|Year : 2015 | Volume
| Issue : 1 | Page : 57-62
Radix entomolaris and paramolaris: A case series
J Arun, BS Mayuri, TN Nandini, K Mallikarjun Goud
Department of Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital, Davangere, Karnataka, India
|Date of Web Publication||7-Dec-2015|
Department of Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital, Davangere, Karnataka
Source of Support: None, Conflict of Interest: None
Root canal anatomy is highly complex and unpredictable. These case series focus mainly on the diagnosis and management of variable root canal anatomy like Radix entomolaris and paramolaris in mandibular molars.
Keywords: Radix entomolaris, radix paramolaris, permanent mandibular molars
|How to cite this article:|
Arun J, Mayuri B S, Nandini T N, Goud K M. Radix entomolaris and paramolaris: A case series. Int J Oral Health Sci 2015;5:57-62
| Introduction|| |
As stated by Barrett, "of all the phases of anatomic study in the human system, one of the most complex is that of pulp cavity morphology.",
A complete knowledge and potential variations in the dental anatomy from normal are essential to gain success in endodontic therapy. Root canal anatomy is highly complex and unpredictable. An awareness and understanding of the presence of additional root and unusual root canal morphology are essential, as it determines the successful outcome of endodontic treatment. Inadequate knowledge about these variations might be one of the reasons for the failure of the root canal therapy (RCT). Hence, successful endodontic treatment depends on the location of the canals; thorough chemomechanical debridement followed by three-dimensional (3D) obturation with a perfect fluid tight seal.,,
The first mandibular permanent molar is the earliest permanent posterior tooth to erupt. It is responsible for development of occlusion and important for physiologic functions. Commonly, it is the one most frequently in need of endodontic treatment. Thus, it is of utmost importance that the clinician can be familiar with variations in the root and root canal anatomy of the mandibular first molar., They usually have two roots placed mesially and distally, and three root canals but variations in the number of roots and in canal morphology are not uncommon. The presence of a third root of the permanent first molar is the major variant in this group.,
This additional third root, first mentioned in the literature by Carabelli (1844), is called as radix entomolaris (RE), when located distolingual and is called as the radix paramolaris (RP) when located on the mesiobuccal side.
| Morphology|| |
Carlsen and Alexanderson classified RE based on the location of its cervical part into four types.,,
Type A–Distally located cervical part with two normal distal root components
Type B–Same as Type A; however, only one normal distal root component
Type C–Mesially located cervical part
Type AC–Central location between mesial and distal root components.
De Moor et al. classified RE-based on the curvature in buccolingual orientation into three types.
Type I–Refers to a straight root/root canal
Type II–Refers to an initially curved entrance which continues as a straight root/root canal
Type III–Refers to an initial curve in the coronal third of the root canal, and a second buccally oriented curve starting from the middle to apical third.
Recently, Wang et al. gave another classification for RE depending on its radiographic appearance.
Type 1: Presents the most identifiable radiographic image
Type 2: A large beam angulation is necessary mesially or distally for their identification
Type 3: Identification becomes extremely difficult because of the overlap of the adjacent distobuccal root.
Carlsen and Alexanderson classified RP based on the location of its cervical part into two types.
Type A–Refers to an RP in which the cervical part is located on the mesial root complex
Type B–Refers to an RP in which the cervical part is located centrally, between the mesial and distal root complexes.
Incidence and prevalence
Anatomical studies have reported an association between the presence of an RE in the first mandibular molar and certain ethnic groups. In the African populations, a maximum frequency of 3% is found while, in the Eurasian and Indian populations, the frequency is <5%. In populations with Mongoloid traits (such as the Chinese, Eskimo, and American Indians), RE occurs with a frequency that ranges from 5% to more than 30%. Because of its high frequency in these populations, the RE is considered to be a normal morphological variant (eumorphic root morphology). In Caucasians, the RE is not very common with a maximum frequency of 3.4–4.2%, which is considered to be unusual (dysmorphic root morphology).,,,, The RE can be found on the first, second, and third mandibular molar, but least frequently on the second molar. The bilateral occurrence of the RE is reported around 50–67%.
RP is very rare and occurs less frequently than the RE. RP is commonly observed in 1.5–3% of the African population whereas RP is less frequent, and frequency of existence is around 2% in the Indian population. The prevalence of RP, as observed by Visser, was found to be 0% for the first mandibular molar, 0.5% for the second, and 2% for the third molar.
