Background/Aim Mouthguard thickness should be maintained to prevent oral trauma by protecting the teeth and the surrounding soft tissue. The aim of this study was to examine the difference in laminated mouthguard thickness according to the laminate order. Materials and methods The mouthguard sheets used in this study were 2.0 mm and 3.0 mm ethylene‐vinyl acetate. The sheets were pressure‐formed using a pressure former, and the laminated mouthguard was fabricated. Two laminate conditions were examined. One condition used the 2.0‐mm sheet for the first layer and the 3.0‐mm sheet for the second layer (condition 2F3S) and the other condition used the 3.0‐mm sheet for the first layer and 2.0‐mm sheet for the second layer (condition 3F2S). The first layer was trimmed to cover the labial surface and incisal edge of the anterior teeth and the buccal and occlusal surfaces of the posterior teeth. The second layer was formed over the first layer. The mouthguard thickness was measured at the labial surface of the central incisor and the buccal and occlusal surfaces of the first molar. Differences in thickness by measurement region of mouthguards formed under different laminate conditions were analyzed by two‐way analysis of variance. Results The mouthguard thickness was significantly different at the measured regions of the central incisors and the first molars (p < .01). The thickness at the labial surface of the central incisor and at the buccal and occlusal surfaces of the first molar became statistically significantly larger with the 3F2S condition than that for the 2F3S condition (p < .05 or p < .01). Conclusions The thickness of the laminated mouthguard became larger when the sheet thickness of the first layer was greater. It is recommended to use the thicker mouthguard sheet as the first layer when fabricating a laminated mouthguard.

These results clarified that the lip contact position with the closed mouth obtained the excellent reproducibility comparing to the conventional methods. These findings suggested that the area of the prolabium of the upper lip might offer an effective index for individual determination of the correct free-way space.

Objectives: Muscle strength decreases with age, causing a decline in physical and orofacial function. However, the impact of physiological and pathophysiological factors on tongue pressure (TP) has not been clarified. The purpose of this systematic review and meta-analysis was to compare and analyse TP and handgrip strength (HGS) between individuals aged <60 and ≥60 years, gender and need for care (independent older adults (IC) and older adults receiving nursing care (NC)). Furthermore, the effect of HGS in physical function on TP was examined.Methods: Human clinical studies reporting HGS and TP were searched systematically using PubMed and Ichushi-Web published from 1969 to Nov 2021. Random-effects meta-regressions were performed to compare between subgroups and to examine the association between HGS and TP (α < .05). Results:Forty-four studies with a total of 10 343 subjects were included. TP and HGS values were significantly higher in people aged <60 years relative to ≥60 years and in IC relative to NC (all p < .001). Regarding gender, there was no significant difference in TP (p = .370). However, a significant gender-dependent difference in TP was observed in people aged <60 years (p < .001), but not in aged ≥60 years in IC group (p = .118) and aged ≥60 years in NC group (p = .895). There was a significant positive correlation of HGS and TP (p < .001).Conclusions: Similar to decrease in HGS, age-related sarcopaenia seems to have an effect on oro-facial muscles like the tongue. Research on rehabilitation measures for oro-facial muscle strength, similar to HGS might be beneficial to improve the personally acquired oro-facial potential.

The purpose of this study was to investigate the characteristics and the detection ability of vertical root fractures in endodontically treated teeth by intraoral radiography and cone-beam computed tomography (CBCT). CBCT images of 50 patients with root fractures in endodontically treated teeth were reviewed, and 36 vertical root fractures were taken in this study. The cause of fracture, core construction, kind of teeth, and fracture direction (bucco-lingual and mesio-distal fractures) were investigated. Detection ability of vertical root fractures by intraoral radiography and CBCT was also examined. Statistical analyses concerning the characteristics were performed by χ2 test, and the detection ability was analyzed by cross-tabulation. All of the fractured teeth were nontraumatized teeth. The vertical root fracture occurrence was not differed by core construction. The vertical root fracture number was largest at the premolar teeth (p = 0.005), and the number of the bucco-lingual fracture was larger than the mesio-distal fracture (p = 0.046). Vertical root fractures were detectable using CBCT, while undetectable by intraoral radiography (p < 0.001). Vertical root fractures occurred easily in premolar teeth with bucco-lingual direction, and CBCT is an adequate radiographic method to diagnose vertical root fracture.

Mouthguards are an important device to help prevent dental trauma. [1][2][3][4] The prevention ability of the mouthguards is influenced by the thickness and the fit of the mouthguard. Mouthguard thickness should be maintained because the mouthguard thickness influences the shock absorption which affects the protection ability. 5 However, the mouthguard thickness becomes thinner after forming with the