10.59987/ads/2016.3.46-51
Aim. The purpose of this study was to evaluate the effects of technique on the filling quality of 2 recently introduced obturation systems comparatively with warm vertical compaction using microcomputed tomography.
Methods. 36 single-rooted teeth were selected, root canals prepared, and assigned to 3 groups (n=12), according to the filling technique: warm vertical compaction technique WVC, GuttaCore (Dentsply Tulsa Dental Specialties, Tulsa, OK) and Gutta Fusion (VDW, Germany). Each specimen was scanned using a micro-CT. Percentage of voids was calculated and data statistically analyzed using Kruskal Wallis test with a significance level of 5%.
Results. All obturations showed satisfactory similar results at the apical level. Differences between the three obturation methods were not significant at 1 mm (-p-value &gt;0.05), 3 mm (-p-value &gt;0.05) and 5 mm (-p- value &gt;0.05). No root fillings were void-free. No significant difference was found between the WVC technique, the GuttaCore technique and the Gutta Fusion technique concerning percentage of apical voids regardless of canal level.
Conclusion. This study shows the efficiency of cross-linked obturators in filling root canals hermetically by comparing them to the warm vertical compaction technique. Results show that these obturation techniques were equally sufficient concerning apical adaptation making them appropriate to use in endodontic obturations.
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Annali di stomatologia
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Quantitative volumetric analysis of cross-linked gutta-percha obturators
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Quantitative volumetric analysis of cross-linked gutta-percha obturators
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                                                                                                     Original article



    Quantitative volumetric analysis of cross-linked
    gutta-percha obturators




                                                                                                                  i
                                                                                                                al
    Carla Zogheib1                                           compaction technique. Results show that these
    Monique Hanna2                                           obturation techniques were equally sufficient




                                                                                                  n
    Damiano Pasqualini3                                      concerning apical adaptation making them appro-
    Alfred Naaman4                                           priate to use in endodontic obturations.




                                                                                               io
                                                             Key words: guttacore, gutta fusion, micro-ct, ob-
    1 Ass Pr, Department of Endodontics, St Joseph           turation, voids.




                                                                 az
    University, Beirut, Lebanon
    2 Department of Endodontics, St Joseph University,

    Beirut, Lebanon                                          Introduction
    3 Ass Pr, Department of Endodontics, University




                                                               rn
    or Turin, Italy                                          One of the main goals of endodontic treatment is
    4 Pr, Department of Endodontics, St Joseph               achieving a hermetic seal of root canals (1). In order to
    University, Beirut, Lebanon                              increase success of endodontically treated teeth, the
                                                             seal must be effective coronally and apically prevent-




                                                             te
                                                             ing bacterial recontamination leading to failure (2, 3)
    Corresponding author:                                    consequently blocking the circulation of tissue fluids
    Carla Zogheib                                            that could be diffused from the periapex. Many at-
    Ass Pr, Department of Endodontics, St Joseph
                                                      In     tempts based on variations in obturation techniques
    University, Beirut                                       have been made to solve problems, such as lack of
    Street/P.O. BoxRue de Damas, P.O. Box 175-208            surface adaptation, incorporation of apical voids com-
    Beirut, Lebanon                                          bined with time effect on sealer composition. Simplified
    E-mail: zogheibcarla@gmail.com                           methods of thermoplasticizing gutta-percha have be-
                                          ni

                                                             come increasingly popular. Schilder introduced the
                                                             concept of warm vertical compaction WVC of gutta-
    Summary                                                  percha in 1967, using an electrically heated plugger to
                                  io


                                                             condense apically (4). In 1978, Johnson proposed a
    Aim. The purpose of this study was to evaluate           gutta-percha coated metallic obturator oven-heated in
    the effects of technique on the filling quality of 2     order to be plasticized before it is inserted into the root
                          iz



    recently introduced obturation systems compara-          canal (5). This system has undergone numerous im-
    tively with warm vertical compaction using micro-        provements: the metal core was replaced by a plastic
    computed tomography.                                     support (1991) and more recently, with a cross-linked
             Ed




