Diederik Hentenaar

36 Chapter 2 of 0.05. Data analysis was performed using IBM SPSS Statistics (Version 23.0 for Windows, Armonk, NY: IBM Corp) and GraphPad software (GraphPad Prism version 7.02 for Windows). The outcomes were tested for normality using the Shapiro-Wilk test. A Chi-square and Fishers exact test were used to analyse the categorical baseline characteristics between the healthy control subjects and peri-implantitis patients. A Mann-Whitney U test was used to evaluate group differences between healthy and diseased implants. A Wilcoxon signed-rank test was applied to analyse within group differences (untreated versus treated peri-implantitis implants). A p value of <0.05 was considered to be statistically significant for all the parameters. RESULTS In this study, a total of 60 samples (healthy implants at baseline (n=20), peri-implantitis implants at baseline (n=20) and 3 months after treatment (n=20)) was collected for further evaluation. The mean age in the peri-implantitis group [10 males, 9 females] and control group [12 males, 5 females] was 56.5 (±11.5) and 63.9 (±17.6) years, respectively (Table 2). No significant differences in the patient and implant characteristics were found between healthy and diseased implants at baseline. However, a greater variety of implant brands was seen in the peri-implantitis group (see Table 2). Table 2. Characteristics of the healthy implants in the control group and the peri-implantitis implants in the test group. Healthy Peri-implantitis Total implants / total patients 20/17 20/19 Mean age (± SD) 63.9 (± 17.6) 56.5 (± 11.5) Sex [M/F] (n) 12/5 10/9 Smokers 3 (17%) 5 (26%) Implants brand, implant surface; n implants • Nobel ◦ Porous anoidized surface, TiUnite® 10 (50%) 6 (30%) • Straumann ◦ Sandblasted large grit acid-etched, SLAactive® 10 (50%) 8 (40%) • Other 0 6 (30%) Luminex™ concentration biomarker levels (in pg/ml per 30 seconds and pg per 30-seconds ) as well as modified concentration levels [in pg/μl ] are presented using the equation described by Wassall & Preshaw (2016) [(Luminex™ x 0.2)/ PICF volume)] to show that correction of biomarker concentration levels for low crevicular fluid volumes creates artificial elevated biomarker levels and therefore a potential source of error for analysis (see tables 3a and 3b). Especially in healthy implants correction shows unreliable