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 Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 27  |  Issue : 3  |  Page : 372-376

Determination of salivary flow rate, pH, and dental caries during pregnancy: A study


1 Department of Oral Medicine and Radiology, Modern Dental College and Research Centre, Indore, Madhya Pradesh, India
2 Department of Oral Medicine and Radiology, Dr. DY Patil Dental College and Hospital, Navi Mumbai, Maharashtra, India

Date of Submission10-Mar-2015
Date of Acceptance05-Nov-2015
Date of Web Publication25-Nov-2015

Correspondence Address:
Amruta A Karnik
302/C, Rajendra Vihar, Evershine Nagar, Malad - (West), Mumbai - 400 064, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-1363.170454

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   Abstract 

Introduction: Saliva is an important diagnostic biofluid and the salivary composition is affected by various systemic conditions including pregnancy. Aims: The study was conducted to evaluate the salivary flow rate and pH in pregnant and non-pregnant Indian women and, consequently, to compare and correlate the salivary flow rate, pH, and prevalence of dental caries in both groups. Settings and Design: A cross-sectional study was conducted in our institute on a sample of 30 pregnant and 30 non-pregnant women. Materials and Methods: The clinical findings for Decayed-Missing-Filled Teeth (DMFT) index were recorded. Unstimulated whole saliva was collected to determine the salivary flow rate and pH. Statistical Analysis Used: Data were statistically analyzed using Student's t-test. Results: Salivary flow rate was lower in pregnant women (0.63 ml/min) as compared to that in non-pregnant women (0.81 ml/min) (P < 0.05) and the pH was also lesser in pregnant women (6.56) than in non-pregnant women (6.86) (P < 0.05). DMFT index showed a strong negative correlation with pH in pregnant women and non-pregnant women (P < 0.05). Conclusion: A difference was observed between the salivary parameters of pregnant and non-pregnant women in this sample. However, all the values were within the normal range. A significant inverse relation was found between salivary pH and dental caries for both the groups.

Keywords: DMFT index, pH of saliva, pregnancy, salivary flow rate, unstimulated whole saliva


How to cite this article:
Karnik AA, Pagare SS, Krishnamurthy V, Vahanwala SP, Waghmare M. Determination of salivary flow rate, pH, and dental caries during pregnancy: A study. J Indian Acad Oral Med Radiol 2015;27:372-6

How to cite this URL:
Karnik AA, Pagare SS, Krishnamurthy V, Vahanwala SP, Waghmare M. Determination of salivary flow rate, pH, and dental caries during pregnancy: A study. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2019 Nov 20];27:372-6. Available from: http://www.jiaomr.in/text.asp?2015/27/3/372/170454


   Introduction Top


Saliva is essential for the maintenance of oral health and it is an important diagnostic biofluid. [1] It plays a pivotal role in protection and lubrication of oral mucosal tissues, remineralization of teeth, and alimentation. [2],[3] The salivary composition gives it many important physical and biochemical properties. [4] It is useful for diagnosis, prognosis, and management of patients with oral and systemic diseases. [1] There is increasing inclination toward using saliva samples for the diagnosis of oral and systemic diseases. [1] Salivary research has gained importance in the fields of dentistry and oral biology. [5]

Oral health is affected by many systemic conditions. It is influenced by female steroid sex hormones through different mechanisms. The composition of human saliva is altered during pregnancy, menstruation, and menopause due to changes in steroid hormone levels. Many human studies indicate that during ovulation time, hormonal change influences the composition of human saliva. [6] During pregnancy, there are profound physiologic changes due to complex hormonal interactions. [7] Pregnancy brings changes in the salivary flow rate, pH of saliva, and biochemical composition. [8] Salivary composition is of great importance for preventing caries incidence. [9] The present study aims to evaluate the effect of pregnancy on salivary flow rate and pH of saliva and to compare and correlate the salivary flow rate, pH of saliva, and prevalence of dental caries in pregnant and non-pregnant Indian women. The a priori hypothesis was there are differences in the salivary flow rate and pH of saliva between pregnant and non-pregnant women.


   Materials and Methods Top


A cross-sectional study was conducted in the Department of Oral Medicine and Radiology of Dr. DY Patil Dental College and Hospital, Navi Mumbai, Maharashtra, India. A total convenience sample of 60 women aged between 18 and 37 years was selected. Subjects willing to participate and aged 18 years and above were included in the study. Subjects with any systemic diseases, complaint of xerostomia, and smoking habit were excluded from the study. Thirty consecutive healthy pregnant women between the third and the ninth months of gestation comprised the pregnant group and 30 non-pregnant women consecutively sampled in the same department composed the comparison group. None of the healthy, non-pregnant women were taking oral contraceptive pills.

