Sealing Ability of Mineral Trioxide Aggregate (OrthoMTA) for File Separation

Objectives: The purpose of this study is to propose new approach to obtain successful endodontic treatment using the sealing ability of OrthoMTA in the case with separated file in apical third of root canal system.
Methods: 1) Access cavity of extracted mandibular and maxillary molar
2) Canal enlargement
3) Make a groove with a disk bur on 3 mm apart from apex of file
4) Insert the grooved file into the apex, and check the file location
5) Rotate the file until it is separates intentionally
6) Take radiograph
7) Canal enlargement to the separating point(#30)
8) NaOCl soaking(10-15 min)
9) Application of watery OrthoMTA using ultrasonic indirectly(10 mins)
10) Dry the canal, and proceed with orthograde canal filling
11) After keeping them in distilled water for 24 hours, teeth were section horizontally into 0.5-1.0mm slabs
12) Examine the cross section under microscope(×200)
Results: (1) Mandibular molar – MB/ML canal (type 2) #25K-file, #25H-file
-0.5mm from apex, 1mm from apex, 2mm from apex, 2.5mm from apex, 3.5mm from apex

(2) Maxillary molar – MB canal #20K-file
-0.0mm from apex, 0.5mm from apex, 1mm from apex, 2.0mm from apex, 3.5mm from apex

(3) Maxillary molar – DB canal #15K-file
-0.5mm from apex, 1.5mm from apex, 1.75mm from apex, 2.0mm from apex, 2.5mm from apex

(4) Maxillary molar – P canal #35K-file
-0.75mm from apex, 1.5mm from apex, 1.75mm from apex, 2.0mm from apex, 3.0mm from apex

Within the limitation of this pilot experiment, a small size (3-5μm) of OrthoMTA particles promote the complete obturation
of the root-canal space between fractured file and canal wall, and also the irregular canal system. Remnants of pulp tissue acts as a barrier interfering with penetration of MTA into root canal system. For dissolving remnants of pulp tissue, NaOCl solutions have been shown to be effective, and NaOCl solution with ultrasonic be more effective.
Conclusions: OrthoMTA that is bacterio-cidal has been expected to control the bacteria. And also the apical side of fractured file could be sealed with OrthoMTA particles regardless of the file shape. Although further studies are needed to evaluate the sealing ability and acceptability in
clinical applications, this method has a great potential in successful endodontic treatment of separated instruments.