Issue 18

F. Felli et alii, Frattura ed Integrità Strutturale, 18 (2011) 14-22; DOI: 10.3221/IGF-ESIS.18.02 22 - the fracture surface morphology of the specimens broken in our test is very similar to the fracture surface of the implants broken in service. It means that the tensile stress occurring in service life is the main reason of the fatigue failure of these implants. The crack initiate near the holes and then propagates through the section of the implant. So the holes on the side surface while promoting osseointegration, are adverse for mechanical strength. The analysis performed on the second implant (the screw type) leads to the following results: - the fatigue tests displayed a fatigue limit of about 600-700 N. This range is high enough to consider valid this kind of implant; the limit is roughly comparable with the actual average stress on most stressed tooth but the implant, in the tests, was not inserted in a dental arch and then it has to bear the whole load applied. - The finite element analysis shows that the most stressed areas are the ones on which the crack actually initiates and propagates. The stress values from the FE analysis are in a good agreement with the static values measured for this implant. R EFERENCES [1] P. I. Branemark, B. O. Hansson, R. Adell, U. Breine, J. Lindstrom, O. Hallen, A. Ohman, Scand. J. Plast. Reconstr. Surg., 3(2) (1969) 8. [2] L. Carlsson, T. Rostlund, B. Albrektsson, T. Albrektsson, P. I. Branemark, Acta Orthop. Scand., 57 (1986) 2885. [3] H. A. Luckey, F. Kubli, ASTM Special Techn. Publs., 796 (1983). [4] D. F. Williams, Titanium and titanium alloys. Fundamental aspects of biocompatibility. Boca Raton FL: CRC Press (1981). [5] B. Rangert, T. Jemt, L. Jorneus, Int. J. Oral Maxillofac. Implants, 4 (1989) 241. [6] A. Wennenberg, T. Alberktsson, B. Andersson, J. J.Krol, Clin. Oral Implants Res., 6 (1995) 24. [7] Y.S. Al Jabbari, R. Fournelle, G. Ziebert, J. Toth, A. M. Iacopino, Journal of Prosthodontics, 17 (3) (2008) 168. [8] W. Slot, G. M. Raghoebar, A. Vissink, J. J. Huddleston Slater, H. J. A. Meijer, Journal of Clinical Periodontology, 37 (1) (2010) 98. [9] A. Behneke, N. Behneke, B. D'hoedt, W. Wagner, Int. J. Oral Maxillofac. Implants, 12 (1997) 749. [10] B. Friberg, H. Nilson, M. Olsson, C. Palmquist, Clin. Oral Implants Res., 8 (1997) 279. [11] R. Leimola-Virtanen, J. Peltola, E. Oksala, H. Helenius, R.P. Happonen, Int. J. Oral Maxillofac. Implants, 10 (1995) 373. [12] D. Buser, R. Merickse-Stern, J.P. Bernard, A. Behneke, N. Behneke, H.P. Hirt, U.C. Belser, N.P. Lang, Clin. Oral Implants, 8 (1997) 161. [13] C. J. Goodacre, J. Y. Kan, K. Runcgharassaeng, J. Prosthet. Dent., 81 (1999) 537. [14] F. M. Saliba, M. Cardoso, M. F. Torres, A. C. Teixeira, E. J. V. Lourenço, D. T. De Moraes, Journal of Applied Oral Science, 19 (1) (2011) 63. [15] D. H. Kohn, J. Oral Implantol., 11 (1992) 391. [16] R. Bedini, G. De Angelis, G. Di Cintio, R. Ielapi, M. Tallarico, U. Romeo, Evaluation of surface treatment on mechanical fatigue performance of titanium plasma-sprayed and sandblasted large-grid and acid-etched titanium dental implants. Rapporti ITISAN (2001). [17] R. Bedini, G. De Angelis, A. Fasano, R. Ielapi, M. Tallarico, L. Pacifici, Mechanical fatigue performance of an experimental dental implant. Rapporti ITISAN (2001). [18] P. I. Branemark, G. A. Zarb, T. Alberktsoon, Tissue-integrated prostheses, osseointegration in clinical dentistry. Chicago Quintessence Publshing Co. Inc. (1985). [19] L. Carlsson, T. Haraldson, In: T. Tissue-integrated prostheses, Eds: P. I. Branemark, G. A. Zarb GA, T. Alberktsoon, Chicago Quintessence Publshing Co. Inc., (1986) 153. [20] M.Weinlander, Dent. Clin. North. Amer., 35 (1991) 585. [21] A. Schroeder, O. Pohler, F. Sutter, SSO Schweiz Monatsschr Zahnheilkd, 86(7) (1976) 713. [22] D. Buser, R. K. Schenk, S. Steinemann, J. P. Fiorellini, C. H. Fox, H. Stich, J. Biomedic Mater. Res., 25 (1991) 889. [23] K. A. Thomas, S. Cook, J. Biomed. Mater. Res., 19 (1985) 875. [24] ISO SC 8 WG 3 Working Draft - CEN/TC 55 Dentistry. Dental Implants - Dynamic continuous fatigue test. Geneva: International Organization for Standardization (1994).