I[NTRODUCTION]{.smallcaps} {#sec1-1}
==========================

Dental caries is greatly determined by number of unhealthy lifestyle factors. Lifestyle constitutes the behaviors performed by an individual, which are linked directly to health outcomes. Healthy lifestyles are the behaviors performed by an individual to protect and promote his or her health. Healthy mouth requires the promotion of healthy lifestyles. Some of the major risk factors for dental caries related to unhealthy lifestyles are consumption of sugar-rich diet, poor nutrition, and use of tobacco, inadequate oral hygiene practices, stress, and inferior living conditions. Unhealthy lifestyles have been found to be correlated with a higher occurrence of dental caries in the previous studies.\[[@ref1][@ref2][@ref3][@ref4][@ref5]\] Moreover, presence of two or more unhealthy habits together in a person can have a larger impact on health than any one habit alone. This study is an attempt to find the collective influence of all possible unhealthy lifestyle factors existing in an individual on the dental health. Hence, it is recommended that comprehensive nature of whole behavior of the person should be taken into consideration in the prevention of caries.\[[@ref6]\]

The concept of lifestyle highlights the personal characteristics of an individual and allows to study behavior in a broader sense. However, there is no uniform concept as to what composes a "lifestyle." According to Abel,\[[@ref7]\] the particulars that measure lifestyle can be selected in accordance with the research purpose. Breslow had recommended seven habits that can be considered for overall healthy lifestyle such as adequate sleep, no habit of smoking, occasional drinking of alcohol, keeping good weight, routine exercise, having daily breakfast, and reduced eating in between meals.\[[@ref8]\] In this study, the eight item self-administered questionnaire to measure health practice index (HPI) developed by Morimoto was used to assess the lifestyle of the people.\[[@ref9][@ref10][@ref11][@ref12][@ref13]\] This approach of categorizing lifestyles has been found helpful for the assessment of individual lifestyle practices in various studies.\[[@ref14][@ref15]\]

Dental caries is preventable if favorable health behavior is successfully established. Exploring the broader concept of lifestyle will be useful to determine that how overall lifestyle of people can affect dental caries. A number of studies have been conducted on single lifestyle-related risk factor, which affect dental caries.\[[@ref16][@ref17][@ref18][@ref19]\] However, very few studies have considered the relation of overall lifestyles, that is, collective influence of all possible lifestyle-related risk factors of an individual or web of many risk factors on the dental health.\[[@ref1][@ref2],[@ref20][@ref21][@ref22]\] To our knowledge, no previous studies in the Udupi district of south Karnataka have investigated whether overall lifestyles of the people can influence their dental health status. The aim of this study was to evaluate the impact of overall/combined lifestyle of an individual (analyzed using HPI) on dental caries of adult population. Determining the influence of overall lifestyles on dental caries can help in developing appropriate oral health promotion strategies.

M[ATERIAL AND]{.smallcaps} M[ETHODS]{.smallcaps} {#sec1-2}
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S[TUDY DESIGN]{.smallcaps} {#sec2-1}
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This was a cross-sectional study performed on the subjects of age over 18 years attending the outreach dental setups of a dental school in India. Ethical approval to conduct the study was acquired from the Kasturba Hospital Ethics Committee, Manipal (IEC 84/2011). Patients were recruited from the various dental camps organized at randomly selected locations from the Udupi district map. Informed consent was obtained from each participant preceding the study.

S[AMPLING METHOD AND CRITERIA]{.smallcaps} {#sec2-2}
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A pilot survey on 50 subjects was carried out prior to the start of the study to measure their dental caries experience. Of these enrolled subjects, 80% (*n* = 40) had at least one decayed, missing, filled teeth (DMFT). The sample size required to carry out the study was calculated taking 95% confidence level (*Z*, standard value of 1.96) and 5% margin of error (*d*, standard value of 0.05). Calculating the sample size by the given prevalence, the minimum sample size required was 245.\[[@ref23]\] Although the study objective had three comparison groups for lifestyles, a final sample size of 800 was chosen considering up to 10% lack of response.

The self-administered questionnaires were then distributed to 800 subjects, of which 780 participants returned the completed questionnaires with the acceptable response rate of 97.5%. The eligibility criteria that had been used for inclusion of the subjects in the study were those who were willing to participate and those able to read the questionnaire.

