A tooth-attach wearable device (C, C1, C2, C3) having a tooth attachment (P1, P2, P3) corresponding to a shape of a tooth, the wearable device (C, C1, C2, C3) comprising: a sensor head configured to couple with one surface of the tooth attachment (P1, P2, P3), to be exposed inside the oral cavity, and to sense a temperature of a patient; by wherein a time measurer configured to measure an amount of time in which the tooth attachment (P1, P2, P3) is attached to the tooth, based on the temperature sensed at the sensor head; wherein a thermoelement is provided to the sensor head, the thermoelement generates electricity and supplies the generated electricity to the time measurer only when the temperature sensed at the sensor head is between 35 °C and 38 °C; wherein the time measurer measures and accumulates the amount of time only in response to receiving the electricity being supplied from the thermoelement; and wherein the wearable device (C, C1, C2, C3) further comprises a sensor chip configured to couple with the sensor head, to fix to the tooth attachment (P1, P2, P3), and to supply electricity to the sensor head, wherein the wearable device (C, C1, C2, C3) comprises a communication controller provided to the tooth attachment (P1, P2, P3), and configured to store temperature information of the patient sensed at the sensor head, and to transmit the stored temperature information, wherein the communication controller comprises a data storage configured to store the temperature information of the patient sensed at the sensor head as data; and a data transmitter configured to remotely transmit the data stored in the data storage, the wearable device (C, C1, C2, C3) further comprising: a snoring sensor configured to couple with one surface of the tooth attachment (P1, P2, P3), and to sense at least one of a vibration, an oxygen saturation, and sound by snoring, wherein the sensor chip is configured to couple with the snoring sensor, and to supply electricity to the snoring sensor; and the communication controller is configured to store at least one of a vibration, an oxygen saturation occurring in breathing, and a snoring sound sensed at the snoring sensor, and to store the sensed at least one of a vibration, an oxygen saturation occurring in breathing, and a snoring sound. a sensor head configured to couple with one surface of the tooth attachment (P1, P2, P3), to be exposed inside the oral cavity, and to sense a temperature of a patient; by wherein a time measurer configured to measure an amount of time in which the tooth attachment (P1, P2, P3) is attached to the tooth, based on the temperature sensed at the sensor head; wherein a thermoelement is provided to the sensor head, the thermoelement generates electricity and supplies the generated electricity to the time measurer only when the temperature sensed at the sensor head is between 35 °C and 38 °C; wherein the time measurer measures and accumulates the amount of time only in response to receiving the electricity being supplied from the thermoelement; and wherein the wearable device (C, C1, C2, C3) further comprises a sensor chip configured to couple with the sensor head, to fix to the tooth attachment (P1, P2, P3), and to supply electricity to the sensor head, wherein the wearable device (C, C1, C2, C3) comprises a communication controller provided to the tooth attachment (P1, P2, P3), and configured to store temperature information of the patient sensed at the sensor head, and to transmit the stored temperature information, wherein the communication controller comprises a data storage configured to store the temperature information of the patient sensed at the sensor head as data; and a data transmitter configured to remotely transmit the data stored in the data storage, the wearable device (C, C1, C2, C3) further comprising: a snoring sensor configured to couple with one surface of the tooth attachment (P1, P2, P3), and to sense at least one of a vibration, an oxygen saturation, and sound by snoring, wherein the sensor chip is configured to couple with the snoring sensor, and to supply electricity to the snoring sensor; and the communication controller is configured to store at least one of a vibration, an oxygen saturation occurring in breathing, and a snoring sound sensed at the snoring sensor, and to store the sensed at least one of a vibration, an oxygen saturation occurring in breathing, and a snoring sound.