Severe Gum Disease and Its Link to Diabetes and Chronic Conditions: A Guide for General Practitioners

Clin Asst Prof Chee Hoe Kit
Senior Consultant, Periodontics Unit, Department of Restorative Dentistry, National Dental Centre Singapore;
Lead, Dental Clinic at Diabetes & Metabolism Centre, Singapore General Hospital

Severe gum disease, or periodontitis, is highly prevalent and strongly linked to systemic conditions, particularly diabetes. Awareness of its risk factors, and bidirectional relationship with chronic diseases can help general practitioners identify early signs, and support multidisciplinary care and overall health outcomes.

INTRODUCTION

Gum disease, known medically as periodontal disease, is a common infection and chronic inflammation of the supporting tissues around the teeth (the gingiva, periodontal ligament and alveolar bone).

The main cause of gum disease is the accumulation of bacterial plaque and calculus on teeth and their root surfaces which results from poor oral hygiene and self-care. Other causes or risk factors of gum disease include smoking, diabetes, stress, medication (with oral side effects), malocclusion (crooked/crowded teeth), hormonal changes (during pregnancy), poor nutrition/obesity, genetics or underlying systemic conditions.

TYPES OF GUM DISEASE

There are two most common types of gum disease - gingivitis and periodontitis.

Gingivitis is the initial form of gum disease and is therefore the mildest condition. The gums are inflamed and appear more reddish (as compared to pink) around the teeth, become puffy, and may bleed easily especially when brushing. Gingivitis, however, is a reversible condition.

Periodontitis is the more serious form of gum disease that follows prolonged untreated gingivitis. This condition has all the same symptoms as gingivitis albeit more pronounced. The distinguishing feature is the loss of attachment where there is alveolar bone resorption around the roots and concomitant gum recession around the teeth. Periodontitis is irreversible and left untreated will result in tooth mobility and ultimately loss of teeth.

STAGES OF PERIODONTITIS

There are four classifications of periodontitis:

Stage 1
Mild or early periodontitis

The infection begins to spread below the gum line causing the gums to pull away from the teeth, creating shallow pockets where bacterial plaque can accumulate. The greatest loss of attachment between two teeth is 1-2 mm and there is generally < 15% bone loss horizontally around the teeth. No tooth loss occurs at this stage.

Stage II
Moderate periodontitis

Progressive form of gum disease with the supporting structures of the teeth experiencing damage. The pockets between the teeth and gums become deeper, allowing more plaque and calculus to accumulate and cause additional damage. The greatest loss of attachment between two teeth is 3-4 mm and there is generally 15-33% bone loss horizontally around the teeth. There is no tooth loss during this stage.

Stage III
Severe periodontitis

Involves deeper infection and more significant gum and bone tissue destruction. Teeth may become loose, shift position, or require extraction due to inadequate support. In addition to the complexity of Stage II periodontitis, the greatest loss of attachment between two teeth is 5 mm or more and bone loss extends to the middle third of the root or beyond with some bone loss vertically and at furcation areas. Tooth loss due to gum disease is no more than four teeth and there is moderate alveolar ridge defects.

Stage IV
Very advanced periodontitis

Involves deeper infection and more significant gum and bone tissue destruction. In addition to the same criteria and complexities of Stage III periodontitis, there is the need for complex rehabilitation due to masticatory dysfunction and bite collapse, teeth drifting or flaring. Loss of five teeth or more due to gum disease falls under this stage and there is severe ridge defects.

PREVALENCE

Gum disease could be the most common disease known to mankind. According to the latest fact sheet of the World Health Organization, severe gum disease is estimated to affect more than 1 billion cases worldwide. The 2021 Global Burden of Disease study reported that countries in Asia have some of the highest prevalences of severe periodontitis.

Based on the 2019 National Adult Oral Health Survey in Singapore, in which 663 adult Singaporeans from a range of household types and ethnic backgrounds completed both the survey questionnaires and clinical examination, it was found that:

• 77.6% suffered from some form of gum disease 
• 56.9% had moderate to severe periodontitis that increased with age, with a higher proportion in males

ASSOCIATIONS WITH DIABETES MELLITUS

Gum disease has been linked to a wide range of common medical conditions and amongst all plausible relationships between oral health and systemic health, the link between gum disease and diabetes has been the most well-studied and established. In reality, however, periodontitis is a complication of diabetes that is under-appreciated by physicians and neglected by diabetes patients largely due to lack of awareness.

