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Year : 2012  |  Volume : 4  |  Issue : 1  |  Page : 56-59

Root canal treatment of bilateral three-rooted maxillary first premolars

Department of Conservative Dentistry and Endodontics, KLE Vishwanath Katti Institute of Dental Sciences, KLE University, Belgaum, Karnataka, India

Date of Web Publication10-Sep-2012

Correspondence Address:
Bhavana Gandhi
Department of Conservative Dentistry and Endodontics, KLE V K Institute of Dental Sciences, KLE University, Nehru Nagar, Belgaum - 590 010, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0975-8844.99878

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In endodontics, several anatomic variations occur in teeth, both externally and in the internal root morphology, which play a very significant role in the diagnosis and treatment outcome. A thorough knowledge of the root canal anatomy, careful interpretation of the angled radiographs, proper endodontic access cavity preparation, and exploration of the root canal are the prerequisites for endodontic success. In a maxillary first premolar, it is rare to find extra roots and canals, and the aim of the present article is to report a case about the successful diagnosis and clinical management of bilateral three-rooted maxillary first premolars, with three independent root canals.

Keywords: Anatomic variation, maxillary first premolar, mini-molars, three-rooted premolars, T-shape access cavity

How to cite this article:
Gandhi B, Majety KK, Gowdra RH. Root canal treatment of bilateral three-rooted maxillary first premolars. J Orofac Sci 2012;4:56-9

How to cite this URL:
Gandhi B, Majety KK, Gowdra RH. Root canal treatment of bilateral three-rooted maxillary first premolars. J Orofac Sci [serial online] 2012 [cited 2022 Oct 3];4:56-9. Available from:

  Introduction Top

Lao Tzu stated, "The journey of a thousand miles begins with a single step." [1] A clear picture and understanding of the pulpal anatomy and the variations that occur in it are essential for the clinician, if effective cleaning, shaping, and obturation of the root canal system are needed. Many endodontic failures that occur are the result of a poor knowledge of this anatomy; missed canals, perforation of the pulpal floor, and canal transportation. If the clinician can imagine a three-dimensional picture of the root canal system prior to instrumentation, then iatrogenic errors are less likely to occur. The practitioner should be aware of how many canals to expect, their location, length, and relationship to each other.

The average length of the maxillary first premolar is 21.5 mm. [1] The pulp chamber is narrow mesiodistally and wide buccopalatally. The floor of the pulp chamber is convex, usually with two canal orifices, one buccal and the other palatal. [1] It has two roots and two root canals in 54.6% of the cases. [1] The incidence of three distinct roots and root canals is very low, 3% as found by Bellizi (1985) and 6% in another study. [2],[3] The frequency of single-rooted maxillary first premolars ranges from 31 to 39% in Caucasians. [4] In people of Mongoloid origin the frequency of maxillary first premolars with one root is in excess of 60%. [5] The purpose of this article is to report the successful root canal treatment of bilateral three-rooted maxillary first premolars.

  Case Report Top

A 25-year-old female had reported to the Department of Conservative Dentistry and Endodontics, at KLE VK Institute of Dental Sciences, Belgaum, with a chief complaint of pain in the upper right and left back tooth region, since a week. Her medical history was non-contributory. On examination of the area of chief complaint, there were deep caries associated with both the maxillary first premolars, 14 and 24; and 15, 16, 25, and 26 were root stumps. On examination of the Intraoral Periapical Radiograph (IOPA), in 14 and 24, there was radiolucency in the crown region of both the teeth approaching the pulp. The preoperative radiograph did not reveal an extra root, as the radiograph was taken in a horizontal angulation [Figure 1]a, b.
Figure 1: (a, b) Preoperative radiographs of 14 and 24 in a straight angulation, showing two roots

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The root canal treatment of the tooth was begun; one tooth at a time, starting with the tooth that was more painful, and in this case it was 14. The middle superior alveolar nerve block was administered on the area to be treated. The access cavity of the tooth was prepared under rubber dam isolation. The access cavity revealed two canal orifices initially. The pulp was extirpated and a working length IOPA was taken, with a mesial angulation of 40°. The working length IOPA revealed an extra buccal root. The access cavity was then further extended mesiodistally on the buccal aspect, to reveal the third orifice, that is the distobuccal. The working length was once again determined for all the three canals using an electronic apex locator, and further confirmed with a radiograph [Figure 2]a, b.
Figure 2: (a) Working length radiograph in a mesial angulation revealing the third root. (b) Master cone radiograph of the three roots

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The cleaning and shaping of the three canals was done with rotary nickel titanium files (Protaper universal, Dentsply) and irrigated with sodium hypochlorite and normal saline. The three canalas were initially enlarged with hand files until the 20 K file freely glided through the canal, following which the canal was enlarged to size F2 using rotary files, and an apical tug back was achieved. An IOPA was taken to confirm the master cone length.

