Cigarette smoking is the number one cause of preventable disease and mortality in the US, leading to 480,000 deaths annually, or 20% of all deaths.

Over 16 million people live with a smoking-related illness in the US, according to figures from the Centers for Disease Control and Prevention (CDC).

In 2014, the CDC estimated that 16.8% of Americans aged 18 years and over were cigarette smokers, or around 40 million adults.

Much recent research has focused on imbalances in the gut microbiota and how they relate to immune disorders such as Crohn's disease and gastrointestinal cancers.

There are around 600 species of bacteria in the human mouth. Over 75% of oral cancers are thought to be linked to smoking, but it remains unclear whether microbial differences in the mouth affect the risk for cancer.

Visiting the dentist may help you to think more clearly in later life, suggests research published in the Journal of the American Geriatrics Society, which links oral health with cognitive well-being. The researchers caution, however, that more studies are needed.

According to the Mayo Clinic, poor oral health may contribute to heart disease, due to the spread of bacteria, while diabetes and HIV/AIDS can exacerbate oral health problems by reducing the body's resistance to infection.

As the older population continues to expand, oral health and cognition have become important areas of study, with researchers speculating that a common inflammatory pathway may hold the key to a link, if such a link exists.

The authors note that around 36% of people in the US aged over 70 years are living with some degree of cognitive decline. According to the Alzheimer's Association, around 5.4 million people in the US have Alzheimer's disease - the most common form of dementia.

Gum disease is a major cause of tooth loss and a challenge to treat. Now, new research suggests why silicon nitride - a ceramic material used in spinal implants - could lead to effective, new types of gum disease treatment.

Periodontitis is a serious, chronic, non-communicable gum disease that damages the soft tissue and bone that support the teeth. Estimates suggest it affects 15-20% of middle-aged (35-44 years) adults. The disease starts when the bacterium Porphyromonas gingivalis infects the tissue around the teeth, giving rise to gum inflammation. If this is not treated, the condition progresses and the bacteria begin to eat away at the bone around the teeth.

The disease starts when the bacterium Porphyromonas gingivalis infects the tissue around the teeth, giving rise to gum inflammation. If this is not treated, the condition progresses and the bacteria begin to eat away at the bone around the teeth.

Having untreated gum disease not only leads to tooth loss, but it also raises risk of heart attack or stroke.

Treatment options include deep cleaning - such as scaling and root planing - to remove the built-up plaque that harbors bacteria, plus antibiotics and surgery.