2.1 | Patients with CHD
Out of a population of 308 patients 102 patients with CHD for whom an CABG surgery was indicated were included at the department of cardiothoracic surgery of the Heart Centre of the University Clinics Halle (Saale) in the study between January and October 2017. Follow-up data were generated from 101 patients between January 2018 to June 2019 (drop out rate 0.98%) (Fig. 1). An experienced cardiac surgeon diagnosed patients with CHD and checked the inclusion and exclusion criteria. The following inclusion criteria had to be met: age > 18 years, at least 60 % stenosis of one of the main coronary arteries demonstrated by angiography, presence of at least four teeth. Exclusion criteria were inability to give written informed consent, subgingival scaling and root planing and/or antibiotic therapy during the last 6 months prior to the examination, pregnancy, and the need of antibiotic prophylaxis against endocarditis according to the criteria of the German Society for Cardiology . Moreover, patients with diseases or disorders such as current drug or alcohol abuse that preclude participation in this clinical study according to investigator judgment were excluded. In order to be able to assess the severity of the CHD the number of coronaries affected was determined (one-, two- or threevessel disease). In addition, Canadian Cardiovascular Society (CCS) stages for angina pectoris were determined. Baseline variables such as age, smoking status (never, past, current smokers and pack years) and current or past diseases (e.g., diabetes mellitus, hypertension, peripheral arterial disease, and dyslipoproteinemia) were assessed as part of the patient’s medical history. A person who smoked a minimum of one cigarette per day at the time of questioning was considered to be a current smoker. A past smoker did not smoke for at least one year at the time of the survey. The number of pack years was calculated by multiplying the number of packs of cigarettes smoked per day by the number of years of smoking. Furthermore, all patients underwent detailed clinical and biochemical investigation. For instance, intake of drugs such as lipid lowering drugs, oral anticoagulants, and antiarrhythmics have been registered. Serum parameters including INR (International Normalized Ratio) score, hemoglobin (Hb) [mmol/l], hematocrit [1/l], creatinine [µmol/l], urea [mmol/l], glycated hemoglobin (HbA1c) [mmol/mol], ], C-reactive protein (CRP) [mg/dl], leukocytes [Gpt/l], and platelets [Gpt/l] were recorded.
The dental anamnesis and examination was done one day before the CABG surgery. The patients were asked about the frequency of brushing teeth per day and whether they practiced interdental hygiene using dental floss or interdental brushes. Furthermore, the question was asked whether periodontal therapy in form of scaling and root planing had ever been carried out. In order to be able to estimate an increased occurrence of severe periodontitis within a family, the patients were asked whether there was premature tooth loss due to tooth loosening within relatives of the first degree.
Before the dental examination, the study participants were asked to rinse with an antibacterial mouthwash solution (Chlorhexamed® FORTE alcohol-free 0.2 %, GlaxoSmithKline Consumer Healthcare GmbH & Co. KG, Munich, Germany) in order to reduce the risk of bacteremia due to the probing of dental pockets. The clinical dental assessment involved determining the plaque index (PI) and bleeding on probing (BOP) . In plaque index four tooth surfaces were evaluated mesio-buccal, mid-buccal, disto-bucca, lingual). In bleeding index six sites around each tooth (mesio-buccal, mid-buccal, disto-buccal, disto-oral, mid-oral, mesio-oral) were examined. BOP was only evaluated after a waiting time of 30 seconds after probing.
The measurements for both maximal clinical probing depth (PD= distance between gingival margin and the apical stop of the probe) and maximum clinical attachment loss (CAL= distance between the cemento-enamel junction and the apical stop of the probe) were taken also at six sites around each tooth. The maximum values for each tooth were taken to calculate the overall mean per participant. In order to obtain reproducible results for BOP, PD, and CAL, the two examiners (L.F. and J.G.) were particularly trained in using a pressure-sensitive dental probe UNC 15 (0.2N) (Aesculap, Tuttlingen, Germany) and calibrated. Particular attention was paid that the examiner oriented the probe in the direction of the tooth axis. The reading was made exactly to the millimeter. If one measuring point (gingival margin or cemento-enamel junction) was between two markers of the measuring scale, the measurement was estimated to 0.5 mm. For the calibration, both examiners determined PD and CAL twice on five periodontal phantom models (phantom model A-PB, frasaco GmbH, Tettnang, Germany) and on five patients. To assess the reproducibility of the double measurements the Bland-Altman method was used . The difference (d) of the two measurements was calculated and plotted against the mean of the two measurements. The measurements are sufficiently reproducible if 95 % of the differences (d) are in the range d ± 2 x s, where s denotes the standard deviation of the differences. Regarding our two rater the differences from two measurements for PD and CAL were to 100 % in this range d ± 2 x s. Thus the examiner L.F. and J.G. were able to generate reproducible measurement results.
The clinical periodontitis case definition was held according to the guidelines of the working group of the Centers for Disease Control and Prevention (CDC) and according the consensus report of the 2017 world workshop on the classification of periodontal and peri-implant diseases and conditions . According CDC a severe periodontitis case was diagnosed if at least ≥ 2 interproximal sites with CAL ≥ 6 mm (not on same tooth) and ≥ 1 interproximal site with PD ≥ 5 mm were present. A moderate periodontitis case was diagnosed if at least ≥ 2 interproximal sites with CAL ≥ 4 mm (not on same tooth) or ≥ 2 interproximal sites with PD ≥ 5 mm (not on one tooth) were present. If no severe or moderate periodontitis was present, periodontitis was diagnosed as mild or absent. When using the new classification, the disease stages I to IV were defined by severity (according to the level of interdental clinical attachment loss, and tooth loss), complexity and extent and distribution. However, since no X-ray images were available, the radiological bone loss could not be taken into account. For this reason too, periodontitis was not classified according to the progression rates A to C.
For a more accurate quantification of the root surface affected by attachment loss and quantification of the inflamed epithelial surface, both the periodontal epithelial surface area (PESA) and the periodontal inflamed surface area (PISA) were calculated . For that purpose, a freely downloadable (www.parsprototo.info<http://www.parsprototo.info) Excel spreadsheet was used. In order to calculate PESA, data of CAL and recession have to be entered. For the calculation of PISA, sites with BOP have to be recorded additionally.