A structured questionnaire was prepared consisting of four parts:

1.  The first part of the questionnaire included respondents' sociodemographic characteristics in terms of age, gender, income/month, education, occupation, and religion. The socioeconomic status of the subjects was calculated with the help of Kuppuswamy scale by adding education, occupation, and income of the subjects.\[[@ref24]\]

2.  The second part of the questionnaire was in regards to dental health behavior to know about frequency and device of cleaning and frequency of dental visits.

3.  The third part of the questionnaire was an "eight item HPI scale" for the evaluation of the total lifestyle, developed by Morimoto which included information regarding smoking, consuming alcohol, having breakfast/day, duration of sleep/night, duration of work/day, physical workout, eating nutritional/balance diet, and mental stress.\[[@ref9][@ref10][@ref11][@ref12]\] Subjects chosen one of two to six multiple choices of each question, and the answers were categorized as either "good" or "poor" health practices as per Morimoto's criteria.

    The language of the questionnaire was translated from English to Kannada (regional language of Karnataka). The face validity of the questionnaire was ensured by back translation method, that is, blind retranslation into English by experts in both languages.

    **Observational Parameters:**

    The "good" health practices were coded as 1 and "poor" health practices were given a code of 0. The total score of each participant varied between 0 and 8 depending upon quantity of good health practices. It was further sorted into poor lifestyles (score = 0--3), moderate lifestyles (scores = 4, 5), and good lifestyle (scores = 6 or higher).

4.  The fourth part consisted of information on dental caries status. Dental caries was recorded in accordance with DMFT index (1986 criteria) using mouth mirror and explorer.

Single trained and calibrated examiner collected the clinical data along with a trained recorder noting down the observations. Intra-examiner reliability was assessed using kappa statistic, which was 0.95 for the DMFT index indicating good conformity in the observations.

S[TATISTICAL]{.smallcaps} A[NALYSIS]{.smallcaps} {#sec1-3}
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The data were analyzed using Statistical Package for the Social Sciences software program, version 16 (SPSS, Chicago, Illinois). Descriptive statistics was used for frequency distribution of study population and calculation of mean ± standard deviation (SD) for DMFT and total DMFT as per subject characteristics. Negative binomial regression was applied to calculate the adjusted odds ratio and the association between the dependent (DMFT----count data) and independent variables. The *P* value of 0.05 or less was set as statistical significance.

R[ESULTS]{.smallcaps} {#sec1-4}
=====================

[Table 1](#T1){ref-type="table"} shows the distribution of the study population in accordance to their demographics, dental health behavior, and lifestyles. The mean age of 780 participants was 35.5 years. There was an approximately equal distribution of the study sample with respect to age and gender of the population. Majority of the study subjects belonged to upper lower (369, 47.3%) and middle class (317, 40.6%) category of socioeconomic status. All the subjects reported to use toothbrush and half of them reported to brush twice daily. Nearly one third of the study population (250, 32.1%) reported that they had never visited the dentist. The study included majority of people with good lifestyle (571, 73.2%) followed by moderate lifestyle (171, 21.9%) and poor lifestyle (38, 4.9%).

###### 

Distribution of study population according to their demographic variables, dental health behavior, and overall lifestyles

