Endodontic masterclass: radix entomolaris

Peet van der Vyver and Martin Vorster kick off a new series by discussing the identification and management of radix entomolaris.

According to Swartz, Skidmore and Griffen (1983), mandibular first molars have a significantly lower success rate compared with other teeth. 

Missed canals and the failure to remove all the microorganisms and pulp remnants from the root canal system are probably the main reasons for persistent infection around endodontically-treated molars. It is therefore important that clinicians have an awareness and good understanding of the variations in root canal morphology of the mandibular first molar. 

Permanent mandibular first molars in Caucasian populations are generally two rooted teeth (one mesial and one distal root) with two mesial and one distal root canals (Barker et al, 1974). The two mesial root canals can end up in two distinct apical foramina or they can merge at the root tip end into one apical foramen (Calberson, De Moor and Deroose, 2007).

The number of roots for the mandibular first molar teeth may also vary. Carabelli (1844) was the first to report on mandibular first molars with supernumerary roots. The third root was located on the distolingual side and was called radix entomolaris (RE). In rare cases, the mandibular first molar can also present with an additional root at the mesiobuccal side and is called radix paramolaris (Calberson, De Moor and Deroose 2007). 

Prevalence of radix entomolaris

The presence of RE in the mandibular first molar is associated with certain ethnic groups. In populations with Mongoloid traits (for example Chinese, Eskimo and American Indians), the frequency can range from 5% to 30% (Turner, 1971; Yew and Chan, 1993; Reichart and Metah, 1981; Walker and Quackenbush, 1985; Curzon, 1973). However, in Eurasian and Indian populations, it is less than 5% and in African populations less than 3% (Ferraz and Pécora, 1993).

RE can be found on first, second and third mandibular molar teeth, occurring least frequently on second molars. Steelman (1985) also reported a bilateral occurrence with a frequency of 50% to 67%.

To read the rest of this article and view some case studies, simply visit www.dentistry.co.uk/cpd.

Get the most out of your membership by subscribing to Dentistry CPD
  • Access 600+ hours of verified CPD courses
  • Includes all GDC recommended topics
  • Powerful CPD tracking tools included
Register for webinar
Add to calendar