The etiology behind the formation of the third root in a mandibular molar is still unclear. In dysmorphic supernumerary roots, its formation could be related to external factors during odontogenesis, or due to penetrance of an atavistic gene (atavism is the reappearance of a trait after several generations of absence), or polygenetic system. In eumorphic roots, racial genetic factors influence the most profound expression of a particular gene that results in the more pronounced phenotypic manifestation.,
The purpose of this article is to present cases on clinical approach for identification, detection, and endodontic management of three RE and one RP in the mandibular first molar.
A female patient, aged 33 years old, reported with a chief complaint of pain in the lower right back tooth region since 1 day. On clinical examination, there was a deep Class II mesio occlusal caries in relation to #46 which was tender on percussion. Thermal and electric pulp test elicited a negative response. Intraoral periapical radiograph (IOPAR) showed mesiocoronal radiolucency approximating pulp space with widening of periodontal ligament space at apical third of the roots. Diagnosis of symptomatic apical periodontitis was made, and RCT was recommended [Figure 1]a,[Figure 1]b,[Figure 1]c.
|Figure 1: (a) Working length radiograph showing extra distolingual root (b) master cone selection radiograph (c) radiograph of obturation and permanent coronal seal|
Click here to view
RCT procedure was initiated under local anesthesia by giving inferior alveolar nerve block (LIGNO × 2% with 1:80,000 adrenaline, Indoco Remedies Ltd., Mumbai, India) with rubber dam isolation. Access cavity was prepared; orifices were located using DG-16 an endodontic explorer (Dentsply, United Kingdom). During this procedure, a dark line guided toward an extra orifice which was located toward distolingual part of pulpal floor indicating the presence of RE, which was confirmed by Type 2 radiographic image. Working length was determined with an apex locator and then confirmed with a radiograph. Radix root showed Type 2 configuration of the canal. Cleaning and shaping were performed with rotary Protaper files (Dentsply, Maillefer, and Swiss made CH-1338 Ballaigues) in crown down manner. Apical preparation was done until size F3 Protaper file (master apical file). The canals were irrigated sequentially with 2.5% sodium hypochlorite, 0.2% w/v chlorhexidine gluconate (Vishal Dentocare Pvt., Ltd., India), and 17% ethylenediaminetetraacetic acid (Edgelube ™) during instrumentation and finally with normal saline. Calcium hydroxide intracanal medicament was placed in the first visit.
In the next visit after 10 days, irrigation was done. The canals were then dried with paper points, master cone selection was done with the help of radiograph and obturated with laterally condensed gutta-percha (Dentsply, Maillefer, Swiss made CH-1338 Ballaigues) and AH plus sealer (Dentsply DeTrey GmbH, Germany). Postendodontic restoration was done with composite.
A 29-year-old male patient reported with a chief complaint of pain in lower left back teeth region since 15 days. On clinical examination, there was a deep Class I caries, and the tooth was tender on percussion in relation to #36. Thermal and electric pulp test elicited a negative response. Radiograph showed coronal radiolucency approximating pulp space with periodontal ligament space widening at apical third of the roots. The tooth was diagnosed with chronic apical periodontitis. RCT was initiated. The location of extra orifice and Type 2 radiogaphic image indicated the presence of RE. Radix root showed Type 1 configuration of the canal. RCT was completed with standard protocol [Figure 2]a,[Figure 2]b,[Figure 2]c,[Figure 2]d.
|Figure 2: (a) Preoperative radiograph (b) working length radiograph showing extra distolingual root (c) master cone selection radiograph (d) radiograph showing obturation with permanent coronal seal|
Click here to view
A 32-year-old male patient reported with a chief complaint of pain in lower right back teeth region since 1 day. On clinical examination, there was a deep Class II mesio occlusal caries, and the tooth was tender on percussion in relation to #46. Thermal and electric pulp test elicited negative response. Radiograph showed mesiocoronal radiolucency approximating pulp space with periodontal ligament space widening at apical third of the roots. Diagnosis of irreversible pulpitis was made, and RCT was recommended. Type 1 radiographic image revealed the presence of additional distobuccal root. Access cavity was modified from triangular to more trapezoidal shape to locate the additional canal. Radix root showed Type 1 configuration of the canal. RCT was completed with standard protocol [Figure 3]a,[Figure 3]b,[Figure 3]c,[Figure 3]d.
|Figure 3: (a) Preoperative radiograph (b) working length radiograph showing extra distolingual root (c) master cone selection radiograph (d) radiograph showing obturation with permanent coronal seal|
Click here to view
Case 4: Radix paramolaris
A 38-year-old female patient reported with a chief complaint of pain in the lower left back teeth region since 2 days. On clinical examination, there was deep Class II distoocclusal restoration with secondary caries in relation to #36. Tooth elicited negative response on vitality testing and was tender on percussion. IOPAR revealed the presence of periodontal ligament widening at apical third of the roots. Diagnosis of symptomatic apical periodontitis was made, and RCT was recommended. During RCT procedure, the location of additional orifice on mesiobuccal aspect and Type 2 radiographic image confirmed the presence of RP. Radix root showed Type A configuration of the canal. The RCT was completed as per the standard protocol [Figure 4]a,[Figure 4]b,[Figure 4]c,[Figure 4]d.