    Methods. 36 single-rooted teeth were selected, root      gutta-percha core obturator. The latest on the market
    canals prepared, and assigned to 3 groups (n=12),        are GuttaCore® (Dentsply Tulsa Dental Specialties,
    according to the filling technique: warm vertical        Tulsa, OK) and Gutta Fusion® (VDW, Germany).
    compaction technique WVC, GuttaCore (Dentsply            These systems promise to be efficient, safe, biocom-
    Tulsa Dental Specialties, Tulsa, OK) and Gutta Fu-       patible, and more effective in filling the complexities of
    sion (VDW, Germany). Each specimen was scanned           the root canal system, compared to other methods cur-
 IC




    using a micro-CT. Percentage of voids was calcu-         rently available (6, 7).To assess the quality of root fill-
    lated and data statistically analyzed using Kruskal      ings, various experimental methods have been used,
    Wallis test with a significance level of 5%.             such as fluid filtration, dye penetration, radioisotope,
    Results. All obturations showed satisfactory similar     SEM analysis, bacterial leakage evaluation and recent-
C




    results at the apical level. Differences between the     ly micro-computed tomography (micro-CT). Micro-CT,
    three obturation methods were not significant at 1       a three-dimensional imaging tool, has the virtues of be-
    mm (-p-value >0.05), 3 mm (-p-value >0.05) and 5         ing highly accurate and nondestructive, so it over-
    mm (-p- value >0.05). No root fillings were void-free.   comes the limitations of the previously used methods
@




    No significant difference was found between the          (8).The aim of this study was to investigate and to cal-
    WVC technique, the GuttaCore technique and the           culate the percentage of volume of voids and gaps in
    Gutta Fusion technique concerning percentage of          root canals filled with GuttaCore and Gutta Fusion ob-
    apical voids regardless of canal level.                  turators comparatively with WVC using micro-CT. The
    Conclusion. This study shows the efficiency of           null hypothesis was that there was no significant differ-
    cross-linked obturators in filling root canals her-      ence between the three techniques considering the
    metically by comparing them to the warm vertical         volume and distribution of voids.

    46                                                                            Annali di Stomatologia 2016;VII (3):46-51
    Quantitative volumetric analysis of cross-linked gutta-percha obturators


    Materials and methods                                          ber markers set accordingly on the obturators. The
                                                                   prefitted obturator was heated in the oven [GuttaCore
    Sample Selection and Specimen Preparation                      TMOven (Dentsply Tulsa Dental Specialties, Tulsa,
                                                                   OK) and Gutta Fusion®Oven (VDW Munich, Ger-
    36 single-rooted extracted teeth with less than 10 de-         many)]. A thin layer of the AH Plus® sealer was ap-
    grees curvature, as determined by Schneider’s                  plied to the canal walls with the verifier. After comple-
                                                                   tion of the heating cycle, the obturator was removed




                                                                                                                    i
    method (9), were collected. Teeth with root resorp-




                                                                                                                  al
    tions, fracture or immature apices were excluded               from the oven and slowly inserted (6 to 7 seconds) in-
    from the study. Preliminary radiographs were taken in          to the canal to the WL. The handle of the carrier was
    bucco-lingual and mesio-distal directions using a digi-        stabilized with finger pressure and then separated at
                                                                   the orifice of the canal. All roots were stored at 37 °C




                                                                                                      n
    tal sensor (ERLM Digora® Optime - Soredex, Fin-
    land). Teeth with previous root canal treatment, multi-        with 100% humidity for about 72 hours to allow the
    ple canals and intracanalar irregularities were dis-           sealers to set completely until being imaged by a mi-




                                                                                                   io
    carded. After scaling of root surfaces, teeth were             cro-CT scan.
    rinsed under running water then kept in Formol 10%
    for 1 week. The crowns were removed with a water-              Micro CT




                                                                        az
    cooled diamond disc (KG Sorensen, Barueri, SP,
    Brazil) and root length adjusted at 16 mm. A #10 K-            The qualitative analysis of the root-canal fillings was
    flexofile (Dentsply, Maillefer, Switzerland) was intro-        carried out using a micro-CT. A v|tome|x 240D (Gen-
    duced, when it reached the apical foramen, working             eral Electric, MA, USA) high-resolution micro-CT was




                                                                      rn
    length (WL) was determined and a radiograph taken.             used to scan the specimens. After adjusting the ap-
                                                                   propriate parameter, each tooth was positioned on
    Root canal instrumentation                                     the specimen stage and scanned with an isotropic




                                                                    te
                                                                   resolution of 4 μm, rotational step of 0.60°, and rota-
    After introduction of hand files and establishment of a        tional angle of 360°. With the datos|x 2.0 software,
    glide path, WaveOne Primary® (25/08) (Dentsply Tul-            images obtained from the scan were reconstructed to
    sa Dental Specialties, Tulsa, OK) was used in a reci-          show slices of the inner structure of the roots in 2D
                                                          In
    procating movement with light pressure. Afterwards,            and velo/CT for the 3D volumetric visualization.
    a size #10 K-file was taken to the WL to check paten-          Two different parameters were assessed: on axial
    cy and irrigation followed with 1ml of 5.25% NaOCl.            sections at 1, 3, and 5 mm from apex, area of
    The previous sequence was repeated until the instru-           voids/gaps in square micrometers and ratio between
                                                ni
    ment reached the WL. WaveOne Large® (40/08)                    voids/gaps and the total canal area in the section was
    (Dentsply Tulsa Dental Specialties, Tulsa, OK) was             calculated. In 3D surface-rendered reconstructions,
    then used to the WL. A final flush of 2 mL 17% EDTA            the volume of voids in cubic micrometers was calcu-
                                       io


    (pH=7.7) SmearClear (SybronEndo, Orange, CA,                   lated then the ratio between volume of voids/gaps
    USA) was used to eliminate the smear layer. Then,              and the total canal volume (Figure 1). Each section
    the canals were washed with 5 mL saline solution               was assessed by the same observer.
                              iz



    and dried with paper points (Dentsply Maillefer).

