Aphthous ulcers treated with a laser:

Aphthous ulcers, also known as canker sores, can cause significant discomfort, featuring painful lesions that occur inside the mouth. The use of laser treatment for these ulcers helps to alleviate pain and promote healing.

When a laser is applied to the affected area, it often increases the temperature of the tissue, which can lead to desensitization. This process occurs because the laser energy can disrupt the nerve endings in the ulcer, reducing the sensation of pain. As a result, the patient experiences less discomfort and a more favorable healing environment.

Additionally, the laser treatment can also help in the formation of new tissue and may eliminate the ulcer more rapidly than traditional methods. However, the immediate effect focuses on the reduction of pain sensitivity, making desensitization the most appropriate choice.

The other options do not accurately capture the effects of laser treatment on aphthous ulcers. The ulcers do not remain unaffected; rather, they undergo significant changes. Sensitization would imply an increase in pain perception, which is contrary to the therapeutic goal of laser application. While some treatments can lead to elimination of the ulcer eventually, the primary action of the laser in this context is based on the desensitization of the tissue.