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Anatomical abnormalities of the root canal system are frequently seen in specialist endodontic practice, and represent a challenge to be faced with skill and thoroughness, beginning with an accurate diagnostic phase and devising the most appropriate treatment plan. Fortunately, much progress has been made in endodontic research thanks to technological advances and the evolution of higher performance instruments, which now consent even very complex cases to be resolved with relative ease. Below are described the salient features of recent progress in endodontics, along with a description of several clinical cases in which the operator has encountered numerous difficulties due to peculiar tooth morphology, overcome successfully thanks to the application of modern tools and consolidated clinical experience in the field.
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Annali di stomatologia
tooth morphology
Resolution of endodontic issues linked to complex anatomy
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Original Article
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2022-08-16
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2023-12-04
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L. Gallottini 
2014
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tooth morphology
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Resolution of endodontic issues linked to complex anatomy
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                                                                                                       Case report



    Resolution of endodontic issues linked
    to complex anatomy




                                                                                                                     li
                                                                na
    Guido Migliau, PhD, DDS                                techniques that favour the resolution of even complex
    Erlind Pepla, MD                                       cases are now becoming routine in the specialist prac-




                                                              io
    Laith Kostantinos Besharat, MD                         tice (1). As regards the tools used for root canal thera-
    Livio Gallottini, PhD, DDS                             py, the use of manual files in conjunction with me-
                                                           chanical drills (e.g., Gates-Glidden and Largo drills) to
                                                           remove interference in the pulp chamber and the




                                                           az
    Department of Oral and Maxillo-facial Sciences,        coronal portion of the canal has all but been super-
    Sapienza University of Rome, Italy                     seded. Nowadays, mechanical files mounted on hand-
                                                           pieces equipped with speed reducers and purpose-
                                                           designed engines are prevalent in endodontic applica-




                                                        rn
    Corresponding author:                                  tions. These devices also benefit from the favourable
    Erlind Pepla                                           properties of nickel-titanium alloy (used to make them)
    Department of Oral and Maxillo-facial Sciences,        and increased taper. Moreover, the latest generation
    Sapienza University of Rome                            of nickel-titanium (NiTi) instruments are very flexible




                                                     te
    Viale Regina Elena 287/a                               and are better able to adapt to even the most accentu-
    00198 Rome, Italy                                      ated curvatures. Thanks to their more enhanced cut-
    E-mail: kledion2004@libero.it                          ting tips, they also consent more flared, more tapered
                                                  In       and more predictable preparations to be made in con-
                                                           siderably shorter time-frames than those required to
    Summary                                                perform similar procedures using manual stainless
                                                           steel files. First and foremost among the technological
    Anatomical abnormalities of the root canal sys-        aids at the endodontist’s disposal nowadays is without
                                      ni
    tem are frequently seen in specialist endodontic       doubt the electronic apex locator, which has become
    practice, and represent a challenge to be faced        much more reliable and performs far better than in the
    with skill and thoroughness, beginning with an         past. Indeed, it allows such precise location of the
    accurate diagnostic phase and devising the most        apex and determination of the working length (2) that
                          o

    appropriate treatment plan. Fortunately, much          many specialist endodontists now refrain from per-
    progress has been made in endodontic research          forming x-rays during surgery altogether. Neverthe-
                      izi


    thanks to technological advances and the evolu-        less, in cases of anomalous endodontic anatomy,
    tion of higher performance instruments, which          there is a high risk of morphological features compli-
    now consent even very complex cases to be re-          cating the correct measurement of the working length,
    solved with relative ease. Below are described the     so particular care needs to be taken in these cases
          Ed




    salient features of recent progress in endodon-        (3). Thankfully, however, with the aid of magnification
    tics, along with a description of several clinical     devices such as Galilean or prism loupes and espe-
    cases in which the operator has encountered nu-        cially the operating microscope, endodontists are able
    merous difficulties due to peculiar tooth morphol-     to observe the operating field up close, and are there-
    ogy, overcome successfully thanks to the appli-        fore better equipped to deal with such troublesome
    cation of modern tools and consolidated clinical       anatomy (4). Thus, the specialist endodontist now has
    C




    experience in the field.                               a range of simplified and more rapid techniques at his
                                                           disposal. That being said, it is not the instruments that
CI




    Key words: complex endodontic therapy, en-             must perform the therapy, so the specialist endodon-
    dodontic anatomy, endodontic diagnosis, nickel-        tist should also be equipped with a complementary
    titanium instrumentation, tooth morphology.            degree of experience, skill and know-how, particularly
                                                           in the use of this array of instruments (manual and
                                                           mechanical) and devices (radiological and diagnostic).
    Introduction                                           With this combination, even the most complex clinical
©




