FIELD OF THE INVENTION

The present invention refers to a gutta-percha sealant for locating endodontic apices and particularly to such a sealant that has an electrode that facilitates the sealant being located during root canal treatment. BACKGROUND OF THE INVENTION

EP 1 219 261 discloses a gutta-percha point for locating an apex, comprising a gutta-percha part having an exterior which is shaped to a root canal to be filled by the part and the exterior having a point end to be inserted and an electrode extending along the gutta-percha part toward the point end. The electrode is shaped and placed to have access to the exterior of the gutta-percha part to be exposed to whatever is in contact with the gutta-percha part there. The electrode extends away from the point end of the part and is connectable to a device for locating an apex.

The gutta-percha point comprises a substantially conical shape, gutta-percha part, which incorporates, in its interior or along its lateral flank, an electrode of a biocompatible material, such as steel, titanium, etc. The electrode terminates at a minimal distance from the deep end part of the point, and the electrode accesses the exterior of the point along its lateral side in a zone that is typically shaped with a slight concavity. The electrode in the concavity is thereafter sealed with sealing cement. On the opposite end, the electrode extends to the exterior of the point in order to be connected to an apical locator. The electrode may extend through the gutta-percha part and exit at the point of the gutta-percha part at its end.

In this way, by having previously wet the gutta-percha point, the electrical impulses of the apical locator are transmitted through the electrode and the liquid medium to the end of the apex, which acts as a conductor. Then, before the final placement of the gutta-percha point with sealing cement, the point is dried. US Patent No. 6,254,392 also discloses a filling means for root canals having an elongate electrically conductive element sheathed in an isoprene -based matrix, a distal end of which lies exposed so as to facilitate attachment of an apical locator.

In both cases the conductive filament is integral with the rubber insert and thus remains permanently inside the root canal after root treatment. To this end, the electrode must be formed of biocompatible material at least at the exterior of the gutta-percha insert where the electrode is in contact with the apical foramen. It is not considered desirable for the conductive filament to remain permanently inside the root canal after root treatment. SUMMARY OF THE INVENTION

It would therefore be desirable to provide an endodontic insert having a conductive filament that is removable after root treatment.

To this end there is provided in accordance with the invention a sealant for root canal treatment, comprising a gutta-percha insert having an exterior which is shaped to a root canal to be filled by the insert, the gutta-percha insert having a conical first end to be inserted into the root canal and a channel extending from the first end to a second end opposite the first end, said channel being configured for removably accommodating therethrough a filament electrode that protrudes from the first end so as to effect electrical contact with an apical foramen of the root canal and that is accessible from an exterior of the gutta-percha insert at the second end thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 shows pictorially a prior art sealant for root canal treatment according to the invention;

Fig. 2 shows pictorially a detail of the end of the electrode of the prior art sealant shown in Fig. 1 ; and

Fig. 3 shows pictorially a sealant for root canal treatment according to the invention. DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, identical components that appear in more than one figure or share similar functionality will be referenced by identical reference symbols.

Fig. 1 shows pictorially a known sealant 10 as disclosed in EP 1 219 261 comprising a substantially conical shape gutta-percha insert 1 1 having a longitudinal channel 12 that accommodates an electrode 13 formed of titanium or steel or of other biocompatible material. The channel 12 is marked schematically, although in the figure it is difficult to distinguish the channel from the electrode since they are of substantially the same diameter, thereby ensuring a tight fit of the electrode within the channel and preventing displacement.

Referring to Fig. 2, the distal end 14 of the electrode 13 is generally at the end zone of the sealant and is flush with the exterior of the sealant so as to make electrical contact with the inner wall or apical foramen of the root canal. The proximal end 15 of the electrode protrudes outside the outer end of the sealant and, during root treatment, is connected to an apex locator 16, having a contact 17 that is typically clamped to the patient's lip so that the measurement can be made. During root canal treatment, while the sealant 10 is pushed into the root canal, electrical pulses generated by the apex locator 16 are conducted through the electrode 13. The circuit is completed when the electrode 13 reaches the apical foramen and the apex locator 16 indicates either audibly or visibly to the dentist that the sealant is fully inserted. The electrode 13 sealant is then removed and the sealant is secured in known manner.

After use the protruding part of the electrode 13 is cut prior to finishing the root treatment and preparing for installation of the crown. Consequently, the electrode 13 remains permanently inside the root canal. It cannot easily be removed since it needs to be held fast within the sealant in order to ensure that, while installing the sealant, the distal end 14 of the electrode 13 remains flush with the exterior of the sealant. Were it easily removed, this would render the electrode liable to movement during installation of the sealant, thereby giving rise to the risk that electrical contact with the inner wall or apical foramen of the root canal will be lost. This cannot be allowed to occur since this electrical contact is essential for operation of the apical locator. In other words, the necessity to maintain good electrical contact requires that the distal end 14 of the electrode 13 remains flush with the exterior of the sealant and this, in turn, militates against its being removable after use. Fig. 3 shows pictorially a known sealant 10 according to the invention which is similar to that shown in Fig. 1 except that the electrode 13 has an S-shaped kink 20 towards its distal end and the channel 12 likewise has a complementary kink 21. Again, no attempt has been made in the figure to distinguish the channel from the electrode: in practice, of course, the internal diameter of the channel must be slightly larger than the outer diameter of the electrode. However, unlike the arrangement of EP 1 219 261 and described above with reference to Fig. 1 , in the invention the complementary kinks 20, 21 in the electrode and the channel prevent unintentional displacement of the one relative to the other and ensure that the distal end 14 of the electrode 13 remain flush with the exterior of the sealant. On the other hand, after finishing the root canal treatment, the protruding end 15 of the electrode may be gripped by pliers and sufficient force exerted to remove the electrode 13 from the sealant prior to preparation of the crown.

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. The scope of the invention is not limited by the specific disclosure herein, but only by the appended claims. Specifically, while the kink in the electrode 13 is shown as S-shaped in the figure, it will be understood that this is by way of example and any other form of kink that serves to retain the electrode in the gutta percha sealant while allowing its removal when required may be equally suitable.