10.59987/ads/2010.3-4.9-13
Introduction. The study evaluated a null-hypothesis of no differences of fit between stock abutments and CAD/CAM titanium, gold sputtered and zirconia abutments when examined for radiographic adaptation and Scanning Electron Microcopy (SEM) at their inner aspect. The agreement between microscopic and radiographic fit was also assessed.
Methods. Implants (Osseospeed, Astra Tech, Mölndal, Sweden) were connected to titanium abutments (Ti-design, Astra Tech, Mölndal, Sweden) (control group n=12), to stock zirconia abutments (Zir-design, Astra Tech) (group 1 n=12) and to third party zirconia abutments (Aadva Zr abutment, GC, Tokyo, Japan) as observed under SEM (JEOL JSM-6060LV, Tokyo, Japan). Two independent operators blindly evaluated the images, according to a three-score scale: perfect adaptation, no complete adaptation, and clear evidence of no adaptation. A Kruskal-Wallis test was applied to assess significant differences in adaptation scores between the groups.
Results. All specimens showed precise SEM adaptation at all tested interfaces and no radiographically apparent gaps. No significant differences were found and therefore the null-hypothesis tested was accepted. Radiographic and SEM scores were in agreement.
Discussion. CAD/CAM titanium, gold sputtered and zirconia abutments and third-part CAD/CAM zirconia abutments show an adaptation to Astra Tech implants that is comparable to that of stock titanium and zirconia abutments. Clinicians might be able to verify such adaptation with an x-ray. In-vivo studies would be needed to evaluate the clinical outcome of CAD/CAM abutments.
application/pdf
1971-1441
203
3-4
en
M. Ferrari 
https://creativecommons.org/licenses/by-nc-nd/4.0
Annali di stomatologia
abutment
Implant adaptation of stock abutments versus CAD/CAM abutments: a radiographic and Scanning Electron Microscopy study
Text.Serial.Journal
https://www.annalidistomatologia.eu/ads
1
Research Article
2022-08-18
2022-08-18
2010-12-01
2023-12-04
9-13
Ann Stomatol (Roma)
M. Ferrari 
2010
10.59987/ads/2010.3-4.9-13
9
1971-1441
3-4
abutment
en
13
Implant adaptation of stock abutments versus CAD/CAM abutments: a radiographic and Scanning Electron Microscopy study
https://www.annalidistomatologia.eu/ads/article/download/203/179
1
    Implant adaptation of stock abutments versus
    CAD/CAM abutments: a radiographic and
    Scanning Electron Microscopy study




                                                                                                  i
                                                                                                al
                                                                                              on
    Davide Apicella, DDS, MS1                                   Discussion. CAD/CAM titanium, gold sputtered and zir-
    Mario Veltri, DDS, MS, PhD3                                 conia abutments and third-part CAD/CAM zirconia abut-
    Nicoletta Chieffi, DDS, MS, PhD1                            ments show an adaptation to Astra Tech implants that is
    Antonella Polimeni, MD, DDS2                                comparable to that of stock titanium and zirconia abut-
    Agostino Giovannetti, DDS2                                  ments. Clinicians might be able to verify such adapta-




                                                                                            zi
    Marco Ferrari, MD, DDS, PhD1                                tion with an x-ray. In-vivo studies would be needed to
                                                                evaluate the clinical outcome of CAD/CAM abutments.

                                                                Key words: titanium, zirconia, interface, abutment.




                                                                    na
    1 University of Florence and Siena, Italy
    Tuscan School of Dental Medicine
    Department of Prosthodontics and Dental Materials
    of Siena,                                                   Introduction
    2 University of Rome "La Sapienza", Rome, Italy




                                                                  er
    Department of Odontostomatological and Maxillofacial        Because of the constant increase of patient’s demands for
    Sciences, Paediatric Dentistry Unit                         dental aesthetics, and consequent attempts of prosthetic
    3 Free practioner
                                                                technology to catch-up with these exigencies, abutments