                                                           situations can be resolved successfully (5).
    Since the 1990s, great strides have been made in en-   The endodontist is likely to have a better idea of the
    dodontics, consenting the achievement of ever more     root canal system anatomy in question before begin-
    predictable and long-lasting outcomes. The introduc-   ning treatment, although he must be ready to deal
    tion of new instruments and technological aids have    with surprises, as it turns out to be far more compli-
    led to the development of a completely different ap-   cated than initially foreseen in a high percentage of
    proach to root canal treatment, and have advanced      cases (Fig. 1). The operating microscope is invalu-

    34                                                                         Annali di Stomatologia 2014; V (1): 34-40
    Resolution of endodontic issues linked to complex anatomy


                                                                      C-shaped configuration of the lower second molars in
                                                                      a Chinese population.
                                                                      The anatomy of the secondary components (sec-
                                                                      ondary canals, apical deltas, anastomoses, isthmis,
                                                                      curves) of the root canal presents extreme variability,




                                                                                                                              li
                                                                      even though its primary components (main canal, pulp
                                                                      chamber, foramina and apices) generally conform to




                                                                          na
                                                                      standardized models based on the probability of a cer-
                                                                      tain configuration. The teeth, which generally present
                                                                      the greatest anatomical complexity, are without doubt
                                                                      the upper molars, especially the first, in which four




                                                                        io
                                                                      canals distributed among three roots are very common
                                                                      indeed (62%). The mesiobuccal root of these teeth
                                                                      usually presents two canals in one of various configu-
    Figure 1. Post-operative x-ray with correct endodontic filling.




                                                                     az
                                                                      rations: 37% being Weine type II (2 coronal orifices
                                                                      and 1 apical foramen) and 25% Weine type III (2 dis-
                                                                      tinct canals). Other teeth that are rather complex to
    able in such cases, and as well as applications in en-            treat due to their anatomy are the lower incisors, as




                                                                  rn
    dodontic surgery that have by now become routine, is              these present 2 buccal-orally distributed canals in 42%
    ever more commonly used in orthograde endodontics                 of cases. The lower premolars are also prone to anom-
    in specialist practice, especially in retreatment and             aly, and in 26% of cases feature a configuration with
    difficult cases (8). Indeed, magnification of the oper-           two canals (Weine type II or III) (14). On the whole, the




                                                               te
    ating field is fundamental for observing complex fea-             anatomy of the other teeth is far less variable, although
    tures of the endodontic anatomy and identifying any               some exceptions are seen (see reported cases). The
    misrecognized, accessory or lateral canal, foramina               curvature of the root can also be problematic, in that
    and particular anatomical conformations (e.g., c-                 abnormalities are common and not easily detected by
    shapes, isthmuses, anastomoses). In retreatment,
                                                            In        radiographical means. The root curvatures most worth
    this device is extremely useful in aiding the removal             of note are the double distal-palatine curve of the up-
    of posts or fragments of files broken off inside the              per lateral incisors and the curved buccal side of the
    canal (9). Furthermore, it may be the only means able             palatine root of the upper molars; these can easily de-
    to confirm a diagnosis of probable fracture, consent-             ceive the endodontist in that their apices are difficult to
                                                ni

    ing an otherwise invisible crack to be discerned. Ra-             see properly on x-ray, and it is therefore easy to make
    diological examination is also very important, and is             an inappropriate choice of tools. This in turn can lead
    generally performed using digital support nowadays:               to perforation or false paths, which are difficult to re-
                              o

    both orthopantomography and periapical-endoral x-                 dress after the fact. One anomalous morphological
    ray data can be processed using purpose-designed                  characteristic that can be observed with some frequen-
                          izi


    software and image optimization that can reveal                   cy in the lower molars (although cases have been re-
    pathologies and varying degrees of anatomical com-                ported in the upper molars and lower first premolars) is
    plexity that are undetectable by clinical examination             a C-shaped pulp chamber. C-shaped mandibular mo-
    alone. Furthermore, the recent introduction of cone-              lars are so called due to the cross-sectional shape of
           Ed




    beam computed tomography (CBCT) now consents                      their root and canals; instead of having several differ-
    observation in three-dimensional space with a very                ent orifices, the pulp chamber of this type of tooth dis-
    low biological cost (they emit a considerably reduced             plays a single cestoid orifice with an arc of 180° (or
    quantity of radiation with respect to conventional CT).           more), which begins at the angle with the mesiolingual
    CBCT also has a sub-millimetricresolution and is                  line and extends buccally or lingually in a circular fash-
    therefore useful for examining fine detail with extreme           ion, ending in the vicinity of the distal wall. Below the
    C