    Root canal filling                                             Statistical analysis
               Ed




    After preparations, all roots were randomly assigned           Statistical analyses were performed using a software
    to 3 experimental groups (n=12) according to the               program (SPSS for Windows, Version 18.0, Chicago,
    choice of filling technique. The first group was filled        IL). The level of significance was set at α=0.05. Vari-
    with WVC technique. A fine-medium sized gutta-per-             able was tested for normal distribution using the Kol-
    cha cone (Dentsply Tulsa Dental) was selected as               mogorov Smirnov test. Kruskal Wallis tests were
 IC




    the master cone, and trimmed to fit within 0.5 mm of           used to explore significant difference among groups.
    the WL. The prefitted master cone coated with a thin
    layer of AH Plus® sealer (Dentsply International) was
    inserted into the canal and down-packed to 5 mm                Results
C




    from the WL with a Touch n’ Heat source (SybronEn-
    do, Orange, CA). Subsequently, 3-4 mm segments of              Mean and standard-deviation of the percentage of
    gutta-percha were backpacked with the Obtura II unit           voids among groups are presented in Table 1 and
    (SybronEndo, Orange, CA) until the canals were                 Figure 2.
@




    completely obturated. The second group was obturat-            This study showed that the volume of voids was mini-
    ed with GuttaCore and AH Plus® and the third with              mal in the three groups and results within the 3
    Gutta Fusion and AH Plus®. In those two groups,                groups were equivalent. None of the root canal filled
    canals were filled with GuttaCore (Dentsply Tulsa              teeth were void-free, and no significant difference
    Dental Specialties, Tulsa, OK) and Gutta Fusion                was found within the three obturation methods at 1
    (VDW Munich, Germany) obturators selected by pas-              mm (-p-value=0.288), 3 mm (-p-value=0.440) and 5
    sively inserting a verifier to WL-0.5 mm and the rub-          mm (-p-value=0.287).

    Annali di Stomatologia 2016;VII (3):46-51                                                                            47
    C. Zogheib et al.




                                                                                                                       i
                                                                                                       n             al
                                                                                                    io
                                                                       az
                                                                     rn
                                                                   te
                                                          In
                                             ni

    Figure 1. Micro-CT three-dimensional reconstructions and horizontal cross-sections at 1, 3 and 5 mm from the apex of root
    canal systems obturated with warm vertical compaction techniques (V12), GuttaCore (GC8) and Gutta Fusion (GF3). Voids,
    when present, are shown in colored spots and calculated at 1, 3 and 5 mm from apex.
                                    io


    Discussion                                                     tional ones have shown several disadvantages: radi-
                            iz



                                                                   ographs provide 2D interpretations only, while the
    The role of root canal filling is to avoid leakage of oral     canal system should be analyzed by a three dimen-
    fluids containing bacteria and their products from the         sionally imaging technology; with the root sectioning,
              Ed




    oral cavity to the apical periodontium through the root        there could be loss of material which might mimic
    canal, and to prevent the exit to the periapex, of mi-         voids; the time taken for fluid filtration and clearing
    croorganisms that persisted in the root canal after            techniques might affect the results, dye penetration
    cleaning and shaping (10). Voids can be captured dur-          studies do not correlate clinically and dye extraction
    ing root filling procedures. In fact, internal voids are       studies evaluate only the apical third of the tooth.
 IC




    not in communication with the canal walls, thus they           Bacterial microleakage studies need long periods of
    could be considered less clinically significant for the        observation and don’t allow quantification of the num-
    endodontic prognosis. In other words, residual bacte-          ber of penetrating bacteria. A noninvasive in vitro an-
    ria, if present, are confined in an unfavorable environ-       alytical method for imaging has been described. Thus,
C




    ment (11). But external and combined voids form a              the analysis using micro-CT can be repeated on the
    gap between the filling materials and the canal walls          same specimen, results obtained from such analysis
    resulting in a space where bacteria can grow and               were comparable to histological studies (14). Artefacts
    leakage takes place due to failure of the sealer (12).         can be eliminated, hence, the data are objective and
@




