Effect of salat (prayer) activity on salivary status and cortisol level

The majority of Indonesian people are Muslim who perform the obligatory prayers five times each day known as salat. The series of activities in salat begins with wudu with a gargle movement that increases salivary secretion through mechanical stimulation. The movement of ruku and sujood when salat causes oxygen-rich blood to flow to the brain is well suited. When a person feels calmer and more psychically relaxed after performing salat and wudu, the parasympathetic nerves increase so normal cortisol levels can secrete more saliva which is aqueous with normal acidity (pH). Oral health will affect the overall health of the body. This study aimed to determine the effect of salat and wudu on the salivary flow rate, pH, and cortisol level as an indicator of oral health. The design of this study was the static group pretest and posttest design. The study was conducted by comparing the value of salivary flow rate, pH, and cortisol levels in 20 subjects consisting of 10 subjects as the treatment group and 10 subjects as the control. Saliva was collected without stimulation before and after salat activity for five minutes, followed by measurement of salivary flow rate and pH level. Salivary cortisol level was measured using Cortisol Assay Elisa kit with λ 540 nm. The results showed an increase in salivary pH, flow rate and cortisol level after the salat activity but there was no significant difference by Kruskal-Wallis test but there was a strong correlation using Kendall’s tau_b test. In conclusion, salat activity may have correlation with an increase in salivary pH, flow rate and cortisol level.


INTRODUCTION
The prevalence of dental and oral disorders in Indonesia is about 25.9%. 1 According to the RISKERDAS 2013 results, people who did dental health care and hygiene counseling were only 5.3%. 2 On the other hand, Indonesia is a big country with various ethnic groups, languages, cultures, and religions. Based on the census data in 2010, 87.51% of Indonesian citizen were Muslim. 3 In Islamic religion there is an obligation to pray which is known as salat in the form of repetitive movement (standing, ruku or bowing, sujood or prostration, and sitting), preceded with wudu. Salat is performed at least five times a day. In salat movement there is ruku and sujood that causes oxygen-rich blood to flow to the brain. The hemodynamics varies with the position of head. The activity of sujood has similarity with prone position. However, when the head is lower than the heart, there is venous congestion leading to an increase in intracranial pressure. The oxygenation improves with sujood positioning. 4 Saliva is a hypotonic fluid secreted by the major and minor salivary glands which have functions to maintain oral conditions. Volume, acidity (pH), and protein components of saliva are important factors that play a role in maintaining the equilibrium in the oral cavity. 5 When salivary volume and salivary acidity are lower than normal, it can reduce the function of saliva as a tissue protector in the oral cavity, teeth lubricant, antibacterial activity, buffer effects, and others. A decrease in salivary function can be used as an early detector for abnormalities in the oral cavity. 6 In addition, there is cortisol as a component of saliva that can be used as an indicator of oral health. Cortisol in the hypothalamus pituitary adrenal axis (HPA Axis) is a hormone produced in the zona fasciculata and the zona reticularis of the adrenal cortex. Circumcision rhythms and stressor cause the hypothalamus to increase the production of corticotropin releasing hormone (CRH) to the anterior pituitary gland then increase adrenocorticotropic hormone (ACTH) targeted at the adrenal cortex cortisol. 7 The highest cortisol level is found early in the morning especially shortly after waking up. 8 Higher cortisol levels are associated with trauma and depression. 9 When someone feels more relaxed and calmer after taking prayer in the morning, it will lower cortisol level. Thus, salivary secretion at the parasympathetic nerve pathway that produces aqueous saliva will be optimum. Sufficient salivary secretion results in an appropriate acidity (pH) to maintain oral health. 10 For instance, salat can decrease the sympathetic component and increase the parasympathetic component in autonomic nervous system (ANS). 11 Based on the description, there is a hypothesis that wudu and salat have effect on increasing salivary secretion through mechanical stimulation especially by gargling, ruku, and sujood which increase the flow of oxygen-rich blood. A series of salat ends with dhikr or praying that psychologically increases the peace of mind, maintains cortisol levels in normal range, and increases parasympathetic nerves in secreting aqueous saliva with normal acidity (pH). This study aimed to reveal the effect of salat and wudu on the salivary flow rate, pH, and cortisol level as an indicator of oral health.

