Tooth fractures can range from minor (involving chipping of the outer tooth layers called enamel and dentin) to severe (involving vertical, diagonal, or horizontal fractures of the tooth and/or root). Enamel and dentin are the two outer protective layers of the tooth. The enamel is the outermost white hard surface. The dentin is a yellow layer lying just beneath the enamel. Enamel and dentin both serve to protect the inner living tooth tissue called the pulp. The portion of the tooth that is visible in the mouth is called the crown and is only a part of the entire tooth structure. The remaining portion of the tooth is buried in the bone and is called the root. Different tests are performed in the mouth to determine if a tooth fracture is present. In some instances, dental X-rays can help to diagnose, locate, and measure the extent of tooth fractures.