This Geneva pilot study used brush cytology and ICP-MS to look for titanium and zirconium in the oral mucosa of 41 people with titanium implants, zirconia implants, or no implants. Zirconium was detected at trace levels, near the detection limit, mainly around zirconia implants. All zirconium results that were detected sat below the limit of quantification.
Key numbers
- Limit of detection for zirconium (zirconium-90, helium mode) 0.07 µg/L in the prepared sample solution (Abstract; Table 1, p. 4719).
- Phase I, zirconia implant group: zirconium detected in 4 of 5 subjects at 0.07 (two subjects), 0.08 and 0.24 µg/L, semi-quantitative mode (Results, p. 4718; Table 1, p. 4719).
- Phase II: zirconium 0.07 and 0.15 ppb at two zirconia implant sites and 0.12 ppb at one contralateral tooth; all below the stated LOQ of 2 ppb (Results, p. 4719 to 4720; Table 2c).
- Phase III (10 control subjects without metallic devices): zirconium detected in two samples, both below the LOQ (Results, p. 4719).
- Zirconium recovery from spiked micro-brushes at 2 µg/L: 86% to 87%; precision RSD up to 11.3% (Methods, p. 4718).
Methods (brief)
Cytologic specimens were taken by rotating a micro-brush on peri-implant mucosa or gingiva after mouth rinsing, digested in dilute nitric and hydrofluoric acid at 80 °C, and analyzed by ICP-MS (Agilent 7700x) with helium collision mode and rhodium and rhenium internal standards. Three phases: method validation (n 13), implant versus no implant with controlled titanium dioxide intake (n 18), and a candy challenge in controls (n 10).
Evidence fitness
Supports the observation that zirconium can be detected at trace levels in oral mucosa samples near zirconia dental implants. Values are solution concentrations from brush samples, not tissue mass concentrations, and are near the detection limit. Does not support dietary exposure, systemic exposure or toxicity claims.
Limitations
Small pilot (41 participants in three phases). Results are reported as concentrations in the prepared solution, so they cannot be converted to tissue concentrations. The paper is internally inconsistent: the abstract and discussion state zirconium was found only around zirconia implants, yet Phase III reports two detections below the LOQ in subjects without metallic devices, and Table 2a lists zirconium readings in two no-implant subjects that the text describes as below the LOD. The LOQ for zirconium is given as 0.5 or 1 µg/L in the methods and as 2 ppb in the Phase II results. No external funding.
Related evidence
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