    Corresponding author:
    Prof. Marco Ferrari
                                                          nt    for implant-supported restorations are among the com-
                                                                ponents that undergo frequent updates (1). In particular,
                                                                because titanium abutments might display a bluish halo
                                                                through thin soft tissues (2), alternative abutment mate-
                                                 iI
    Departments of Oral Sciences                                rials have been sought. Due to its biocompatibility and ae-
    Policlinico Le Scotte
                                                                sthetic properties zirconia is increasingly used for abutment
    Viale Bracci 1 - 53100 Siena, Italy
                                                                manufacturing (3). In addition, zirconia abutments have a
    E-mail: ferrarimar@unisi.it
                                         on

                                                                very high fracture resistance that is only little lower as com-
                                                                pared to titanium (3). Besides zirconia, CAD/CAM pro-
                                                                cessing is increasingly used for abutment manufacturing.
    Summary                                                     The customization possible with CAD/CAM abutments
    Implant adaptation of stock abutments versus CAD/CAM        would allow for more refined prosthetic design and for en-
                               i


    abutments: a radiographic and Scanning Electron Mi-         hanced sustain of the soft tissue contour. Such components
                            iz



    croscopy study.                                             are available in different materials from implant companies
                                                                and lately also from some third party manufacturers. Un-
    Introduction. The study evaluated a null-hypothesis of      fortunately, no or little data assessing the fit of many of the-
           Ed




    no differences of fit between stock abutments and           se new components from either proprietary or third party
    CAD/CAM titanium, gold sputtered and zirconia abut-         companies are available. Nevertheless, the implant abut-
    ments when examined for radiographic adaptation and         ment interface is a critical area for long-term outcome of
    Scanning Electron Microcopy (SEM) at their inner as-        implant-supported prostheses (1). A reliable interfacial con-
    pect. The agreement between microscopic and radi-           tact is desirable to maximize mechanical stability of abut-
    ographic fit was also assessed.                             ments and prosthesis (4) and to avoid possibly associa-
    Methods. Implants (Osseospeed, Astra Tech, Mölndal,         ted biological complications (5). It has been demonstra-
IC




    Sweden) were connected to titanium abutments (Ti-de-        ted that gaps at the implant abutment interface might in-
    sign, Astra Tech, Mölndal, Sweden) (control group n=12),    crease stresses at prosthetic components, implants and
    to stock zirconia abutments (Zir-design, Astra Tech)        peri-implant bone (6). As a consequence of misfit-caused
    (group 1 n=12) and to third party zirconia abutments
                                                                stresses, screw loosening or fracture might happen (7). The-
C




    (Aadva Zr abutment, GC, Tokyo, Japan) as observed
                                                                se events have been described as the most common me-
    under SEM (JEOL JSM-6060LV, Tokyo, Japan). Two inde-
                                                                chanical complication during -3 to -5 years clinical trials
    pendent operators blindly evaluated the images, ac-
    cording to a three-score scale: perfect adaptation, no
                                                                (5, 8). In addition, the implant abutment margin could fa-
    complete adaptation, and clear evidence of no adapta-       vor bacterial accumulation and therefore it could be a sour-
©




    tion. A Kruskal-Wallis test was applied to assess signif-   ce of peri-implant inflammation (9). It was even hypothe-
    icant differences in adaptation scores between the          sized that bacterial leakage at the implant abutment in-
    groups.                                                     terface may play an etiologic role in peri-implantitis (10-11)
    Results. All specimens showed precise SEM adaptation        however its low prevalence in the literature seems to con-
    at all tested interfaces and no radiographically apparent   tradict this theory (12). In any case because precision of
    gaps. No significant differences were found and there-      the implant abutment interface might influence the rate of
    fore the null-hypothesis tested was accepted. Radi-         biological and mechanical complications it seem highly de-
    ographic and SEM scores were in agreement.                  sirable to have a tight marginal fit at this interface.

    Annali di Stomatologia 2010; I (3-4): 9-13                                                                                9
    D. Apicella et al.