While both periodontitis and diabetes are complex chronic diseases, the inter-relationship between these two is bidirectional.

Diabetes and Periodontal Risk

People living with diabetes are 2-3 times more at risk for periodontitis compared to individuals without diabetes. This may be because people with diabetes are more susceptible to contracting infections. The risk for periodontitis increases with poorer glycaemic management.

Glycaemic Level and Link to Diabetes

Similarly, periodontitis is associated with higher glycated haemoglobin (HbA1c) levels and worse diabetes complications in type 2 diabetes. In people without diabetes, periodontitis is associated with higher fasting blood glucose levels, with severe periodontitis associated with elevated risk of developing diabetes.

Screening Opportunity

The presence of gum disease therefore may be an early sign of diabetes mellitus. Since early diagnosis of prediabetes or diabetes is essential for the prevention of diabetes complications, severe gum disease has been shown to serve as a valuable risk indicator.

Since the individual visits the dentist more frequently than to a medical practitioner, the dental office can be a strategic location to screen for unknown hyperglycaemia. Based on the strong connection between gum disease and diabetes, a large study conducted in National Dental Centre Singapore (NDCS) found that routine dental visits could play a crucial role in identifying undiagnosed diabetes and prediabetes.

DIABETES AND GUM DISEASE

Understanding the link for better oral-systemic health

• Diabetes increases the risk of having gum disease (periodontitis) as compared to people without diabetes. 
• Severe gum disease may cause blood sugar to increase and make it more difficult to control
• Proper treatment of gum disease will improve oral health and may help to control blood sugar.

NDCS Study

In 1,074 dental patients who reported no known diabetes and completed a medical questionnaire with a full-mouth periodontal examination followed by a finger-prick blood point-of-care HbA1c test, those with HbA1c >6.0% were then referred to their medical doctor to confirm their glycaemic status, whereafter 65 (6.1%) received a confirmatory diagnosis of type 2 diabetes and 83 (7.7%) with prediabetes.

Notably, the study showed that patients with severe or Stage III/IV periodontitis and traditional risk factors such as high BMI, family history of diabetes and smoking were significantly at risk of undiagnosed diabetes.

Pathophysiology

The pathogenic mechanisms linking diabetes and gum disease are likely attributed to the upregulation of inflammation of each condition that adversely affects the other.

In individuals with diabetes, the increased deposition of advanced glycation end-products (AGEs) in the periodontal tissues and interactions between AGEs and their receptors lead to activation of local immune and inflammatory responses which contributes to increased inflammation and thus increases the risk for periodontitis.

On the other hand, periodontal microbiome and their products, with inflammatory mediators produced locally in the infected periodontal tissues, enter the circulation and contribute to upregulated systemic inflammation resulting in impaired insulin signalling and insulin resistance, thus exacerbating HbA1c levels, which in turn, contribute to increased risk of diabetes complications (including periodontitis).

Treatment Outcomes

Treatment of periodontitis in people with diabetes has demonstrated improved glycaemic management, with moderate‐certainty evidence of an absolute reduction in HbA1c of 0.43% (4.7 mmol/mol) at 3-4 months after treatment of periodontitis; an absolute reduction in HbA1c of 0.30% (3.3 mmol/mol) after 6 months and an absolute reduction of 0.50% (5.4 mmol/mol) after 12 months.

A recently published longitudinal cohort study performed locally in Singapore found that non-surgical periodontal therapy including maintenance significantly improved glycaemic outcomes in 154 nonsmoking participants living with type 2 diabetes patients, particularly those with baseline HbA1c > 8.0%.

Clinical Implications

Given that treatment of periodontitis may result in clinically relevant reductions in HbA1c, the oral healthcare team has an important role in the management of patients with diabetes. Improved interprofessional collaboration in relation to diabetes and periodontitis has been advocated by international professional and scientific organisations, though practical and systemic barriers make this challenging globally.

