This cross-sectional study was performed between 2017 and 2019 and was approved by the research ethical committee at King Abdulaziz University, faculty of dentistry. The study was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2013. The study population included adult not diagnosed with diabetes or prediabetes. who attended the undergraduate dental clinic, graduate periodontal clinic, and the periodontics specialty clinic at the school of dentistry King Abdulaziz University.Other exclusion criteria were: 1) use of hypoglycemic medications, 2) current long-term use of corticosteroids, 3) renal insufficiency, 4) pregnant women, 5) patients with HIV infection, and 6) antibiotic use within the last 6 months or need for prophylactic antibiotic before any dental procedures.
Study groups and sampling:
Following a comprehensive periodontal exam, eligible patients were divided based on their periodontal diagnosis into three categories: 1) no periodontitis, 2) periodontitis stage I & II, 3) periodontitis stage III & IV. An equal number of participants was randomly selected from each category.
Sample size calculation:
Sample size was calculated using G*Power version 188.8.131.52, to detect an effect size f = 0.36 with a degree of freedom df = 2, representing 0.2 differential in HbA1c between the three equally sized periodontitis groups (5.5%, 5.7% and 5.9%), by assuming an overall mean (SD) HbA1c = 5.7% (0.45) in a group of 38 among non-diabetic Saudi individuals. 20 The statistical power was set to 0.9 and type 1 error to 0.05, the total sample size was N = 102, i.e. 34 participants in each periodontitis group. The sample size was increased to 45 by group for higher statistical power.
Patients received full-mouth periodontal examination performed by two periodontists. The exam included measurements of the probing depth and the gingival margin position taken at six sites per tooth for all teeth in the mouth except third molars. Clinical attachment level was calculated by adding the probing depth reading to the gingival margin level when recession was present, and by subtracting the gingival margin level from the probing depth reading when the gingival margin was coronal to the CEJ. Alveolar bone loss was determined in the molar and premolar teeth on horizontal bitewings radiographs and in the anterior teeth on periapical radiographs. All radiographs were taken and assessed before the periodontal examination.
The stage of Periodontitis was established according to the 2018 EFP/AAP periodontitis classification for periodontal diseases and condition.21 Patients were recognized as having periodontitis when there were at least two non-adjacent interproximal sites with clinical attachment loss > 2mm. The site with greatest loss in clinical attachment was used to establish the periodontitis stage. When other complexity factors were present, the stage was shifted to a higher degree. The stage of periodontitis was categorized as follow:
- Stage 1: CAL is 1-2 mm, bone loss is less than 15%, and not tooth loss due to periodontitis.
- Stage 2: CAL is 3-4 mm, bone loss is less than 15-20%, and not tooth loss due to periodontitis.
- Stage 3: CAL is ≥ 5mm, bone loss is beyond the middle of the root, and no more than 4 teeth lost due to periodontitis.
- Stage 3: CAL is ≥ 5mm, bone loss is beyond the middle of the root, more than 4 teeth lost due to periodontitis, and grade 2/3 mobility.
Assessment of HbA1C:
The glycemic state of subjects was determined using the chair-side HbA1C and it was defined according the American Diabetes Association criteria.22 * The analyzer is certified according to the International Federation of Clinical Chemistry & Laboratory Medicine (IFCC) and the National Glycohemoglobin Standardization Program (NGSP). First, the test cartridge was placed in the analyzer, and a 4 mL finger-prick capillary blood sample was obtained. The blood sample was collected in the sampling area of the reagent pack, which was then inserted in the cartridge test in the analyzer. The percentage of HbA1c level for each patient was available in 5 minutes. Single-use check-up cartridges were used for quality control every month before samples were tested or on suspicion of an inaccurate result.
Despite that none of the patients has been previously diagnosed with diabetes, patients were recognized in the diabetes category if the HbA1c percentage was 6.5% or higher, in prediabetes category if the HbA1c was between 5.7% and 6.4%, and non-diabetes if the HbA1c was less than 5.7%.
The BMI was calculated using the height and weight measurements and patients were categorized as underweight for BMI <18.5 kg/m2; 2) healthy weight for BMI 18.5 to 24.9 kg/m2; 3) overweight for BMI 25 to 30 kg/m2; or 4) obese for BMI >30 kg/m2.
Other patient’s data:
All participants completed a questionnaire that comprised questions about: the patient’s age, sex, level of education, family history of diabetes, sign and symptoms of diabetes, history of gestational diabetes for women, smoking status, history of hypertension, and dyslipidemia.
The mean HbA1c and standard deviation (SD) were calculated by characteristics of the study population. Descriptive statistics were also calculated for the study participants by categories of diabetes diagnoses i.e. non-diabetes, pre-diabetes, and diabetes. Chi square tests were used to compare categorical variables, and t-test and ANOVA to compare continuous variables. Linear regression models were used to estimate the mean change in HbA1c comparing the periodontitis stages I/II group and the periodontitis stage III/IV group to the non-periodontitis group (reference). The model was adjusted for the confounding variables including age, sex, BMI, smoking, level of education and family history of diabetes. The power of the analysis, a=0.5, was calculated and it was 0.95. Analysis was done using SAS statistical software (version 9.4; SAS Institute, Cary, NC).