    Aim of this study is therefore to evaluate by radiographic      ment margin and observed under SEM (JSM 6060 LV,
    and Scanning Electron Microscopy (SEM) examination at           JEOL, Tokyo, Japan). To assign a score to each interface
    their inner aspect the fit of Astra Tech stock titanium and     fit, the inner adaptation under SEM (as marginal gap bet-
    zirconia abutments, Aadva CAD/CAM zirconia abutments            ween the fixture and the abutment) was digitally measu-
    and Atlantis CAD/CAM titanium, gold sputtered and zirconia      red with a freeware image analysis software (15). In par-




                                                                                                        i
    abutments. A correlation between microscopic and ra-            ticular a 0 score was assigned to gaps not exceeding 5 mi-




                                                                                                      al
    diographic fit will also be assessed. A null-hypothesis of      crons (perfect adaptation), a score of 1 was assigned to
    no differences between stock and CAD/CAM abutments              gaps greater than 5 microns but not exceeding 20 microns
    will be tested.                                                 (no complete adaptation), and finally 2 was assigned to
                                                                    gaps greater than 20 microns (clear evidence of no adap-




                                                                                                    on
                                                                    tation). Two independent operators blindly evaluated the
    Material and methods                                            serial images according to the above-mentioned scale.

    Seventy-two implants (Osseospeed, Astra Tech, Mölndal,          Statistical analysis




                                                                                                  zi
    Sweden) were used in this study. They were randomly di-         Kappa coefficient was computed to evaluate interobser-
    vided into six equally sized groups. Implants in group 1 were   ver agreement. The Kruskal-Wallis test was applied to as-
    connected to titanium abutments (Ti-design 5,5 h1,5, Astra      sess statistical significance among the adaptation scores
    Tech, Mölndal, Sweden); implants in group 2 were con-           between the six experimental groups. The level of signifi-




                                                                        na
    nected to zirconia abutments (Zir-design 5,5 h1,5, Astra        cance was set at p<0.05. Altman-Bland’s method (16) was
    Tech, Mölndal, Sweden); implants in group 3 were con-           employed to check the agreement between the im-
    nected to CAD/CAM zirconia abutments (Aadva Zr abut-            plant/abutment fit measured by SEM and x-rays.
    ment, GC, Tokyo, Japan); implants in group 4 were con-




                                                                      er
    nected to CAD/CAM titanium abutments (Atlantis, Astra
    Tech); implants in group 5 were connected to CAD/CAM            Results
    gold coated titanium abutments (Gold Hue, Atlantis,
    Astra Tech); implant in group 6 were connected to               No disagreement between the operators resulted with a
    CAD/CAM zirconia abutments (Atlantis, Astra Tech). Im-
    plants and stock abutments were all from the same lot num-
    ber as provided by manufacturer. CAD/CAM abutments
    were provided by the manufacturers. In essence, both
                                                              nt    Kappa coefficient of 1. All the abutment groups showed sa-
                                                                    tisfactory adaptation by both X-ray and SEM evaluation.
                                                                    All the groups scored zero with regard to radiographic adap-
                                                                    tation (figure 1). SEM evaluation demonstrated mean in-
                                                    iI
    Atlantis and Aadva systems scanned the fixture interface        ternal gaps (figure 2) not higher than 5 microns in all the
    and afterwards the abutment was designed through a CAM          groups and consequently a zero score was assigned to all
    process aiming at matching the design of Astra Tech Ti-         the groups. No statistically significant differences were found
                                      on

    and Zir-Design abutments. At the end of the machining pha-      (table 1). Radiographic examination scores were in perfect
    se the CAD/CAM abutments had a similar shape to the             agreement with SEM scores with limits of agreement cal-
    stock abutments investigated.                                   culated by the Altman-Bland’s method of 0.

    X-ray evaluation
                             i


    This part of the study was intended to simulate the eva-        Discussion
                          iz



    luation of implant abutment adaptation that may be done
    in clinical practice (13, 14). Firstly specimens were sub-      Aiming at improved reliability and aesthetic outcomes of
    jected to radiographic analysis using conventional film (Ul-    implant-supported restorations, continuous strives are put
           Ed




    tra-Speed, Kodak, Rochester, NY, USA) and a dental tube
    (096 Belray, Takara Belmont, Osaka, Japan) placed per-
    pendicular to the implant abutment interface with the aid
    of a film holder (XCP, Dentsply Rinn, Elgin, IL, USA). Films
    were developed using fresh developer and fixer solutions
    (GBX Chemicals, Kodak Rochester, NY, USA).
    Proper adaptation of the abutment into the corresponding
IC




    fixture was assessed. The evaluation aimed at determining
    the precision of fit between the bearing surfaces and the
    top of the external hexagon of the implant with the supe-
    rior surface of the internal hexagon of the abutment. The
C




    adaptation of each abutment was scored from 0 (perfect
    adaptation), 1 (no complete adaptation) to 2 (clear evidence
    of no adaptation). Two operators made scores in double
    blind and in case of different scores the case was re-eva-
©




    luated and an agreement was found.

