今回はEMR(Electric Measuring of Root canal length)の精度についての文献です。

作業長の決定に当たり、｢APEX｣と｢0.5｣における

ファイルの実際の位置を顕微鏡で測定しています。

使用している機器はRoot ZXとi-Rootの2種類です。

A measuring instrument must be both accurate and reliable. This study compared the reliability of the “0.5″ and “APEX” mark measurements by using 2 impedance quotient-based electronic apex locators (EALs).

One hundred four extracted human premolars were used in this study. After access preparation, the teeth were embedded in an alginate model. By using 2 EALs (Root ZX and i-Root), the tooth length was measured at the “0.5″ and “APEX” marks with K-files. The file was then cemented, and the apical 3-4 mm was trimmed for the photograph under an operating microscope. The distance between the tip of the file and major foramen (MF) was measured. The intraclass correlation coefficient, the Bland-Altman plot, and box plot were used to compare the reliability.

The intraclass correlation coefficient ranged from 0.976-0.994, indicating excellent agreement in both “0.5″ and “APEX” marks. The Bland-Altman plots showed that the limits of agreement (mean ± 2 standard deviations) were small enough to confirm that both marks of the 2 EALs can be used for clinical purposes. The distribution of the measurements and outliers was analyzed by using box plots, and it was found that there was no significant difference between the 2 marks.

There was no significant difference in the reliability of the “0.5″ and “APEX” marks for locating the MF in both devices. Accordingly, knowing where each mark indicates is more important for determining the working length than which mark to choose.

つまり…

右図の様に｢APEX｣は一貫して解剖学的根尖孔の位置を示したが

｢0.5｣は実際に解剖学的根尖孔から0.5mm手前の場所を

表してはおらず、根尖最狭窄部というよりはむしろ

解剖学的根尖孔のわずか手前を示した

といことです。

.

根尖最狭窄部の位置を推し量る上で

｢0.5｣の位置でそのまま器具操作することは

オーバートリートメントになる可能性が高まることが

分かりました。

..

引用文献

Jung IY, Yoon BH, Lee SJ, Lee SJ.

Comparison of the reliability of “0.5″ and “APEX” mark measurements in two frequency-based electronic apex locators.

J Endod. 2011 Jan;37(1):49-52.