[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.
PURPOSEThe purpose of this study was to estimate the effects of occlusal stability to identify action mechanisms of mouthguards, known to have a modulatory effect on limb muscle function.MATERIALS AND METHODSThis study included 20 male subjects to perform the isokinetic muscle tests and the Wingate anaerobic power test on both knee joints under five closed-mouth conditions: without or with 4 types of mouthguards with thickness of 2 mm based on premolar area: (1) full-coverage, (2) anterior partial-coverage, (3) right posterior partial-coverage, and (4) left posterior partial-coverage. The obtained results were subjected to One-way ANOVA with repeated measures, followed by post hoc test of the contrast method (α=.05).RESULTSThere was no significant difference between the closed position with and without a full-coverage mouthguard in all variables. However, significant differences were observed between with and without a partial-coverage mouthguard in muscular endurance during extension of the left knee, muscular power and endurance during flexion of the right knee. Additionally, significant differences were found between occlusal states with full- and partial-coverage mouthguards in muscular power and endurance during extension of the left knee.CONCLUSIONThese findings indicate the elevation of vertical dimension by 2 mm or the inducement of occlusal stability had little effect on isokinetic muscle strength and anaerobic performance, while uneven distribution of occlusal force might have some positive effects.
Previously, we showed that Sox2-Cre;Fam20C fl/fl mice in which Fam20C was ubiquitously inactivated had severe defects in dentin, enamel, and bone, along with hypophosphatemia. It remains to be determined if the enamel defects in the mice with universal inactivation of Family with sequence similarity 20-C (FAM20C) were associated with the dentin defects and whether hypophosphatemia in the knockout mice contributed to the enamel defects. In this study, we crossed Fam20C fl/fl mice with keratin 14-Cre (K14-Cre) transgenic mice to specifically inactivate Fam20C in the epithelial cells, including the dental epithelial cells that are responsible for forming tooth enamel. X-ray, backscattered scanning electron microscopic, and histological analyses showed that the K14-Cre;Fam20C fl/fl mice had severe enamel and ameloblast defects, while their dentin and alveolar bone were not significantly affected. Accordingly, serum biochemistry of the K14-Cre;Fam20C fl/fl mice showed normal phosphate and FGF23 levels in the circulation. Analysis of these data indicates that, while FAM20C is a molecule essential to amelogenesis, its inactivation in the dental epithelium does not significantly affect dentinogenesis. Hypophosphatemia makes no significant contribution to the enamel defects in the mice with the ubiquitous deletion of Fam20C. A supplemental appendix to this article is published electronically only at http://jdr.sagepub.com/supplemental.
Background Oral mucocele is the most common minor salivary gland lesion with good prognosis after surgical removal. However, its recurrence is not rare, sometimes bothersome. This study aimed to identify the possible predictive variables affecting the recurrence rate of oral mucocele. Material and Methods The histoclinical data of 164 patients diagnosed with oral mucocele were retrospectively obtained by reviewing dental records. The predictive variables for its recurrence were identified by analyzing its recurrence rate according to clinical variables. Results The recurrence rate showed the significant differences according to location and age. Oral mucocele recurred with significantly higher frequency on the ventral mucosa of tongue (50.0%) than on the labial/buccal mucosa (8.8%). Its recurrence was significantly more common in the younger patients (aged < 30 years, 16.0%) than in the older patients (aged > 30 years, 4.4%). However, there was no significant difference in recurrence rates between surgical procedures using scalpels and those using lasers. Conclusions Patients with oral mucocele should be more carefully informed of its possible recurrence, especially when it is found on the ventral surface of the tongue or in a younger population. Key words: Age, laser, oral mucocele, recurrence, tongue.
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