  Variables                                                     No. of subjects (%)
  ---------------------------- -------------------------------- ---------------------
  Gender                       Male                             386 (49.5%)
                               Female                           394 (50.5%)
  Age                          20--35 years                     394 (50.5%)
                               36--50 years                     386 (49.5%)
  Location                     Urban                            392 (50.3%)
                               Rural                            388 (49.7%)
  Occupation                   Unemployed                       347 (44.5%)
                               Unskilled                        137 (17.6%)
                               Skilled/semiskilled              111 (14.2%)
                               Clerical, farmer, and business   158 (20.3%)
                               Semiprofessional/ professional   27 (3.5%)
  Education                    Primary school                   144 (18.5%)
                               Middle school                    125 (16%)
                               High school                      173 (22.2%)
                               P.U.C/diploma                    146 (18.7%)
                               Graduate/postgraduate            192 (24.6%)
  Income/month                 \<10,356                         500 (64.1%)
                               10,357--20,714                   134 (17.2%)
                               20,715--41,429                   67 (8.6%)
                               \>41,430                         79 (10.1%)
  SES                          Upper                            14 (1.8%)
                               Upper middle                     135 (17.3%)
                               Lower middle                     182 (23.3%)
                               Upper lower                      369 (47.3%)
                               Lower                            80 (10.3%)
  Religion                     Hindu                            464 (59.5%)
                               Christian                        211 (27.1%)
                               Muslim                           102 (13.1%)
                               others                           3 (0.4%)
  Frequency of dental visits   Once in 1--2 years               247 (31.7%)
                               Rarely                           283 (36.3%)
                               Never                            250 (32.1%)
  Frequency of brushing        Once                             390 (50%)
                               Twice                            382 (49%)
                               More                             8 (1%)
  Overall lifestyle            Poor lifestyle                   38 (4.9%)
                               Moderate lifestyle               171 (21.9%)
                               Good lifestyle                   571 (73.2%)
                               Total                            780 (100%)

P.U.C = Pre-university college, SES = Socio-economic status

[Table 2](#T2){ref-type="table"} shows the mean of DMFT and total DMFT scores of subjects based on their various characteristics. Negative binomial regression was applied considering discrete nature and over dispersion of the dependent variable (DMFT) with mean = 6.04 and SD = 4.8. The model fitted the data well as Pearson chi-square value for goodness of fit of the model was 0.53 and a highly statistically significant omnibus test for the overall model (*P* \< 0.001). Negative binomial regression model identified the following variable, which had shown statistically significant effect on dental caries, that is, age (*P* \< 0.001), gender (*P* \< 0.001), occupation (*P* \< 0.001), education (*P* \< 0.001), income (*P* = 0.05), socioeconomic status (*P* \< 0.001), frequency of dental visit (*P* \< 0.001), frequency of brushing (*P* = 0.02), and whole lifestyles (*P* \< 0.001). All the variables in the model showed a significant effect on dental caries except the location (*P* = 0.98) and religion (*P* = 0.11).

###### 

Decayed, missing, and filled teeth (DMFT) and total DMFT according to subject characteristics

