Can you  interpret together the  data and the results of the study "Comparison of gingival crevicular fluid and serum human beta-defensin-2 levels between periodontal health and disease" and especially concerning HBD-2?  These are the results :1. Participant selection and clinical evaluations
“In this cross-sectional study, 42 CP patients and 59 controls were recruited from either patients attending to the Department of Periodontology, Faculty of Dentistry, or from the personal patient populations of the academic faculty and postgraduate students at the Ondokuz Mayis University between June 2014 and May 2015. Ethics committee approval was received from Ondokuz Mayıs University clinical research ethics committee with decision number 2014/556-630(2013/416-447).
Individuals included in the study were informed about the purpose and content of the study and signed an informed consent form indicating they voluntarily participated in the study.”,
2. Inclusion criteria
“Individuals included were over 18 years old and willing to provide in- formed consent. In addition, they did not have any systemic diseases including cardiovascular diseases, diabetes, chronic renal failure, and hepatitis B and C, and were not using any chronic anti-inflammatory drugs. Moreover, participants who are pregnant or lactating at the time of the study or receive any periodontal treatment within the preceding six months were excluded from the study. All subjects were evaluated clinically and radiographically at the first clinical visit; periapical and panoramic radiographs were obtained from all patients to verify the clinical periodontal diagnosis and the extent of alveolar bone loss. All clinical parameters were evaluated by a single investigator (S.K). The examiner was calibrated against an expert periodontist. Calibration was validated if 90% of the recordings could be reproduced within a 1.0-mm difference (Badersten, Nilvéaus, & Egelberg, 1984). The following clinical parameters were assessed at six sites per tooth: probing pocket depth (PD); clinical attachment loss (CAL); bleeding on probing (BOP) (Ainamo & Bay, 1975); plaque index (PI) (Silness & Löe, 1964); gingi- val index (GI) (Löe & Silness, 1963); and the number of missing teeth, mobility, and furcation involvement. PD was defined as the distance between the coronal-most margin of the free gingiva to the most apical penetration of the Michigan-0 probe. CAL was defined as the distance from the cemento-enamel junction to the most apical penetration of the Michigan-O probe. The presence of supragingival plaque was recorded dichotomously during PD measurements. Bleeding on probing (BOP) within 20s was recorded dichotomously.Clinical and radiographic criteria proposed by the 1999 International World Workshop were used for diagnosis.”,
3. Control group
“Patients had no history of periodontitis, and no furcation involvement and mobility. Their PD was smaller than 3 mm.”,
4. CP group inclusion criteria
“Radiographic evidence of alveolar bone loss and at least ≥4 mm PDD in two interdental areas, not on the same tooth (Eke, Page, Wei, Thornton-Evans, & Genco, 2012).”,
5. Collection and storage of samples
“GCF samples were obtained for analyses (mainly from the maxillary premolar area for standardization). The supragingival plaque was removed without touching the gingival margin. The area was care- fully washed with water to prevent salivary contamination, the tooth was isolated with cotton rolls, and the area was dried with air for 10 s. For sampling, paper strips (Periopaper, ProFlow, Amityville, NY,USA) were carefully placed in the gingival sulcus and held there for 30 s. If the paper strips were contaminated with blood or saliva, they were discarded and replaced. The volume of each paper strip was determined with Periotron 8,000 (ProFlow, Amityville, NY, USA). The samples were placed with 50 microliters of phosphate-buffered saline (pH 7.0) in an Eppendorf tube. Two milliliters of peripheral venous blood samples were taken from each subject, using a standard venipuncture method. The sam- ples were then transferred to tubes containing 8% liquid EDTA. GCF samples were centrifuged at 1,000 × g for 10 min; blood samples were centrifuged at 3,000 × g for 10 min by a centrifuge device (Shimadzu UV160A, SNo: 28006648, Japan). The supernatants obtained from GCF and serum samples were separated for the study. The samples were mixed thoroughly with a vortex and stored at −80oC until the working day. On the working day, the samples were brought to room temperature.” .1.Determination of hBD-2 concentrations
“Serum and GCF hBD-2 concentrations were studied by the commercially available Human BioD2 ELISA Kit (Sun-Red Bio Company, Cat No. 201-12-1937, Shanghai, China), in the Ondokuz Mayıs University, Faculty of Medicine, by the Medical Biochemistry Research Laboratory. The “double-antibody sandwich” enzyme-linked immunosorbent assay (ELISA) procedure was used for this analysis. All working solutions were freshly prepared and stored at room temperature (25°C) until use.
