Activin-A and Interleukin-1β Levels in Periodontitis

Activin-A belongs to the transforming growth factor-beta superfamily and is a multifunctional cytokine that plays a role in inflammation, immune response, tissue repair and regeneration. Proinflammatory cytokine interleukin-1beta (IL-1β) can increase Activin-A expression in various cell types. This study aims to evaluate gingival crevicular fluid (GCF) and salivary Activin-A and IL-β levels in stage III periodontitis. Seventy-five systemically healthy and non-smoker volunteers consisting of 23 stage III periodontitis, 26 gingivitis and 26 periodontally healthy were enrolled. Full-mouth clinical periodontal indices were recorded, unstimulated whole saliva and GCF samples were obtained, Activin-A and IL-1β total amounts were determined by enzyme-linked immunosorbent assay. Statistical comparisons were performed using non-parametric tests.

Participants were divided into three groups according to the diagnostic criteria proposed by the Classification of Periodontal and Peri-implant Diseases and Conditions; I. Periodontitis group (n=23), II. Gingivitis group (n=26) III. Periodontally healthy group (n=26)

Clinical periodontal indices included probing depth (PD), clinical attachment loss (CAL), the dichotomous scoring of bleeding on probing (BOP +/-), gingival index (GI), and plaque index (PI). Clinical recordings were performed at six points (mesiobuccal, buccal, distobuccal, mesiopalatal/mesiolingual, palatal/lingual, and distopalatal/distolingual) of all teeth, except the 3rd molars, by a single investigator using a conventional periodontal probe.

Interproximal radiographic bone loss on the digital panoramic radiographs were evaluated, as the ratio of the distance between the bone crest and the cemento-enamel junction to the length of the root.

GCF and unstimulated whole saliva samples were obtained 1 day following the clinical periodontal measurements. Immediately after saliva collection, GCF was collected from the buccal aspects of non-contiguous interproximal sites in two single-rooted teeth via steril paper strips. Fluid samples were obtained from two deepest pockets in periodontitis group and the most inflamed sites with clinical signs of redness or edema in gingivitis group. In the periodontally healthy groups, samples were taken from the sites without visible inflammation. All samples were stored at -80 °C until further analysis.

Measurement of Activin-A and IL-1β levels in GCF and saliva samples were performed by the commercially available enzyme-linked immunosorbent assay (ELISA) kits. While GCF cytokine levels were expressed as both total amounts at two samples per 30 s and concentrations, salivary cytokine levels were presented as concentrations.

A statistical software package was used for all data analyses. If the clinical and biochemical data did not present normal distribution as checked by Shapiro Wilk's normality test, the analyses were performed by using nonparametric methods. The Kruskal-Wallis test with Dunn-Bonferroni post hoc method was applied to compare the study groups regarding clinical indices and oral biofluid levels of Activin-A and IL-1β. The presence and degree of linear association of cytokine levels in GCF and saliva with clinical indices were analyzed by Spearman rank correlation coefficient. p\<0.05 was considered as a threshold for statistical significance.

Eligibility Criteria:
Inclusion Criteria:

* the presence of no history of smoking (determined by self-reporting)
* at least 18 natural teeth excluding 3rd molars.

Exclusion Criteria:

* the presence of systemic conditions (diabetes mellitus, rheumatoid arthritis, cardiovascular system diseases, endocrine, immunologic, and mucocutaneous disorders) - use of antibiotics, antihypertensives immunosuppressive and anti-inflammatory drugs within the past 6 months and topical antiseptic solutions in the last 3 months
* having periodontal treatment in the previous year
* wearing removable partial dentures or orthodontic appliances
* restorative and endodontic therapy requirements
* pregnant or nursing women.