10.59987/ads/2016.1-2.11-15
Aim. The goal of the study was to compare the ability of two different carrier based obturation (CBO) techniques to reach working length and fill in threedimensions root canal systems, by using CBCT.
Materials and Methods. Twenty-six extracted molars were scanned with CBCT and 40 curved canals were selected (between 30° and 90°) and divided in two similar groups (n=20). All canals were prepared up to size 25 taper .06 using nickel-titanium instrumentation. The canals in the Group SC were obturated using Soft-Core obturators (Kerr, Romulus, Mi, USA), while Group TH canals (n= 20) were obturated using Thermafil Endodontic Obturators (Tulsa Dental Products, Tulsa, OK, USA), strictly following manufacturers’ instructions for use. The obturations were analyzed by means of CBCT to measure the distance from the apical limit of obturation to the apical foramen and the presence of voids inside root canals.
Results. There was no significant difference between the two groups in the mean distance of the apical extent of the obturation (t test, p&gt;0.05). Overfilling occurred in only 3 cases (2 in Group TH and 1 in Group SC). The percentages of voids in both groups were very low with no significant difference (Z test, p&gt;0.05). Conclusions. The two tested CBO techniques showed similar positive results in terms of performance, even if, after checking with verifiers, in most cases the size of the selected Soft-Core obturator was one size smaller than Thermafil.
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Annali di stomatologia
Cone-beam Computed Tomography
In vitro evaluation of carrier based obturation technique: a CBCT study
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Original Article
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Ann Stomatol (Roma)
L. Testarelli
2016
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Department of Oral and Maxillo-Facial Sciences, “Sapienza” University of Rome, Italy
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Cone-beam Computed Tomography
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In vitro evaluation of carrier based obturation technique: a CBCT study
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                                                                                             Original article



In vitro evaluation of carrier based obturation
technique: a CBCT study


Gianluca Gambarini, MD, DDS1                            TH and 1 in Group SC). The percentages of voids
Lucila Piasecki, PhD, DDS2                              in both groups were very low with no significant
Giovanni Schianchi, DDS1                                difference (Z test, p>0.05). Conclusions. The two
Dario Di Nardo, DDS1                                    tested CBO techniques showed similar positive
Gabriele Miccoli, DDS1                                  results in terms of performance, even if, after
Dina Al Sudani, PhD, DDS3                               checking with verifiers, in most cases the size of
Roberto Di Giorgio, DDS1                                the selected Soft-Core obturator was one size
Luca Testarelli, PhD, DDS1                              smaller than Thermafil.

                                                        Key words: endodontic obturation, Thermafil,
1 Department of Oral and Maxillo-Facial Sciences,       Soft-Core, Cone-beam Computed Tomography.
“Sapienza” University of Rome, Italy
2 Department of Periodontics and Endodontics,

