## 1 Introduction  
Peri-implant diseases (PIDs) pose a clear threat to the maintenance of dental implants. For this reason, early detection is of great importance.  
In general, PIDs include peri-implant mucositis and peri-implantitis (PI). In Spain, the frequency of PIDs is approximately 50%, with the percentage of PI being 20% at the implant level and 24% at the patient level [1].  
According to the 2018 World Workshop, the characteristic clinical signs that allow the diagnosis of peri-implantitis are a greater probing depth, bleeding on probing, suppuration, and radiographic evidence of bone loss after initial healing or a combination of these [2]. They are all late signs.  
Given the irreversible destruction of tissue caused by PI, the development of new diagnostic tests that identify patients at risk of early PI is necessary.  
A simple way to assess peri-implant health status could be by monitoring peri-implant cricular fluid (PICF). Through PICF, the presence of subgingival pathogens, markers of tissue destruction or host responses through cytokines could be identified [3; 4; 5; 6; 7].  
Because PI is considered a dysbiosis (similar to periodontitis), the bacterial component is considered the main triggering factor [8; 9].  
Some of these bacteria correspond to the Socransky red and orange complexes [10]. When healthy implants (HIs) were compared with diseased implants with PI, at least 19 bacteria were identified, including _Porphyromonas gingivalis_ and _Tannerella forysthia_. _Aggregatibacter actinomycetemcomitants_, _Eikenella cordens_, _Fusobacterium nucleatum_, _Prevotella intermedia_, _Porphyromonas gingivalis_, and _Tannerella forysthia_[2]. Other lesser-known species have also been identified, such as _Desulfoublus spp._, _Fififactor alcis_, and _TM7 spp_[11; 12]. On the other hand, we know that the presence of these bacteria alone need not indicate disease and that their presence in healthy conditions has been documented by [PERSON] and other relevant sources [10]. Furthermore, some PIs appear to be more resistant to treatment. This could be due both to local or systemic factors and to differences in the composition of the subgingival biofilm [13; 14]. Therefore, having a clinical test to individualize treatment (a chairside test), especially for those patients who are refractory to treatment, is of great clinical interest [15].  
Metagenomics analyses have enabled a better understanding of the species involved. Its application as a point-of-care (POC) remains slow and is often expensive, making its clinical application difficult. Therefore, the development of a simple \"chairside test\" for use as a \"POC\" is of great interest as a screening measure.  
Periopoc(r) is a new test based on the identification of the five bacteria most frequently associated with PIDs and periodontitis (PO). Its application requires a total of 20 min, and the results are qualitative, i.e., the presence or absence of target bacteria. In addition, controls are included to determine if the samples were processed properly in terms of sample amount and the incorporation of reagents.  
The objective of this study was to validate this new diagnostic test, which claims to identify the five bacteria most frequently associated with the presence of PID and PO, against the clinical gold standard.