Examination for the Factors Involving to Joint Effusion in Patients with Temporomandibular Disorders Using Magnetic Resonance Imaging.

BACKGROUND: This study investigated the factors involving joint effusion in patients with temporomandibular disorders. METHODS: The magnetic resonance images of 131 temporomandibular joints (TMJs) of patients with temporomandibular disorders were evaluated. Gender, age, disease classification, duration of manifestation, muscle pain, TMJ pain, jaw opening disturbance, disc displacement with and without reduction, deformation of the articular disc, deformation of bone, and joint effusion were investigated. Differences in the appearance of symptoms and observations were evaluated using cross-tabulation. The differences in the amounts of synovial fluid in joint effusion vs. duration of manifestation were analyzed using the Kruskal-Wallis test. Multiple logistic regression analysis was performed to analyze the factors contributing to joint effusion. RESULTS: Manifestation duration was significantly longer when joint effusion was not recognized (p < 0.05). Arthralgia and deformation of the articular disc were related to a high risk of joint effusion (p < 0.05). CONCLUSIONS: The results of this study suggest that joint effusion recognized in magnetic resonance imaging was easily observed when the manifestation duration was short, and arthralgia and deformation of the articular disc were related to a higher risk of joint effusion.

Difference in thickness of vacuum-formed mouthguards using ethylene vinyl acetate and polyolefin sheets.

BACKGROUND/AIM: Polyolefin sheets are fabricated in the same manner as ethylene vinyl acetate sheets. The aim of this study was to examine the difference of vacuum-formed mouthguard thickness according to each heating condition using ethylene vinyl acetate and polyolefin sheets. MATERIALS AND METHODS: Mouthguard sheets of 3.0 mm ethylene vinyl acetate and polyolefin were vacuum-formed on working models at three heating temperatures: 85, 95, and 105°C. The thickness of the mouthguard was measured at the labial surface of the central incisor, the buccal surface of the first molar, and occlusal surface of the first molar. Differences in the thickness of the mouthguards according to the sheet materials and the heating conditions were analyzed by two-way analysis of variance. RESULTS: Mouthguard thickness varied between the ethylene vinyl acetate and the polyolefin sheets (p < .01), and the thickness of the ethylene vinyl acetate sheet was greater than that of the polyolefin sheet at all heating conditions. The thicknesses of mouthguards fabricated using the ethylene vinyl acetate and the polyolefin sheets were not different for the three heating conditions in this study. CONCLUSIONS: The thickness was greater for mouthguards fabricated using ethylene vinyl acetate sheet than when polyolefin sheet was used. The thickness of the mouthguards was not different for the three heating temperatures for both the ethylene vinyl acetate and the polyolefin sheets.

Relationship between tongue pressure and handgrip strength: A systematic review and meta-analysis.

OBJECTIVES: Muscle strength decreases with age, causing a decline in physical and oro-facial 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.

Diagnosis of Vertical Root Fractures in Endodontically Treated Teeth by Cone-Beam Computed Tomography.

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.

Examination of facial measurement on the image using a noncontact three-dimensional measurement device.

Background: Producing dentures for edentulous patients is important to improve quality of life of elderly. The determination of the occlusal vertical dimension on producing dentures is one of the key factors for using the dentures comfortably. The purpose of this study is to consider the usefulness of the determination of the occlusal vertical dimension of a facial measurement method applied on scanned facial image using a noncontact three-dimensional measurement device. Materials and Methods: Twenty-four dentulous individuals (mean age 26.6 ± 2.4 years old) were examined in this study. A noncontact three-dimensional measurement device was used for the scanning of the face both in the holding by hand and the fixing to the camera stands situations. The distances between subnasal and gnathion, pupil and oral slit, middle of glabella and subnasal, and right and left corners of the mouth were measured on the scanned face image and compared with the actual values. Results: The significant differences were not recognized on the four measurement items between the distance of actual values and obtained on scanned data (fixing conditions). The coefficients of variation of the distances between subnasal and gnathion, and pupil and oral slit on scanned data (fixing condition) were significantly lower than those at actual conditions (P < 0.05). Conclusion: The results of this study suggested that a stable facial measurement can be successfully implemented by using a noncontact three-dimensional measurement device. This method yields outcomes which match the actual values.