  Variables                                                     Decayed      Missing       Filled       DMFT
  ---------------------------- -------------------------------- ------------ ------------- ------------ -------------
  Gender                       Male                             2.39 ± 2.9   1.35 ± 1.9    1.4 ± 2.6    5.14 ± 4.2
                               Female                           2.9 ± 2.8    2.14 ± 3      1.89 ± 3.1   6.93 ± 5.2
  Age                          20--35 years                     2.57 ± 2.7   0.96 ± 1.5    1.42 ± 2.7   4.95 ± 4.4
                               36--50 years                     2.73 ± 3     2.57 ± 3.1    1.87 ± 3.1   7.16 ± 4.9
  Location                     Urban                            1.91 ± 2.1   1.68 ± 2.7    2.73 ± 3.5   6.32 ± 4.9
                               Rural                            3.39 ± 3.3   1.82 ± 2.4    0.55 ± 1.6   5.77 ± 4.6
  Occupation                   Unemployed                       2.73 ± 2.6   2.05 ± 3      1.79 ± 3.2   6.57 ± 5.2
                               Unskilled                        3.42 ± 3.3   2.36 ± 2.5    0.41 ± 1.1   6.19 ± 4.7
                               Skilled/semiskilled              1.89 ± 2.6   1.44 ± 2.1    1.68 ± 3     5.02 ± 4.36
                               Clerical, farmer, and business   2.41 ± 3.1   0.96 ± 1.6    2.01 ± 2.9   5.38 ± 4
                               Semiprofessional/professional    2.15 ± 2.6   0.74 ± 0.8    3.74 ± 3.5   6.63 ± 4.2
  Education                    Primary school                   3.37 ± 2.9   2.26 ± 2.5    0.29 ± 1     5.92 ± 4.5
                               Middle school                    3.46 ± 4     2.2 ± 3.2     0.66 ± 1.7   6.31 ± 5.5
                               High school                      2.38 ± 2.3   1.79 ± 2.4    1.61 ± 2.9   5.78 ± 4.4
                               P.U.C/diploma                    2.49 ± 2.9   1.29 ± 2      1.6 ± 2.6    5.37 ± 4.5
                               Graduate/postgraduate            1.94 ± 2.1   1.4 ± 2.6     3.38 ± 3.8   6.71 ± 5
  Income/month                 \<10,356                         2.83 ± 2.9   1.93 ± 2.7    1.17 ± 2.6   5.94 ± 4.9
                               10,357--20,714                   2.51 ± 3.2   1.55 ± 2.2    2.17 ± 3     6.24 ± 4.6
                               20,715--41,429                   2.45 ± 2.1   1.60 ± 2.5    1.78 ± 2.6   5.82 ± 4.5
                               \>41,430                         1.86 ± 2.3   1.09 ± 2.1    3.62 ± 3.9   6.57 ± 4.9
  SES                          Upper                            3.21 ± 3.1   0.79 ± 0.8    3.07 ± 3     7.07 ± 4.3
                               Upper middle                     1.85 ± 2     1.23 ± 2.2    2.98 ± 3.8   6.06 ± 4.8
                               Lower middle                     2.46 ± 2.9   1.23 ± 1.9    2.66 ± 3.2   6.35 ± 4.7
                               Upper lower                      2.75 ± 3     2.01 ± 2.7    0.88 ± 2.3   5.63 ± 4.9
                               Lower                            3.85 ± 2.9   2.83 ± 3.1    0.36 ± 1.1   7.04 ± 4.9
  Religion                     Hindu                            2.67 ± 2.8   1.87 ± 2.8    1.45 ± 2.8   5.99 ± 5
                               Christian                        2.92 ± 3.1   1.50 ± 2.1    2.11 ± 3.2   6.54 ± 4.8
                               Muslim                           2.05 ± 2.2   1.78 ± 2.3    1.50 ± 2.7   5.33 ± 3.8
                               others                           0.67 ± 1.2   0.33 ± 0.58   3.33 ± 3.1   4.33 ± 2.9
  Frequency of dental visits   Once in 1--2 years               2.27 ± 2.5   2.24 ± 3.1    3.23 ± 3.8   7.74 ± 5.3
                               Rarely                           2.59 ± 2.7   1.67 ± 2.2    1.10 ± 2     5.36 ± 4.4
                               Never                            3.08 ± 3.2   1.36 ± 2.3    0.70 ± 1.9   5.14 ± 4.3
  Frequency of brushing        Once                             2.95 ± 2.9   1.64 ± 2.4    1.19 ± 2.4   5.78 ± 4.4
                               Twice                            2.36 ± 2.7   1.87 ± 2.7    2.11 ± 3.3   6.35 ± 5.1
                               More                             1.38 ± 2.3   1.88 ± 2      1.50 ± 1.3   4.75 ± 2.8
  Overall lifestyle            Poor lifestyle                   4.08 ± 4.4   1.63 ± 1.7    0.68 ± 1.9   6.39 ± 3.9
                               Moderate lifestyle               3.08 ± 3     2.33 ± 2.4    1.10 ± 2.2   6.5 ± 4.5
                               Good lifestyle                   2.42 ± 2.6   1.59 ± 2.6    1.87 ± 3.1   5.9 ± 4.9

SD = standard deviation, DMFT = decayed, missing, and filled teeth

The study subjects those with older age (RR = 1.48), those were females (RR = 1.24), those were unemployed (RR = 1.27) and unskilled (RR = 1.37), with lower education (RR = 0.80), with lesser income (RR = 1.15), with lower socioeconomic status (RR = 0.71), those never visited dentist (RR = 1.45), those with lesser frequency of cleaning teeth (RR = 1.56), those with overall poorer lifestyles (RR = 1.32), and those having moderate lifestyles (RR = 1.20) were more prone to have dental caries than their counterparts \[[Table 3](#T3){ref-type="table"}\].

