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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 2  »  Accuracy of a new apex locator: an in vitro study
Accuracy of a new apex locator: an in vitro study
Discussion - References.

Root length determination is a crucial factor for successful root canal treatment (McDonald 1992, Cohen & Burns 1998). The traditional radiographic method has shortcomings (Kaufman & Katz 1993), including its inaccuracy (Stein & Corcoran 1992). Since their introduction, electronic apex locators have gained in popularity, especially since the development of the most recent generation. This generation uses two frequencies and enables tooth length measurements in the presence of electrical conductive media in the root canals (Kobayashi 1995). Accuracy of the recent generation of EAL averages around 90% (Fouad et al. 1993, Frank & Torabinejad 1993, Lin et al. 1993, Mayeda et al. 1993, Ulman et al. 1996). An EAL that further improves the accuracy rate is desirable and, if proven to be a reliable tool, could potentially replace, in many instances, the classic radiographic method for tooth length determination.

Mean differences between EL and RL compared to AL in different contents of the root canals
Table 2. Mean differences between EL and RL compared to AL in different contents of the root canals (in mm).

The manufacturers of the Bingo 1020 claim that their measuring method (based on root mean square) to locate the position of the file as it advances in the root canal produces more accurate measurements. This study tested that claim by comparing the Bingo 1020 to the Root ZX in an in vitro model. The reference point was the actual length (AL) as measured by introducing a file until it was seen in the apical foramen. Initial measurements (before root canal preparation) revealed that measurements obtained using the Bingo 1020 were constantly closer to the actual length than those of the Root ZX (average 0.08 mm). Although this difference was statistically significant, it has no clinical relevance. Similar results were obtained after completion of the root canal preparation and measuring the root canals in the presence of different irrigants, with the exception of chlorhexidine.
Chlorhexidine digluconate is antiseptic and has an affinity to hydroxyapatite. It has been suggested as an irrigant and as an intracanal medication (Kuruvilla & Kamath 1998, Lindskog et al. 1998, Segura et al. 1999). To date, no study has been conducted to test the effect of this solution on electronic measurements. The results of the present study indicate that the electronic measurement in the presence of chlorhexidine can be performed safely because the results are similar to those obtained in the presence of NaOCl.
Xylol is often used in retreatment cases. Its effect on electronic measurements has not been investigated. The results of this study indicate that measurements in the presence of Xylol give shorter results (average 0.5 mm). Thus, relying on these measurements alone could lead to an incomplete debridement of the root canal system. With both EALs, EDTA and saline gave the closest results to the actual length. Thus, these irrigants can be considered as reliable solutions for electronic measurements.
Comparisons were made between electronic and radiographic measurements performed before and after root canal preparations. The in vitro model provided an opportunity to take the radiographs with ideal geometrical relationships. However, a statistically significant difference was found when comparing the electronic measurement to the radiographic one. Compared to the actual length, the radiographic measurements were longer (average 0.35 mm), whilst the electronic measurements were shorter (average 0.4 mm). No statistical difference was found between the two EALs regarding this finding. These results are in accordance with Stein & Corcoran (1992), who found a difference of 0.7 mm between the real file positions to that calculated on radiographs.
Today, the common practice is to verify electronic measurements by radiographs and to refer to the radiographs as the most reliable source for root length determination (Cohen & Burns 1998). The result of this in vitro study needs to be verified in an in vivo study.


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