Diederik Hentenaar

120 Chapter 5 Table 5. Average differences in BoP, SoP, and PPD between control and test group at 3-month follow-up Outcome variable Crude model* β (95% CI) p -value Adjusted model** β (95% CI) p -value % Sites BoP % Sites SoP Mean PPD 16.2 (-7.9 to 40.3) 0.0 (-10.9 to 10.9) 0.6 (-0.6 to 1.8) 0.743 1.000 0.205 7.9 (-16.4 to 32.3) 0.7 (-10.1 to 11.4) 0.2 (-1.0 to 1.3) 0.821 0.882 0.470 The reference category for intervention effect is the control group. The regression coefficients (β) indicate the average differences in clinical outcomes between control and test group at three month follow-up. BoP, bleeding on probing; SoP, suppuration on probing; PPD, probing pocket depth; 95% CI, 95% confidence interval. *Adjusted for baseline values. **Adjusted for baseline values, smoking and mean bone loss at baseline DISCUSSION This randomized controlled trial aimed to determine the effect of 35% phosphoric etching gel on decontamination of the implant surface during resective surgical treatment of peri-implantitis. Both decontamination procedures (mechanical debridement with curettes and gauzes combined with phosphoric acid 35% and mechanical debridement combined with sterile saline) resulted in a significant immediate reduction in counts of anaerobic bacteria on the implant surface. This immediate reduction was greater when phosphoric acid was used. Although the difference in log-transformed mean anaerobic counts between both decontaminating procedures did not reach the level of statistical significance ( p = 0.108), there were significantly less culture-positive implants after the decontamination procedure in the phosphoric acid group ( p = 0.042). As our study focused on the decontaminating effect of phosphoric acid on implant surfaces we used the microbiological parameter as primary outcome variable. To evaluate the effect of the intervention on this microbiological parameter an in-vivo situation was chosen to benefit the influence of a clinical situation. In addition we evaluated secondary outcome parameters indicating the clinical effect of the treatment procedure, i.e. disease resolution 3 months after active treatment. At 3 months post-surgery disease resolution was more frequently observed in the control group (75% of implants) than in the test group (63.3% of implants)). However no significant differences in clinical and microbiological outcomes between control and test group were found. Although the study was ‘a priori’ not powered to detect clinical differences, no trend was observed for superior results of one decontamination procedure over the other. To our knowledge, this is the first randomized controlled clinical trial reporting on the effect of phosphoric acid in relation to peri-implantitis treatment. The reason for