Teeth have different shapes and sizes. Teeth that have deep grooves are susceptible to cavities because they tend to catch and retain food particles easily. These teeth are hard to clean because at their deepest point, the groove is close to the root of the tooth. Any erosion of enamel around this point will make the tooth vulnerable to sensitivity and pain. If left uncleaned or partially cleaned, decay in these grooves will cause cavities. Thus, it is important to use mouthwash regularly and also ensure that you brush your teeth effectively, two or three times a day.