[Purpose] Smartphones are widely used by teenagers and adults for various purposes. As teenagers use smartphones more actively than adults, they are more prone to be addicted to smartphones. Furthermore, excessive usage of smartphones can lead to various psychosocial and physical symptoms. [Subjects and Methods] One hundred teenage subjects were recruited and divided into normal and addiction groups, based on the criteria of the smartphone addiction scale-short version questionnaire. Craniocervical posture and mobility were examined by lateral cephalometric analysis and a cervical range of motion instrument. [Results] Cephalometric analysis showed no significant difference in the craniocervical angles of the resting positions of the two groups. However, measurement using an inclinometer revealed a significantly flexed cervical posture while using smartphones and decreased cervical range of motion in the smartphone-addicted teenagers. The clinical profile of temporomandibular disorders revealed that muscular problems were more frequently presented in the smartphone-addicted teenagers. [Conclusion] These findings suggest that smartphone addiction has a negative influence on craniocervical posture and mobility. Further, it can be postulated that smartphone addiction among teenagers may have contributed to the occurrence of myogenous temporomandibular disorders. In conclusion, smartphone-addicted teenagers may be more frequently subjected to muscular disturbance in the craniocervical area, which probably affects the pathologic process of temporomandibular disorders in teenagers.

Dislocation of temporomandibular joint (TMJ) is troublesome condition which was most commonly shown far anteriorly displaced mandibular condyle to the articular eminence, thereby make it impossible to close one's mouth. It is often referred to as 'open lock' in clinically. Although anatomical modification of the articular eminence through eminectomy has been considered most satisfactory and efffective treatment for managing the recurrent dislocation, it seldom performs clinically due to its invasiveness and patient's reluctance. We thought a shortterm intermaxillary fixation could be of benefit to the patient suffering from recurrent dislocation. A 21-year-old male patient with recurrent TMJ dislocation which had developed after excessive mouth opening, was successfully treated with intermaxillay fixation using microimplant for 2 months. It is more conservative and less complicated method than eminectomy in treating recurrent TMJ dislocation. Transient intermaxillary fixation using microimplant and elastics could be one of treatment options for recurrent TMJ dislocation.