Chronic periodontitis among diabetics and nondiabetics aged 35-65 years, in a rural block in Vellore, Tamil Nadu: A cross-sectional study.

BACKGROUND: Chronic periodontitis is a common cause of poor oral health globally. Those at higher risk of this preventable and easily treatable condition need to be identified so that efforts can be taken to decrease disease burden and subsequent consequences. AIMS: The aims of the study were (1) To compare the prevalence of chronic periodontitis among individuals with and without type 2 diabetes, aged 35-65 years from a rural block in Vellore, Tamil Nadu and (2) to assess risk factors for chronic periodontitis among individuals with diabetes. SETTINGS AND
DESIGN: A cross-sectional study was done in nine villages of Kaniyambadi block, Vellore, between October 2015 and July 2016 among participants aged 35-65 years of a previous cross-sectional survey which had identified individuals with and without type 2 diabetes.
MATERIALS AND METHODS: Chronic periodontitis was assessed using the Community Periodontal Index and Treatment Needs index. Oral hygiene was assessed clinically using the Simplified Oral Hygiene Index. Diabetes was defined as on medication for type 2 diabetes or detected to have fasting blood glucose ≥126 mg/dl (in a previous survey). STATISTICAL ANALYSIS: Chi-square test and odds ratios (adjusted using logistic regression) were used to study risk factors for periodontitis among those with diabetes.
RESULTS: Prevalence of chronic periodontitis was 45.9% (95% confidence interval [CI]: 40.88%-50.9%) among 98 individuals with diabetes and 35.6% (95% CI: 30.91-40.29%) among 104 individuals without diabetes. Poor oral hygiene (odds ratio: 8.33, 95% CI: 3.33-25.00), low socioeconomic status (odds ratio: 3.19, 95% CI: 1.00-10.12), and smoking (odds ratio: 3.51, 95% CI: 1.17-10.51) were associated with periodontitis among diabetics.
CONCLUSIONS: Individuals with type 2 diabetes have a higher prevalence of periodontitis. As poor oral hygiene is a strong risk factor for periodontitis, there is a need for targeted education regarding dental hygiene to reduce this preventable condition.

INTRODUCTION

Periodontitis is an inflammatory disease of supporting tissues of the teeth caused by specific microorganisms, resulting in progressive destruction of the periodontal ligament and alveolar bone, with periodontal pocket formation, gingival recession, or both. Periodontal disease and caries are the most common dental problems worldwide. Globally, around 15%–20% of middle-aged adults have severe periodontal disease, with Asians having the third highest prevalence rates.[1] In India, according to the National Oral Health Survey (2002–2003), the prevalence was 89.6% and 79.9% among those aged 35–44 and 65–74 years, respectively.[2] Periodontal infection is associated with many modifiable and nonmodifiable risk factors which need to be identified to plan prevention and control.[345]

This study was done to compare the prevalence of chronic periodontitis in individuals with and without type 2 diabetes, aged 35–65 years, residing in a rural block in Vellore, Tamil Nadu. Factors associated with chronic periodontitis among those with diabetes and prevalence of other dental conditions were also assessed.

MATERIALS AND METHODS

The study was done between October 2015 and April 2016, in nine villages of Kaniyambadi block in Vellore, Tamil Nadu where a World Health Organization (WHO) STEPS survey had been carried out in 2010–2012, among 3799 participants.[6] The literacy rate in this rural population was 63% and the main occupations were agriculture and manual labor among men and manual labor or household work among women.[6] A list of individuals with and without diabetes currently aged 35–65 years was obtained for the current study on periodontitis, using the results of the previous cross-sectional survey.[6]

Inclusion criteria

Cases: Individuals with type 2 diabetes (on medication or diagnosed in a previous survey based on fasting blood glucose ≥126 mg/dl), aged 35–65 years, in the selected villages.

Control group for comparison: individuals without diabetes in the selected villages aged 35–65 years.

Exclusion criteria

Participants who had <10 teeth currently or those who had undergone any periodontal treatment within the past 1 year were excluded from the study.

Sampling

The study population had 348 individuals with type 2 diabetes, of 3105 individuals aged 30–64 years [Figure 1]. A sampling frame of 250 diabetic patients was selected by simple random sampling from the list of 348 individuals with diabetes. A list of 250 nondiabetics was also obtained by simple random sampling from the list of participants who did not have diabetes in the previous survey [Figure 1], to obtain a frequency-matched control group for comparison with the group with diabetes. No individual matching was done. The dentist who collected the data was not aware of who was a diabetic, from the given list of all selected participants. The dental examination was done initially for assessing periodontitis and oral hygiene status, before asking questions related to diabetes, to decrease information bias by blinding the investigator to the diabetic status of the participant.

Figure 1

Flowchart showing selection of study participants

Assuming prevalence of chronic periodontitis among diabetics and nondiabetics, respectively, as 59.0%[7] and 34.8% (p1 and p2),[8] alpha error of 5%, and power of 80%, the sample size needed was seventy in each group. The formula used was the sample size calculation for difference in proportions: 2 pq (Zα + Zβ)2/(p1 − p2)2, where P is an average of p1 and p2, while q is 1-p. As there was a possibility that the participants identified in the previous study in 2010–2012 may have moved out, refuse participation or be unavailable, a list of 250 participants from each group was used to obtain the required number of seventy participants in each group. The participants were contacted consecutively from the list until the sample size in each group was met.