    SEM examination
    All the specimens were embedded in acrylic resin (Te-
    chnovit 2100e, Kuler, Werheim, Germany) and cut using
    a low speed diamond saw (Isomet, Buehler, Lake Bluff, IL,
    USA) under water-cooling. All the abutments were then cut       Figure 1 - From left, radiographic adaptation of Ti-design, Zir-de-
    parallel to the mesio-distal direction of the scalloped abut-   sign and Aadva Zr abutments.


    10                                                                                      Annali di Stomatologia 2010; I (3-4): 9-13
    Implant adaptation of stock abutments versus CAD/CAM abutments: a radiographic and Scanning Electron Microscopy




                                                                                                             i
                                                                                                           al
                                                                                                         on
                                                                                                       zi
                                                                              na
    Figure 2 - SEM images of the adaptation at the inner aspect of the implant abutment interface after cross sectioning.




                                                                            er
    Table 1 - Scores related to abutments' adaptation to Osseospeed       All the abutments, when examined from the inner aspect,
    fixtures.                                                             showed a gap never exceeding 5 microns. A very good


                             0
                                 RX Score

                                    1       2        0
                                                      SEM Score

                                                           1     2
                                                                      nt  marginal adaptation, among the best between several te-
                                                                          sted systems, was already documented for the Astra Tech
                                                                          titanium abutment (18). Nevertheless, much as precisely
                                                         iI
                                                                          fitting, Astra Tech abutments are not able to prevent ex-
    Ti Design               12      -       -       12     -      -
                                                                          perimental bacterial (18) or endotoxin leakage (19) simi-
    Zir Design              12      -       -       12     -      -
                                                                          larly to others systems on the market (18). Nevertheless,
    Aadva Zr                12      -       -       12     -      -
                                            on

    Ti Atlantis             12      -       -       12     -      -
                                                                          because a tight fit between implant and abutment is de-
    Zir Atlantis            12      -       -       12     -      -       sirable for optimal mechanical stability of the interface (4),
    Gold Hue Atlantis       12      -       -       12     -      -       the observation that both stock zirconia abutments and
                                                                          CAD/CAM abutments obtained with the Atlantis and
    Legend: Rx Score = score performed by X-ray (0 = perfect adap-        Aadva systems are able to replicate the same precise mar-
                               i


    tation; 1 = no complete adaptation; 2 = clear evidence of no adap-    ginal adaptation of Astra’s conical design connection se-
                            iz



    tation); SEM Score = score of internal adaptation performed by        ems of interest.
    SEM (0 = gap less than 5 microns between fixture and abutment,        The marginal precision together with the mechanical re-
    perfect adaptation; 1 = when the gap was between 5 and 20 mi-         liability of Atlantis zirconia abutments was already tested
           Ed




    crons, no complete adaptation; 2 = when it was higher than 20         in a previous study where they were found to be accep-
    microns, clear evidence of no adaptation).                            table for clinical use (20). Similarly this study, where the
                                                                          evaluation of Atlantis abutments was extended to all the
                                                                          available materials, showed that their fit to the fixture is com-
                                                                          parable to that of stock titanium abutments.
    in the advancement of prosthetic components and te-                   Conversely to the best of authors’ knowledge no previous
    chniques. At present the use of zirconia and CAD/CAM pro-             studies ever evaluated the marginal fit of Aadva abutments.
IC




    cessing is the forefront of the prosthetic technology. Zir-           It is also of interest to highlight that, opposite to the uniform
    conia abutments could be used when bluish halo of tita-               smoothness of stock abutments, SEM analysis of the Aad-
    nium through thin soft tissues is of concern (3). In addi-            va abutment surface showed large shallow grooves ap-
    tion for enhanced matching to patient’s tissues (17) pre-             parently as a result of the machining procedure, such groo-
C




    made abutments can be customized in the laboratory by                 ves were also present on Atlantis abutments although they
    grinding or they can be obtained through CAD/CAM pro-                 appeared much smaller. In any case such grooves were ab-
    cessing with. Little literature at present evaluates the fit of       sent in the area of the abutment that interfaces with the im-
    these new prosthetic components.                                      plant and therefore, possibly, they were not jeopardizing mar-
©




