-and-through leakage was observed in all groups. Statistically significant differences were observed in maximum pore diameter: 1r > 3r, and 1r > 5r; in mean flow pore diameter: 1r > 2r, 2r < 4r (p < 0.05). Typical Nd:YAG glazing effects were observed when the smear layer was present and exposed to the laser fiber (i.e., in the groups without use of EDTA) or when the fiber tip made direct contact with a smear-layer free RC wall. CONCLUSIONS: The reduction in through-and-through leakage is significantly higher with the Nd:YAG laser as smear-layer modifier than when smear layer is removed with an EDTA rinsing solution.

Longitudinal study on the influence of Nd:YAG laser irradiation on microleakage associated with two filling techniques.

OBJECTIVE: This study investigates the effects of Nd:YAG laser irradiation on apical and coronal seals, when used prior to two root canal filling techniques. BACKGROUND DATA: Limited information exists regarding the effects of morphologic changes to dentin walls following Nd:YAG laser irradiation on the sealing ability of root fillings. METHODS: Two hundred forty teeth were analyzed by observing coronal and apical leakage of Indian ink (DL), and 60 were analyzed for through-and-through leakage using the fluid transport model (FTM). The Nd:YAG laser parameters were 1.5 W, 100 mJ, and 15 Hz (four times for 5 s at 20 s intervals). Each group consisted of a lased and a nonlased subgroup: each subgroup had root fills done by either cold lateral condensation (CLC) or hybrid condensation (HC). Leakage was assessed after 48 h, and then at 1, 6, and 12 months. The DL group was divided into four groups of 15 teeth for each evaluation point. Through-and-through leakage (L in microliters/day) was measured for 48 h under a pressure of 1.2 atm using FTM, and recorded as L = 0 (L1), 0 < L 10 (L3). RESULTS: Apical and coronal dye leakage was observed in all groups. Significant differences (p < 0.05) in apical leakage were found between HC and HC + Nd after 1, 6, and 12 months, and between CLC and CLC + Nd at 6 and 12 months. No significant differences were found between laser-irradiated and non-laser-irradiated groups with FTM. CONCLUSION: Pulsed Nd:YAG laser irradiation following root canal preparation may reduce apical leakage in association with hybrid gutta-percha condensation.