Study definitions and tools

Four posterior and two anterior teeth were examined for chronic periodontitis and oral hygiene. Chronic periodontitis was diagnosed based on the periodontal pocket depth, presence of calculus, and presence of bleeding on probing. Each index tooth was given a score based on the Community Periodontal Index and Treatment Needs (CPITN) codes, with codes 2 and above classified as chronic periodontitis.[91011] Those with CPITN code 2 were classified as mild periodontitis, code 3 as moderate, and code 4 as severe periodontitis. The CPITN index also called the CPI is recommended by the WHO as a validated tool which can be used in epidemiological surveys on oral health.[12] Clinical examination of the mouth was done using a dental probe, mouth mirror, and a CPI probe.

The Simplified Oral Hygiene Index (OHI-S) (Greene and Vermillion 1964) was used to determine oral hygiene, summing the simplified debris index and the simplified calculus index scores, based on numerical calculations representing the amount of debris and calculus formed on the six selected tooth surfaces.[11] Poor oral hygiene was defined as OHI-S scores between 3.1 and 6.0. The OHI-S, a simpler validated version of the 12 surface OHI, shown to have a high correlation with the OHI by Greene and Vermillion, is useful for population-based epidemiological surveys on periodontal disease.[11]

Glycemic control was defined based on the latest (within last 3 months) blood sugar levels available or a random capillary glucose measurement at the time of data collection. Poor glycemic control was defined as fasting blood sugar level >130 mg/dl, postprandial value >200 mg/dl, HbA1c >7%, or random capillary glucose >200 mg/dl, depending on which measure was available.[13] Risk factors for chronic periodontitis as well as for moderate-to-severe periodontitis were analyzed using unadjusted and adjusted odds ratios obtained using logistic regression.

RESULTS

The number of participants with type 2 diabetes was 98, while the number of participants without diabetes was 104. The proportion of males among the group with type 2 diabetes was 42.9%, while it was 29.8% among the group without diabetes, Chi-square, P = 0.054. The mean age of those with diabetes was 56.39 and 49.54 years for those without diabetes, independent t-test, P < 0.001. The median duration of diabetes was 60 months (range: 1–228 months), with only four individuals who had been diagnosed within the past 12 months.

The prevalence of chronic periodontitis among the group with diabetes was 45.9% (95% confidence interval [CI]: 40.9%-–50.9%), while it was 35.6% (95% CI: 30.91%–40.29%) among those without diabetes, odds ratio: 1.53 (95% CI: 0.87–2.70), Table 1. As there was a significant age difference between the diabetic group and the nondiabetic group, the prevalence rate of chronic periodontitis in the nondiabetic group was adjusted by direct standardization to the age distribution of the group with diabetes. The age-adjusted rate of chronic periodontitis in the group without diabetes was 37.8% (95% CI: 28.1%–47.6%).

Table 1

Prevalence of chronic periodontitis among diabetics and nondiabetics

As there was a difference in gender distribution among the two groups, with a higher proportion of males in the group with diabetes, the results of prevalence of periodontitis are shown separately for both genders [Table 1]. Among females, diabetics were more likely to have periodontitis than nondiabetics, odds ratio: 2.46 (95% CI: 1.18–5.14). However, there was no significant difference in the prevalence of periodontitis among males with and without diabetes [Table 1].

The comparison of severity of periodontitis among diabetics and nondiabetics is also shown in Table 1, with 38.8% of diabetics having moderate-to-severe periodontitis, as compared to 29.9% among nondiabetics. The prevalence of other dental disorders was similar in both groups, with dental caries being present in 43.5% of those with diabetes and 56.5% of those without diabetes [Table 2].

Table 2

Prevalence of other dental disorders among those with and without diabetes

Analysis of risk factors for chronic periodontitis among those with type 2 diabetes revealed that poor oral hygiene (odds ratio: 8.33, 95% CI: 3.33–25.00) and smoking (odds ratio 3.51, 95% CI: 1.17–10.51) were the most significant risk factors for periodontitis among those with diabetes [Table 3]. Individuals with a low socioeconomic status also had a higher prevalence of periodontitis than those with higher socioeconomic status, odds ratio: 3.19, (95% CI: 1.00–10.12) [Table 3].

Table 3

Factors associated with chronic periodontitis among subjects with diabetes

Analysis of risk factors for moderate-to-severe forms of periodontitis also showed that poor oral hygiene was the most important risk factor, odds ratio: 10.59 (95% CI: 3.95–28.30) [Table 4].

