Causes

Your mouth is teeming with microorganisms — as many as 500 different species of fungi, viruses and bacteria. In fact, a healthy mouth can contain anywhere from 1,000 to 100,000 bacteria per tooth. Most of these bacteria are beneficial, helping to break down food and protecting you from harmful microorganisms. A few, such as Streptococcus mutans, the bacterium that causes tooth decay, can be extremely destructive. In a healthy mouth, however, the good microorganisms normally keep the bad ones in check.

But in trench mouth, harmful bacteria grow out of control — first inflaming your gums and eventually damaging or destroying the delicate gum tissue (gingiva) that surrounds and supports your teeth. Large ulcers, often filled with bacteria, food debris and decaying tissue, may form on your gums, leading to severe pain, bad breath and a foul taste in your mouth. In time, as gum and bone tissue is destroyed, you may lose some of your teeth.

Nutritional deficiencies, poor oral hygiene, tobacco use, emotional stress and a compromised immune system can all change the environment in your mouth, leading to an overgrowth of harmful bacteria. Doctors don't fully understand how these bacteria destroy gum tissue, but certain substances, including enzymes and toxins, produced by the bacteria may play a role.

Risk factors

You're much more prone to all types of gum (periodontal) disease, including trench mouth, if you don't brush and floss your teeth regularly. Other risk factors include:

• poor diet

• Smoking or chewing tobacco

• Emotional stress

• A severely compromised immune system, such as occurs in HIV/AIDS