Research and Education| Volume 129, ISSUE 6, P906.e1-906.e10, June 2023

Download started.


Micro-CT analysis of marginal and internal fit of milled and pressed polyetheretherketone single crowns


      Statement of problem

      Polyetheretherketone (PEEK) has been increasingly used as a framework material in prosthetic dentistry. However, data on the marginal and internal fit of PEEK restorations fabricated by using either the computer-aided design and computer-aided manufacturing (CAD-CAM) or heat-pressing technique are sparse.


      The aim of this in vitro study was to assess the marginal and internal fit of milled and pressed PEEK single crowns by using microcomputed tomography (μCT).

      Material and methods

      A custom-made, single stainless-steel die was designed to replicate a maxillary first premolar prepared for a ceramic crown. PEEK copings (N=30) were fabricated and allocated to 3 groups (n=10) according to the fabrication technique: milled from a prefabricated PEEK blank, heat pressed from PEEK pellets, and heat pressed from PEEK granules. All copings were veneered with a composite resin material. The marginal fit was recorded at 4 predetermined points and the internal fit at 8 predetermined points on each crown by using μCT. Two-way ANOVA, pair-wise Tukey honestly significant difference (HSD), and simple main effect tests were used for statistical analysis of the data (α=.05).


      Concerning marginal fit, the milled crowns demonstrated the best marginal fit overall (44 ±3 μm), followed by those pressed from pellets (92 ±3 μm), and finally by those pressed from granules (137 ±7 μm) (P<.001). The interaction between the effects of the fabrication technique and the measurement point on the marginal fit was not statistically significant (P=.142). The milled crowns demonstrated the lowest mean gap values overall, followed by those pressed from pellets and those pressed from granules (P<.001). The interaction between the effects of the fabrication technique and the measurement point on the internal fit was statistically significant (P<.001). Except for the distal occlusal gap and mesial occlusal gap, all tested groups showed a statistically significant difference (P<.001). In addition, statistically significant differences were observed among all measurement points in different fabrication techniques (P<.001).


