【目的】 探究不同髓腔体积根管模型对 Er:YAG 激光激活荡洗过程中流体动力的限制性影响，进一步评估其解决方案 SWEEPS 技术中不同脉冲间隔参数对流体动力的影响，为临床上安全、有效应用 Er:YAG 激光进行根管荡洗提供理论基础和实验支持。 【方法】 (1)设计 4 种髓腔体积根管模型各 3 个，记为 V1、V2、V3、V4 组，其髓室顶/底直径依次为 4/2、6/4、8/6、10/8 mm。设置 Er:YAG 激光器参数为超短脉宽模式(Super Short Pulse, SSP)、频率为 20 Hz。单脉冲能量设置为 10、20、30、40、50 mЈ。高速摄像系统记录每组模型在不同单脉冲能量条件下的气泡形态变化，并通过高频脉动压力传感器获取每组模型在不同单脉冲能量条件下的根尖瞬时峰值压强(The Transient Peak Pressure, TAPP)。每组重复实验 4 次，各测量指标取均值。 (2)设计前牙单根管树脂模型，其髓室顶/底直径为 4/2 mm，Er:YAG 激光器参数设置：SWEEPS 模式、频率为 20 Hz，单脉冲能量为 20 mЈ,脉冲间隔时间(Tp)设置为 120、210、300、400、500 µs 。应用高速摄像系统记录不同脉冲间隔条件下髓腔内气泡形态变化。通过高频脉动压力传感器获取每组模型在不同脉冲间隔条件下的 TAPP。每组重复实验 4 次，各测量指标取均值。 【结果】 (1) V1、V2 组在 20 ~ 50 mJ 单脉冲能量条件下发生液面破裂，V3、V4 组仅在 50 mJ 下发生液面破裂。髓腔体积和单脉冲能量对 Vmax、R 和 TAPP 均有显著影响（均 P < 0.001）。V1、V2、V3 和 V4 组单脉冲能量与 TAPP 的线性回归拟合分析结果显示，在 30 ~ 50 mJ 单脉冲能量条件下均为一次函数线性增长模式，回归系数（β1）依次增大（均 P < 0.05）。(2) Tp 为 120 µs 时 TAPP 显著高于 Tp 为 210 µs 时，差异具有统计学意义（P˂ 0.05）；Tp 为 300 µs 与 400 µs 时，TAPP 均显著低于 Tp 为 500 µs 时，差异具有统计学意义（P ˂0.05）；Tp 为 120 µs 与 500 µs 时，两组 TAPP 均无显著差异（P > 0.05）。 【结论】 (1) 髓腔体积对 Er:YAG 激光激活荡洗的相关流体动力具有限制性影响。TAPP 随单脉冲能量提升的幅度在 30 ~ 50 mJ 范围小于 10 ~ 30 mJ；在 30 ~ 50 mJ单脉冲能量条件下，TAPP 随单脉冲能量提升的幅度随髓腔体积的减小而减小。安全性方面，当髓腔体积较小（V1、V2 组）时建议单脉冲能量< 20 mJ，当髓腔体积较大（V3、V4 组）时可根据需要选择< 50 mJ 的单脉冲能量，以降低液面破裂及软组织损伤风险。 (2)在五种脉冲间隔(Tp)条件下，SWEEPS 双脉冲模式激活荡洗过程中，荡洗液面始终保持稳定，均未出现液面破裂导致荡洗液飞溅的现象。Tp 为 120 µs 在具有较强流体动力的同时具备更短的激光作用时间，临床上推荐使用该参数，以保证根管荡洗效率的同时提升流体动力。

Objective: This study aimed to investigate the restrictive influence of different pulp chamber volumes on fluid dynamics during Er:YAG laser-activated irrigation in root canal models. Furthermore, we evaluated the influence of pulse interval settings in the SWEEPS mode under a fixed pulp chamber volume, providing theoretical and experimental support for the safe and effective clinical application of Er:YAG laser in root canal irrigation. Methods: (1) Four types of resin root canal models with varying pulp chamber volumes were fabricated (V1-V4), with coronal/apical pulp chamber diameters of 4/2 mm, 6/4 mm, 8/6 mm, and 10/8 mm, respectively (n = 3 per group). The Er:YAG laser was set to a super short pulse (SSP) mode at 20 Hz, with single pulse energies of 10, 20, 30, 40, and 50 mJ. Bubble morphology was recorded using high-speed videography, and The Apical Transient Peak Pressure (TAPP) was measured using a high-frequency pressure transducer. All tests were repeated four times, and the average values were used for analysis. (2) A standardized anterior single-root canal resin model was used, coronal/apical pulp chamber diameter 4/2 mm. The Er:YAG laser was set to SWEEPS mode (frequency 20 Hz, energy 20 mJ), with pulse intervals of 120, 210, 300, 400, and 500 µs. Bubble morphology was recorded using high-speed videography. TAPP was measured under each pulse interval condition. All experiments were repeated four times and averaged. Results: (1) Liquid surface rupture occurred in groups V1 and V2 at 20-50 mJ, and in groups V3 and V4 only at 50 mJ. Both pulp chamber volume and single pulse energy significantly influenced Vmax, R, and TAPP (all P < 0.001). Linear regression analysis between energy (30-50 mJ) and TAPP revealed positive linear trends in all groups, with β1 coefficients increasing ( P < 0.05). (2)For TAPP, 120 µs was significantly higher than 210 µs (P < 0.05); TAPP at 300 and 400 µs was significantly lower than at 500 µs (P < 0.05); no significant differences were found between 120 µs and 500 µs (P > 0.05). Conclusion: (1) Pulp chamber volume exerts a restrictive influence on Er:YAG laser-activated irrigation, affecting fluid dynamics including bubble volume, morphology, and TAPP. The increment in TAPP at higher energy levels (30-50 mJ) was smaller compared to lower energies (10-30 mJ), and the degree of TAPP enhancement decreased as chamber volume decreased. From a safety perspective, single pulse energy should be < 20 mJ in small-volume chambers (V1, V2), while up to < 50 mJ may be acceptable in large-volume chambers (V3, V4) to reduce the risk of liquid surface rupture and soft tissue damage. (2) Across all Tp conditions, the liquid surface remained stable with no observed splashing caused by surface rupture. Given that 120 µs achieves strong fluid dynamicswith a shorter activation time, it is recommended as the optimal Tp setting for clinically efficient and safe SWEEPS-based root canal irrigation.