Evaluation of Pro-inflammatory Mediators Around Astra Tech Dental Implant Abutments Following a Minimum of 6 Months of Clinical Function

The aim of this cross-sectional study is to utilize the paper strip-based peri-implant crevicular fluid (PICF) sampling technique to evaluate the influence that transmucosal abutment biomaterials of either titanium or zirconium oxide, which have been in situ for greater than six months, have in the expression of specific pro-inflammatory and bone-mediators.

Subjects who had previously undergone single-tooth implant replacement therapy are invited to participate and informed consent is obtained.

All participants receive a clinical and radiographic exam of the implant site that is sampled for PICF. Clinical and radiographic parameters such as implant mobility, presence or absence of supragingival plaque, and interproximal bone levels were assessed. Peri-apical radiographs, utilizing a paralleling technique, will be obtained from each implant fixture to evaluate the marginal bone level compared to baseline periapical radiographs made at the time of definitive prosthesis delivery. Each participant's implant site is isolated with cotton rolls, light air is applied over the site to eliminate the potential for ambient salivary contamination of the PICF sample. The implant site is sampled for 30 seconds at four distinct sites (mesio-buccal, disto-buccal, mesio-lingual, disto-lingual) by one clinician under loupe magnification. The fluid volumes collected on each strip will be quantified using the Periotron 8000 Instrument.

Cytokine, chemokine, and bone mediator quantities (pg/30 s) were determined using a commercial 22-multiplexed fluorescent bead-based immunoassay. Two specific multiplex kits are utilized (Milliplex MAP Human cytokine/Chemokine Immunoassay & Milliplex MAP Human Bone Panel 1B Immunoassay).

Biostatisticians are masked to the implant abutment biomaterial designations (masked as "A" and "B") during data analysis. Initial bivariate analysis using the Wilcoxon-Mann-Whitney (Wilcoxon Rank Sum) test will be employed to assess the difference in distribution between the two groups (titanium dioxide or zirconium oxide) for each cytokine/bone mediator and for age. The same approach is used to consider whether a gender difference was associated with a particular cytokine/bone mediator. Gender distribution in the two groups will be compared using the Fisher exact test. The Spearman rank correlation will be used to assess the possibility of a relationship with age for each cytokine. Rank-based regression models will be used to adjust for possible effects of age and gender for both cytokine and bone mediator levels.