"Tea tree oil has been found to aid in some dental and oral hygiene needs, such as thrush, gingivitis, and canker sores.
For instance, in one study, it was found to reduce the inflammation caused by gingivitis. Toothpaste containing tea tree oil may help gum disease"
...but it probably won't reduce plaque.
In an unsupervised study of nearly fifty individuals, it was found that brushing your teeth with a tea tree containing gel twice a day reduced the incidence of gingivitis, which is an inflammation of the gums frequently occurring because of not cleaning your teeth regularly.
You might be able to achieve similar results by adding a drop of tea tree oil to your toothbrush and toothpaste before brushing. You can read the results of the study from this 2004 Australian Dental Journal article here. A Canadian study of thrush in patients with HIV/AIDS (PHAs) found that a mouthwash containing Tea Tree oil was effective. The patients had previously been treated with but failed to respond to oral fluconazole 400 mg/day. A little better than one out of four were cured (28%) according to the study. You can read more at the Canadian AIDS Treatment Information Exchange
My Mom used to say that Canker Sores were caused by eating acid foods, strawberries and pineapple mostly. I don't know is that's true or not, unless possibly a food allergy. Just about anything can bring on a case of Canker Sores, also known as mouth ulcers.
They seem to affect more women than men, and may be induced during a particularly stressful time, by a poor diet, or a vitamin or mineral deficiency. Another time may be during hormonal changes or a viral infection of some sort. It's possible you might not ever know what the cause is.
Tea tree oil can be used straight to ease the pain and quite possibly relieve the sore quickly. It's great against viral, bacterial, and fungal infections, and so may work on your canker sore as well. The biggest drawback may be the taste.
To try this home remedy, you'll need 100% pure tea tree oil and some cotton tip swabs. Just soak the swab with tea tree oil, and gently dab it on the sore. you may feel a little tingling sensation, and a little numbing action as the tea tree oil is absorbed into the sore.Click on this text to find out more
Besides working for dental health, tea tree oil might work as a preventative for mouth ulcers. Using tea tree oil toothpaste, followed by a tea tree oil mouthwash, may help to keep your mouth canker sore free. Good dental and oral hygiene helps prevent a lot of problems.