    Leakage or percolation was defined by the AAE                  quantitative or qualitative evaluations are reliable
    (American Association of Endodontists) as the move-            (15). In endodontics, this technology has been used
    ment of periradicular tissue fluids, micro-organisms           for the evaluation of root canal anatomy, assessment
    and their toxins along the interface between dentinal          of root canal morphology after instrumentation, and
    walls and the filling materials (13). New methods              analysis of obturated root canals. Several compar-
    have been used to evaluate the sealing ability of root-        isons between obturation techniques in vitro com-
    filling techniques and materials because the conven-           pared different parameters such as length of fill, de-

    48                                                                                 Annali di Stomatologia 2016;VII (3):46-51
    Quantitative volumetric analysis of cross-linked gutta-percha obturators


    Table 1. Mean percentage of voids among groups.

    Percentage of voids               Methods                     Mean                          Standard Deviation
                                      WVC                         1.111                         2.350
    1 mm                              GuttaCore                   1.343                         1.901
                                      Gutta Fusion                1.388                         1.466




                                                                                                                   i
                                                                                                                 al
                                      WVC                         0.613                         1.225
    3 mm                              GuttaCore                   0.728                         0.712
                                      Gutta Fusion                1.377                         1.551




                                                                                                     n
                                      WVC                         0.805                         1.712




                                                                                                  io
    5 mm                              GuttaCore                   1.007                         1.285
                                      Gutta Fusion                0.827                         0.832




                                                                        az
                                                                                                Figure 2. Mean percentage
                                                                                                of voids among groups.




                                                                      rn
                                                                    te
                                                          In
                                                  ni
                                       io
                              iz



    fect replication and gutta-percha density. In this stu-        canal obturations (17, 18). Endodontic sealers differ
    dy, a volume analysis was performed with micro-CT              in physical properties which might determine the seal-
               Ed




    in which the focus was on the volume of voids creat-           ing ability of the root filling (11). The AH 26® and AH
    ed in the fillings. Micro-CT can differentiate the vol-        Plus® (Dentsply International) used in association
    ume percentage of gutta-percha and sealer in the ob-           with gutta percha, have been known for their quality
    turating material by different colors. But, like in previ-     and advantages; this is why most of the studies in-
    ous micro-CT studies (8, 16), sealer and gutta-percha          cluding ours that compared the microleakage of gut-
    were segmented together and analyzed as a single               ta-percha with any other filling material use this seal-
 IC




    root-filling entity because the majority of obturators         er. Besides, the good dimensional stability of AH
    fillings sealer was indistinguishable from gutta-per-          Plus® sealer has been demonstrated (19, 20) and its
    cha. Since, micro-CT offers the possibility of repeated        application can be suggested.
    scanning; it will be possible to evaluate changes of           It is important to obturate the whole length of root
C




    filling over time (15). On the other hand, the micro-CT        canal. However, since the apical third is especially
    has limitations with in vivo applications, and the use         important, all the measurements were done for the
    of this technique is restrained to the examination of          apical third. One of the reasons for the inadequately
    specimens of limited size (15). In this study, the use of      filled canals could be that the canal anatomy prevents
@




    WaveOne Large® 40/8 till the WL has been support-              adequate cleaning of the narrow fissured areas with
    ed by several previous studies because the increase            circular root files since the canal lumen is irregular
    in the final preparation taper improves irrigant re-           and the risk of subsequently creating voids is high
    placement and wall shear stress. Moreover, enlarging           (21, 22). Moreover, inadequately filled canals could
    the apical third (especially the last 3 mm) of root            be the consequence of root filling technique.
    canals to an 8% taper is necessary to achieve a bet-           Based on the results of the present study, none of the
    ter sealing ability and thus long-term success for root        tested techniques provided a void-free filling at the

    Annali di Stomatologia 2016;VII (3):46-51                                                                           49
    C. Zogheib et al.


    apical third. This finding is similar with the study of       Aknowledgements
    Somma et al. in 2011 who compared the quality of
    root fillings completed by two thermoplasticized gutta-       This study was supported by the Saint Joseph Uni-
    percha techniques (Thermafil and System B) and a              versity Research Committee, Beirut, Lebanon.
    cold gutta-percha technique (single point) by micro-
    CT analysis.                                                  Conflict of interest statement
    All techniques produced comparable results in terms           All Authors declare that there is no conflict of interest




                                                                                                                              i
    of percentage of filling and void distribution (11). In




                                                                                                                            al
                                                                  of any kind regarding the publication of this paper.
    particular, most of filling techniques do not completely
    fill the root canal system (8, 11, 16). However, when
    ultrasonic (UL) was used to lower gap volumes be-             References




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                                                                                                         io
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    Annali di Stomatologia 2016;VII (3):46-51                                                                                              51