The canals were then obturated with AH plus® root canal sealer and Gutta percha. After the completion of obturation a post endodontic restoration was placed using a dual cure, hard fluoride releasing, core build-up material by Pulpdent® . A post-obturation IOPA was taken.

Similarly tooth 24 was diagnosed with having three independent roots and root canals, and was treated with root canal [Figure 3]a, b.
Figure 3: (a, b) Obturation radiograph of 14 and 24

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  Discussion Top

The anatomy of the root canal is unpredictable. It is extremely important that clinicians use all the armamentaria at their disposal to locate and treat the entire root canal system. Endodontic prognosis is maximized in the teeth, whose root canal systems are cleaned, shaped, and obturated in all their dimensions. [6],[7]

An elusive canal is a canal missed by the dentist during a routine root canal procedure. These canals are seen additional to the normal complement of root canals. [6] Their detection, biomechanical preparation, and obturation are a tedious process. There are multiple concepts, armamentaria, and instruments that are useful to find missed canals as follows.

  1. Anatomic familiarity - The form, configuration, and the number of root orifices and canals should be kept in mind before beginning an endodontic procedure. Many a times the MB2 canal of the maxillary molars is not searched for, as it has become a habit and practice to believe that that the maxillary molars have three canals. However, the prevalence of these teeth having an extra canal is high, and the operator should use all the armamentaria at his disposal to locate a missed canal.
  2. Beer and bauman - Suggested geometrical techniques to identify missed canals in maxillary molars. They proposed three lines; the first line connected the mesiobuccal canal to the palatal canal; the second line was drawn perpendicular to line one, at a point one-third the inter-canal distance from the palatal canal, such that, this line passed over the distobuccal canal. The distobuccal canal might be somewhere along line 2. A fourth canal lay somewhere along line 3, which deviated approximately 10°. [6] Krasner and Rankow (2004), proposed anatomic laws, which helped in locating missed canals.
  3. Law of centrality - The floor of the pulp chamber is always located in the center of the tooth at the level of the cementoenamel junction (CEJ). Law of concentricity - The walls of the pulp chamber are concentric to the external outline of the tooth at the level of the CEJ. Law of the CEJ - CEJ is the most consistent, repeatable landmark for locating the position of the pulp chamber.
  4. Symmetry - Krasner and Rankow also proposed the rules of symmetry, which were observed in all teeth, except the maxillary molars.
    • If a line is drawn in a mesial-distal direction across the center of the floor of the pulp chamber, the orifices of the canals on either side of the line are equidistant
    • If a line is drawn in a mesial-distal direction across the center of the floor of the pulp chamber, the orifices of the canals on either side are perpendicular to it
    • The orifices of the root canals are always located at the junction of the walls and the floor
    • The orifices of the root canals are located at the vertices of the floor-wall junction
    • The orifices of the root canals are located at the terminus of the root developmental fusion lines [6]
  5. Radiographic analysis - Periapical films should be taken with the cone directed in at least two different angulations. Straight angulation of the radiograph produces superimposition of the tissues on the resulting image and leads to a false interpretation. A mesiodistal angulation (buccal object rule) leads to separation of the roots and canals. The SLOB rule is an acronym for Same Lingual Opposite Buccal. In this method one radiograph is taken straight on at a 90 degree angle to the tooth and a second radiograph is taken with the tubehead shifted either mesially or distally. The rule says that the object imaged will move in the same direction as the tubehead is moved, if it is located on the lingual (Same Lingual). Conversely, the object being imaged will move opposite the tubehead movement if it is located on the buccal (Opposite Buccal). Digital radiography, computed tomography, and Cone Beam Computed Tomography, significantly enhance the radiographic diagnostics in identifying hidden, calcified, or untreated canals. [6]
  6. Vision - The use of magnification glasses, headlamps, and transilluminating devices, improves the vision of the access cavity, thereby, identifying the missed canals. A dental operating microscope (DOM) provides an easier and more accurate outcome of endodontic treatment. Long shank burs are used not because they can reach deeper in the access cavity, but because they enhance direct vision by importantly moving the head of the handpiece further away from the occlusal table, and improving the line of sight along the shaft of the bur. [8]