    precision (10). Its major application is in implant               orifice of the C-shaped molar, a wide variety of
    surgery, but it is also very useful in orthograde, and            anatomical variations in the structure of the canal sys-
CI




    especially retrograde, endodontics, helping to identify           tem are possible. These variants can be classified into
    and locate apex lesions, anatomical variants and re-              two groups: (a) those featuring a single cestoid C-
    lationships with adjacent anatomical structures (max-             shaped canal extending from the orifice to the apex;
    illary sinus, inferior alveolar nerve). Moreover, it con-         and (b) those featuring three distinct canals below the
    sents visualization of external and internal resorption,          C-shaped orifice. The latter type is far more common
    as well as root canal perforations and fractures, ac-             than the former, which represent the exception rather
©




    cessory canals and lateral apices (11). In fact, a re-            than the rule (15).The prevalence of C-shaped molars
    cent study by Patel and Horner (12) highlighted the               is strongly influenced by racial factors. In fact, this
    fact that CBCT can be used to diagnose almost 100%                anatomical variant is far more common in Asian popu-
    of apex lesions, as compared to 28% using conven-                 lations with respect to Caucasians (16). Developmen-
    tional endoral x-ray. Zhang et al. (13) also used                 tal dental defects can also cause procedural difficulties
    CBCT to highlight the frequency of triradicular lower             in endodontic treatment. These anomalies can be clas-
    first molars (43% even featured four canals) and the              sified as follows:

    Annali di Stomatologia 2014; V (1): 34-40                                                                                 35
    G. Migliau et al.


    -    Fusion: fusion of two adjoining teeth due to close      there is a risk of underestimating the problem. This
         contact between tooth buds; this can involve the        can lead to failure, not only of the root canal therapy
         entire teeth or only the crowns;                        itself, but also of the subsequent direct or indirect
    - Gemination (twinning): incomplete division of the          restoration. Indeed, this was the case in a patient
         tooth bud resulting in an otherwise normal tooth        who presented caries pathology with pulpal inflamma-




                                                                                                                            li
         joined to its supernumerary offshoot;                   tion at the 3.3, which needed to be used as anchor-
    - Concrescence: fusion of the cementum of two                age for a mobile prosthesis and was accordingly re-




                                                                     na
         adjoining teeth, generally due to trauma;               stored by means of a glass-fibre intracanal post and a
    - Dens in dente (dens invaginatus): the develop-             ceramic-fused-to-gold crown. Upon completion of
         ment of part of a tooth inside another; the defect      treatment, which lasted roughly six months, the pa-
         is termed coronal, radicular or corono-radicular,       tient continued to complain of discomfort at the ca-




                                                                   io
         depending on the portion of the tooth it occupies.      nine while chewing. This was initially attributed to a
    Weinstein et al. reported a clinical case of geminated       problem of occlusion, but digital magnification of the
    upper second molar that, despite the anatomy-related         periapical-endoral x-ray showed that the tooth fea-




                                                                az
    difficulty, they managed to treat with the aid of an op-     tured a further oral root that had previously escaped
    erating microscope and ultrasonic tips. Likewise Zey-        notice and had therefore not been treated (Fig. 2).
    labi et al. (17) successfully treated a lower third molar    Once the problem had been identified, the case was
    fused with a supernumerary disto-molar. Aguiar et al.,       simple to resolve, and the symptoms disappeared up-




                                                             rn
    on the other hand, described complex endodontic              on treatment of the painful root (Fig. 3). A similar clin-
    treatment of a lower premolar with two roots and             ical case was that of an upper premolar that present-
    three canals. Other authors (18) have presented a            ed three roots, two buccal and one palatal, a tooth
    case of dens in dente of an upper canine, treated sat-       that had previously been treated and restored with a




                                                          te
    isfactorily despite the complexity of the internal mor-      single crown (Fig. 4). Also in this case, close exami-
    phology of the canal system.                                 nation of the x-rays brought to light the unexpected
                                                                 anatomical variant and retreatment resolved the pain
                                                                 (Fig. 5). Both cases, despite their diagnostic com-
    Clinical series
                                                       In        plexity, were not particularly difficult to treat. However
                                                                 certain cases of shape anomaly are more trouble-
    In complex clinical situations it is necessary to per-       some, especially during the operative phase (17).
    form careful evaluation of the case beforehand and           This was the case in a patient who reported algic
    establish an appropriate treatment plan, otherwise           symptoms in the left lower sector. Scrutiny of the or-
                            o             ni
                        izi
           Ed
    C
CI
©




    Figure 2. X-ray of a left mandibular canine with two roots
    and two canals (one untreated).                              Figure 3. Post-operative x-ray.

