Journal of Prosthetic Dentistry

Fracture resistance of lithium disilicate restorations after endodontic access preparation: An in vitro study


      Statement of problem

      Endodontic access preparation through a lithium disilicate restoration is a frequently encountered clinical situation. The common practice of repairing the accessed crown with composite resin may result in a weakened restoration.


      The purpose of this in vitro study was to determine the effect of endodontic access preparation on the fracture resistance and microstructural integrity of monolithic pressed and monolithic milled lithium disilicate complete coverage restorations.

      Material and methods

      Twenty monolithic pressed (IPS e.max Press) and 20 monolithic milled (IPS e.max CAD) lithium disilicate restorations were fabricated. Ten of the pressed and 10 of the milled crowns were accessed for a simulated endodontic treatment and subsequently repaired by using a porcelain repair system and composite resin. All specimens were submitted to cyclic loading and then loaded to failure. Force data were recorded and analyzed with 2-way ANOVA followed by a post hoc test (Sidak correction) to indicate significant differences among the groups (α=.05). A Weibull analysis was also performed for each group. Eight (4 pressed and 4 milled) additional restorations were fabricated to complete a scanning electron microscope (SEM) analysis and evaluate the surface damage created by the endodontic access preparation.


      A statistically significant difference (P=.019) was found between the pressed intact and pressed repaired restorations and between the pressed intact and milled repaired restorations (P=.002). Specimens that were examined with an SEM showed edge chipping involving primarily the glaze layer around the access openings.