      The marginal and internal fit of milled PEEK crowns was significantly better than pressed crowns. However, both CAD-CAM and heat-pressing techniques produced PEEK crowns with a clinically acceptable marginal and internal fit. The mean marginal gap of the PEEK crowns pressed from granules was above the range of clinically acceptable value.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Prosthetic Dentistry
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Kurtz S.M.
        • Devine J.N.
        PEEK biomaterials in trauma, orthopedic, and spinal implants.
        Biomaterials. 2007; 28: 4845-4869
        • Stawarczyk B.
        • Taufall S.
        • Roos M.
        • Schmidlin P.R.
        • Lümkemann N.
        Bonding of composite resins to PEEK: the influence of adhesive systems and air-abrasion parameters.
        Clin Oral Investig. 2018; 22: 763-771
        • Laux K.A.
        • Sue H.J.
        • Montoya A.
        • Bremner T.
        Wear behavior of polyaryletherketones under multi-directional sliding and fretting conditions.
        Tribol Lett. 2015; 58: 41
        • Dede D.Ö.
        • Küçükekenci A.S.
        • Kahveci Ç.
        Influence of chairside surface treatments on the shear bond strength of PEKK polymer to veneering resin materials: an in vitro study.
        J Prosthet Dent. 2021; 125: 703.e1-703.e7
        • Jin H.Y.
        • Teng M.H.
        • Wang Z.J.
        • et al.
        Comparative evaluation of BioHPP and titanium as a framework veneered with composite resin for implant-supported fixed dental prostheses.
        J Prosthet Dent. 2019; 122: 383-388
        • Robinson D.
        • Aguilar L.
        • Gatti A.
        • Abduo J.
        • Lee P.V.
        • Ackland D.
        Load response of the natural tooth and dental implant: a comparative biomechanics study.
        J Adv Prosthodont. 2019; 11: 169-178
        • Ayyadanveettil P.
        • Thavakkara V.
        • Latha N.
        • Pavanan M.
        • Saraswathy A.
        • Kuruniyan M.S.
        Randomized clinical trial of zirconia and polyetheretherketone implant abutments for single-tooth implant restorations: a 5-year evaluation.
        J Prosthet Dent. 2022; 128: 1275-1281
        • Najeeb S.
        • Zafar M.S.
        • Khurshid Z.
        • Siddiqui F.
        Applications of polyetheretherketone (PEEK) in implantology and prosthodontics.
        J Prosthodont Res. 2016; 60: 12-19
        • Fuhrmann G.
        • Steiner M.
        • Freitag-Wolf S.
        • Kern M.
        Resin bonding to three types of polyaryletherketones (PAEKs)-durability and influence of surface conditioning.
        Dent Mater. 2014; 30: 357-363
        • Gouveia D.D.N.M.
        • Razzoog M.E.
        • Sierraalta M.
        • Alfaro M.F.
        Effect of surface treatment and manufacturing process on the shear bond strength of veneering composite resin to polyetherketoneketone (PEKK) and polyetheretherketone (PEEK).
        J Prosthet Dent. 2022; 128: 1061-1066
        • Iyer S.B.
        • Dube A.
        • Dube N.M.
        • Roy P.
        • Sailaja R.R.N.
        Sliding wear and friction characteristics of polymer nanocomposite PAEK-PDMS with nano-hydroxyapatite and nano-carbon fibres as fillers.
        J Mech Behav Biomed Mater. 2018; 86: 23-32
        • Rosentritt M.
        • Schneider-Feyrer S.
        • Behr M.
        • Preis V.
        In vitro shock absorption tests on implant-supported crowns: influence of crown materials and luting agents.
        Int J Oral Maxillofac Implants. 2018; 33: 116-122
        • Wagner C.
        • Stock V.
        • Merk S.
        • et al.
        Retention load of telescopic crowns with different taper angles between cobalt-chromium and polyetheretherketone made with three different manufacturing processes examined by pull-off test.
        J Prosthodont. 2018; 27: 162-168
        • Zoidis P.
        • Bakiri E.
        • Polyzois G.
        Using modified polyetheretherketone (PEEK) as an alternative material for endocrown restorations: a short-term clinical report.
        J Prosthet Dent. 2016; 117: 335-339
        • Zoidis P.
        • Papathanasiou I.
        • Polyzois G.
        The use of a modified polyether-ether-ketone (PEEK) as an alternative framework material for removable dental prostheses. A clinical report.
        J Prosthodont. 2016; 25: 580-584
        • Kaleli N.
        • Sarac D.
        • Kulunk S.
        • Ozturk O.
        Effect of different restorative crown and customized abutment materials on stress distribution in single implants and peripheral bone: a three-dimensional finite element analysis study.
        J Prosthet Dent. 2017; 119: 437-445
        • Zoidis P.
        The all-on-4 modified polyetheretherketone treatment approach: a clinical report.
        J Prosthet Dent. 2018; 119: 516-521
        • Rikitoku S.
        • Otake S.
        • Nozaki K.
        • Yoshida K.
        • Miura H.
        Influence of SiO2 content of polyetheretherketone (PEEK) on flexural properties and tensile bond strength to resin cement.
