A case control study was carried out between two groups’ diabetic and non-diabetic. Each group based on the age factor subdivided into young adults and old age adults with and without dental caries. The study had been carried out for one year and two months, (July 2015 to August 2016) respectively.

Patients between age group of 20-39 years (young adult group) and 40-64 years (older adult group) who came for dental treatment in the Outpatient Department of Conservative Dentistry and Endodontics were considered for salivary evaluation. By obtaining their consent, their diabetic status was assessed by routine random blood and urine sugar levels by Erba auto analyser and Benedict’s method respectively. Patients with random blood sugar greater than 160 mg/dl and urine sugar of 0.5% (green colour) were considered as diabetic and values below that as control.

Subjects of either sex, between 20-39 years and 40-64 years age group who were diabetic/non diabetic with OHI of 0.1-1.2 (good oral hygiene) were included in the study. Subjects of age below 20 years and above 64 years with any other oral lesions, systemic illness, tobacco habits, intake of medications causing xerostomia and OHI of 3-1.6 were excluded from the study. OHI was assessed and only subjects in both control and study group with OHI of 0.1-1.2 were taken for the study because poor oral hygiene is also one of the contributing factor for progression of caries.

The sample size was calculated based on assumption of standard deviation 0.5 and 0.75 & mean difference of 0.52 between diabetic and control group. The power used 90% and 5% of error the sample size was obtained 24 in each group. (n-mastering software Vellore)

A total 96 patient’s were included in the study. They were broadly divided into two groups- Control and Experimental /diabetic group based on their diabetic status. In each group they were divided into two age groups, 20 to 39 years (young adults) and 40 to 64 years (older adult), since older individuals show decreased salivary secretion as a part of normal ageing process. They were further subdivided into patients with caries and without caries [Table/Fig-1].

[Table/Fig-1]:

The sample grouping.

Ethical clearance was taken and informed written consent was obtained from each of the subjects and dental caries was assessed using Decayed, Missing, Filled Tooth (DMFT) index.

Collection of Saliva for Salivary Analysis: The subjects were asked to rinse their mouth with 15ml of distilled water to wash out the exfoliated cells. A 5ml of unstimulated whole saliva was then collected by asking the subjects to expectorate into sterile tubes. The collected saliva was centrifuged and the supernatant obtained was evaluated using an Erba autoanalyser Chem 5X N110825 for Na, K, Cl, Ca, P. When the evaluation could not be done immediately, it was stored at 4⁰C for subsequent analysis.

Independent sample t-test was used to correlate the salivary electrolytes concentration among the groups. A p-value of 0.05 or less was considered significant. Results are presented as mean±standard deviation. SPSS 17 software analysis was used.

In the control group there was no significant change in the salivary electrolyte levels considered, between persons with or without caries in young adult age group [Table/Fig-2a]. But in the older adult group K and Cl levels were statistically higher in caries active patients [Table/Fig-2b].

In the diabetic group, except for the Cl levels all the other four electrolytes showed a significant decrease in caries active patients in the young adults [Table/Fig-3a] and no changes of significance was noted in the older adults [Table/Fig-3b].

Between the control and diabetic patients without caries, K and P levels were high in young adults diabetics [Table/Fig-4a] and only K was higher in diabetics of older adult group [Table/Fig-4b].

The comparison of the caries patient’s salivary electrolyte levels between control and diabetic group showed a notable decrease in all except Cl levels in young adults [Table/Fig-5a], without any significant difference in the older adults [Table/Fig-5b].

Evaluation of the impact of alterations in the salivary electrolyte levels of diabetic patients on dental caries revealed that the decrease of Na, K, Ca, and P levels in caries active individuals of young adults was significant than in the older adult group.

In the present study, diabetic group, except for the Cl levels all the other four electrolytes showed a significant decrease in caries active patients in the young adults [Table/Fig-3a] and no changes of significance was noted in the older adults [Table/Fig-3b]. The result evaluate that diabetes plays a vital role in salivary electrolytes concentration which indirectly promotes the progression of caries in young patients compared to older individuals. A positive correlation of other salivary electrolytes such as sodium, chloride and potassium with diabetics have been reported [3].

The role of calcium and phosphorous in dental remineralisation is well known and their concentration in whole stimulated saliva reflects their level in plaque. Study has proven that Phosphorous have caries prevention effect [9]. High levels of calcium and phosphorous in whole and parotid saliva were found to be associated with a low dental caries rate [10]. Study had shown that low levels of salivary calcium and phosphate have a modest association with caries susceptibility. Calcium and Phosphorous are known to reduce enamel solubility thus, decreasing incidence of dental caries [11].

A study which was carried out on salivary electrolytes as a biomarker in caries active type II diabetes had revealed that altered salivary electrolytes had impact on prevalence of dental caries in diabetic patients when compared to non-diabetics [12]. However, this study did not consider the normal ageing process, which is known to alter the salivary gland function.

Hence, the current study evaluated the prevalence of dental caries among diabetics and non-diabetics in young adults (20-39 years) and older adults (40-64 years) with and without caries teeth by analysing the salivary electrolytes. It was found that salivary Na, K, Ca, P levels were less in caries active individuals of diabetics in the young adult group than in older adult group. But in control group (Young adult group) there was no significant difference among these groups with or without caries, but K and Cl levels showed significantly higher levels in older age group with caries. Investigator also reported higher potassium and chloride levels in saliva from caries active individuals [10]. From this we could understand that the decreased levels of salivary electrolytes have more impact on prevalence of dental caries in young adults than the older adults.

The comparison of the salivary electrolyte level between control and diabetic patients without caries revealed high K and P levels and high P levels in young adults and older adults respectively. Similar comparison in caries active individuals showed a notable decrease in all the electrolyte levels except Cl in young adults only. These results suggest that irrespective of age group non carious individuals showed alterations of K and P electrolytes. Apart from this Ca & Na levels are also being altered in caries active individuals of young adults only.

Within the limitations of this study, age factor plays a vital role in dental caries prevalence in diabetic conditions. In this study it had showed that diabetes had its impact on salivary electrolytes alteration resulted in prevalence of dental caries in young adults. But in old age adults apart from diabetes other factors also plays an important role in dental caries prevalence.

The probable explanation for a slight increase in Cl level in diabetic group could be the hyperchloremia seen in diabetics [12] and the decrease in other electrolytes due to the decrease in salivary output [13].

In relation to the future prospective of the present study the sodium ions from the blood are transferred to the salivary glands and secreted with the bicarbonate ions [11]. The mechanism behind this reaction has not yet been extensively studied and still requires more research.

Diabetes played a significant role in caries progression in young diabetic adult patients when compare to old age adults. There is a marked decrease in salivary electrolyte concentration in young adults. Therefore, maintaining the salivary electrolyte concentration in young diabetic individuals helps to prevent demineralisation of the tooth.