University at Buffalo (NY), USA
3 Department of Restorative Dental Sciences,            Introduction
College of Dentistry, King Saud University, Riyadh,
Saudi Arabia                                            The success of endodontic therapy is directly related
                                                        to the sealing of the root canal system, by means of a
                                                        three-dimensional hermetic endodontic filling (1, 2).
Corresponding author:                                   The primary objective of the endodontic obturation in
Lucila Piasecki                                         root canal treatment is to prevent the ingress of mi-
Department of Periodontics and Endodontics,             croorganisms or fluids, from both oral cavity or peri-
University at Buffalo                                   apical area, and also refrain the growth of any resid-
240 Squire Hall                                         ual bacteria left in the canal system (1-4). An inade-
14214 Buffalo (NY), USA                                 quate seal might result in contamination of the canal
E-mail: lucilapiasecki@hotmail.com                      spaces, thus leading to periapical disease (1, 2, 4).
                                                        The combination of gutta-percha with a layer of en-
                                                        dodontic sealer is the most commonly used material
Summary                                                 for root canal obturations. A variety of techniques
                                                        have been developed to provide the proper adapta-
Aim. The goal of the study was to compare the abil-     tion of the gutta-percha root canal walls, aiming the
ity of two different carrier based obturation (CBO)     complete filling of the root canal system (2, 4). John-
techniques to reach working length and fill in three-   son (5) developed an obturation technique using flexi-
dimensions root canal systems, by using CBCT.           ble metal/plastic carriers coated with α-phase gutta-
Materials and Methods. Twenty-six extracted mo-         percha (Thermafil Endodontic Obturator, Tulsa Dental
lars were scanned with CBCT and 40 curved               Products, Tulsa, OK, USA). The main goal of this car-
canals were selected (between 30° and 90°) and          rier based obturation (CBO) technique is to obtain a
divided in two similar groups (n=20). All canals        predictable thermo-plasticization and the consequent
were prepared up to size 25 taper .06 using nick-       flow of the gutta-percha, by using a specific oven with
el-titanium instrumentation. The canals in the          a precise temperature control.
Group SC were obturated using Soft-Core obtura-         Previous studies have reported a good sealing ability
tors (Kerr, Romulus, Mi, USA), while Group TH           of Thermafil obturations (6-10). The advantages of
canals (n= 20) were obturated using Thermafil En-       the carrier-based obturation (CBO) are related to the
dodontic Obturators (Tulsa Dental Products, Tul-        flow of the gutta-percha inside the root canal space,
sa, OK, USA), strictly following manufacturers’ in-     which is achieved by the combination of the heating
structions for use. The obturations were analyzed       process and the fact that the carrier facilitates the in-
by means of CBCT to measure the distance from           sertion of filling material and also slightly pressure it
the apical limit of obturation to the apical foramen    alongside the canal walls. Moreover, the simplicity of
and the presence of voids inside root canals.           the CBO prevents the risks and problems related to
Results. There was no significant difference be-        the use of spreaders, pluggers, heaters and com-
tween the two groups in the mean distance of the        pactors inside complex root canals. Therefore, differ-
apical extent of the obturation (t test, p>0.05).       ent types of CBO have been developed, such as the
Overfilling occurred in only 3 cases (2 in Group        Soft-Core™ obturators (Kerr, Romulus, MI, USA). Ac-

Annali di Stomatologia 2016;VII (1-2): 11-15                                                                  11
     G. Gambarini et al.