|Figure 4: (a) Preoperative radiograph (b) working length radiograph showing extra mesiobuccal root (c) master cone selection radiograph (d) radiograph showing obturation with permanent coronal seal|
Click here to view
The full metal crown was delivered for all four patients. Clinical and radiographic evaluations following 3 and 6 months recall visits found to be satisfactory.
| Discussion|| |
A thorough knowledge of the root canal anatomy is very important for the clinician. With the advent of newer technologies and recent concept on access preparation, it is very easy to locate the aberrant canals. Inadequate knowledge of anatomic variations resulting in missed canals is one of the critical reasons for failure of endodontic therapy. About 97.8% of mandibular first molars have two roots, and among them, 64.4% have three canals two canals are located in the mesial root and one canal in the distal root. The single distal canal is usually larger, centrally placed, and more oval in cross-section than the mesial canals. The incidence of two distal canals has been reported in 28% of cases, where the orifices are small and are located either buccally or lingually.
There are various methods to locate additional canals such as, knowledge of law of symmetry, law of orifice location, visualizing the dentinal map and canal bleeding points. The tactile sensation using hand instrument like Endodontic explorer, Pathfinder, DG 16 probe and Micro-openers are also helpful. champagne bubble test is another useful means of locating the orifice. The remaining pulpal tissue in the canal produce effervescent bubbles when sodium hypochlorite is placed in the pulp chamber, indicating the location of canal orifice. Advanced imaging techniques can aid to locate and confirm additional canals in case of multirooted teeth, especially molars. These techniques include digital radiography, fiber-optic illumination, dental endoscopy and orascopy, surgical loupes, operating microscope, micro-computed tomography (CT), visualization endograph using Ruddle's solution, and magnetic resonance microscopy.,,,,,, With the advent of newer radiographic modalities such as radiovisiography and spiral CT, detection of RE is easier. Although a spiral CT is a 3D modality, it is an expensive and an inconvenient tool. Moreover, it is not appropriate to subject the patient to high doses of radiation of spiral CT for endodontic diagnostic purposes and can be used occasionally for study purposes only. Hence, conventional and digitalized radiography would suffice for the diagnosis of RE/RP.
In the present case series, the variations in distal root anatomy were identified through careful reading of angled IOPA radiographs. The first radiograph was taken with conventional angulation, and the second one with a mesial shift of approximately 20°. This buccal object rule has also been called same lingual, opposite buccal rule/Clark's rule/Walton's projection., An additional root appears as a shadow or a thin radiolucent line in the radiographs. In order to confirm the location of this additional root, an H-file was inserted in other canals, and a K-file was introduced into the additional canal before taking the radiograph., The existence of an accessory cusp (tuberculum paramolare) and periodontal probing for cervical prominences can also provide an indication of an additional root., For the first three cases, an IOPAR imaged with mesial angulation was used to identify and treat the RE, and for the fourth case, an IOPAR imaged with distal angulation was used to identify and treat the RP. When the third root is detected, it should be cleaned and shaped like every other canal.
Sometimes, radix canal orifice could be occluded by secondary or calcified dentine. With every access preparation in a calcified root, there is a risk of perforating the tooth. When searching for hidden canals, one should remember that secondary dentine is generally whitish or opaque, whereas the floor chamber is darker and gray in appearance. Therefore, the visual access and superior control during access procedures make a convenient tool in such cases.
Straight-line access in this respect has to be emphasized, as the majority of the radix root is curved. With the advent of rotary instruments, access burs such as Endo Z, SS white access burs, access can be modified to get a straight line access. This was a part of our protocol for the treated cases., The distal root typically has one kidney-shaped root canal, if the orifice is particularly narrow and round, a second distal canal may be present. The conventional triangular access cavity should be modified into a more trapezoidal cavity in order to locate and open the orifice.,,,
Thus, knowledge of the location of additional roots and its root canal orifices, adapted clinical approach, avoids or overcomes procedural errors during endodontic therapy and reduces incidence of retreatment.
| Conclusion|| |
Ability to correctly interpret the radiograph, careful inspection of the pulp chamber floor, and use of recent concepts in access cavity preparation along with the sound knowledge of the variable anatomy of the root canal are very important for the clinician to locate and treat the root canals in case of RE or paramolaris.
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Conflicts of interest
There are no conflicts of interest.
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