        Dent Mater J. 2019; 38: 464-470
        • Al-Rabab’ah M.
        • Hamadneh W.
        • Alsalem I.
        • Khraisat A.
        • Abu K.A.
        Use of high performance polymers as dental implant abutments and frameworks: a case series report.
        J Prosthodont. 2019; 28: 365-372
        • Heimer S.
        • Schmidlin P.R.
        • Roos M.
        • Stawarczyk B.
        Surface properties of polyetheretherketone after different laboratory and chairside polishing protocols.
        J Prosthet Dent. 2017; 117: 419-425
        • Panayotov I.V.
        • Orti V.
        • Cuisinier F.
        • Yachouh J.
        Polyetheretherketone (PEEK) for medical applications.
        J Mater Sci Mater Med. 2016; 27: 1-11
        • Monich P.R.
        • Berti F.V.
        • Porto L.M.
        • et al.
        Physicochemical and biological assessment of PEEK composites embedding natural amorphous silica fibers for biomedical applications.
        Mater Sci Eng C Mater Biol Appl. 2017; 79: 354-362
        • Schwitalla A.D.
        • Spintig T.
        • Kallage I.
        • Müller W.
        Flexural behavior of PEEK materials for dental application.
        Dent Mater. 2015; 31: 1377-1384
        • Lee W.T.
        • Koak J.Y.
        • Lim Y.J.
        • Kim S.K.
        • Kwon H.B.
        • Kim M.J.
        Stress shielding and fatigue limits of poly-ether-ether-ketone dental implants.
        J Biomed Mater Res B Appl Biomater. 2012; 100: 1044-1052
        • Zoidis P.
        • Papathanasiou I.
        Modified PEEK resin-bonded fixed dental prosthesis as an interim restoration after implant placement.
        J Prosthet Dent. 2016; 116: 637-641
        • Stawarczyk B.
        • Eichberger M.
        • Uhrenbacher J.
        • Wimmer T.
        • Edelhoff D.
        • Schmidlin P.R.
        Three-unit reinforced polyetheretherketone composite FDPs: influence of fabrication method on load-bearing capacity and failure types.
        Dent Mater J. 2015; 34: 7-12
        • Abdullah A.O.
        • Tsitrou E.A.
        • Pollington S.
        Comparative in vitro evaluation of CAD-CAM vs conventional provisional crowns.
        J Appl Oral Sci. 2016; 24: 258-263
        • Luthardt R.
        • Weber A.
        • Rudolph H.
        • Schone C.
        • Quaas S.
        • Walter M.
        Design and production of dental prosthetic restorations: basic research on dental CAD/CAM technology.
        Int J Comput Dent. 2002; 5: 165-176
        • Beuer F.
        • Naumann M.
        • Gernet W.
        • Sorensen J.A.
        Precision of fit: zirconia three unit fixed dental prostheses.
        Clin Oral Investig. 2009; 13: 343-349
        • Alsadon O.
        • Wood D.
        • Patrick D.
        • Pollington S.
        Comparing the optical and mechanical properties of PEKK polymer when CAD/CAM milled and pressed using a ceramic pressing furnace.
        J Mech Behav Biomed Mater. 2019; 89: 234-236
        • Aldegheishem A.
        • Ioannidis G.
        • Att W.
        • Petridis H.
        Success and survival of various types of all-ceramic single crowns: a critical review and analysis of studies with a mean follow-up of 5 years or longer.
        Int J Prosthodont. 2017; 30: 168-181
        • Molin M.K.
        • Karlsson S.L.
        • Kristiansen M.S.
        Influence of film thickness on joint bend strength of a ceramic/resin composite joint.
        Dent Mater. 1996; 12: 245-249
        • Chochlidakis K.M.
        • Papaspyridakos P.
        • Geminiani A.
        • Chen C.J.
        • Feng I.J.
        • Ercoli C.
        Digital versus conventional impressions for fixed prosthodontics: a systematic review and meta-analysis.
        J Prosthet Dent. 2016; 116: 184-190
        • McLean J.W.
        • von Fraunhofer J.A.
        The estimation of cement film thickness by an vivo technique.
        Br Dent J. 1971; 131: 107-111
        • Yuksel E.
        • Zaimoglu A.
        Influence of marginal fit and cement types on microleakage of all-ceramic crown systems.
        Braz Oral Res. 2011; 25: 261-266
        • May L.G.
        • Kelly J.R.
        • Bottino M.A.
        • Hill T.
        Effects of cement thickness and bonding on the failure loads of CAD/CAM ceramic crowns: multiphysics FEA modeling and monotonic testing.
        Dent Mater. 2012; 28: e99-e109
        • Quintas A.F.
        • Oliveira F.
        • Bottino M.A.
        Vertical marginal discrepancy of ceramic copings with different ceramic materials, finish lines, and luting agents: an in vitro evaluation.
        J Prosthet Dent. 2004; 92: 250-257
        • Nawafleh N.A.
        • Mack F.
        • Evans J.
        • Mackay J.
        • Hatamleh M.M.
        Accuracy and reliability of methods to measure marginal adaptation of crowns and FDPs: a literature review.
        J Prosthodont. 2013; 22: 419-428
        • Kosyfaki P.
        • del Pilar Pinilla Martín M.
        • Strub J.R.
        Relationship between crowns and the periodontium: a literature update.
        Quintessence Int. 2010; 41: 109-126
        • Pak H.-S.
