## 4 Discussion
Regarding differences found after probiotic and chlorhexidine application, dissimilarities and a significantly gradual reduction in probing pocket depth (PPD) was assessed for both products as well as: plaque index (PI); gingival bleeding index (GBI); bleeding score (BS); and marginal mucosal conditions (MMC). There were no significant intergroup changes; however, regarding PPD and GBI, comparing the changes for the two groups from T0 to T3, there was a higher reduction in values using Biorepair Parodontgel Intensive compared to Curasept Periodontal Gel. On the basis of these results, both gels appear to be valuable tools for the management of peri-implant mucositis. However, until now, the effectiveness of these new products in dentistry has been under-researched. In dentistry, a very common antiseptic agent is chlorhexidine thanks to its wide-spectrum antibacterial properties. It reduces dental plaque, gum inflammation and bleeding [47]. However, several side effects are linked to its prolonged and excessive use, including tooth discoloration, dysgneusia, oral burning, bacterial resistance, and mucosal inflammation [48]. Consequently, the introduction of new bioactive biomolecules, such as 'biotics', is recommended. However, no extensive literature is present. Currently, there are few studies related to postbiotics in the periodontal setting [49; 50; 51; 52]; conversely, their use in implantology has not been investigated to date. The outcomes of this study illustrate that postbiotics are as effective as chlorhexidine. To the best of our knowledge, no clinical studies have been performed previously. It was not possible comparing these results with other studies because, to date, they have not been performed. The products used in the present study were effective to reduce the clinical indexes of peri-implant mucositis because chlorhexidine has a high antiseptic power, while the postbiotics have both antiseptic and antioxidant and immunomododulating properties, leading to an antiphlogistic effect on peri-implant tissues. Thus, it is possible to suggest that postbiotics may lead a positive effect for a longer time than chlorhexidine. In addition, it must be considered that chlorhexidine should be used for a maximum of 15 days, thus avoiding the previously described side effects, unlike postbiotics. Several critical points emerged during the preparation, conduct and processing of the data for this study. It would have been interesting to make analyses using variables such as the type of prosthesis supported by implants, average age and sex, all factors that the small number of patients included did not allow for. Another limitation was the absence of a radiographic control that led to a partial evaluation of the importance that could be given to the PPD index; the literature of the last years in fact clearly expresses the variability of the probing depth among the various implant sites, influenced by the positioning of the implant, the type of connection, the shape of the prosthesis and the width of the mucous tunnel decided during surgery. Not only single crown implants were considered, but also bridge abutment or circular implants: obviously in the latter type of patient, plaque control is more difficult and consequently, also the maintenance of low inflammatory indices. Furthermore, during home applications of chlorhexidine and probiotic products, contamination of sites by the control product with the test product and vice versa cannot be ruled out, although the emergence of intergroup differences might suggest that this contamination is not so significant, but further in-depth studies would be needed to verify this consideration. The findings that the tested postbiotic gel could be effective in improving inflammatory indices should be further investigated. Based on these observations and because of the lack of comparable studies, it is not possible to draw definitive conclusions about their use in implantology.