Tooth hypersensitivity is a frequent condition that causes discomfort and sometimes severe pain. It is caused by exposure of spots of dentinal tubules to the oral environment. Conventional desensitizing agents (professional pastes, toothpastes, mouthwashes) aim to obliterate the exposed dentinal tubules. Laser desensitization was introduced as an alternative efficient tool for the immediate treatment of tooth hypersensitivity. We explored in vitro the microscopical occluding effects of the Er:YAG laser on exposed dentinal tubules. The clinical application of this technique is also described.