    36                                                                                Annali di Stomatologia 2014; V (1): 34-40
    Resolution of endodontic issues linked to complex anatomy




                                                                                                                         li
                                                                    na
                                                                  io
                                                               az
                                                            rn
                                                         te
                                                      In
                                                ni
    Figure 4. X-ray of a right upper premolar that presented
    three roots, two buccal and one palatal.
                              o


    thopantomograph (OPT) (Fig. 6) revealed a deep ob-
                          izi


    turation troubled by caries relapse on the mesial sur-
    face of the left lower second molar, which was fused        Figure 5. Post-operative x-ray.
    to the adjacent third molar (Fig. 7). Root canal treat-
    ment was hampered by the peculiar anatomy, espe-
           Ed




    cially in the pulp chamber shaping phase and the
    identification of the canal orifices. In particular, four
    canals were present: larger mesial and distal (Fig. 8)
    and two smaller intermediate (Fig. 9); the mesial
    canal was housed in the mesial root, while the other
    three were all found in the distal (Fig. 10). Accentuat-
    C




    ed curves can also cause some difficulty during root
    canal therapy (Fig. 11). In the past these would have
CI




    been treated using pre-curved stainless steel files, an
    operation that took considerable time, and one that
    would have led to canal straightening. Today, howev-
                                                                Figure 6. Orthopantomograph that revealed a deep obtura-
    er, thanks to modern NiTi files and the use of a mixed
                                                                tion with secondary caries on the mesial surface of the left
    technique (stainless steel – NiTi) more flared prepa-       lower second molar.
    rations can be accomplished and the original curva-
©




    ture maintained without undue time being necessary.
    This was the case in a patient presenting to our at-
    tention with considerable pain in the fourth quadrant.      12). The patient did not wish to undergo osseointe-
    Clinical examination and OPT revealed a, by then, in-       grated implant surgery and so the only option, without
    congruent bridge spanning four tooth positions (from        resorting to a mobile prosthesis, was treatment and
    4.5 to 4.8), whose posterior supporting tooth had be-       restoration of the 4.8. The anatomy of the third molar
    come affected by secondary caries and pulpitis (Fig.        is known for its complexity and abnormality, and this

    Annali di Stomatologia 2014; V (1): 34-40                                                                            37
    G. Migliau et al.




                                                                                                                           li
                                                                         na
                                                                       io
                                                                    az
                                                              Figure10. Post-operative x-ray.

    Figure 7. Left lower second molar fused to the adjacent
    third molar.




                                                                 rn
                                                              te
                                                           In
                                            ni

                                                              Figure11. Post-operative x-ray with correct endodontic filling.
                              o

    Figure 8. Intra-operative x-rays for working length.
                          izi
           Ed
    C




                                                              Figure 12. Orthopantomograph that revealed incongruent
                                                              bridge spanning four tooth positions (from 4.5 to 4.8),
CI




                                                              whose posterior supporting tooth had become affected by
                                                              secondary caries.



    Figure 9. Intra-operative x-rays for working length.
                                                              ing manual stainless steel and rotary NiTi files; the
©




                                                              tooth was then restored via the insertion of two glass-
                                                              fibre posts and prepared as a posterior support for
    case was no exception; it was mesiodistally elongat-      the fixed prosthesis of 5 teeth, thereby rehabilitating
    ed, buccolingually narrow and featured two roots with     the patient’s fourth quadrant (Fig. 13). Another com-
    two canals of accentuated distal curvature. In spite of   plex case to treat is the so-called “MB2,” or fourth
    the considerable challenges presented by the case, it     canal (two in the mesiobuccal root), of the upper mo-
    was resolved successfully by a mixed technique us-        lars. It is mandatory to look out for this defect as it is

    38                                                                              Annali di Stomatologia 2014; V (1): 34-40
    Resolution of endodontic issues linked to complex anatomy


    present in a high percentage of patients. In such cas-
    es, (Fig. 14) the canal is often very narrow and
    curved, and needs to sought in the mesiobuccal root
    (Fig. 15) displaced palatally and slightly mesial to the
    main mesiobuccal canal (Fig. 16).




