Identification of Monoclinic Zirconia Phase In Dental Implants by Raman-Microspectroscopy

Methods: The cervical collar and the threaded root part of WhiteSky and Zit-Z zirconia dental implants (n=3) were analyzed as received by Raman microspectoscopy. Three regions were randomly located on the collar and the root of each implant with the optical system of the microscope (10X optical objective) and analyzed under the following conditions: Ar laser (532 nm), 10 mW power at sample, 50X LWD objective, 1800 grit/mm grating, 1000 μm confocal hole, 100 μm slit, 10 s acquisition. The tetragonal (262 cm-1 Raman shift) and monoclinic (180 and 190 cm-1 Raman shift) ZrO2 phases were identified from the presence of the corresponding peaks. In addition, the area distribution of the phases was investigated employing

a 20x35 μm sampling area scanned at 5 μm steps and 5 s acquisition time.

Results: The Raman spectra taken from the collar and the root parts of both implants showed the presence of the monoclinic ZrO2 phase, although the tetragonal ZrO2 phase was the predominating one. The root parts exhibited more intense peaks of monoclinic ZrO2. Raman mapping showed that the distribution of the monoclinic phase followed the pattern of deep machining grooves. A more uniform distribution was found on the alumina- sandblasted root parts, especially in Zit-Z.

Conclusion: The weak monoclinic ZrO2 phase was identified in both implants in the as received state at cervical and root locations. The extent to which this weak phase may affect the long-term implant performance is unknown.