A Comparison of Zirconia and Titanium Abutments for Microleakage.
BACKGROUND
Microleakage through the interface has been documented in implant systems with titanium (Ti) abutments. There is a current increase in the use of zirconia (Zi) abutments especially in esthetic zone in where higher risk of visible metal color through the peri-implant tissues exists.


OBJECTIVE
The aim of the present in vitro study is to evaluate the leakage at the implant fixture-abutment interface with two different screw-retained abutment systems at different torque values in a nonloading condition.


METHODS
In vitro study design included four groups (Ti and Zi torqued at 25 and 15 Ncm [N = 8/group]). Microcomputed tomography (micro-CT) was chosen to detect microgap. Microleakage from the implant chamber to the external milieu was evaluated using limulus amebocyte lysate (LAL) test, while microleakage from external milieu to the implant chamber was evaluated using toluidine blue dye (TBD) and colorimeter.


RESULTS
Micro-CT images did not reveal any microgap. LAL test showed that there is a time-, abutment-, and torque-dependent increase in microleakage (p = .001) with Zi torqued at 15 Ncm having higher leakage with time compared with Ti torqued at 15 Ncm (p = .002), as well as Zi torqued at 15 Ncm having higher leakage with time compared with Zi torqued at 25 Ncm (p = .01). TBD test showed a nonsignificant increase in microleakage with higher leakage related to titanium abutment groups (p > .05). Repeated torque/antitorque handling differentially affected microleakage (p = .01).


CONCLUSIONS
Within the limits of this study, there is a statistically significant difference in bidirectional microleakage with time, abutment type, and torque values being major players for leakage from internal implant chamber to external milieu, while the abutment type and time but not the torque value being important factors for leakage from external milieu into implant chamber in nonloading condition. Future studies are needed to determine peri-implant health around Zi abutments.
Division of Prosthodontics, The Ohio State University, currently private office, Columbus, OH, USA.
Mohamed I
MI
Abdelhamed
Division of Biosciences, The Ohio State University, Columbus, OH, USA.
Jeffrey D
JD
Galley
Division of Biosciences, The Ohio State University, Columbus, OH, USA.
Michael T
MT
Bailey
Division of Prosthodontics, The Ohio State University, Columbus, OH, USA.
William M
WM
Johnston
Division of Prosthodontics, The Ohio State University, Columbus, OH, USA.|Department of Prosthodontics, University of Iowa, Iowa City, Iowa, USA.
Julie
J
Holloway
Division of Prosthodontics, The Ohio State University, Columbus, OH, USA.
Edwin
E
McGlumphy
Division of Periodontology, The Ohio State University, Columbus, Ohio, USA.
Binnaz
B
Leblebicioglu
D000044:Dental Abutments / Q000009:adverse effects*; D059605:Dental Implant-Abutment Design / Q000009:adverse effects / Q000379:methods; D003763:Dental Leakage / Q000209:etiology*; D006801:Humans; D066298:In Vitro Techniques; D014025:Titanium / Q000009:adverse effects / Q000627:therapeutic use*; D055114:X-Ray Microtomography; D015040:Zirconium / Q000009:adverse effects / Q000627:therapeutic use*
D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide
abutments; implant; microleakage; titanium; zirconia