Objectives: Periodontitis is a multifactorial biofilm-induced inflammatory disease; however, clinical and radiographic information reflects events that have already occurred. aMMP-8 lateral-flow chairside or point-of-care-test (POC-test) results have also come to complement the overall status of the patient's current situation. The current study aimed to clarify the usefulness of aMMP-8 chairside-test (aMMP-8 POCT) results to alert the initial or early periodontitis in adolescents, a potential periodontitis risk group with cut off 20 ng/ml in Stage I periodontitis, according to the current periodontitis classification system. Material and Methods: A total of 117 adolescents were aMMP-8 POC tested for aMMP-8 levels and examined for the full mouth and were interviewed for questions concerning health behavior. Results: Of all 117 participants, N = 38 (32.5%) was aMMP-8 POCT positive, and N = 34 (29.1%) had at least one 4 mm periodontal deepened pocket; however, only N = 16 (13.7%) had both characteristics. The subclinical stage (N = 47) could not be classified either as gingivitis or Stage I. Of the participants, who did not have any deepened periodontal pockets, 18 tested negative. Conclusions: Stage I is preceded by antecedent stages that should be tackled by oral healthcare prevention and personalized treatment modalities by professionals. Elevated (>20 ng/ml), positive aMMP-8 POCT results can be regarded as initial alarmer such as emerging risk. This should be utilized in the preventive personalized interventions by oral health professionals.