can you produce the risk of bias according to the Agency for Healthcare Research and Quality for the study "Impact of smoking on protein levels of beta-defensins in periodontal disease" while i provide you with the following data from the study :  1. Study design
"The study protocol was approved by the Ethics Committee on Human Research of the School of Dentistry at Araraquara - UNESP (protocol number 01394712.5.0000.5416). The purpose and content of the study were explained to eligible subjects, and written informed consent was obtained from all participants for inclusion in the study. A total of 70 participants were recruited from June 2016 to March 2018 at the Periodontology Clinic, School of Dentistry at Araraquara - UNESP. The diagnosis of periodontitis was performed according to the classification of the 2017 World Workshop on the Classification of Periodontal and Peri-implant Diseases and Conditions 12 . All patients should present a minimum of 15 natural teeth. Twenty patients were included in the periodontally healthy control group. All subjects were free of systemic and periodontal diseases. They should present probing depth (PD) ≤ 3 mm, no bleeding on probing (BOP), no clinical attachment loss, plaque index (PI) and gingival index (GI) ≤ 15%. Fifty patients with periodontitis stage III or IV were included in periodontitis groups. In addition to the diagnostic criteria 12 , they should present at least five sites in non-adjacent teeth with PD ≥ 4 mm, BOP, and clinical attachment level (CAL) ≥ 4 mm, except for third molars. From the 50 patients, 25 had never smoked and 25 were smokers who should smoke at least 10 cigarettes/day for a minimum of 5 years.
None of the patients had a history of systemic diseases or immunological disorders. Subjects who had received antibiotics and anti-inflammatory drugs within the last 3 months or received periodontal treatment within the last 6 months were not included in the study. Patients using hormone replacement therapy, pregnant and lactating women and orthodontic patients were also excluded.
The sample size was calculated using statistical software (GPower 3.1 Statistical Power Analysis for Windows, Düsseldorf, Germany). Considering mean values of hBD expression and standard deviation from previous studies 13 , 14 , 15 , an effect size of 0.3 was obtained. Based on this effect size, a significance level of 0.05 and a study power of 0.80, a sample size of 20 individuals per group were determined to be necessary.", 2.Clinical examination
"One calibrated examiner performed all clinical examinations. The intra-examiner reproducibility was assessed by measuring the PD in six teeth (16, 21, 24, 36, 41 and 44), according to the Ramfjord index, in a total of six patients (36 sites/patient) on two different occasions in a time interval of 7 days. Data were submitted to Kappa concordance analysis (k=0.91). The parameters PD, BOP and CAL were assessed at six sites per tooth (mesio-buccal, mid-buccal, disto-buccal, mesio-lingual, mid-lingual, disto-lingual), while PI and GI were registered as absence (negative site) or presence (positive site) of visible plaque and gingival bleeding at four sites per tooth (mesial, distal, buccal and lingual), excluding the third molars. Measurements were performed with a manual periodontal probe (UNC15; Hu-Friedy, Chicago, IL, USA)."