Radix entermolaris and Radix paramolaris

• Extra root present on lower molars. Non concentric position and easily missed in RCT
• RE is present distolingually in lower molars but can be located as far messially as the central portion between the mesial and distal roots.
• RP is present mesiobuccally but can be found centrally between the mesial and distal roots
• RE Rare in Caucasian populations Max 3-4%
• RE Eurasian and Indian <5%
• RE Mongoloid population (Chinese, eskimo and american indians) 5% - >30%
• RE can be found on and lower molar but occurs most commonly on the 6 and least commonly on the 7. 50-67% bilateral
• Morphology can vary from a short conical extension to a mature root with normal length and root canal. In general, the RE is smaller than the DB and mesial roots and can be separate from or partially fused
• RP is very rare. 2% 3rd molar, 0.5% 2nd molar, 0% first molar but other studies have found RP in first molars. 
• An additional cusp (Tuberculum paramole) may be present on the buccal side in a tooth with RP however an additional cusp does not necessarily indicate the presence of an RP. However, and additional root almost always shows an increased number of cusps with an increased number of root canals. The clinical sign may just be a more prominent occlusal or distolingual lobe
• A RE almost always is situated in the same buccolingual plane as the distobuccal root so is difficult to spot on an Xray
• Unclear view (Difficult to see) or outline (Discontinuous PDL space) of the distal view can indicate an RE. A second xray should be taken with a 30 degree mesial or distal angle to reveal the RE
• Periodontal probing of the cervical morphology can find an additional root. a cervical prominence or convexity can indicate an extra root. 
• The orifice of the RE is located disto to mesiolingually from the main canal. An extension of the triangular access to the distolingual will form a more rectangular or trapezoidal shape. 
• A dark line on the pulp chamber floor can indicate the location of a RE orifice. The pulp chamber roof or calcification overlying the RE orifice can obscure the RE. Relocation of the orifice to the lingal can achieve straight line access.