Integrated Multidisciplinary Care

The need for multidisciplinary care in the context of periodontitis and diabetes is long overdue and although the implementation of models of collaborative practice between the dentist and endocrinologist is a challenge, the dental clinic in the Diabetes & Metabolism Centre is presently a worthy collaboration between NDCS and Singapore General Hospital to screen for gum disease in diabetes patients, to educate patients on the links between gum disease and diabetes and to treat diabetes patients with periodontitis.

The setting up of a dental clinic within a one-stop diabetes centre thus promotes periodontal care as part of overall diabetes management which not only minimises or prevents tooth loss due to severe gum disease but may also contribute to better HbA1c levels and thus reduce diabetes-related complications.

ASSOCIATIONS WITH OTHER MEDICAL CONDITIONS

While a causal relationship has not been conclusively established, research suggests that gum disease may contribute to the progression of other diseases which can lead to serious health complications if left untreated. Apart from diabetes, studies have shown that periodontitis is associated with cardiovascular disease and adverse pregnancy outcomes, among others.

Gum disease and cardiovascular disease (CVD)

Epidemiological evidence supports a robust association between gum disease and CVD. Severe periodontitis increases the risk of major adverse cardiovascular events, such as myocardial infarction or stroke, by a factor of 1.4. The primary mechanisms linking both these conditions include chronic inflammation, endothelial dysfunction and microbial dissemination.

Gum disease and chronic kidney disease (CKD)

Gum disease and CKD also share a bidirectional relationship. Patients with CKD are predisposed due to immune dysfunction; as such, they may experience persistent periodontal inflammation that, in turn, accelerates CKD progression with systemic oxidative stress being identified as an important mediator. Observational studies have also shown that patients with advanced periodontal disease are at an increased risk of developing further renal impairment.

Gum disease and adverse pregnancy outcomes

Gum disease has been shown to be significantly correlated with adverse pregnancy outcomes, including preterm birth, low birth weight and preeclampsia. In pregnant women with untreated periodontitis, the risk of such outcomes is about 1.5 times greater than in those without periodontitis. Periodontal infection is thought to alter fetal intrauterine development through systemic inflammation and the dissemination of microflora from periodontal pockets.

Gum disease and rheumatoid arthritis (RA)

Gum disease and rheumatoid arthritis share common inflammatory pathways and genetic predispositions, which underpin the relationship between both these conditions. Studies have shown that individuals with RA are nearly twice as likely to develop periodontitis compared to the general population. This is a reciprocal association, as periodontitis exacerbates systemic inflammation in RA, potentially worsening joint symptoms.

A GP’s Quick Checklist

Identifying Gum Disease in Primary Care

• Red, swollen, or tender gums 
• Bleeding while brushing, flossing or eating hard foods 
• Gums that are receding or pulling away from the teeth, causing the teeth to look longer than before 
• Shaky teeth 
• Teeth drifting away from each other causing spaces that did not appear before 
• Pus oozing between the gums and teeth 
• Persistent bad breath 
• A change in the way the teeth fit together when biting on the upper and lower teeth

CONCLUSION

Collaborative care across dental and medical disciplines can address the systemic effects of severe gum disease, improving both oral and general health outcomes. Given the rising prevalence of periodontitis due to ageing populations, increased life expectancy, and lifestyle issues, such an effort is especially timely.

By considering oral health as an integral component of systemic well-being, healthcare providers can be better positioned to improve quality of life of patients and mitigate the overall impact of severe gum disease.

Dr Chee Hoe Kit has been working as a periodontist in the National Dental Centre Singapore (NDCS) since 2005.

Dr Chee is also a Senior Clinical Lecturer for the National University of Singapore, Faculty of Dentistry postgraduate Periodontology residents and a fellow at the Center for Dentistry and Oral Hygiene, University Medical Center Groningen (UMCG) in the Netherlands.

Dr Chee was a former recipient of the SingHealth Health Manpower Development Plan (HMDP) award in ‘Periodontal Plastic Surgery around Natural Teeth & Implants and Guided Bone Regeneration’ at the Department of Periodontics, University of Washington School of Dentistry in Seattle, USA.

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