Recent studies that zoom in on titanium surface physico-chemistry reveal interesting results [38, 39]. Kotsakis et al. [38] hypothesized that chemical residues alter the titanium surface physicochemistry and subsequently compromise cellular response to these decontaminated surfaces. However, they report on effective restoring of biocompatibility when sterile saline, citric acid, and EDTA/sodium hypochlorite (NaOCl-EDTA) were used, in contrast to chlorhexidine. Therefore, they propose the use of sterile saline, citric acid, and NaOCl-EDTA in the treatment of peri-implantitis not only for their antimicrobial properties but also for the preservation of the titanium material properties. In contrast, a study by [39] found noticeable morphological changes and corrosion on the titanium surface when the synergistic effect of acidic environments (i.e., citric acid, 15% hydrogen peroxide, tetracycline, peroxyacetic acid) and mechanical forces (rubbing with cotton swabs) was investigated. Dissolution of the oxide layer (which can result in corrosion) was observed when using peroxyacetic and citric acid. It is therefore hypothesized that surface damage of dental alloys may potentially be induced after detoxification and maintenance treatments with acidic solutions and subsequently might hinder re-osseointegration. No visibly evident damage of the surfaces was shown by [39] when neutral or basic treatments such as sodium fluoride 0.12, 0.20, and 1.10% were used, which might be explained by the neutral electrochemical environment [40].

Interpreting the results of these in vitro studies has to be done cautiously since the results among the studies are not homogenous and the effects of the chemical environment coupled with mechanical force in the oral environment has to be further evaluated. In our study, however, phosphoric acid neither seemed to have a positive nor a negative effect on clinical outcomes.

The current study is based on a follow-up time of 3 months and therefore the long-term results on the use of phosphoric acid remain unclear.