2.2. Outcome Measures

Three sets of outcomes were obtained: 1. salivary flow rate (UWSFR, SWSFR), salivary pH, 2. oral and periodontal status, 3. interincisal distance, OHRQoL. UWSFR and SWSFR were collected in graduated tubes with a 1.5 cm diameter opening using the spit method. Sialometry was performed according to the guidelines of Navazesh [12]. Whole saliva was collected during the follicular phase of the cycle in fertile women. The pH of saliva was determined using indicator paper left in the oral cavity for one minute. We compared the color of the indicator paper with the color of the attached scale (Merck KGaA, Darmstadt, Germany). The pH reference value of saliva is 6.0 to 6.5. Saliva can be acidic or alkaline depending on whether the pH of saliva is below or above the reference value. Dental status was assessed using the DMFT index, excluding third molars [13]. If carious teeth were suspected, radiographic examination was performed in addition to the clinical examination. The initial periodontal examination was performed according to a standardized protocol using a dental mirror and a CPI (Community Periodontal Index) probe in daylight [14]. The applied probe force was equivalent to the weight of 25 g (0.025 kg × 9.81 m/s²). Data were recorded in the form recommended by the World Health Organization [15]. The CPI index values were as follows: 0—healthy periodontium, 1—gingival bleeding after probing, 2—calculus and bleeding, 3—shallow periodontal pockets (4–5 mm), and 4—deep periodontal pockets (6 mm and more). Periodontal pocket depth (PPD) was measured twice on all teeth. If the values obtained differed by >2 mm, the measurement was performed a third time, and the two closest values were retained. The PPD values at each site (mesio-buccal, mid-buccal, disto-buccal, mesio-lingual, mid-lingual, disto-lingual) were averaged. Clinical attachment level (CAL) was measured once for each tooth. The presence of periodontitis in a given tooth was defined as either PPD > 3 mm or CAL ≥ 5.5 mm [16,17]. The interincisal distance was measured at the beginning of the periodontal examination. This is important to avoid bias due to prolonged opening of the mouth. Patients were asked to open their mouths as wide as possible. The interincisal distance was measured as the distance from the incisal edge of the lower central incisor to the incisal edge of the upper central incisor [18]. Interincisal distance was measured in edentulous subjects with dentures in the mouth. The Croatian version of the Oral Health Impact Profile-49 (OHIP-49) was used to assess OHRQoL, without modifications relative to the published version [19].