Background/Aims
The appropriate heating temperature for the fabrication of mouthguards using ethylene vinyl acetate sheets is reported to be 80‐120°C. However, the measurement side of the heating temperature has not been determined. The aim of this study was to investigate the influence of the measurement side of the heating temperature when fabricating mouthguards.
Materials and methods
Mouthguard sheets of 3.8 mm ethylene vinyl acetate were vacuum‐formed on working models until the sheet was heated to 120°C. The sheet temperature was measured at the upper side and the lower side. The thickness of the mouthguard was measured at the labial surface of the central incisor, and the buccal and occlusal surfaces of the first molar. The fit of the mouthguard was examined at the central incisor and the first molar by measuring the distance between the mouthguard and the cervical margin of the working model. Differences in the thickness and fit of the mouthguards were analyzed by two‐way analysis of variance.
Results
Mouthguard thickness varied among the measured regions of the central incisors and first molars (P < .01). The thicknesses at the labial surface of the central incisor and buccal surface of the first molar were larger when the sheet temperature measured at the lower side was 120°C compared to when the sheet temperature measured at the upper side was 120°C (P < .01). The fit of the mouthguard was better when the sheet temperature measured at the lower side was 120°C (P < .05).
Conclusions
The sheet temperature should be measured at the lower side of the sheet and it should be 120°C for fabricating mouthguards.
Novel oligonucleotides bearing a polyamine-intercalator conjugate modified at the terminal or the internal position were reported. These modified oligonucleotides showed duplex-stabilization effect, and the thermodynamic analysis and the salt concentration dependency of the duplex stability revealed that the polyamine moiety also acted as the duplex stabilizer by neutralization of the phosphate negative charge.
Background/AimThe aim of this study was to investigate the diagnostic method of root fracture, and to investigate the characteristics of root fractures.MethodsWe reviewed the CBCT images of 45 patients with root fracture. The frequency of diagnosable and impossible to diagnosis on root fracture tooth was counted at first for each radiography technique (intraoral radiography, panoramic radiography, and CBCT). Six characteristics that were considered to influence the occurrence of root fracture were investigated. Diagnostic propriety of root fracture was analyzed by cross‐tabulation. Statistical analysis of each characteristic of root fractures was performed by χ2 test.ResultsThe diagnostic propriety was different by radiography (P < .001). The occurrence of root fracture was different by pulpal vitality (P < .001). The frequency of root fracture was smaller at the tooth with a history of trauma (P < .001). The frequency of root fracture was larger at posterior teeth in comparison with anterior teeth (P = .025). State of root fracture was not different between vertical fracture and horizontal fracture (P = .053). The frequency of the occurrence of root fracture was smaller at caries tooth (P = .014). There was no statistically significant difference among cast core, composite resin core, and no core to the occurrence of root fracture (P = .828).ConclusionsIt was indicated that CBCT was useful for the diagnosis of root fracture. These results suggested that pulpal vitality and position of tooth influenced the occurrence of root fracture, but core construction was not influenced the occurrence of root fracture.
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