根尖孔大小对RootZX准确性影响的体外研究

目的研究根尖孔大小对Root ZX测量准确性的影响。方法采用离体牙模型，在根尖狭窄完整和破坏的情况下，分别测量实际根管长度（L）、实际根管工作长度（L′）、电测根管长度（L1）、电测根管工作长度（L2）和根尖孔面积（S），并采用SPSS 12.0软件对根尖孔面积与Root ZX电测法测量偏差的相关性进行分析。结果在根尖狭窄完整情况下，根尖孔面积与Root ZX测量准确性之间无显著相关性（P>0.05）；当根尖狭窄破坏后，根尖孔面积与Root ZX测量准确性有显著的负相关关系（P<0.001），直线回归方程为ΔL2=- 0.623+6.596S。当测量误差设定在0.5 mm时，根尖孔开口面积为0.135 mm2。结论根尖狭窄被破坏后，根尖孔大小对Root ZX测量准确性有影响。临床上对根尖有吸收破坏或根尖未发育完全的患牙采用Root ZX电测法测量时，应谨慎参考根管工作长度值。

In vitro evaluation of correlation between the size of apical foramen and the accuracy of Root ZX

OBJECTIVE: The study was designed to investigate the relationship between the accuracy of Root ZX and the size of apical foramen, when the apical constrictions were intact or not. Methods Lengths were taken when the needle reached the '0.5' mark and 'APEX' mark on the Root ZX. The electronic apex locator (EAL)-measured canal working length (L2) and EAL-measured canal length (L1) were then compared with the actual canal working length (L') and actual canal length (L). Besides, the areas of apical foramens CS) were measured when the apical constriction were intact or not. Then the measurement deviations and the areas of apical foramens were analyzed by linear correlation and linear regression using the software SPSS 12.0. Statistical significance was considered at P < 0.05. RESULTS: There were no significantly correlations between the area of apical foramen and the accuracy of Root ZX if the apical constriction was intact (P > 0.05). However, the accuracy of Root ZX and the size of apical foramen had significant negative correlation when the apical constriction was destroyed (P < 0.001). Then the linear regression was completed, and the linear regression equation was deltaL2 = -0.623 + 6.5965, so the critical area of the apical foramen was 0.135 mm2 if the tolerant error was set at 0.5 mm according to the statistic control. CONCLUSION: The size of apical foramen has little effect on the accuracy of Root ZX if the apical constriction is intact. However the measurements of Root ZX should be used carefully when the apical constriction was destroyed.