MATERIALS AND METHODS
This study used static group pretest and posttest design. The subjects were 20 men, with an age range of 18 to 25 years old, healthy, did not suffer from any systemic diseases, did not use parasympathomimetic drugs, and did not use orthodontics or denture. The subjects were instructed to brush their teeth and eat for 30 minutes before collecting saliva sample. The subjects were divided into two groups, 10 men each. The first group consisted of those who did salat and wudu, while the other group as the control consisted of non Muslim who did not perform salat and wudu. The procedure of this study was approved by the Ethics Committee of the Faculty of Dentistry, Universitas Gadjah Mada (Ethical Clearance No. 001417 / KKEP / FKG-UGM / EC / 2018). An informed consent was signed from each subject who participated in this study.
Saliva sample was collected without stimulation for five minutes in the morning before and after salat and wudu. In the control group, saliva was collected at 04.30 am. Salivary flow rate was measured by weighing the salivary sample in a graded balance. Salivary pH level was measured by pH meter. Salivary cortisol level was measured by Cortisol Assay Elisa Kit (R & D Systems Inc., USA) and read by Elisa reader with λ 540 nm.
Data normality and homogeneity of variance were verified by the Shapiro-Wilk and the Levene's test, respectively. Statistical analysis was done by Kruskal-Wallis test and Kendall's tau_b correlation. Significance level was set at p<0.05. The data were processed using SPSS IBM Version 22 for Windows (SPSS Inc; Chicago, IL, USA).

RESULTS
The results of salivary flow rate, pH, and cortisol levels are shown in Table 1. Data normality, homogeneity, and Kruskal-Wallis are demonstrated in Table 2. Table 2 indicates some data p<0.05 or it could be assumed that the data had skewed distribution but the Levene's test showed p>0.05 meaning that the data were homogenous. The Kruskal-Wallis test showed p>0.05, indicating that salat and wudu had no significant difference. The analysis was continued to determine the correlation between the activity of salat and wudu with salivary flow rate, pH and cortisol levels by Kendall's tau_b as shown in Table 3. Table 3 shows p = 0.744 and p = 0.695, meaning that there was a strong correlation between salivary pH and flow rate; salivary pH and cortisol level but a weak correlation between salivary flow rate and cortisol levels (p = 0.473). This indicates that the activity of salat and wudu may have correlation to increase salivary pH, flow rate, and cortisol level.

DISCUSSION
The activity of salat and wudu increases the pH, shown in the mean of the treatment group of 7.80 ± 0.31 which is higher than that of the control. Increased salivary flow rate and cortisol levels were also seen in the treatment group although the results did not have any significant difference. This is probably due to the gargle activity during wudu which stimulates salivary secretion repeatedly. 6 The increase in salivary volume is directly proportional to the increase in the salivary flow rate, therefore maintaining the pH within the normal range. Ruku and sujood movement during salat could increase oxygen-rich blood flow to the brain to be more optimal so as to minimize stress due to lack of oxygen supply. 4 Optimal blood supply and minimal stress lead to a decrease in cortisol hormone levels which stimulates parasympathetic nervous system, resulting in more salivary secretionwhich is aqueous and rich in enzymes. 9 However, there are many factors influencing salivary secretion that could not be controlled in this study such as stress and psychic condition. This is because stress could lower the secretion of salivary. 6 The cortisol levels are higher in the treatment group than the control group (4.95 ± 2.88). The comparison between the cortisol levels in the treatment group and those in the control group showed no significance difference despite the apparent increase in cortisol levels after wudu and salat. Increased levels of cortisol are affected by circadian rhythms and stress. 7 However, due to lack of study about the correlation between salat and wudu with cortisol level, we still did not know about this phenomenon. In accordance with previous study, the lack of oxygen supply to organs could increase stress, thereby increasing cortisol levels. 10 Based on the analysis of the correlation between salat and wudu on pH, flow rate and cortisol levels, it is found that an increase in pH is correlated with an increase in salivary flow rate, and cortisol level. An increase in salivary secretions increases pH to maintain oral health in order to retain homeostasis. 5 Thus, an increased salivary flow rate will increase salivary pH. In addition, changes in cortisol levels may be characterized by an increase in salivary pH level.
The results of this study showed that elevated cortisol levels will be correlated to increased pH as well. These results indicate that salat and wudu have a strong effect on the salivary pH, flow rate and cortisol level in saliva which has a role to maintain oral health.

CONCLUSION
Salat activity may have correlation with an increase in salivary pH, flow rate, and cortisol level as an indicator of oral health