  7. Access cavities - Access cavities should be expanded and finished to enhance vision, improved diagnostics, and provide straight-line access to the orifice. The isthmus area and / or developmental grooves should be probed with an explorer, in order to find a 'catch.' Luebke has made an important point that an entire wall need not be extended in the event that an instrument impingement occurs owing to a severely curved root or an extra canal. By extending only that portion of the wall needed to free the instrument, a cloverleaf appearance may evolve as the outline form. Hence, Luebke has termed this a 'shamrock preparation'. [8]
  8. Piezoelectric ultrsonics - These help in exploring and identifying calcified and missed canals, avoiding the bulky heads of the handpieces. Thereby, they improve vision by illuminating the operating field unlike the handpieces, which block the light. The abrasive coatings on their working ends help in efficiently removing the calcifications and dentinal obstruction to the missed canals. [8]
  9. Micro-openers (Dentsply International) - Combine the canal finding capabilities of an explorer with the instrumentation capabilities of a K-file. They are ISO-sized hand instruments with 7 mm k-type flutes. The Micro-Openers are available in sizes 10 and 15 with .04 and .06 tapers. The exaggerated taper enhances the instruments' tensile strength. This makes it easier to locate, penetrate, and initially instrument even the most difficult or calcified canals. These instruments provide unobstructed vision when operating on difficult teeth, with limited access. [8]
  10. Dyes - Various dyes, such as, iodine in potassium iodide, ophthalmic dye, or 1% methylene blue can be irrigated into the pulp chambers of the teeth and rinsed thoroughly with water, dried, and visualized. The dye will be absorbed into the orifices, fins, and isthmus areas, and serves to 'roadmap' the anatomy, aiding in the identification of missed canals and fractures. [6],[8]
  11. Bubble test / champagne test - Sodium hypochlorite flooded into the chamber reacts with the organic tissue or the chelator used. This indicates a positive 'bubble test or champagne test'. This helps in clearing the pulp chamber and improving visibility in the hidden orifices and missed canals. [6]
  12. Transillumination - In this procedure, the light is shone through the gingival tissue to the root and pulp chamber. The canal's light transmission differs from the rest of the tooth, as it is hollow, and appears as a dark spot in an otherwise bright structure. [8]
  13. Explorer pressure - An endodontic probe (e.g., DG16, CK17) is a double-ended long probe, which helps in identifying missed canals. It is used to punch through the secondary dentin and calcifications to expose hidden orifices. [8]
  14. White line test - When a shelf of dentin meets the pulpal floor it forms a groove. During access preparation and exploring with ultrasonics, dust collects in such grooves and forms a visible roadmap that can be followed to locate the missed canals. [8]
  15. Red line test - In vital cases, blood frequently moves into an isthmus area and absorbs into orifices, fins, and isthmuses, which serve to roadmap and aid in the identification of the underlying anatomy. [8]
  16. Restorative disassembly - It provides better orientation to the underlying tooth structure and improves safe access to the pulp chamber. [8]
  17. Perio probing - Probing the sulcus can provide important information as to the relationship between the long axis of the clinical crown and the underlying root, as well as indicate a possible root fracture. [8]
  18. Color - Orifices appear in a darker color than the surrounding area and can be differentiated and followed to locate the missed canals. [8]

Whenever the mesiodistal width of the mid-root image is equal to or greater than the mesiodistal width of the crown, the tooth most likely has three roots. [9]

The presence of an eccentric orifice, other than in its normal location, buccopalatally in premolars, leads to the suspicion of the presence of an extra canal. In such a tooth we should consider a third canal orifice and extend the outline by making a cut at the buccal-proximo angle from the entrance of the buccal canals to the cavosurface angle, as suggested by Balleri et al. [8],[9] The normal figure 8-shaped access cavity of the maxillary first premolar needs to be modified to a 'T' shaped one, with the horizontal portion of the letter representing the mesiobuccal and distobuccal orifices and the vertical end depicting the palatal orifice. [10],[11],[12] The root canal anatomy of the three-rooted maxillary premolars shows a close resemblance to that of the maxillary molars, and therefore, they have been termed as mini-molars or as being 'ridiculous'. [13],[14]

With newer technology, various diagnostic aids have been introduced, which assist in identifying the variations and root canal anatomy. A clinician should always be alert and keenly observe such cases.

