An observational study was performed in 45 hyperlipidemic(22 females, 23 males) and 45 age and sex matched normolipidemic (25 females, 20 males) healthy controls. The participants were recruited as a joint collaboration between Periodontology Department of the Faculty of Dentistry and the Endocrinology and Metabolic Diseases Department of the Faculty of Medicine at Ondokuz Mayis University in Samsun, Turkey between january 2013 and august 2014.The study protocol was approved by the Local Ethics Committee, and written informed consent was obtained from all study participants in accordance with the Helsinki Declaration (revised in 2000) It has been asserted that elevated serum lipid levels create a pro-inflammatory state, which leads to an increase in oxidative state by composing an imbalanced production between highly reactive molecular species and antioxidant defences, consequently predisposing one to infections. Hyperlipidemia claimed to lead an increase in production of reactive oxygen species (ROS) and lipid peroxidation (LPO). On the other hand it has been suggested that high-cholesterol diet increases OS and causes oxidative damage in various organs. Also, OS related mediators have frequently shown to be associated with chronic periodontitis (CP) related inflammatory responses . Excessive ROS derived radical formations reported to have an important role in the inflammatory process by leading to damage to proteins, DNA, carbohydrates, and lipids.
Hyperlipidemia was defined as the presence of one or more altered values of the lipid profile and the following cut-off values were used according to the laboratory's recommendation: TC>200mg/dl; TG>200mg/dl; LDL cholesterol >130 mg/dl; HDL <35mg/dl).
Periodontal status was determined by evaluating the following clinical parameters: Silness & Löe plaque index ; Löe & Silness gingival index ; Probing pocket dept,clinical attachment level, bleeding on probing (BOP) measurements were performed on 6 sites per tooth (mesio-buccal, mid-buccal, disto-buccal, mesio-lingual, mid-lingual, disto-lingual) using a Williams periodontal probe. GCF collection was subsequently performed using those sites that fit the criteria for GCF sampling described below.
All samples were collected between 8-10 am on the day following periodontal status assessment. Samples were collected from the deepest 6 sites in the chronic periodontitis group. In the gingivitis group samples were collected from the teeth with bleeding on probing, whereas teeth without BOP were chosen in the healthy group. GCF samples were collected from the similar 6 sites in the gingivitis and periodontally healthy groups in order to maintain consistency of sampling. Accordingly, total of 90 GCF samples were taken from each of the 6 groups (15 individuals per group x 6 sites).