    In this study a null-hypothesis of no differences in the fit of       ginal adaptation (figure 3). The influence of such grooves
    Atlantis and Aadva CAD/CAM abutments to Astra Tech im-                on soft tissues and clinical outcomes is at present unknown.
    plants as compared with the fit of Astra Tech proprietary             Therefore, although good results emerged from this inve-
    zirconia and titanium abutments is accepted. As a conse-              stigation, further research is desirable on the Aadva system.
    quence, at least for the tested implant system, and as far            The data regarding the fit of the CAD/CAM abutments here
    as marginal adaptation is concerned, Aadva and Atlantis               investigated are analogous to the fit of CAD/CAM zirco-
    CAD/CAM abutments seem a suitable alternative to stock                nia external connection abutments that never exceeded 5
    abutments when a fully customized prosthesis is desired.              microns of gap even after dynamic loading (21). Never-

    Annali di Stomatologia 2010; I (3-4): 9-13                                                                                          11
    D. Apicella et al.




                                                                                                               i
                                                                                                             al
                                                                                                           on
                                                                                                         zi
                                                                                 na
                                                                               er
    Figure 3 - Low magnification of all the investigated abutments. Opposite to Astra abutment, Aadva abutment surface showed large
    shallow grooves apparently as a result of the machining procedure. However the portion that interfaces with the implant was free from
    such grooves thus leaving unaffected marginal adaptation.



    theless, it has to be taken into consideration, that the con-
    figuration of the external connection systems, with the pre-
                                                                    nt    4.
                                                                                J Dent. 2007; 35: 819-26.
                                                                                Byrne D, Houston F, Cleary R, Claffey N. The fit of cast and
                                                         iI
    sence of a marginal bevel, makes gap data not easily com-                   premachined implant abutments. J Prosthet Dent. 1998; 80:
    parable (21).                                                               184-92.
    Additionally with regard to the clinical applicability of this        5.    Jemt T, Pettersson P. A three-year follow-up study on single
                                                                                implant treatment. J Dent. 1993; 21: 203-8.
    study, radiographic evaluation of the implant abutment fit
                                         on

                                                                          6.    White GE. Osseointegrated Dental Technology. London:
    has been described as a sufficient consistent way to eva-
                                                                                Quintessence, 1993: 82–83.
    luate clinically precise abutment seating, especially in case
                                                                          7.    Binon PP. The effect of implant ⁄ abutment hexagonal misfit
    of subgingival location of the above-mentioned interface.                   on screw joint stability. Int J Prosthodont. 1996; 9: 149.
    However, it has also been pointed out that, for a reliable            8.    Henry PJ, Laney WR, Jemt T, Harris D, Krogh PH, Polizzi G,
                               i


    evaluation, orthogonal angulation is mandatory, as small                    Zarb GA, Herrmann I. Osseointegrated implants for single-
                            iz



    angulations deviations hide the presence of a gap. The                      tooth replacement: a prospective 5-year multicenter study.
    agreement here found between SEM and x-ray evaluation                       Int J Oral Maxillofac Implants. 1996; 11: 450-5.
    of the marginal adaptation seems of relevance. Conse-                 9.    Broggini N, McManus LM, Hermann JS, Medina R, Schenk
           Ed




    quently, it is reasonable to say that, when precise radio-                  RK, Buser D, Cochran DL. Peri-implant inflammation defi-
    graphic orthogonal orientation is attained like in this stu-                ned by the implant-abutment interface. J Dent Res. 2006;
    dy, clinicians can control abutment adaptation on Astra Tech                85: 473-8.
    implants by intraoral x-rays as radiographic adaptation cor-          10.   Quirynen M, Bollen CM, Eyssen H, van Steenberghe D. Mi-
    responds to precise microscopic seating.                                    crobial penetration along the implant components of the
    In conclusion Aadva and Atlantis CAD/CAM abutments                          Brånemark system. An in vitro study. Clin Oral Implants Res.
                                                                                1994; 5: 239-44.
    showed a fit to the Astra Tech fixture that was compara-
IC




