## 4 Discussion  
The diagnosis of PDs and PI is based primarily on clinical measurements such as probing depth, insertion loss, and bleeding on probing together with radiographic exami  
Figure 9: Fagan nomogram. The prevalence of peri-implantitis was 52% (prior probability), with an infinite positive likelihood ratio (LR+) and a negative likelihood ratio (LR\(-\)) of 0.91. The post-test probability of a negative test was 50%. nations. These procedures identify damage that has already occurred but do not provide any information about disease activity or future evolution [19]. Currently, more than 700 species of bacteria have been identified as potentially responsible for PDs and PI [15]. These bacteria form a complex network called biofilm that enhances their pathogenicity [10; 20]. The presence of these bacteria is relevant because they are the main etiological factor and serve as early indicators of the need to start treatment, thus avoiding unnecessary overtreatment [21; 22; 23]. However, a positive microbiological test result does not necessarily imply the presence of disease or the need to use an antibiotic [24]. Furthermore, with the growing tendency of resistant bacteria, the need for a diagnostic test is imperative to reduce the uncertainty of starting treatment [25]. The choice of implants with one to one and a half years of loading was made due to the aggressive and rapidly progressive nature of peri-implantitis. For this reason, its early diagnosis and early treatment could significantly change the long-term outcome, without taking into account the other variables that could have influenced the presence of early-onset and highly aggressive peri-implantitis. Time, technical difficulties, and cost must be considered for the routine application of tests. Despite the many potential markers and tests that exist, only a few have verified clinical usefulness [26]. Unfortunately, there is a long way to go regarding the development and validation of easy and reliable tests for the identification of microbial or host markers [4; 5; 7]. Diagnostic tests aim to provide quantitative information about the presence or absence of a particular condition or disease. To assess the diagnostic capability of a test, performance is quantified by providing calculating sensitivity, specificity, positive and negative predictive values, and likelihood ratios. These measures help determine how well a test can correctly identify true positive and true negative cases. Diagnostic tests are often evaluated by comparing their results with a reference standard, i.e., the gold standard for diagnosis. Currently, to assess the presence of PI, the gold standard is still clinical and radiographic findings. To our knowledge, only one previous study has evaluated the diagnostic value of PeriPoc ([PERSON] et al. [15]). The other relevant sources are technical notes and reports from the manufacturer. [PERSON] et al. [15] provided sensitivity (85.15%) and specificity (100%) values. Herein, those data were used to calculate the predictive values and likelihood ratios and, thus, construct a Fagan nomogram. The data provided by [PERSON] et al. [15] pertain to 497 patients, of whom 397 had PI and a true positive test result on 338 occasions and a false-negative test result on 59 occasions. There were a total of 100 healthy individuals, with 100 true-negative test results and 0 false-positive test results. In our study, the sample consisted of 21 patients, 10 of whom were healthy and 11 of whom had PI. Next, the data obtained herein are compared with the data reported by [PERSON] et al. [15]. The prevalence of the disease indicates the proportion of healthy and non-healthy sick individuals that make up the study sample. In the study by [PERSON] et al. [15], their sample was composed mainly of patients with PDs (79%), while in our study, the sample had an almost equal proportion of patients with PI (52%) and patients without PI. This proportion has little effect on sensitivity and specificity because both are intrinsic to the test.