     cording to the manufacturer, the Soft-Core obturators                 Soft-Core, while Thermafill Obturators were used for
     present one universal taper size and a thinner core in                the Group TH (n= 20). For each group the correspon-
     apical part to allow greater flexibility to navigate curved           dent oven and verifiers were used, strictly following
     canals.                                                               manufacturers’ instructions for use. Briefly, first it was
     On the other hand, the disadvantages of CBO tech-                     inserted a verifier up to the WL to check the correct
     niques include the possible risk of overfilling (apical               obturator size. Then, the root canal was coated with a
     extrusion of the sealer, gutta-percha, and/or carrier)                small layer of endodontic sealer (Tubliseal Xpress,
     and underfilling, if the obturators do not reach the full             Kerr, Romulus, MI, USA) with the aid of a K-10 file.
     working length (WL) due to the complex canal curva-                   The obturator was calibrated at the WL with a rubber
     tures or less tapered preparation (11, 12). Another                   stop, heated in the oven and then inserted into the
     potential disadvantage of CBO, especially in severely                 root canal. All the procedures were conducted by the
     curved canals, is the gutta-percha separating from                    same operator.
     the carrier, thus leading to the formation of gaps                    The teeth of both groups were radiographed in me-
     (voids) between the root canal filling and the canal                  siodistal and buccolingual directions and then kept at
     walls. Moreover, CBO might be influenced by many                      100% humidity and 37° C for 1 week, for the setting
     factors (e.g., different ovens with different tempera-                of the sealer. The post-operative CBCT was taken by
     tures, type/amount of gutta-percha, design/dimen-                     using the i-Cat 500 (0,12 mm resolution). The quality
     sions of carrier, flexibility and material of the carrier,            of obturation was assessed by an experienced radiol-
     etc.), which might impair the apical sealing, mostly in               ogist, using the I-Cat Vision software (Kavo, Biberach
     curved canals (11, 13, 14).                                           an der Riss, Germany).
     Therefore, the aim of the present study was to com-                   Images were analyzed in the three planes (coronal,
     pare the two different CBO brands, Thermafil and                      transversal and sagittal) to detect visible voids and to
     Soft-Core, in the ability to fill curved root canal sys-              check the apical limit of obturation. The number of
     tems, by using Cone-beam computed tomographic                         visible voids were calculated for each canal, while the
     (CBCT) evaluation.                                                    underfilling was measured by determining the dis-
                                                                           tance (in mm) from the apex to the end of the root
                                                                           canal obturation. The CBCT images were submitted
     Materials and methods                                                 to a rendering process to visualize more clearly any
                                                                           defects of the obturation (voids or underfilling) in the
     A total of 26 molar was obtained from a pool of ex-                   three-dimensional reconstructions. Data was submit-
     tracted teeth. A pre-operative CBCT scan evaluation                   ted to statistical analysis with significance set at
     was conducted to analyze the anatomical parameters                    p<0.05.
     and 40 canals presenting curvatures between 30 o
     and 90o were selected. The canals were divided into
     two groups (n=20), with similar curvatures.                           Results
     After access cavity in the teeth, each selected canal
     was checked for patency and the working length was                    In three cases a slight overfilling of gutta-percha was
     established 0.5 mm short to the apical foramen. A                     observed of the root canals (2 in the Group TH and 1
     mechanical glide path was performed with manual                       in for the SC). These cases were excluded for the
     stainless steel K-files attached to the M4 handpiece                  measurement of the distance between the limit of ob-
     (SybronEndo, Glendora, CA, USA), up to a size 15.                     turation and the apical foramen (Tab. 1). No signifi-
     Then, each canal was prepared using TFA nickel-tita-                  cant differences were noted between the mean dis-
     nium instruments (SybronEndo, Glendora, CA, USA)                      tances of the groups (t test, p>0.05). Visible voids
     sizes 04.20 and 06.25. Irrigation was performed after                 were detected only in three canals (2 of Group TH
     each instrument using NAOCl 5% and final rinse with                   and 1 of Group SC) and in only one case more than
     3 mL of 17% EDTA and saline. After shaping proce-                     one void was present inside the canal (Fig. 1). The
     dures were completed, all canals were checked for                     proportions Z test showed no difference in the per-
     patency with a 10 K-file and dried by paper points.                   centage of canals with voids between the two groups
     The Group SC canals (n=20) were obturated using                       (p >0.05).



     Table 1. Distance between the apical limit of the obturation to the apical foramen (mm) and percentage of the cases with
     voids.

                                     Distance                                                 Voids
     Group                    n                 Mean (SD)                              n                      %
     Thermafil                18                0.32 a   (0.24)                        2                      10% a
     Soft-Core                19                0.27 a (0.18)                          1                      5% a
     Different superscript letters indicate statistically significant difference within column.


     12                                                                                           Annali di Stomatologia 2016;VII (1-2): 11-15

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     In vitro evaluation of carrier based obturation technique: a CBCT study


                                                                                     Figure 1. The CBCT (sagittal plane) and
                                                                                     3D rendering of the same obturated
                                                                                     tooth showing the presence of voids (ar-
                                                                                     rows).