The study protocol was in compliance with the Helsinki Declaration and an approval was obtained from the institution's ethical committee. A written informed consent was obtained from all participants prior to the study procedure. A questionnaire was structured to acquire data on oral hygiene habits (tooth brushing frequency and method, use of interproximal brushes, dental floss, tongue cleaning habit). Information regarding pregnancy trimester and use of medication was procured from the subject's medical charts. The intraoral examination was conducted by a single examiner under favorable lighting conditions using a sterile mouth mirror, diagnostic probe, and explorer. The clinical findings were recorded in the study proforma. The Decayed-Missing-Filled Teeth (DMFT) index, an irreversible index, was obtained to determine the prevalence of dental caries.

The saliva sample collection procedure was standardized prior to the study. The collection of unstimulated whole saliva was performed under resting conditions between 9.00 am and 11.00 am. The participants refrained from eating and drinking for a minimum of 1 h prior to saliva collection. The subjects were advised to rinse their mouth several times with deionized (distilled) water and then relax for 5 min before the procedure. The subjects were asked to sit comfortably with head tilted slightly forward and expectorate the saliva accumulated in the floor of the mouth into disposable plastic containers for duration of 5 min. Each saliva sample was collected on ice. The salivary samples were quantified volumetrically using graduated measuring cylinder. The salivary flow rate was expressed as ml/min. The saliva samples were centrifuged (centrifugal force: 1000 rpm) for the removal of bacteria and extraneous material. The resulting supernatant fluid was used to measure salivary pH using a bench type pH meter.

Statistical analysis was done using SPSS software version 15.0 using Student's t-test. All the dependent variables in the study were measured using ratio-scale parametric statistical tests and were appropriate for comparison with respect to the independent variable, i.e. the pregnant and non-pregnant groups. Comparison of all the variables between the pregnant and non-pregnant groups was performed using Student's t-test for independent samples. The correlations between DMFT index and saliva parameters were measured using Pearson's correlation coefficients. P value <0.05 was considered statistically significant.


   Results Top


Data of all 60 subjects were available and statistically analyzed. The mean age of women belonging to the pregnant group was 24.57 years and that of the non-pregnant group was 22.27 years. In the pregnant group, 11 (36.6%) subjects belonged to the age group of 18-22 years, 12 (40%) subjects to 23-27 years, 6 (20%) subjects to 28-32 years, and 1 (3.33%) to 33-37 years. In the non-pregnant group, 20 (66.67%) belonged to the age group of 18-22 years followed by 6 (20%) subjects to 23-27 years, 4 (13.33%) subjects to 28-32 years, and no subject belonged to the age range of 33-37 years. Among the pregnant women, 1 (4%) was in the first trimester, 7 (23%) were in the second trimester, and 22 (73%) were in the third trimester [Graph 1].



The pregnant women had lower salivary flow rate (0.63 ± 0.24 ml/min) as compared to the non-pregnant women (0.81 ± 0.15 ml/min) (P = 0.001). On comparison, the pH of saliva was also lesser in pregnant women (6.56 ± 0.35) than in non-pregnant women (6.86 ± 0.42) (P = 0.004). There was a statistically significant difference in the salivary flow rate and pH between pregnant and non-pregnant women [Table 1] and [Table 2]. The DMFT index was higher in non-pregnant group (8.23) than in the pregnant group (7.97) [Table 1]. However, this was statistically insignificant (P > 0.05) [Table 2].
Table 1: Minimum, maximum, mean, standard deviation, and 95% confi dence interval for salivary flow rate, pH, and DMFT index for the pregnant and non-pregnant groups

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Table 2: Comparison of variables for pregnant and non-pregnant groups

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DMFT index showed a strong correlation with pH in pregnant women (P = 0.002) and non-pregnant women (P = 0.01). The regression coefficients were negative for both the groups, suggesting a significant inverse relationship in the pH of saliva and caries prevalence. No correlation was found in DMFT index and salivary flow rate for both the groups [Table 3]. Data regarding the oral hygiene habits were recorded, which showed that 21 pregnant patients (70%) and 19 non-pregnant patients (63.34%) brushed their teeth twice daily. Eight pregnant patients (26.67%) and five non-pregnant patients (16.67%) used dental floss. Seventeen (56.67%) pregnant patients and 14 (46.67%) non-pregnant patients had received professional guidance for oral hygiene care previously.
Table 3: Correlation between DMFT index and salivary flow rate and pH of saliva for pregnant and non-pregnant groups

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   Discussion Top


In the present study, the salivary flow rate and pH of saliva were lower in pregnant women than in non-pregnant women. An inverse relation was found between pH of saliva and caries prevalence, but no relation was present between salivary flow rate and caries prevalence for both the groups. For the purpose of this study, unstimulated whole saliva was collected for evaluation of salivary flow rate and pH of saliva, as unstimulated whole saliva plays a major role in maintenance of oral health and it is predominantly secreted through the day and at night time. [6] The salivary composition and flow rate are altered during pregnancy, menstruation, and menopause due to changes in steroid hormone levels. [6] However, no direct influence of age is seen on the salivary flow rate of unstimulated whole saliva. [10],[11]