###### 

Negative binomial regression model: dependent variable: total decayed, missing, and filled teeth

  Variables                                                     Adjusted RR (95% CI)   *P* value
  ---------------------------- -------------------------------- ---------------------- -----------
  Gender                       Female                           1.24 (1.14--1.35)      \<0.001
                               Male                             1                      
  Age                          36--50 years                     1.48 (1.39--1.58)      \<0.001
                               20--35 years                     1                      
  Location                     Rural                            1.00 (0.92--1.83)      0.975
                               Urban                            1                      
  Occupation                   Unemployed                       1.27 (0.97--1.67)      0.008
                               Unskilled                        1.37 (1.04--1.82)      0.03
                               Skilled/semiskilled              0.99 (0.75--1.30)      0.94
                               Clerical, farmer, and business   0.90(0.69--1.17)       0.42
                               Semiprofessional/professional    1                      
  Education                    Primary school                   0.80(0.70--0.91)       0.001
                               Middle school                    1.02 (0.91--1.14)      0.05
                               High school                      0.90 (0.82--1.0)       0.04
                               P.U.C/diploma                    0.88 (0.80--1.0)       0.008
                               Graduate/postgraduate            1                      
  Income/month                 \<10356                          1.15 (0.91--1.44)      0.05
                               10,357--20,714                   1.01 (0.81--1.24)      0.96
                               20,715--41,429                   0.94 (0.82--1.08)      0.38
                               \>41,430                         1                      
  SES                          Lower                            0.71 (0.43--1.17)      \<0.001
                               Upper lower                      0.65 (0.40--1.05)      0.01
                               Lower middle                     0.92 (0.60--1.43)      0.72
                               Upper middle                     0.84 (0.60--1.17)      0.3
                               Upper                            1                      
  Religion                     Hindu                            1.77(1.01--3.09)       0.11
                               Christian                        1.85(1.06--3.24)       0.45
                               Muslim                           1.78(1.01--3.13)       0.98
                               others                           1                      
  Frequency of dental visits   Never                            1.45 (1.34--1.57)      \<0.001
                               Rarely                           1.02 (0.95--1.11)      \<0.001
                               Once in 1--2 years               1                      
  Frequency of brushing        Once                             1.56 (1.12--2.16)      0.01
                               Twice                            1.49 (1.07--2.07)      0.02
                               More                             1                      
  Lifestyle                    Poor lifestyle                   1.32 (1.14--1.53)      \<0.001
                               Moderate lifestyle               1.20 (1.12--1.29)      \<0.001
                               Good lifestyle                   1                      

RR = risk ratio, CI = confidence interval

Model: (intercept), age, gender, location, occupation, education, income, socioeconomic status, religion, frequency of dental visits, frequency of brushing, and overall lifestyles

*p* \< 0.05 = Significant

D[ISCUSSION]{.smallcaps} {#sec1-5}
========================

The healthy lifestyle directly relates to good health is a well-understood concept.\[[@ref21][@ref25]\] Studies in the past had proven that people with unhealthy lifestyles had more general health and oral health-related problems.\[[@ref20]\] There may be more than one risk factor in the same individual that can impact his/her health as explained by web of causation concept.\[[@ref8][@ref26]\] Hence, overall lifestyle concept that is based on all possible health-related risk factors will be able to explain better health-orientated behavior of a person than the previous studies based on one or two risk factors. In other words, this concept gives an opportunity to study overall self-care behavior of a person. According to HPI used in this study, good lifestyles encompass not to smoke, not to consuming alcohol daily, to eat healthy breakfast daily, to sleep at least 7--8h every night, not to work more than 10h per day, to exercise at least once a week, to eat a nutritionally healthy diet, and to keep mental stress levels moderate. The purpose of this study was to evaluate the impact of overall/combined lifestyle of an individual (analyzed using HPI) on dental caries of adult population.

It was ascertained in this study that subjects with poorer lifestyles had much greater risk of getting caries than the subjects with good lifestyles. This was in accordance with the earlier findings reported in the past that unhealthy lifestyle was directly related to more frequency of occurrence of dental caries.\[[@ref1][@ref2][@ref3][@ref4][@ref5][@ref16][@ref17][@ref18][@ref19]\] It was noticed in this study that subjects with poorer lifestyles had much higher decayed teeth and very less filled teeth than good lifestyle subjects, which strengthens the explanation of their lack of health-oriented behavior. A number of lifestyle diseases including dental caries are partly preventable by developing behaviors that are beneficial for their health. If health has to be promoted, efforts must be taken at the individual level for developing self-care practices such as good oral hygiene behavior and regular dental visits.