                                                                          11.   Quirynen M, van Steenberghe D. Bacterial colonization of
    ble to the stock titanium and zirconia abutments. In-vivo
                                                                                the internal part of two-stage implants. An in vivo study. Clin
    studies are needed to evaluate the clinical results of the
                                                                                Oral Implants Res. 1993; 4: 158-61.
    investigated CAD/CAM abutment systems.                                12.   Esposito M, Hirsch JM, Lekholm U, Thomsen P. Biological fac-
C




                                                                                tors contributing to failures of osseointegrated oral implants.
                                                                                (II). Etiopathogenesis. Eur J Oral Sci. 1998; 106: 721-64.
    References                                                            13.   Cameron SM, Joyce A, Brousseau JS, Parker MH. Radio-
                                                                                graphic verification of implant abutment seating. J Prosthet
    1.   Binon PP. Implants and components: entering the new mil-               Dent. 1998; 79: 298-303.
©




         lennium. Int J Oral Maxillofac Implants. 2000; 15: 76-94.        14.   Begoña Ormaechea M, Millstein P, Hirayama H. Tube an-
    2.   Glauser R, Sailer I, Wohlwend A, Studer S, Schibli M, Scha-            gulation effect on radiographic analysis of the implant-abut-
         rer P. Experimental zirconia abutments for implant-suppor-             ment interface. Int J Oral Maxillofac Implants. 1999; 14:
         ted single-tooth restorations in esthetically demanding                77-85.
         regions: 4-year results of a prospective clinical study. Int J   15.   Rasband, W.S., ImageJ, U. S. National Institutes of Health,
         Prosthodont. 2004; 17: 285-90.                                         Bethesda, Maryland, USA, http://rsb.info.nih.gov/ij/, 1997-
    3.   Manicone PF, Rossi-Iommetti P, Raffaelli L. An overview of             2008.
         zirconia ceramics: basic properties and clinical applications.   16.   Bland JM, Altman DG. Statistical methods for assessing


    12                                                                                             Annali di Stomatologia 2010; I (3-4): 9-13
    Implant adaptation of stock abutments versus CAD/CAM abutments: a radiographic and Scanning Electron Microscopy


        agreement between two methods of clinical measurement.               in vitro investigation of tightness of internal conical implant-
        Lancet. 1986; 1: 307-10.                                             abutment connections against endotoxin penetration. Clin
    17. Conrad HJ, Seong WJ, Pesun IJ. Current ceramic materials             Oral Investig. 2009 DOI 10.1007/s00784-009-0317-x (epub
        and systems with clinical recommendations: A systematic              ahead of print)
        review. J Prosthet Dent. 2007; 98: 389-404.                      20. Kerstein RB, Radke J. A comparison of fabrication precision
    18. Jansen VK, Conrads G, Richter EJ. Microbial leakage and              and mechanical reliability of 2 zirconia implant abutments.




                                                                                                             i
                                                                                                           al
        marginal fit of the implant-abutment interface. Int J Oral Ma-       Int J Oral Maxillofac Implants. 2008; 23: 1029-36.
        xillofac Implants. 1997; 12: 527-40                              21. Yuzugullu B, Avci M. The implant-abutment interface of alu-
    19. Harder S, Dimaczek B, Açil Y, Terheyden H, Freitag-Wolf S,           mina and zirconia abutments. Clin Implant Dent Relat Res.
        Kern M. Molecular leakage at implant-abutment connection-            2008; 10: 113-21.




                                                                                                         on
                                                                                                       zi
                                                                             na
                                                                           er
                                                                   nt
                                                        iI
                               i         on
                            iz
           Ed
IC
C
©




    Annali di Stomatologia 2010; I (3-4): 9-13                                                                                           13
