Salivary flow rate, pH, and concentrations of calcium, phosphate, and sIgA in Brazilian pregnant and non-pregnant women

Head & Face Medicine Salivary flow rate, pH, and concentrations of calcium, phosphate, and sIgA in Brazilian pregnant and non-pregnant women Maria I Rockenbach 2 Sandra A Marinho 1 Elaine B Veeck 2 Laura Lindemann 0 Rosemary S Shinkai 3 0 Private practice , Porto Alegre , Brazil 1 Graduate Program in Oral Medicine, Pontifical Catholic University of Rio Grande do Sul , Porto Alegre , Brazil 2 Department of Oral Surgery, Pontifical Catholic University of Rio Grande do Sul , Porto Alegre , Brazil 3 Department of Prosthodontics, Pontifical Catholic University of Rio Grande do Sul , Porto Alegre , Brazil Background: Studies on salivary variables and pregnancy in Latin America are scarce. This study aimed to compare salivary flow rate, pH, and concentrations of calcium, phosphate, and sIgA of unstimulated whole saliva in pregnant and non-pregnant Brazilians. Methods: Cross-sectional study. Sample was composed by 22 pregnant and 22 non-pregnant women attending the Obstetrics and Gynecology Clinics, So Lucas Hospital, in Porto Alegre city, South region of Brazil. Unstimulated whole saliva was collected to determine salivary flow rate, pH, and biochemical composition. Data were analyzed by Student t test and ANCOVA (two-tailed = 0.05). Results: No difference was found for salivary flow rates and concentrations of total calcium and phosphate between pregnant and non-pregnant women (p > 0.05). Pregnant women had lower pH (6.7) than non-pregnant women (7.5) (p < 0.001), but higher sIgA level (118.9 mg/L) than the latter (90.1 mg/L) (p = 0.026). Conclusion: Some of the tested variables of unstimulated whole saliva were different between pregnant and non-pregnant Brazilians in this sample. Overall, the values of the tested salivary parameters were within the range of international references of normality. - Background Hormonal changes in females may affect the physiology of the entire body including the oral cavity. Besides the direct effect on the metabolism of periodontal tissues, pregnancy, menstruation, and hormone replacement therapy may induce short-term changes in salivary flow rates, buffering capacity, and biochemical composition [1-5]. Changes in salivary composition and flow rates may compromise the integrity of the soft and hard tissues in the oral cavity, because saliva functions include food and bacteria clearance, mastication and digestion, lubrication, antimicrobial defense, and buffering effect [6,7]. Saliva is composed of water and organic and inorganic molecules, but a large intra- and inter-subject variability in composition is reported [2,6]. Most studies focusing on the influence of pregnancy and hormonal alterations on salivary characteristics were performed in European countries, and some reference standards for normality [6,8] are derived from data obtained in specific populations. The Latin American literature on this topic is scarce. A preliminary search of the electronic database Latin American and Caribbean Literature on the Health Sciences (LILACS) using the terms "saliva" and "pregnancy" resulted in eleven articles published in the last 20 years, and only one evaluated salivary flow rates and/or pH in pregnant women [9]. A similar search of PubMed MEDLINE yielded another study in Latin American women [10]. Therefore, it is difficult to compare results from populations with potential differences of genetics and dietary habits. This cross-sectional study aimed to compare the salivary flow rates, pH, and concentrations of calcium, phosphate, and secretory immunoglobulin A (sIgA) of the unstimulated whole saliva in pregnant and non-pregnant women, residents in the metropolitan area of Porto Alegre city, in the South region of Brazil. The a priori hypothesis was that there are differences of salivary flow rate, pH, and biochemical composition of saliva between pregnant and non-pregnant women. Methods A convenience sample was composed of 44 women aged between 18 and 38 years-old, selected among the patients attending the Obstetrics and Gynecology Clinics, So Lucas Hospital, in Porto Alegre city, South region of Brazil. All of the subjects were healthy, functioning individuals attending the clinics for regular exam, with no complaint of xerostomia. Twenty-two consecutive pregnant women (mean age: 27.9 years-old), between the fifth and ninth month of pregnancy, comprised the pregnant group. Exclusion criteria were high-risk pregnancy and unwillingness to participate in the study. The comparison group was composed of 22 non-pregnant women (mean age: 29.5 years-old), who attended the same clinics for routine exam. The research protocol was in compliance with the Helsinki Declaration and was approved by the institutional review board of the Pontifical Catholic University of Rio Grande do Sul. All subjects signed an informed consent form before the study procedures. A structured questionnaire was used to collect data on oral hygiene habits (frequency of tooth brushing, use of dental floss), professional counseling on oral health and hygiene, and presence of gingival bleeding. Data on medical conditions and use of medications were retrieved from the subject's medical charts. Sialometrical analysis The collection of unstimulated whole saliva was performed under resting conditions between 07:30 and 10:30 am, at least 1 h after eating, following standard procedures [11]. Subjects were asked to sit passively and expectorate into pre-weighed plastic containers for 5 min as the saliva accumulated in the floor of the mouth. Salivary samples were collected on ice, and the volume was determined gravimetrically: The weight of each saliva sample (g) was equated to volume (mL), since the specific gravity of saliva is 1.0 [12,13]. Salivary flow rates were expressed as mL/min. Sialochemical analysis Saliva samples were centrifuged (centrifugal force: 1,000 g) to remove bacteria and other extraneous material. The resulting clarified fluid was used for the biochemical assays to measure salivary pH and the concentrations of the following parameters: total calcium, inorganic phosphate, and sIgA. Salivary pH was determined by means of micro-electrodes of a blood gas analyzer that measured the hydrogen ion concentration. Salivary pH values were reported as the log of the mean hydrogen ion activity. Total calcium was determined using the CPC photometric method based on the work of Gitelman [14]. Calcium ions form a violet complex with o-cresolphthalein complexone in an alkaline medium. The reaction is measured colorimetrically with CPC at 545 nm. The intensity of the colour is directly proportional to calcium concentration in the sample. Inorganic phosphate was determined using the phosphomolybdate/UV method of Daly and Ertingshausen [15], which relies on the formation of a UV absorbing complex between phosphorus and molybdate. Inorganic phosphorus reacts with ammonium molybdate in the presence of sulfuric acid to form an unreduced phosphomolybdate complex which is mea (...truncated)