Dental Education Lecture: Unique Root Canals
Root canal structures of the lower 2nd molars (2 in Fig.1,6,11) are sometimes unique, particularly in Chinese origin. When the teeth are opened for root canal treatment (RCT), two or three root canals can be found (1-2 or 3 in Fig.2,7,12). These canals (black circles in Fig.3,8,13) are often interconnected (red lines) to form C-shaped configuration, so-called C canals. C canals are quite common in Chinese and rare in other races. When Chinese patients go to see American dentists, the latter may be puzzled by the bizarre structures when the teeth are opened. Then the Chinese patients need to see specialists to finish RCT.
With practice, general dentists can identify the teeth with C canals in advance: two roots fuse each other at the root tip (2 in Fig.1,6,11). With good lighting and magnification, two or three canal openings can be seen (1-2 or 3 in Fig.2,7,12). After thorough cleaning, root canals are filled (Fig.4,9,14). Several months later, the root tip infection (arrowheads in Fig.4,9) is no longer visible on X-ray (arrowheads in Fig.5,10).
Three cases of C canals are reported here. The first patient (Fig.1-5) has big cavity in 2nd molar next to 3rd molar (3 Fig.1). Before doing RCT for the 2nd molar, the 3rd molar is extracted. The 1st molar (1 in Fig.1) has had root canal treatment and crown, but still has root tip infection (Fig.1,4,5).
The 2nd patient (Fig.6-10) has lost the 1st molar, which is replaced by a bridge (B in Fig.6). One of the anchor teeth (2nd molar) has a cavity underneath crown (arrowhead in Fig.6). After root tip infection resolves, an implant (I in Fig.10) is placed to restore the 1st molar later on.
The third patient (Fig.11-4) has also lost the 1st molar. As you may notice, the 2nd and 3rd molars have tilted and shifted to the space of the 1st molar (Fig.11). The 2nd molar has pain after placement of large filling (F in Fig.11) so that RCT is needed (Fig.14). After treatment, pain disappears. Soon she gets pregnant. We do not have chance to take X-ray for follow-up.
Xin Wei, DDS, PhD, MS 1st edition 06/10/2010, last revision 06/10/2010