We found that there was numerically lesser salivary flow rate in pregnant women than in non-pregnant women. Studies conducted by Hugoson [12] and González et al.[13] showed similar findings of decreased salivary flow rate in pregnant women. Salivary flow rate has a definitive influence on the pH of saliva. At higher flow rate, there is an increased level of salivary pH because the bicarbonate concentration increases with elevated flow rate. [4],[9] It was found in our study that the salivary pH was lower in pregnant women than in non-pregnant women. The pH of saliva for both the groups was within the normal range of 5.5-7.4, according to the international reference values. [14] At a pH lower than the critical level of 5.5, the hydroxyapatite crystals begin to dissolve causing demineralization of teeth. [15] In this study, the salivary pH levels for both the groups were above the critical level of 5.5. Rosenthal et al.[8] compared the pH of saliva in pregnant and non-pregnant women; they reported that the mean pH value of saliva of pregnant women was 6.5 and that of non-pregnant women was 7.0. Decreased salivary pH in pregnant women was also reported in a previous study conducted by Kullander and Soneson. [16] Laine et al.[17] reported that the salivary pH decreased toward late pregnancy, followed by a rapid increase after childbirth. Rockenbach et al.[18] reported that pregnant women had reduced level of salivary pH (6.7) than non-pregnant women (7.5).

During pregnancy, the levels of progesterone and estrogen (estradiol, estriol, and estrone) increase gradually to a great extent due to placental production of these hormones. Levels of human chorionic gonadotropin (HCG), cortisol, and beta-endorphin also increase in pregnancy and to a greater extent in the third trimester of pregnancy. Estradiol and estriol (biologically active forms of estrogen) increase by 100-fold and 1000-fold, respectively, during pregnancy. As a result, physiological changes occur in women that lead to adaptive changes at both systemic and oral levels. [19] In the second trimester, there is increased HCG causing decrease in the salivary flow rate. During pregnancy, the levels of human chorionic somatomammotropin (HCS) and progesterone increase markedly, which leads to reduction in the salivary flow rate. [7],[20],[21] Also, the increased progesterone decreases the plasma bicarbonate level resulting in a decrease in the pH of saliva. [22]

During the third trimester of pregnancy, salivary pH and buffering capacity reach their lowest levels, which increases the risk of caries incidence with higher levels of Streptococcus mutans. [6],[17] Maternal saliva is the main vehicle for bacterial transfer to the children. [23],[24],[25] Hence, it is essential to evaluate the prevalence of caries in pregnant women. We chose to use DMFT index to evaluate the caries prevalence. We found that the DMFT index was higher in non-pregnant women than in pregnant women. However, these values were not statistically significant [Table 1] and [Table 2]. It has been established that the flow rate and pH of saliva are significant in the development of caries. [5],[26] Hence, we considered evaluating the correlation between salivary pH and flow rate with DMFT index in Indian pregnant women.

In this study, DMFT index showed a strong negative correlation with the pH of saliva in both pregnant and non-pregnant women, suggesting an inverse relationship between salivary pH and caries prevalence. Heintze et al.[27] suggested that on a population level, an inverse relationship exists between the buffering capacity of saliva and caries susceptibility. In the present study, no relation was found between salivary flow rate and caries prevalence. Birkhed and Heintze [28] and Russell et al.[29] suggested that no linear relationship exists between salivary secretion rate, DMFT/DMFS index, and caries activity. Mandel [2.30] and Russell et al.[29] reported that only weak or no association was found between salivary secretion rate and caries incidence.

Vadiakas and Lianos [31] studied the correlation between pregnancy and dental caries. They noted that changes in oral microflora and saliva, nutritional changes, vomiting, and neglected oral hygiene are significantly important in relation to caries during pregnancy. Conversely, Orosz et al.[32] suggested that a positive correlation exists between pregnancy and caries. The bacteria ferment carbohydrates, which leads to increased production of organic acids that decrease the pH of saliva and plaque resulting in caries. Thus, maintenance of oral hygiene is essential for prevention of caries. [25] In this study, patients in the pregnant group had better oral hygiene maintenance than the patients belonging to the non-pregnant group. The values of salivary variables reported in this study group of pregnant and non-pregnant Indian women are similar to the values reported for other populations and are within international references of normality. The differences detected in the saliva of pregnant and non-pregnant women in our study and those reported in previous studies are small in absolute values and they do not seem to affect the oral health and prevalence of dental caries in these individuals.


   Conclusion Top


In conclusion, the salivary flow rate and pH of saliva were lower in pregnant women than in non-pregnant women. DMFT index showed a strong negative correlation with pH in pregnant women and non-pregnant women; hence, a significant inverse relationship was found between pH and caries prevalence. However, further studies are essential evaluating salivary parameters in medically compromised women with high-risk pregnancy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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