Objectives <p>To explore longitudinal changes and prognostic applications of salivary IL-1β and MMP-8 in determining gingivitis susceptibility.</p> Materials and methods <p>Twenty-seven systemically healthy adults with periodontal health or gingivitis were enrolled. Participants underwent a 3-week hygiene phase (V₁ to V₄) with professional cleaning, followed by a 3-week experimental gingivitis phase (V₄ to V₇), in a randomly selected maxillary quadrant. The resolution phase began at V₇, and participants received professional cleaning, resumed oral hygiene, and were reviewed 3 weeks later (V₈). At each visit, salivary IL-1β and MMP-8 levels were quantified, alongside clinical assessments of gingivitis index (GI), bleeding on probing (BOP), and plaque index (PI). Using clustering analysis, participants were classified as high and low gingivitis susceptibility according to the longitudinal profiles of BOP and mean GI.</p> Results <p>Ten and 17 participants had high and low gingivitis susceptibility, respectively. While there were no differences in the biomarker profiles during the experimental gingivitis phase, high susceptibility individuals were associated with a profile of elevated IL-1β and MMP-8 during the hygienic phase (<i>p</i> = 0.024) and increased salivary IL-1β at V₁ predicted rapid development of gingivitis (<i>p</i> = 0.026). Incidentally, males were more susceptible despite no differences in demographic or biomarker profiles.</p> Conclusion <p>Salivary biomarker profiles during the hygienic phase may offer insights into an individual’s susceptibility to gingivitis. Additional research will be needed to validate these findings for the general population, translating these biomarkers into prognostic tools that enable personalised periodontal care.</p> Clinical Relevance <p>Salivary biomarkers may provide additional prognostic insight into gingivitis susceptibility.</p>