        • Han J.-S.
        • Lee J.-B.
        • Kim S.-H.
        • Yang J.-H.
        Influence of porcelain veneering on the marginal fit of Digident and Lava CAD-CAM zirconia ceramic crowns.
        J Adv Prosthodont. 2010; 2: 33-38
        • Groten M.
        • Axmann D.
        • Probster L.
        • Weber H.
        Determination of the minimum number of marginal gap measurements required for practical in-vitro testing.
        J Prosthet Dent. 2000; 83: 40-49
        • Att W.
        • Komine F.
        • Gerds T.
        • Strub J.R.
        The marginal accuracy of zirconia fixed dental prostheses is influenced by manufacturing technique.
        J Prosthet Dent. 2009; 101: 239-247
        • Pimenta M.A.
        • Frasca L.C.
        • Lopes R.
        • Rivaldo E.
        Evaluation of marginal and internal fit of ceramic and metallic crown copings using x-ray microtomography (micro-CT) technology.
        J Prosthet Dent. 2015; 114: 223-228
        • Contrepois M.
        • Soenen A.
        • Bartala M.
        • Laviole O.
        Marginal adaptation of ceramic crowns: a systematic review.
        J Prosthet Dent. 2013; 110: 447-454
        • Neves F.D.
        • Prado C.J.
        • Prudente M.S.
        • et al.
        Micro-computed tomography evaluation of marginal fit of lithium disilicate crowns fabricated by using chairside CAD/CAM systems or the heat-pressing technique.
        J Prosthet Dent. 2014; 112: 1134-1140
        • Sadid-Zadeh R.
        • Li R.
        • Miller L.M.
        • Simon M.
        Effect of fabrication technique on the marginal discrepancy and resistance of lithium disilicate crowns: an in vitro study.
        J Prosthodont. 2019; 28: 1005-1010
        • Daou E.E.
        • Ounsi H.
        • Ozcan M.
        • Al-Haj Husain N.
        • Salameh Z.
        Marginal and internal fit of pre-sintered Co-Cr and zirconia 3-unit fixed dental prostheses as measured using microcomputed tomography.
        J Prosthet Dent. 2018; 120: 409-414
        • Peroz I.
        • Mitsas T.
        • Erdelt K.
        • Kopsahilis N.
        Marginal adaptation of lithium disilicate ceramic crowns cemented with three different resin cements.
        Clin Oral Investig. 2019; 23: 315-320
        • Seo D.
        • Yi Y.
        • Roh B.
        The effect of preparation designs on the marginal and internal gaps in Cerec3 partial ceramic crowns.
        J Dent. 2009; 37: 374-382
        • Della Bona A.
        • Kelly J.R.
        The clinical success of all-ceramic restorations.
        J Am Dent Assoc. 2008; 139 Suppl: 8S-13S
        • Park J.Y.
        • Bae S.Y.
        • Lee J.J.
        • Kim J.H.
        • Kim H.Y.
        • Kim W.C.
        Evaluation of the marginal and internal gaps of three different dental prostheses: comparison of the silicone replica technique and three-dimensional superimposition analysis.
        J Adv Prosthodont. 2017; 9: 159-169
        • Hamza T.A.
        • Sherif R.M.
        In vitro evaluation of marginal discrepancy of monolithic zirconia restorations fabricated with different CAD-CAM systems.
        J Prosthet Dent. 2017; 117: 762-766
        • Son K.
        • Lee S.
        • Kang S.H.
        • et al.
        A comparison study of marginal and internal fit assessment methods for fixed dental prostheses.
        J Clin Med. 2019; 8: 785
        • Faul F.
        • Erdfelder E.
        • Lang A.G.
        • Buchner A.
        G∗Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences.
        Behav Res Methods. 2007; 39: 175-191
        • Attia M.A.
        • Shokry T.E.
        Effect of different fabrication techniques on the marginal precision of polyetheretherketone single-crown copings.
        J Prosthet Dent. 2020; 124: 565.e1-565.e7
        • Oilo M.
        • Kvam K.
        • Gjerdet N.R.
        Simulation of clinical fractures for three different all-ceramic crowns.
        Eur J Oral Sci. 2014; 122: 245-250
        • Park J.Y.
        • Kim H.Y.
        • Kim J.H.
        • Kim J.H.
        • Kim W.C.
        Comparison of prosthetic models produced by traditional and additive manufacturing methods.
        J Adv Prosthodont. 2015; 7: 294-302
        • Lifton J.J.
        • Liu T.
        Evaluation of the standard measurement uncertainty due to the ISO 50 surface determination method for dimensional computed tomography.
        Precis Eng. 2020; 61: 82-92
        • Abduo J.
        • Lyons K.
        • Bennamoun M.
        Trends in computer-aided manufacturing in prosthodontics: a review of the available streams.
        Int J Dent. 2014; 2014: 783948
        • Shin Y.
        • Park S.
        • Park J.W.
        • Kim K.M.
        • Park Y.B.
        • Roh B.D.
        Evaluation of the marginal and internal discrepancies of CAD-CAM endocrowns with different cavity depths: an in vitro study.
        J Prosthet Dent. 2017; 117: 109-115
        • Pera P.
        • Gilodi S.
        • Bassi F.
        • Carossa S.
        In vitro marginal adaptation of alumina porcelain ceramic crowns.
        J Prosthet Dent. 1994; 72: 585-590