C SHAPED CANAL The C shaped canal is a special feature of some lower second molars. Approximately 1% of lower second molars have C-shaped canals. The name comes from the appearance of the pulp chamber floor when viewed from above. Some or all of the canal orifices are joined in the form of a groove or isthmus with a shape of the letter C.
Good radiographic technique should alert the practitioner to unusual anatomy, such as C shaped canals. The C shaped canal may have the appearance of a fused root with very fine canals. A pulp chamber that looks unusual the dentine areas on the pulp floor map should give some idea of the location of root canals, and of the relationship of the floor to surrounding tooth structure.
Melton in 1991 divided the C-shaped canals into three types. Type I : The continuous C-shaped canal Type II : The semicolon shaped canal Type III : Two discrete and separate canals. He further added that C-shaped canals could vary in number and shape along the length of the root.
CLEANING AND SHAPING A 20 Hedstrom file was directed into the mesial corner and a 40 HedStrom file was placed into the most distal aspect of the canal in order to determine the apical extension and possible bifurcation of the C-shaped canal. A working length radiograph was then taken.
CLEANING AND SHAPING The root canals were enlarged using H files with 0.5 % sodium hypochlorite as the irrigating solution. A sonic vibratory instrument with # 35 was used to enlarge and flare the canals. The mesial portions of the C-shaped canal were fully instrumented prior to the debridement of the connecting trough.
CLEANING AND SHAPING The trough was very narrow in the buccolingual dimension but appeared to extend the entire length of the C-shaped canal. The instrumentation of the trough was difficult. Hedstrom files #10, #15 and #20 were used for the initial enlargement and the sonic vibratory device with file # 20 was used with advantage in the final debridement and irrigation of the trough.
CLEANING AND SHAPING The final shaping of the canals was achieved with hand instruments. The root canals were once more irrigated with 0.5% sodium hypochlorite and dried with sterile paper points. Standardized gutta-percha cones of corresponding widths were selected.
MASTER CONES PLACEMENT To ensure proper placement of the master cones within the C-shaped canal, a large diameter file was placed into the most distal portion of the canal. The master cone for the mesial portion was then coated with sealer and guided into place. The file was removed without dislodging the mesial master cone and the distal master cone was inserted
Additional accessory gutta-percha cones were coated with sealer and inserted into the middle portion of the C-shaped canal. A mid-obturation radiograph was taken. This revealed the presence of root canal sealer and gutta-percha between the mesial and distal aspects of the C-shaped canal.
Warm Lateral Condensation A heated instrument is introduced into a tooth already obturated by lateral condensation to soften the gutta-percha mass and enhance adaptation to the internal anatomy of the canal. This technique is useful to increase the adaptation and density of teeth obturated with lateral condensation, it is especially indicated for C-shaped canals
REFERENCES CASE HISTORY Frederic Barnett D.M.Q, University of Pennsyivania, Endodontics Problem-Solving in Clinical Practice TR Pitt Ford, BDS, PhD, FDS RCPS JS Rhodes, BDS, MSc, MRD RCS, MFGDP