     Discussion

     Several methods have been proposed to investigate
     the quality of root canal fillings technique (1, 3, 8, 9,
     11-13, 15-17), such as radiographs, biolumines-
     cence, histological sections, dye leakage, microleak-
     age models and clearing techniques. The use of CT
     or CBCT is a quite recent methodology, which has
     many advantages: convenience, decreased examina-
     tion time, lack of removal dentinal tissue, lack of dam-
     age of samples, possibility of different plane of exam-
     ination and different sections of canals, and repeata-
     bility. CT is more costly and time consuming, but
     more precise. CBCT is easier and quicker to perform,
     and is more similar to clinical imaging. Moreover, the
     CBCT analysis allowed not only the evaluation of
     voids, but also the precise measurement of the apical
     length of the obturation. Although the CBCT images
     can be more easily visualized by three-dimensional
     rendering using specific softwares (Fig. 1), this image
     processing was made as an experimental model to
     confirm the CBCT findings (Fig. 2).
     Results of the present study showed that there was             Figure 2. Detection of voids (arrow) and measurement of
     no significant difference between the two tested CBO           distance between apical foramen and obturation (dashed
     techniques in the apical extent of the root canal fill-        line), using 3D rendering.
     ing. Differently from some previous studies (11, 12),
     we found that despite the canal curvature, the apical
     limit of obturation was very satisfactory. Most of ca-         smaller coronal dimensions and a bigger plastic core,
     nals were sealed very close to the established work-           while Soft-Core obturators have a thinner core and a
     ing length, and a slight overfilling of gutta-percha was       greater amount of gutta-percha. A thinner core could
     recorded in only two Thermafill cases and in a Soft-           also be related to a denser filling, since a greater gut-
     Core one, but there was no carrier protrusion beyond           ta-percha ratio is considered preferable in maintain-
     the apex.                                                      ing the long-term apical seal (8, 9).
     These positive results are clearly related to a proper         The apparently mismatch of sizes among the CBO
     use of verifiers. Although the root canals were                brands proved not to be clinically relevant because
     shaped up to a taper .06 and size 25, for the SC               the results of both were similar and satisfactory. This
     group the majority of canals (n=16) were filled with           might be explained by the fact that in a CBO tech-
     obturator size 20. It was observed that the Soft-Core          nique, the obturator is always well plasticized along
     verifier size 20 was correctly reaching WL while the           its entire length. Accordingly, Marciano et al. showed
     size 25 verifier was short in thoses cases. For TH             that both Thermafil and System B were more effec-
     group, 18 all canals were obturated with size 25. This         tive than cold condensation techniques in the obtura-
     difference between the brands are probably related to          tion of roots with isthmuses (9). Therefore, the gutta-
     their features: the Thermafil obturators present a             percha flows not only apically but also laterally, filling

     Annali di Stomatologia 2016;VII (1-2): 11-15                                                                          13
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     G. Gambarini et al.


     a slightly wider canal space adequately, especially if
     we have more mass of gutta-percha, likewise in the
     Soft-Core obturators. Nevertheless, CBO are less ef-
     fective than other warm obturation techniques in the
     filling of internal resorptive cavities (15).
     Moreover a more flexible and smaller size carrier will
     reach working length with less risk of striping of the
     gutta-percha (11). Clinicians need only to pay atten-
     tion at not pushing the carrier beyond the apex, which
     can be easily achieved by correctly placing the rubber
     stop on the obturator at the proper working length.
     Overall, when size 20 was used, Soft-Core obturators
     reached working length in severely curved canals
     more easily and predictably than Thermafil size 25.
     Table 1 shows the mean data concerning the dis-
     tance between the apical foramen and root canal fill-
     ing for both techniques.
     Likewise, no significant difference in terms of voids
     and gaps was found between the two techniques,
     showing the excellent performance of CBO in severe
     curvatures. The 3D rendering images clearly shows
     how canals were three-dimensionally filled (Figs. 3,
     4). Present results are in agreement with previous re-        Figure 4. 3D rendering of a tooth obturated with Thermafil.
     searches that also showed no difference in the per-
     centage of canal area filled and voids between Ther-
     mafil and Soft-Core (15).                                     rates when filling the root canals with Soft-Core or lat-
     There have been many studies comparing obturation             eral condensation. Another clinical study (20) did not
     methods in vitro showing the effectiveness and sim-           find any difference in clinical outcomes between the
     plicity of CBO techniques (6-10, 15). The findings of         lateral condensation and CBO technique performed
     the present study confirmed these positive results,           with Thermafil obturator.
     with a minimal amount of voids and underfilling. De           Hence we may conclude that the two tested CBO
     Moor and Hommez compared different obturation ma-             showed similar positive results. Both filling systems
     terials with a dye leakage study and found that there         were quick and easy to perform even when severe
     were no differences in the long-term sealing ability          curvatures were present. The present study empha-
     between Thermafil and Soft-Core (18). A prospective           tized the need to precisely verify the matching be-
     clinical study (19) found no difference in success            tween preparation and obturators with verifiers.


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     Annali di Stomatologia 2016;VII (1-2): 11-15                                                                                                15
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