Overview

People may be rather surprised to hear about the relationship between oral health and mental health. Studies indicate an unexpectedly close interaction between the two, with oral conditions such as tooth decay and tooth loss increasing the risk of mental disorders including psychosis, depression and anxiety (and vice versa). Maintaining oral health through regular visits to the dentist proves to be more common among individuals with better mental health.¹ It is worth nothing, though, that good oral health is one of the many components of a healthy lifestyle, which is crucial in ensuring good mental health, alongside regular sleep cycles, controlled alcohol consumption and a healthy diet.

What is Tooth Decay?

Despite improvement in recent years, tooth decay remains a common oral problem in the UK, with 31% of adults having the condition as of 2024. Tooth decays result in cavities, which are holes formed on the hard surface of the teeth. If untreated, the holes can grow larger, causing cavities to affect the deeper areas of the tooth, including the nerves and roots. 

Symptoms

Symptoms of severe cavities include the following:

• Constant toothache
• Tooth Sensitivity when drinking/eating something cold or/and hot
• Tooth pain when biting
• Visible black/brown holes and stains

Such symptoms can be mistaken for worn-down tooth enamel or cracked/chipped tooth, thus it is difficult to self-diagnose. Early stages of cavities are usually asymptomatic, leaving them unnoticed. For such reasons, regular visits to the dentist is important to find possible signs of tooth decay and avoid invasive treatment that would be required for more severe cavities. 

Causes and Risk Factors

Tooth decay occurs due to a combination of – 1) a sugary diet and 2) the lack of, or incorrect brushing techniques. Poor tooth brushing results in plaque formation which damages the teeth over time. 

These plaques are formed due to bacteria that exist in your mouth.² These bacteria feed on sugars and produce acids which erode the teeth, eventually growing into cavities. These plaques can be removed by correct brushing techniques and regular maintenance by dentists.

Although a high sugar diet is a key contributor to tooth decay, recent studies have revealed a range of other factors too, including oral microbiome, age, sex, teeth structure, social class, geographical location and salivary flow.³ Certain bacteria that live in the mouth, for example, mutans streptococci is considered to be the main culprit of tooth decay, because they produce strong acids by feeding on sugar.⁴ Meanwhile, although sex differences in oral decay are small in young children, in the older population, women are more likely to possess restored teeth compared to men.⁵

Understanding Mental Health

Common Mental Health Issues

Depression

Although a large fraction of the population may still consider depression as a temporary period of feeling down or as a trivial condition, depression is a real condition that affects a significant part of the UK population. In 2021, around one in six adults were reported to have experienced depression according to the Office for National Statistics. Depression is defined as a mood disorder that causes a persistent feeling of sadness and lack of interest. Depression has detrimental effects on one's life standard as it is associated with somatic and cognitive changes that can significantly affect one’s lifestyle.⁶

Generalised Anxiety Disorder (GAD)

GAD is a condition where an individual experiences long-term anxiety against multiple situations or events, resulting in unrest for many days. The condition tends to be observed more frequently in the younger population, with 28% of young adults between the ages of 16 and 29 in the UK experiencing some form of anxiety.

Interrelationship Between Oral and Mental Health

Impact of Tooth Decay on Mental Health

Poor oral health can affect mental health in different ways. 

• Firstly, patients who experience pain from tooth cavities may feel uncomfortable eating/drinking. In severe cases, this can affect the patient's social life and contribute to a range of mental health issues
• Secondly, patients with severe tooth decay may feel worried about their oral health, resulting in the development of prolonged anxiety. It is important that people have the correct knowledge about oral health to avoid feeling overly concerned about their condition. Regular dentist visits are a great opportunity to learn and talk about oral health. In truth, studies show that more frequent dental visits are associated with better mental health¹ 
• Patients with cavities on the incisors/canines (front region of teeth) may feel bothered by the dark stains that appear on the surface of the tooth. This can negatively affect the patient’s self esteem and body image

Impact of Mental Health on Tooth Decay

Mental health issues are thought to also have a range of detrimental effects on oral health.

• One of the common symptoms of depression is the lack of care towards oneself. This includes oral care as well, as the frequency of brushing teeth and flossing decreases in depressed individuals.⁷ This increases the risk of tooth decay and other oral diseases
• Patients with anxiety may also have an irrational fear of dentists, also known as dental phobia. Lack of, or insufficient visits to dental clinics can accelerate plaque development and cavity, resulting in aggravation of symptoms
• Another symptom of depression is poor diet. High sugar consumption and an imbalanced diet can increase the likelihood of tooth decay

Other Oral Diseases Caused by Poor Mental Health

Dry Mouth

Dry mouth is a common side-effect associated with anti-depressants, anti-psychotics and mood stabilizers.⁸ Saliva contains many antimicrobial peptides such as lysozyme and lactoferrin, which can kill bacteria that cause tooth decay.⁹ Hence, dry mouth can elevate the risk of tooth erosion. 

Teeth Erosion

Vigorous brushing action is known to remove the gum and teeth enamel, leading to teeth sensitivity. Such behaviour is typically observed in patients with bipolar disorder or obsessive-compulsive disorder.¹⁰

Bruxism

Psychological factors are known to be one of the key contributors to bruxism, or teeth grinding. Not only people can teeth grind during the night, those who experience a lot of stress, competitiveness and anger can teeth grind when they are awake too. Teeth that are under high mechanical stress may appear flat, or in worse cases be clipped/cracked. Bruxism can cause teeth sensitivity, jaw pain, headaches and lack of movement in the temporomandibular joint, which can all contribute to frustration and prolonged anxiety.¹¹

Clinical Implications and Challenges

The connection between mental health and tooth decay has been fairly established by scientific and statistical analysis. Such findings have helped to raise awareness about the importance of mental health in preventing tooth decay, with more clinics and healthcare websites producing articles and videos about its significance. These can improve the overall health of the population and also encourage individuals to consider therapy to check for any mental disorders. Perhaps it can provide possible solutions for individuals who struggle with maintaining good oral health or brushing/flossing habits. To further support this, professional dental clinics could advise therapies, counselling and antidepressant medication if the patient's condition is found to be associated with poor mental health.

In other words, however, patients who struggle to maintain oral hygiene due to poor mental health would require additional therapy. This is likely to greatly complicate and prolong the treatment than usual, while the oral disease may relapse if the patient continues to suffer from mental health issues. Therefore, there is great importance in building a clear treatment plan and accurately communicating with the patient about their condition. Educating the patient with the correct brushing and flossing technique is also important to prevent anxiety-induced over-brushing. Building up healthy dental habits takes time too, hence a lot of patience and consistent effort is required for improvement of dental health, which can be difficult in patients with mental health issues. 

Summary

Oral health and mental health are closely interconnected and issues in either one can significantly affect the other. Frequent dental visits help to improve mental health by managing/treating tooth decay that can damage mental health and self-esteem, while it is also an opportunity to learn about correct brushing techniques and oral care. Some people with GAD may have dental phobia, which prevents them from visiting dental clinics. In such scenarios, therapies and counselling are helpful, while healthcare websites are great resources filled with information about oral health and dental care.