5.25%NaOCl冲洗液在两种不同机械预备根管时对牙本质微硬度的影响

目的:比较不锈钢器械和机用镍钛器械预备根管5.25%次氯酸钠(NaOCl)作冲洗液对根管牙本质微硬度的影响。方法:29个磨牙根随机分为4组,8个牙根摘除牙髓后用5.25%NaOCl冲洗;16个牙根分别用不锈钢器械和机用镍钛器械预备根管,5.25%NaOCl作冲洗液;5个牙根摘除牙髓后用蒸馏水冲洗作对照。用微硬度测定仪检测根管牙本质的微硬度。结果:5.25%NaOCl对牙本质微硬度产生一定的影响;各组牙本质在距髓腔500μm和1000μm处微硬度有显著差异;不锈钢器械预备后的牙本质微硬度显著低于镍钛器械。结论:根管器械预备和NaOCl冲洗液改变牙本质的机械性能,镍钛器械的使用可降低冲洗液对牙本质的不良影响。

Effect of 5.25%NaOCl Irrigation on the Microhardness of Root Dentin with Two Different Types of Instrumentation

Objective: To compare root-dentin microhardness after instrumentation with two types of files and irrigating with 5.25% sodium hypochlorite. Methods: Twenty-nine roots were involved in this experiment. 8 roots with the pulp extirpated followed irrigation only. 16 roots were instrumented with stainless steel K files and rotary nickel-titanium files respectively, each followed with irrigation. 5 roots had the pulp extirpated as the contrast. The roots were sliced and root-dentin microhardness was measured. Results: Sodium hypochlorite irrigation decreased root-dentin microhardness. Significant differences were found between the microhardness at depths of 500 μm and 1 000 μm from the pulp-dentin interface in all roots. Instrumentation with SS K file affected dentin microhardness significantly to a lesser extent than instrumentation with Ni-Ti files did. Conclusion: Instrumentation and NaOCl irrigation affect microhardness of dentine. Ni-Ti instrument decreases the influence of irrigation on root canal dentin microhardness.