In vitro study on sealing dentinal tubules of children by combining EDTA gel with Nd: YAG laser

Dentin hypersensitivity is a common oral discomfort in children, mainly caused by exposed dentinal tubules responding to thermal, mechanical, and chemical stimuli. Effective sealing of dentinal tubules is crucial for alleviating sensitivity. This study aimed to evaluate, in vitro, the effect of EDTA gel combined with Nd: YAG laser on sealing dentinal tubules in children’s teeth. Thirty extracted healthy premolars and molars from children were prepared into standardized dentin specimens. All samples were pretreated with 17% EDTA solution for 5 min to simulate tubule exposure and then randomly assigned to three groups: (1) EDTA gel group (n = 20); (2) Nd: YAG laser group (1 W, 10 Hz, 100 mJ, 85 J/cm², n = 20); and (3) combined EDTA gel plus Nd: YAG laser group (n = 20). Dentin permeability was measured using a hydraulic conductance method, while scanning electron microscopy was employed to evaluate tubule number, diameter, and occlusion. Dentinal cell count and tubule re-exposure rate after thermal cycling were also assessed. Data were expressed as mean ± standard deviation, and group comparisons were performed by one-way ANOVA. Both EDTA gel and Nd: YAG laser alone partially reduced dentin permeability and promoted tubule occlusion, but with limited effectiveness. In contrast, the combined group demonstrated the most favorable outcomes: dentin permeability (89.22 ± 2.23) and dentinal cell count (434.23 ± 15.26) were significantly increased (p < 0.05), while the number (26.43 ± 8.56) and diameter (0.81 ± 0.13 μm) of open tubules were significantly reduced (p < 0.05). The occlusion rate reached 85.33%, markedly higher than that of the single-treatment groups. Moreover, the combined group showed the lowest re-exposure rate under thermal cycling (1.37%), indicating strong long-term stability. EDTA gel removes the smear layer and exposes tubule orifices, while Nd: YAG laser seals tubules via thermal effects. When combined, the two approaches act synergistically, achieving nearly complete occlusion of dentinal tubules, improving sealing efficiency and durability. This combined treatment shows superior performance over single applications in vitro and presents promising potential as an effective therapeutic strategy for managing dentin hypersensitivity in children.