Five standards were prepared with the serial dilution method using human hBD-2 standard (S1–6.4 ng/ml, S2–3.2 ng/ml, S3–1.6 ng/ml, S4–0.8 ng/ml, and S5–0.4 ng/ml). The wells were identified on the ELISA plate for blank, standards, and samples. Nothing was added to the blank well except Chromogen A, Chromogen B, and a stop solution. The same procedure used with the sample was applied to the standards. Fifty μL of standard (S1–S5) was pipetted into each well, and 40 μl + 10 μl of hBD-2 antibody was pipetted from each sample. Then, 50 μl Streptavidin–Horseradish peroxidase was added to the standards and samples and incubated at 370C for 60 min. After incubation, the plate was washed 5 times with 350 μl washing solution with the help of an automatic washer. 50 μl Chromogen A and 50 μl Chromogen B were added to all wells and incubated at 37°C for 10 min. Then, the reaction was stopped by pipetting 50 μl of stop solution. At the end of the study, absorbance at 450 nm wavelength was read by a microplate reader. Sample hBD-2 concentrations were calculated according to the standard curve generated using standard values, and the concentrations obtained were expressed in ng/ml. Kit sensitivity 0.05 ng/ml and assay range 0.1 ng/ml-10 ng/ml were given. High concentration samples were confirmed by working twice.”,
2. Statistical analysis
"Data analysis was performed using R program version 3.5.1. (R Core Team, 2019). Data are expressed as means and standard deviations (SD) or medians and interquartile ranges (IR) as appropriate. Data were analyzed for normal distribution by the Shapiro–Wilk test. A chi-square test was used for comparison of categorical variables. An independent- sample t test was used to detect the statistical significance between the two groups, based on the clinical variables obtained, such as age, probing depth, clinical attachment loss, and others. Univariable and multivariable logistic regressions were used to assess the association between the outcome (periodontal disease) with serum and GCF hBD-2 levels and other covariates. Correlation between each clinical parameter and serum and GCF hBD-2 levels was analyzed using the Spearman correlation coefficient. A p-value of <.05 was considered statistically significant. The estimated power of the test was 0.80.
3. Clinical findings
“A total of 101 participants, 59 controls and 42 patients with CP, were assessed. Of the volunteers included in the study, only 8 in the control group and only 5 in the CP group were smokers. Thirty- seven (37) females and 22 males (mean age 27.69 ± 7.78) were included in the control group, and 28 females and 14 males (mean age 42.67 ± 10.62) were included in the CP group. There was no statisti- cal difference between the groups in terms of smoking and gender distribution (p > .05). The distribution of demographic data is shown in Table 1.
Age was found to be significantly higher in the CP group (p < .001). The mean age of all participants was 33.93 (±11.68) years; the mean age of the control group was 27.69 (±7.78), and the mean age of the CP group was 42.67 (±10.62) (Table 1).”,
4. Clinical variables
“All recorded clinical parameters (BOP, CAL, PI, GI, and PD) were significantly higher in the CP group than in the control group (p < .001) (Table 2). CP was reclassified according to the modification of the new international classification of periodontitis (Tonetti, Greenwell, & Kornman, 2018). Accordingly, cases were classified as Stage II (n = 3; 7%); Stage III (n = 34; 81%); Stage IV (n = 5; 12%); and Grade B (n = 25; 60%) to C (n = 17; 40%) periodontitis. Of these, 67% of CP patients were generalized CP, and 33% were localized CP.The mean hBD-2 levels of GCF samples in the CP group were 2.77 (±0.74) ng/30 s and 2.51 (±0.54) ng/30 s in the control group. The GCF levels of the mean hBD-2 were significantly higher in the CP group compared with those in healthy controls (p = .047; Figure 1). Adjusting for potential confounders such as smoking, age, and gender did not alter this association (p = .036). Conversely, the mean hBD-2 levels of serum samples in the CP group were lower (2.92 ± 3.07 ng/ ml) compared with those of the control group (7.75 ± 6.37 ng/ml; p < .001; Figure 2). Similarly, adjusting for smoking status, age, and gender did not alter this association (p < .001). Additionally, we tested the difference of hBD-2 level between generalized and localized CP. The difference between the groups both in serum (p = .25) and in GCF hBD-2 levels (p = .51) was not statistically significant.”,
5. Correlations
“The correlation between serum and GCF hBD-2 expression and clinical periodontal measures was analyzed. No correlation was observed between serum and GCF hBD-2 levels (r = .004, n = 99, p = .97). In both GCF and serum samples, no correlations were ob- served between hBD-2 and the clinical parameters of periodontal disease such as PD, GI, PI, CAL, and number of teeth present. On the other hand, both localized GCF and serum hBD-2 were correlated with BOP within the periodontitis group. However, after adjustment by the Bonferroni method for multiple comparisons, a statistically significant correlation remained only between GCF hBD-2 and BOP (r = .54, p = .0002; Table 3).” .