Diabetes mellitus and salivary pH and its correlation with Dental Caries

INTRODUCTION

Diabetes mellitus is a group of metabolic diseases characterized by high blood sugar level due to problems in insulin secretion or action or both. As a result, chronic hyperglycaemia with frequent disorders of carbohydrate metabolism can be associated with obesity, protein and electrolyte disorders and other diseases. The numbers of individuals with Diabetes mellitus are increasing day by day. It has been reported that salivary flow-rate is low in diabetic individuals and the saliva is also acidic and hence it has more caries risk¹.

The pandemic of diabetes has risen to almost 177 million worldwide from 30 million diabetics in 1985 to over 150 million in 2000. This figure predicts a rise to almost 333 million by the year 2025. It is estimated that there is 58% increase in the type 2 diabetic populations, and it is estimated that from 57 million people with type 2 diabetes in 2010, it will reach to 87 million people with type 2 diabetes in 2030 in 1 India . Siudekiene et al reported that both stimulated and unstimulated salivary flowrate are reduced in diabetic patients¹. Mata et al and Lopez et alreported that diabetic patients have more acidic saliva than normal^2,3 . On the other hand, Reutterving et al. have not reported this difference⁴. Thus the aim of this study is to compare the salivary pH and caries in diabetic and non-diabetic individuals.

MATERIALS AND METHODS

A total of 120 subjects were selected. They were divided into two groups. Group A consisted of 60 diabetic patients, while group B included 60 non-diabetic individuals. All subjects were in the age group of 60 to 70 years. For group A, those suffering from any systemic disease except diabetes were not included in the study. For group B, non-diabetics, subjects suffering from systemic disease and those on medications were not included. Their salivary pH was tested by collecting saliva sample in a sterile deepen glass individually in fasting (unstimulated) and two hours after the lunch condition (stimulated). Simultaneously, the fasting blood sugar (FBS) and post prandial blood sugar (PPBS) were also determined with the glucometer (One-touch Horizon). An FBS value of <110 mg/dL was considered normal, a value of 110-126 mg/dL was considered impaired and value > 126 mg/dL was considered high. For PPBS, a value of < 140 mg/dL was normal, 140-200 mg/dL was considered impaired while a value of > 200 mg/dL was considered high. The same procedure was followed in the group A diabetic individuals.

RESULTS

Stimulated and unstimulated salivary pH

The stimulated salivary pH of 12 subjects in group A was acidic with a value less than 6, 16 patients had an alkaline pH while 32 subjects had a pH ranging from 6-8. The unstimulated salivary pH was found to be less than 6 in 16 subjects while 20 subjects had an alkaline pH (Tables 1 and 2).

In group B, 20 subjects had an acidic pH, 12 had an alkaline pH, while 24 subjects had a pH between 6-8 in case of unstimulated saliva. For stimulated saliva, 20 subjects had an acidic pH, 12 had an alkaline pH while 28 had a pH between 6-8 (Tables 3 and 4).

Fasting and postprandial blood sugar levels

12 out of 60 patients in group A had a high fasting blood glucose level while 8 patients demonstrated a high PPBS level (Tables 5 and 6).

Incidence of caries in group A and group B

In group A, 16 patients demonstrated carious involvement in multiple teeth while in group B, none of the subjects demonstrated carious involvement in more than two teeth (Tables 7 and 8) . 

DISCUSSION The clinical results of the present study indicate an increased vulnerability to dental caries in patients with diabetes compared with non-diabetic individuals. These results were in agreement with those of Arrieta-Blanco et al⁵ . Dental caries is an infectious disorder involving multiple factors that coincide at a given point and at a given time. The basic factors are the presence of the causal microorganism, the host (tooth), substrate (diet) and immune capacity of the patient³ . Diabetic adults usually present altered salivary secretion that can cause disorders of hard and soft tissues of the mouth leading to cariostatic lesions^6,7 . Karjalainen et al. reported that in poorly controlled children and adolescents the DFS (decayed, filled surfaces) indices were significantly high and diabetes was associated with caries⁸ . These results were similar to those in our study where 16 out of 60 subjects demonstrated carious involvement in multiple teeth. On one hand, some authors have reported fewer caries in type 1 diabetic patients – relating this observation to the diet prescribed in such patients, with restricted sugar intake. However, other studies have reported an increased presence of caries in diabetic patients – attributing this observation to the existence of poorer metabolic control in such individuals^9,10,11 .

Some studies have reported an association between diabetes and acidic salivary pH. Lopez et al in their study on salivary characteristics of diabetic children attributed this finding to microbial activity or to a decrease of bicarbonate with flow rate in such patients³ . No such correlation was seen in this study.

CONCLUSION

The results of this study clearly indicate that diabetic patients have a higher incidence of caries than non-diabetics. No correlation between acidic pH and diabetes could be demonstrated in this study. Along with salivary pH many other factors like dietary habits, structural anatomy of the teeth, alignment of the teeth, salivary calcium, flow of saliva also need to be considered.