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24 Dental Tribune Middle East & Africa Edition | March-April 2015referral clinic > Page 26 Troughing: Detection of three canals in the mesial root of an upper molars By Dr. Carlos Vidal Tudela S ummary The complex anatomy of the root canal system is a determining factor in the suc- cess of Endodontic therapy. Its localization and permeability can become a very complex task even for the most experienced dentists. The combination of the use of the microscope to- gether with the arrival of the ul- trasound to the area of the root canal means that manoeuvres such as “troughing” make it eas- ier and more effective to locate the entrance to the conducts. In this article we present some guidelines which will help the dentist to understand and carry out such work together with the illustrations of a clinical case study, in which as a result three main conducts in the buccal root of an upper molar were cleaned, shaped and filled. Key words Troughing, Surgical micro- scope, Ultrasonic, Three canal Mesiobuccal root. Introduction The healing of endodontic pa- thology is conditioned by the capacity of controlling the infec- tion within the complex system of the root canals (1). The upper first molar is a tooth that presents a complex anat- omy in its mesiobuccal root. Pineda (2), Weine (3), Vertucci (4), and Brown Herbranson (5) describe the anatomical com- plexities a practitioner should confront. On the other hand, the identifi- cation of three conducts in the mesiobuccal root of an upper molar is a fact relatively rare as shown in the specialised litera- ture (5). Traditionally, the DG 16 exploration probe has been the clinical method used to find either the second buccal or lin- guomesial conduct (6). With the arrival of the Surgical Microscope (7) and the use of ul- trasound in endodontic therapy, the “troughing” manoeuvre is being carried out, which means to create a depression or open a path at the floor of the pulp chamber for better access to the orifices of the pulp canals. The aim of this article is to de- scribe the Troughing manoeu- vre and to illustrate a clinical case in which three conducts in the Mesiobuccal root of a upper first molar are present. Classification of weine for the conducts of the mesiobuccal root Weine proposes four types to de- scribe the configuration of the main conducts in the mesiobuc- cal root (3), of the upper molars (Fig. 1): • Type I: one conduct from the entrance orifice to the apex. • Type II: two orifices that con- verge into one at the apical fora- men. • Type III: two orifices of en- trance at the pulp chamber and two separated conducts from origin to the apex. • Type IV: one orifice of entrance at the pulp chamber to then diverge into two separate con- ducts with independent apical foramen. The configurations of Type II and III represent almost 95% of the cases (Fig. 1). Classification of vertucci for the mesiobuccal root • Type I: one conduct, one fora- men. • Type II: two conducts that fuse at the apical third. • Type III: two conducts that di- vide in two and re-join into one. • Type IV: two separate conduct till the apex. • Type V: one conduct dividing near the apex. • Type VI: two conducts that fuse along the root and divide once again at the apex. • Type VII: one conduct that di- vides fuses and finally has 2 fo- ramina exits. • Type VIII: three separate ca- nals in a root. Description of the troughing maneuver or path opening at the angle line of the orifices of entrance to the mesial root of a upper molar The technique of access to the pulp chamber is a key procedure for good practice in Endodontic treatment. The opening should be direct at the possible site of entrance of the pulp chamber with refined walls. Over-ex- tensions of the roof of the pulp chamber should be avoided and perfect visualisation should be permitted at all entrances of the conducts, which should be situ- ated at the angle lines between the walls of the pulp chambers and the floor. The use of the surgical micro- scope allows a better vision of the dentin we wish to remove in order to locate the conducts. At first, by using the probe DG16 we locate the three orifices of entry of mesiobuccal, distobuc- cal and palatal conducts, prob- ably in its traditional triangular disposition. At this point, we should refine the access to the pulp cham- ber by using ultrasound, in this case directly connected to the equipment hose. We use a Kavo scaler (Fig. 3), with flat head and diamond tip (Komet), which will avoid steps on the pulp chamber floor. Thus, the ultrasound will allows us to eliminate small cal- cifications and delimit the angle lines connecting the three main conducts. Finally the use of the ultrasound permits a direct ac- cess for the observation with the Surgical Microscope and the instrumentation of the conduct exempt of interferences (Fig. 4, 5 and 6). Among the different options to permeabilization the mesiobuc- cal conducts 2 and 3, if there were any; we propose the Pro- Taper file F1 or Reciproc R25 in order to open these extra canals without permeabilization. No matter how risky this manoeu- vre may seem, it is efficient as long as we keep its use to the coronal millimetres and refrain the temptation of continuing to the apical zone of the mesiobuc- cal conduct, to avoid the screw and blockage effect, which would lead to fracture. Once opened, the mesiobuccal conducts 2 and 3 are permeabi- lised with the apical files size 10 and 15, and we can determine our conductometry with the use of apex locators and continue the instrumentation till the obtu- ration (Figs. 8 and 9). Discussion With the NITI rotary files, the new optical illumination, mag- nifying methods and with the contribution of the ultrasound, the “troughing” manoeuvres are necessary for the opening access of the teeth, both in RCT and retreat, where a high per- centage of the refractory chronic periodontitis towards an endo- dontic therapy is due to the to non-localisation of more than one conduct in a root (8). According to Wolcott and cols, while endodontic literature shows numerous articles re- lated to the prevalence of two conducts in the mesiobuccal root of an upper molar, there are not so many articles describing the presence of a third conduct in the mesiobuccal root of an up- per molar. Although the literature already indicates the existence of a third canal in the mesiobuccal root is not common, there are authors that refer to the percentage of a molar with a type 8 configura- tion in root as 0% (9). The lack of knowledge thereof can lead to treatment failure (10). It is important to full understand the anatomy of the upper first mo- lar, and with the help of a mi- croscope and ultrasound will be able to master the mesiobuccal root of the upper molars. In our day to day practice it is normal to find more than two conducts, as it can be observed in the following clinical exam- ples. We need to understand that Fig. 1 Fig. 3 Fig. 2 Fig. 4: Small calcification on the floor of the pulp chamber. Only the main conducts are located. Fig. 8: View of the five conducts treat- ed during drying step. Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 9: A) Initial sealing x-ray. B ) Fi- nal sealing/filling x-ray. Fig. 6: Opening finished with conduct orifice angle lines, the walls and the refined pulp floor. Fig. 7: Detailed view of three root con- duct orifices of mesiobuccal root. Fig. 5: Removal of the slightly calci- fied floor with Ultrasound. Note that the ultrasound allows full visibility of the chamber while work- ing. The troughing manoeuvre al- lows the view of the conducts Orifices mb2 and mb3. the mesiobuccal root is oval- shape root and not round root. In most cases if there is more than one canal we will find isth- mus we will need to prepare.