  Conclusion Top

The only source of knowledge is experience and that alone teaches the variability among the normal. There are numerous cases in the literature regarding the root canal anatomy of the maxillary first premolar. The occurrence of a single canal is 28.5%, two canals is 68.5%, and three canals is 3% (Sert, 2004). [4] It should always be assumed that two canals are present, and the third canal is shown to exist in high enough numbers and should be searched for, beginning with the preoperative radiographs and also with the various techniques and armamentarium available, as mentioned in the article, which would help in achieving a successful endodontic treatment outcome.

  References Top

1.Anatomy of Pulp Cavity and its Access Opening. In: Suresh Chandra B, Gopi Krishna V, editors. Grossman's Endodontic Practice. 12 th ed. Philadelphia: Wolters Kuwer. Lippincott Williams and Wilkins Publishers; 2010. p. 176-220.  Back to cited text no. 1
2.Al-Abdul Wahhab B. Maxillary First Premolar with three canals: Case report. Smile Dent J 2010;5:34-6.  Back to cited text no. 2
3.Cleghorn BM, Goodacre CJ, Christie WH. Morphology of teeth and their root canal systems. In: Ingle, Bakland, Baumgartner, editors. Ingle's Endodontics. 6 th ed. Netherlands: BC Decker Publishers; 2008. p. 151-220.  Back to cited text no. 3
4.Vertucci FJ, Gegauff A. Root canal morphology of the maxillary first premolar. J Am Dent Assoc 1979;99:194-8.  Back to cited text no. 4
5.Walker RT. Root form and canal anatomy of maxillary first premolars in a southern Chinese population. Endod Dent Traumatol 1987;3:130-4.  Back to cited text no. 5
6.Rakesh Rajan R, Senthil Kumar, Mohan Kumar NS, Karunakaran JV. Elusive canals in Endodontics. J Indian Acad Dent Spec 2011;2:37-42.  Back to cited text no. 6
7.Burns RC, Herbranson EJ. Tooth morphology and cavity preparations. In: Cohen S, Burns RC, editors. Pathways of the pulp. 7 th ed. St. Louis: Mosby Co.; 1998.  Back to cited text no. 7
8.Gluskin AH, Peters CI, Ming Wong RD, Ruddle CJ. In: Ingle, Bakland, Baumgartner, editors. Ingle's Endodontics. 6 th ed. Netherlands: BC Decker Publishers; 2008. p. 1088-161.  Back to cited text no. 8
9.Sieraski SM, Taylor GN, Kohn RA. Identification and endodontic management of three -canalled maxillary premolars. J Endod 1989;15:29-32.  Back to cited text no. 9
10.Coutinho Filho T, La Cerda RS, Gurgel Filho ED, de Deus GA, Magalhães KM. The influence of the surgical operating microscope in locating the mesiolingual canal orifice: A laboratory analysis. Braz Oral Res 2006;20:59-63.  Back to cited text no. 10
11.Balleri P, Gesi A, Ferrari M. Primer premolar superior com tres raices. Endod Pract 1997;3:13-5.  Back to cited text no. 11
12.Arisu HD, Alacam T. Diagnosis and Treatment of Three-Rooted Maxillary Premolars. Eur J Dent 2009;3:62-6.  Back to cited text no. 12
13.Maibaum WW. Endodontic treatment of a "ridiculous" maxillary premolar. Gen Dent 1989;37:340-1.  Back to cited text no. 13
14.Goon W. The "ridiculous" maxillary premolar: Recognition diagnosis and case report of surgical intervention. Northwest Dent 1993;72:31-3.  Back to cited text no. 14


  [Figure 1], [Figure 2], [Figure 3]

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