                                                                                                                          li
                                                                          na
                                                                        io
                                                                     az
                                                                    Figure 15. Post-operative x-rays with correct endodontic
                                                                    filling and evidence of the “MB2” canal.




                                                                  rn
                                                               te
    Figure 13. Post-operative x-ray with correct endodontic fill-
    ing and build up with two glass-fibre posts.
                                                            In
                              o                 ni

                                                                    Figure 16. Post-operative x-rays with correct endodontic
                          izi


                                                                    filling and evidence of the “MB2” canal.
           Ed




                                                                    preparation, disinfection and sealing of the root
                                                                    canal system (7). Nowadays, however, when plan-
                                                                    ning treatment, the endodontist can rely on far
                                                                    greater safety and precision in diagnostic tools with
    Figure 14. Pre-operative x-ray of left first maxillary molar.   respect to the past.
    C




                                                                    Conclusions
CI




    Discussion
                                                                    Endodontics is an extremely important branch of den-
    Diagnosis is one of the fundamental steps in medi-
    cine and dentistry in general, and for endodontics in           tistry whose aim is the recovery of severely compro-
    particular. Indeed, an appropriate treatment plan               mised teeth. This can be accomplished with varying
    cannot be defined without accurate diagnosis and a              degrees of difficulty, depending on the complexity of
©




    thorough preliminary study of the clinical case; only           the clinical case in question. As we have seen, partic-
    in this way will it be possible to deal with unexpected         ularly complex cases need to be managed with par-
    occurrences in the best possible fashion (6). The en-           ticular care in both the diagnostic and intervention
    dodontic anatomy is particularly challenging and for            phases, both of which can be greatly aided by the ad-
    the clinician, so an optimal diagnostic approach,               vanced technologies, instruments and innovative ma-
    suitable access techniques and highly professional              terials at our disposal. These not only serve to simpli-
    skill are indispensable for the successful location,            fy techniques, but also confer results with greater out-

    Annali di Stomatologia 2014; V (1): 34-40                                                                            39
    G. Migliau et al.


    come predictability and long-term success rates with                  7. Pablo OV, Estevez R, Hellborn C, Cohenca N. Root anato-
    respect to the past, even in extremely difficult cases                   my and canal configuration of the permanent mandibular first
    (19). It is therefore vital that an endodontist is highly                molar: Clinical implications and recommendations. Quin-
                                                                             tessence Int. 2012; 43(1):15-27.
    skilled, a specialist able to deal with even the most
                                                                          8. Weinstein T, Rosano G, Del Fabbro M, Taschieri S. En-
    complex clinical situations, in both orthograde treat-




                                                                                                                                         li
                                                                             dodontic treatment of geminated maxillary second molar us-
    ment and retrograde surgery. Furthermore, the mod-                       ing an endoscope as magnification device. Int. Endod J. 2010;
    ern-day endodontist needs to be proficient in post-en-




                                                                             na
                                                                             43(5):4543-50.
    dodontic restoration, managing adhesive reconstruc-                   9. Aguiar C, Mendes D, Camara A., Figueiredo J. Endodontic
    tion techniques and endocanal posts, in order to ob-                     treatment of mandibular second premolar with three root
    tain a tight seal at both the crown and the apex, both                   canals. J Contemp Dent Pract. 2010; 11(2):78-84.
    necessary to ensure the success of treatment. In line                10. Patel S, Mannocci F, Shemesh H, Wu MK, Wesselink P, Lam-




                                                                           io
                                                                             brechts P. Radiographs and CBCT – time for a reassess-
    with international trends, the philosophy of our school
                                                                             ment? IntEndod J. 2011; 44(10):887-8.
    is that the endodontist should be able to complete                   11. Zheng Q, Zhang L, Zhou X, Wang Q, Wang Y, Tang L, Song
    and resolve the case of a severely compromised                           F, Huang D. C-shaped root canal system in mandibular sec-




                                                                        az
    tooth from beginning to end, including, as a last re-                    ond molars in Chinese population evacuate by cone-beam
    sort (when it cannot be saved) its extraction and re-                    computed tomography. Int Endod J. 2011; 44(9):857-62.
    placement with an osseointegrated implant (20).                      12. Patel S, Horner K. The use of cone beam computed to-
                                                                             mography in endodontics. Int Endod J. 2009; 42(9):755-6.




                                                                     rn
                                                                         13. Zhang R, Wang H, Tian YY, Yu X, Hu T, Dummer PM. Use
                                                                             of cone beam computed tomography to evaluate root and
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           Ed
    C
CI
©




    40                                                                                          Annali di Stomatologia 2014; V (1): 34-40
