title: Mechanical testing of thin-walled zirconia abutments.
abstract: Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bi-component aesthetic abutments has been suggested.
  
  
  OBJECTIVE
  Mechanical testing of customized thin-walled titanium-zirconia abutments at the connection with the implant was performed in order to characterize the fatigue behavior and the failure modes for straight and angled abutments.
  
  
  METHODS
  Twenty custom-made bi-component abutments were tested according to ISO 14801:2007 either at a straight or a 25° angle inclination (n=10 each group). Fatigue was conducted at 15 Hz for 5 million cycles in dry conditions at 20°C±5°C. Mean values and standard deviations were calculated for each group. All comparisons were performed by t-tests assuming unequal variances. The level of statistical significance was set at p≤0.05. Failed samples were inspected in a polarized-light and then in a scanning electron microscope.
  
  
  RESULTS
  Straight and angled abutments mean maximum load was 296.7 N and 1,145 N, the dynamic loading mean Fmax was 237.4 N and 240.7 N, respectively. No significant differences resulted between the straight and angled bi-component abutments in both static (p=0.253) and dynamic testing (p=0.135). A significant difference in the bending moment required for fracture was detected between the groups (p=0.01). Fractures in the angled group occurred mainly at the point of load application, whereas in the straight abutments, fractures were located coronally and close to the thinly designed areas at the cervical region.
  
  
  CONCLUSIONS
  Angled or straight thin-walled zirconia abutments presented similar Fmax under fatigue testing despite the different bending moments required for fracture. The main implication is that although zirconia angled or straight abutments presented similar mechanical behavior, the failure mode tended to be more catastrophic in straight (fracture at the cervical region) compared to angled abutments.
authors.affiliation: Department of Biomaterials and Biomimetics, New York University College of Dentistry, NY, USA.
authors.forename: Luigi
authors.initials: L
authors.lastname: Canullo
authors.forename: Paulo G
authors.initials: PG
authors.lastname: Coelho
authors.forename: Estevam A
authors.initials: EA
authors.lastname: Bonfante
mesh_terms: D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide
references.citation: Swed Dent J. 1978;2(5):167-75
references.pmid: 281771
references.citation: Eur J Oral Sci. 2011 Aug;119(4):323-30
references.pmid: 21726295
references.citation: Clin Oral Implants Res. 2011 Aug;22(8):808-14
references.pmid: 21320166
references.citation: Clin Oral Implants Res. 2009 Aug;20(8):802-8
references.pmid: 19486077
references.citation: J Appl Oral Sci. 2011 Aug;19(4):413-20
references.pmid: 21710094
references.citation: Clin Oral Implants Res. 2009 Sep;20 Suppl 4:4-31
references.pmid: 19663946
references.citation: J Prosthodont. 2010 Jun;19(4):263-73
references.pmid: 20136704
references.citation: Int J Prosthodont. 1999 Nov-Dec;12(6):483-91
references.pmid: 10815600
references.citation: J Craniomandib Disord. 1987 Fall;1(3):162-9
references.pmid: 3325528
references.citation: Acta Odontol Scand. 1977;35(6):297-303
references.pmid: 271452
references.citation: Dent Mater. 2009 Nov;25(11):1426-32
references.pmid: 19643468
references.citation: Int J Oral Maxillofac Implants. 2009 Sep-Oct;24(5):850-8
references.pmid: 19865625
references.citation: Int J Prosthodont. 2007 Sep-Oct;20(5):489-93
references.pmid: 17944337
references.citation: Dent Mater. 2009 Nov;25(11):1419-25
references.pmid: 19646746
references.citation: Int J Prosthodont. 2007 Sep-Oct;20(5):486-8
references.pmid: 17944336
references.citation: J Prosthet Dent. 1996 Sep;76(3):288-91
references.pmid: 8887802
references.citation: Clin Oral Implants Res. 1999 Dec;10(6):453-8
references.pmid: 10740454
references.citation: Eur J Esthet Dent. 2007 Autumn;2(3):296-310
references.pmid: 19655552
references.citation: Int J Oral Maxillofac Implants. 1999 Mar-Apr;14(2):181-8
references.pmid: 10212534
references.citation: J Dent Res. 2009 Apr;88(4):382-6
references.pmid: 19407162
references.citation: J Prosthodont Res. 2012 Jan;56(1):19-24
references.pmid: 21398198