It was also noticed that female subjects had higher risk for dental caries than the males in this study. But, in explaining this usual tendency of caries being more in females, other contributing factors can be taken into account such as hormonal, diet, and genetic variations, along with social roles among their family.\[[@ref27]\] In addition, subjects with better education, occupation, income, and socioeconomic status also had lesser risk of dental caries. This was in accordance with a large number of epidemiological studies that had reported a greater prevalence of dental caries in those people with worse socioeconomic indicators.\[[@ref28]\] It is believed that subjects with low socioeconomic status may be having less accessibility, affordability to dental services and oral hygiene products, poorer knowledge, and less awareness regarding oral health and oral hygiene, which might lead to greater frequency of dental caries.\[[@ref29]\] Socially disadvantaged individuals have been reported to experience low health in general.\[[@ref30]\] Even in this study, rural group was found to have much higher decayed teeth and much lesser filled teeth than the urban group. Hence, it is important to consider social inequalities to improve population health.

Lack of self-care behavior and poor use of dental health services are major contributing factors to the high prevalence of dental caries. Oral health-promoting behaviors such as brushing habit of study subjects and habit of regularly visiting dentist are required for maintaining good oral health. It was ascertained in this study that subjects who had taken care of their oral health by brushing more than once and visited dentist regularly had better lifestyles and less dental caries than their counterparts. This was in line with the studies that reported routine dental attendance was associated with better oral health\[[@ref31]\] and self-reported infrequent brushers' showed higher carious lesions than frequent brushers.\[[@ref32]\]

C[ONCLUSION]{.smallcaps} {#sec1-6}
========================

This study's linkage between lifestyle calculated using HPI including eight lifestyle factors and dental caries proves the concept that behavior should be taken in a broader sense for the prevention of dental caries. Maintaining a healthy lifestyle could be simply by inheriting healthy behaviors in ones lives. Patients' involvement in self-care by promoting healthy behaviors such as brushing twice a day, visiting dentist regularly, negating orally abusive substance addiction, having breakfast every day, eating a balanced diet, and reducing stress leads to an overall good lifestyle. These factors along with sleeping a minimum of 7--8h per night and working for 8--9h/day and ample daily exercise may help patients improve or protect their oral health for years to come. The public health programs emphasizing on individual lifestyle as a determinant of health are needed.

F[INANCIAL SUPPORT AND SPONSORSHIP]{.smallcaps} {#sec2-4}
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Nil.

C[ONFLICTS OF INTEREST]{.smallcaps} {#sec2-5}
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There are no conflicts of interest.

A[UTHOR CONTRIBUTIONS]{.smallcaps} {#sec2-6}
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The authors' responsibilities were as follows- NS and SA: designed the research. NS, RS wrote the manuscript; NS and RS: conducted the research and had primary responsibility for the final content of the manuscript; and all authors: read and approved the final manuscript. None of the authors had a conflict of interest.

E[THICAL POLICY AND INSTITUTIONAL REVIEW BOARD STATEMENT]{.smallcaps} {#sec2-7}
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The authors confirm that the study has been conducted as per the ethical guidelines laid down by Deceleration of Helsinki and approved by the Kasturba Medical College and Kasturba Hospital Institutional Ethics Committee, Manipal (IEC 84/2011).

P[ATIENT DECLARATION OF CONSENT]{.smallcaps} {#sec2-8}
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The authors confirm that all the study subjects were explained about the details of the study through Participation Information Sheet and the Informed written Consent was obtained for voluntary participation. Participants were given freedom to withdraw from the trial at any point. Regular care was ensured to the participant in the case of withdrawal. They were explained that data related to this study will be maintained confidentially and will be used only for academic purpose or may be published in journals without disclosing their identity.

D[ATA AVAILABILITY STATEMENT]{.smallcaps} {#sec2-9}
-----------------------------------------

The data that support the study results are available from the corresponding author (Dr. Ritesh Singla, e-mail: <ritesh.singla@manipal.edu>) on request.

Nil.
