Periodontitis in young individuals - follow up of treatment and disease progression

Background and aims: Periodontitis in young individuals, though rare, is often characterized by early onset, rapid progression, and aggressive clinical presentation. Despite the substantial disease burden, long-term data on treatment outcomes, risk factors for disease progression, and tooth loss in this population are limited. This thesis aims to evaluate treatment compliance, long- term disease progression, predictors of tooth loss, and the diagnostic potential of salivary and crevicular cytokines in young patients with periodontitis, followed over at least 10 years. The findings are based on a series of four studies that provide complementary perspectives on both clinical and molecular determinants of periodontal outcomes. Material and methods: Study I is a retrospective case-control study of 234 patients with aggressive periodontitis (AgP) compared to controls with chronic periodontitis (ChP), investigating treatment interruption rates and associated factors. Study II is a retrospective cohort study involving 215 individuals diagnosed with periodontitis before age 36 and re-examined after at least 10 years. Clinical, radiographic, and questionnaire-based data were collected to assess longitudinal marginal bone loss (MBL) and its relationship to behavioural and clinical parameters. In Study III we used national dental and demographic registers to evaluate tooth loss in a cohort of 471 young periodontitis patients and applied analysis to identify risk factors including socioeconomic status and treatment adherence. Study IV explored cytokine profiles in gingival crevicular fluid (GCF) and stimulated saliva in the same cohort as in study II, analysing 18 inflammatory cytokines and their correlation with periodontal grade according to the 2018 periodontal classification. Results: In Study I we found that patients with AgP were significantly more likely to discontinue periodontal treatment than controls (46% vs. 34%, p<0.01). Smoking and more severe baseline periodontal conditions were strong predictors of non-compliance. In Study II, the majority of patients initially diagnosed with stage III (83%) and grade C periodontitis (79%) showed clinical stability over time, with only 17 % classified as grade C at follow-up. However, smoking, high levels of bleeding on probing (BOP), and discontinuation of periodontal treatment were significantly associated with increased longitudinal MBL, while baseline stage and grade had limited prognostic value. Study III revealed that while 63% of individuals experienced no tooth loss, a small high-risk group (3.6%) lost >10 teeth. Generalized periodontitis, stage IV periodontitis, low education, smoking, and interruption of active periodontal treatment (APT) were significantly correlated with tooth loss. Furthermore, periodontal stage IV, low income and education were associated with treatment dropout. In Study IV, salivary levels of IL-1B, IL-6, and IL-18 were significantly elevated in patients with grade C periodontitis, while GCF samples from the same group showed significantly elevated IL-1ß but decreased levels of IL-4, IL-10, IL-15, IP-10, and MIG. Among the cytokines analysed, IL-18 in saliva and IL-4, IL-15, and MIG in GCF demonstrated the highest diagnostic potential in differentiating grade C from grade A, with area under the curve (AUC) values ranging from 0.84 to 0.86. Conclusions: This thesis provides evidence that while long-term periodontal stability is achievable in many young patients, specific risk factors, including poor treatment adherence, smoking, and lower socioeconomic status, are strongly associated with progression and tooth loss. A severe periodontal disease (stage (IV) may also be a predictive variable in this age group for tooth loss and interruption of periodontal treatment. In addition, cytokine profiling shows promising potential for early identification of individuals at risk of high disease progression. These findings support the need for individualized, prevention- oriented care strategies that integrate clinical, behavioural, and molecular assessments to optimize periodontal outcomes in young populations. List of scientific papers I. Treatment compliance in patients with aggressive periodontitis - a retrospective case-control study. Modin C, Abadji D, Adler L, Jansson L. Acta Odontologica Scandinavia 2017, 75:2, 94-99. https://doi.org/10.1080/00016357.2016.1259497 II. Periodontitis in young individuals: Important factors for disease progression. Modin C, Dolk-Rinon C, Faham A, Gustafsson A, Yucel- Lindberg T, Jansson L. Journal of clinical Periodontology 2024 Jan;51(1):74-85. https://doi.org/10.1111/jcpe.13884 III. Factors influencing tooth loss over 9 - 11 years in young individuals with periodontitis. Modin C, Cederlund A, Gustafsson A, Yucel- Lindberg T, Jansson L. Journal of Periodontology 2025, Aug 2. https://doi.org/10.1002/JPER.24-0687 IV. Cytokine profile in saliva and gingival crevicular fluid in relation to periodontal grade. Modin C, Dolk-Rinon C, Faham A, Eskander F, Jansson L, Gustafsson A, Yucel-Lindberg T. [Manuscript]