Table 4

Factors affecting moderate-to-severe periodontitis among those with diabetes

DISCUSSION

This cross-sectional study in rural Vellore, Tamil Nadu, found that the age-adjusted prevalence of chronic periodontitis among the general population aged 35–65 years was 37.8%, as compared to 45.9% among those with diabetes. The prevalence among the general population was lower than the national prevalence of 86.6% from the National Oral Health Survey (2002–2003), as well as a study from Chennai (2010), which showed a prevalence of 82% among those aged 15–60 years.[214] However, a study done in urban Nagpur had also shown a similar prevalence of periodontitis (34.8%) in the general population.[8] The lower prevalence in Vellore may be associated with the fact that this rural block is well covered by both private and public health-care systems and therefore may have increased accessibility for oral health care. A recent systematic review of studies between 2006 and 2015, highlighted the need for a representative district-wide nationwide survey, which could also help in planning population-based control programs, similar to the findings of a review in 2011.[1516]

A study in Pakistan (2015) among those aged 20–60 years found a similar prevalence of periodontitis of 34.5%, another in Bangladesh (1990) found a prevalence of 42%, while a study among urban residents of Brazil (2004) showed a prevalence of 79% of clinical attachment loss.[171819] Studies done in developed countries such as the United States and Canada showed a prevalence of 47% and 67.8%, while a study in France among those aged 35–64 years showed a higher prevalence of 82.23%.[202122]

A positive association between type 2 diabetes and chronic periodontitis has been found previously, with diabetes mellitus associated with severe forms of the disease.[23] In this study also, the prevalence of chronic periodontitis was higher among those with diabetes (45.9%) as compared to those without (37.8%). A case–control study done in Bangalore showed that individuals with diabetes had 2.1 times higher odds of having chronic periodontitis as compared to those without diabetes.[24]

In this study, poor oral hygiene was the most important risk factor associated with chronic periodontitis among those with type 2 diabetes, as prevalence in those with poor oral hygiene was 71.4% as compared to 30.3% among those with good oral hygiene. A similar result was seen in a hospital-based study in Karnataka among patients attending a dental clinic, where 81.3% of those with poor oral hygiene had periodontitis as compared to 14.5% with good oral hygiene.[25] Thus, importance of improving oral hygiene status is an important preventive measure that needs to be universally emphasized to reduce the burden of chronic periodontitis.

Low socioeconomic status was also associated with chronic periodontitis, similar to a study from Nellore.[4] This may be related to poor oral hygiene as well as poor access to dental care. Smoking was also found to be associated with chronic periodontitis in this study, similar to the results from previous studies, indicating the need to target this modifiable risk factor for promoting oral health.[1826]

Visits to a dentist and obesity were not significantly associated with chronic periodontitis as found in some other studies, possibly due to a lower sample size in this study.[2627] We also did not find any significant association between glycemic control and chronic periodontitis although other studies have found higher glycemic status to be associated with periodontitis.[28] However, our analysis was limited by lack of uniform availability of data on glycemic control. Inability to obtain a venous blood sugar or glycosylated hemoglobin measurement to check glycemic control for all those with diabetes was a limitation of the study. Similarly, duration of diabetes, which has previously been found to be a significant risk factor associated with periodontitis,[7] was not found to be significant in this study, probably because the median duration of diabetes in this study was only 5 years and the effect of diabetes on the periodontium may take longer.

A review article, examining the relationship between diabetes and chronic periodontitis, concluded that the relationship is bidirectional, and more understanding is required regarding the impact of periodontal diseases on diabetes.[16] Given the high proportion (45.9%) of those with diabetes who are affected by this condition, long-term effect of periodontitis on diabetes needs further research.

The main strength of this study was that the sample was a population-based sample, rather than a hospital-based study where the participants are usually not representative of all those with or without diabetes. One of the constraints was the small sample size, especially for studying risk factors, which was due to the difficulty in conducting a house-to-house survey to identify participants and conduct a dental examination. Therefore, the prevalence of periodontitis among persons with and without diabetes from this study is not generalizable to the whole of rural India. Although the CPI is an acceptable tool used in epidemiological surveys on oral health, it is limited by a low sensitivity (58%) but has a higher specificity (80.6%).[29] This indicates that the prevalence obtained in this study may be an underestimate of the true prevalence of chronic periodontitis.

CONCLUSIONS

The management of a tooth affected with chronic periodontitis is scaling or complex periodontal surgery, depending on the severity. However, nonsurgical management is the first line of management following which surgical management may be required. If diabetes plays a role in the progression of chronic periodontitis, then current management practices alone may not be effective, as they would be unable to target the root cause of the disease progression, which would be the effect that diabetes has on the periodontium.[22] Management of diabetes leading to good glycemic control would be an important strategy for prevention of chronic periodontitis in individuals with diabetes, along with promoting better oral hygiene, especially among those with lower socioeconomic status. Long-term dental follow-up visits are required for all those with diabetes. As periodontitis has also found to be significantly associated with cardiovascular diseases such as coronary artery disease, targeting patients with diabetes for prevention of periodontitis is even more important given the rise in cardiovascular mortality in India.[30] Active efforts to include primary prevention for chronic dental diseases need to be a part of the country's efforts to control the burden of noncommunicable diseases. Promotion of healthy habits to improve oral hygiene will be a key component of such efforts.

Financial support and sponsorship

This study was financially supported by Fluid research grant, Christian Medical College, Vellore, Tamil Nadu, India.

Conflicts of interest

There are no conflicts of interest.