      Endodontic access preparation of lithium disilicate restorations resulted in a significantly reduced load to failure in the pressed specimens, but not in the milled specimens.
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        • Bergenholtz G.
        • Nyman S.
        Endodontic complications following periodontal and prosthetic treatment of patients with advanced periodontal disease.
        J Periodontol. 1984; 55: 63-68
        • Cheung G.S.
        A preliminary investigation into the longevity and causes of failure of single unit extracoronal restorations.
        J Dent. 1991; 19: 160-163
        • Goldman M.
        • Laosonthorn P.
        • White R.R.
        Microleakage–full crowns and the dental pulp.
        J Endod. 1992; 18: 473-475
        • Goodacre C.J.
        • Bernal G.
        • Rungcharassaeng K.
        • Kan J.Y.
        Clinical complications in fixed prosthodontics.
        J Prosthet Dent. 2003; 90: 31-41
        • Thompson J.Y.
        • Anusavice K.J.
        • Naman A.
        • Morris H.F.
        Fracture surface characterization of clinically failed all-ceramic crowns.
        J Dent Res. 1994; 73: 1824-1832
        • Michanowicz A.E.
        • Michanowicz J.P.
        Endodontic access to the pulp chamber via porcelain jacket crowns.
        Oral Surg Oral Med Oral Pathol. 1962; 15: 1483-1488
        • Sutherland J.K.
        • Teplitsky P.E.
        • Moulding M.B.
        Endodontic access of all-ceramic crowns.
        J Prosthet Dent. 1989; 61: 146-149
        • Teplitsky P.E.
        • Sutherland J.K.
        Endodontic access of Cerestore crowns.
        J Endod. 1985; 11: 555-558
        • Haselton D.R.
        • Lloyd P.M.
        • Johnson W.T.
        A comparison of the effects of two burs on endodontic access in all-ceramic high leucite crowns.
        Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2000; 89: 486-492
        • Davis M.W.
        Providing endodontic care for teeth with ceramic crowns.
        J Am Dent Assoc. 1998; 129: 1746-1747
        • Sabourin C.R.
        • Flinn B.D.
        • Pitts D.L.
        • Gatten T.L.
        • Johnson J.D.
        A novel method for creating endodontic access preparations through all-ceramic restorations: air abrasion and its effect relative to diamond and carbide bur use.
        J Endod. 2005; 31: 616-619
        • Guess P.C.
        • Schultheis S.
        • Bonfante E.A.
        • Coelho P.G.
        • Ferencz J.L.
        • Silva N.R.
        All-ceramic systems: laboratory and clinical performance.
        Dent Clin North Am. 2011; 55 (ix): 333-352
        • Blatz M.B.
        • Sadan A.
        • Kern M.
        Resin-ceramic bonding: a review of the literature.
        J Prosthet Dent. 2003; 89: 268-274
        • Colares R.C.
        • Neri J.R.
        • Souza A.M.
        • Pontes K.M.
        • Mendonça J.S.
        • Santiago S.L.
        Effect of surface pretreatments on the microtensile bond strength of lithium-disilicate ceramic repaired with composite resin.
        Braz Dent J. 2013; 24: 349-352
        • Filho A.M.
        • Vieira L.C.
        • Araújo E.
        • Monteiro Júnior S.
        Effect of different ceramic surface treatments on resin microtensile bond strength.
        J Prosthodont. 2004; 13: 28-35
        • Kelly J.R.
        Dental ceramics: current thinking and trends.
        Dent Clin North Am. 2004; 48 (513–30): viii
        • Kimmich M.
        • Stappert C.F.
        Intraoral treatment of veneering porcelain chipping of fixed dental restorations: a review and clinical application.
        J Am Dent Assoc. 2013; 144: 31-44
        • Soderholm K.J.
        • Shang S.W.
        Molecular orientation of silane at the surface of colloidal silica.
        J Dent Res. 1993; 72: 1050-1054
        • Yen T.W.
        • Blackman R.B.
        • Baez R.J.
        Effect of acid etching on the flexural strength of a feldspathic porcelain and a castable glass ceramic.
        J Prosthet Dent. 1993; 70: 224-233
        • Menees T.S.
        • Lawson N.C.
        • Beck P.R.
        • Burgess J.O.
        Influence of particle abrasion or hydrofluoric acid etching on lithium disilicate flexural strength.
        J Prosthet Dent. 2014; 112: 1164-1170
        • Wood K.C.
        • Berzins D.W.
        • Luo Q.
        • Thompson G.A.
        • Toth J.M.
        • Nagy W.W.
        Resistance to fracture of two all-ceramic crown materials following endodontic access.
        J Prosthet Dent. 2006; 95: 33-41
        • Qeblawi D.
        • Hill T.
        • Chlosta K.
        The effect of endodontic access preparation on the failure load of lithium disilicate glass-ceramic restorations.
        J Prosthet Dent. 2011; 106: 328-336
        • Rosentritt M.
        • Behr M.
        • Gebhard R.
        • Handel G.
        Influence of stress simulation parameters on the fracture strength of all-ceramic fixed-partial dentures.
        Dent Mater. 2006; 22: 176-182
        • Borges G.A.
        • Caldas D.
        • Taskonak B.
        • Yan J.
        • Sobrinho L.C.
        • de Oliveira W.J.
        Fracture loads of all-ceramic crowns under wet and dry fatigue conditions.
        J Prosthodont. 2009; 18: 649-655
        • Senyilmaz D.P.
        • Canay S.
        • Heydecke G.
        • Strub J.R.
        Influence of thermomechanical fatigue loading on the fracture resistance of all-ceramic posterior crowns.
        Eur J Prosthodont Restor Dent. 2010; 18: 50-54
        • Kelly J.R.
        Clinically relevant approach to failure testing of all-ceramic restorations.
        J Prosthet Dent. 1999; 81: 652-661
        • Kelly J.R.
        • Rungruanganunt P.
        • Hunter B.
        • Vailati F.
        Development of a clinically validated bulk failure test for ceramic crowns.
        J Prosthet Dent. 2010; 104: 228-238
        • Christensen G.J.
        The all-ceramic restoration dilemma: where are we?.
        J Am Dent Assoc. 2011; 142: 668-671
        • Pieger S.
        • Salman A.
        • Bidra A.S.
        Clinical outcomes of lithium disilicate single crowns and partial fixed dental prostheses: a systematic review.
        J Prosthet Dent. 2014; 112: 22-30
        • Harrington Z.
        • McDonald A.
        • Knowles J.
        An in vitro study to investigate the load at fracture of Procera AllCeram crowns with various thickness of occlusal veneer porcelain.
        Int J Prosthodont. 2003; 16: 54-58
        • Pallis K.
        • Griggs J.A.
        • Woody R.D.
        • Guillen G.E.
        • Miller A.W.
        Fracture resistance of three all-ceramic restorative systems for posterior applications.
        J Prosthet Dent. 2004; 91: 561-569
        • Neiva G.
        • Yaman P.
        • Dennison J.B.
        • Razzoog M.E.
        • Lang B.R.
        Resistance to fracture of three all-ceramic systems.
        J Esthet Dent. 1998; 10: 60-66
        • DeLong R.
        • Sakaguchi R.L.
        • Douglas W.H.
        • Pintado M.R.
        The wear of dental amalgam in an artificial mouth: a clinical correlation.
        Dent Mater. 1985; 1: 238-242
        • Gibbs C.H.
        • Mahan P.E.
        • Mauderli A.
        • Lundeen H.C.
        • Walsh E.K.
        Limits of human bite strength.
        J Prosthet Dent. 1986; 56: 226-229