Appropriate fabrication method for pressure-formed mouthguards using polyolefin sheets.

BACKGROUND/AIM: Polyolefin sheet mouthguards are usually formed in the same manner as ethylene-vinyl acetate sheet mouthguards. However, the heating condition of the polyolefin sheet for the pressure-forming process has not been determined. The aim of this study was to examine the appropriate heating condition for polyolefin sheet mouthguards when fabricated with the pressure-formed technique. MATERIALS AND METHODS: Mouthguard sheets of 3.0 mm polyolefin were pressure formed on working models at three heating temperatures: 90°C, 105°C, and 120°C. 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 according to the heating conditions and the measured regions were analyzed using two-way analysis of variance. RESULTS: Mouthguard thickness varied among the measured regions of the central incisors and first molars (p < .01). The greatest thickness was found at the labial surface of the central incisor in mouthguards fabricated with the heating temperature of 90°C (p < .01). The greatest thickness was found in mouthguards fabricated with the heating temperature of 105°C at the buccal surface of the first molar (p < .01), and 105°C or 120°C at the occlusal surface of the first molar (p < .01). The fit was not significantly different among the three heating conditions both at the central incisor and the first molar. CONCLUSIONS: The appropriate heating condition for pressure-formed mouthguards using polyolefin sheets was 90°C to maintain the mouthguard thickness at the anterior teeth area with proper fit.

Difference in laminated mouthguard thickness according to the laminate order.

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.

Protein Ingredient in Saliva on Oral Dryness Patients Caused by Calcium Blocker.

Oral dryness as a side effect of certain drugs is increasing. The aim of this study was to examine the change of the protein ingredient in saliva of oral dryness patients caused by calcium blocker. Six patients taking calcium blocker and six healthy elderly were enrolled. Unstimulated salivary flow rate, protein concentration, and flow rate of protein were measured and compared between the patients taking calcium blocker and healthy elderly. iTRAQ (Isobaric Tag for Relative and Absolute Quantitation) proteomic analysis was performed to extract the salivary protein changed in patient taking calcium blocker, and the intensities of Western blotting products were quantified (unpaired t-test). Unstimulated salivary flow rate was significantly lower on patients taking calcium blocker (p < 0.01). Protein concentration tended to be higher and the flow rate of protein tended to be lower on patients. As the result of iTRAQ proteomic analysis, calmodulin-like protein 3, glutathione S-transferase P, and keratin type I cytoskeletal 13 increased characteristically in patient taking calcium blocker, and the expression in calmodulin-like protein 3 was significantly larger (p < 0.01). The results of this study indicated that calmodulin-like protein 3 increased in patients taking calcium blocker and could be a salivary biomarker for oral dryness caused by calcium blocker.

Fabrication of vacuum-formed and pressure-formed mouthguards using polyolefin sheet.

BACKGROUND: Mouthguard should be worn to decrease orofacial trauma. Custom-made mouthguards are usually fabricated using ethylene vinyl acetate sheet or polyolefin sheet. However, the difference of the characteristics of the mouthguard formed by polyolefin sheet has not been cleared enough. The aim of this study was to investigate the characteristics of the mouthguard fabricated by polyolefin sheet with the vacuum-forming method and the pressure-forming method. MATERIAL AND METHODS: Mouthguard sheets of polyolefin (3.0 mm thickness) were formed on working model using a vacuum former and a pressure former. Mouthguard thickness was measured at the central incisor (labial surface) and the first molar (buccal surface). The thickness at the first molar (occlusal surface) was also measured. The mouthguard fit was examined at the right central incisor and the right first molar by investigating the distance between the cervical part of the working model and the fabricated mouthguard. Differences in the mouthguard thickness and mouthguard fit fabricated by the vacuum-forming method and the pressure-forming method were analyzed by two-way analysis of variance. RESULTS: Mouthguard thickness was different among the measurement parts on both the central incisors and the first molars (P < 0.05 or P < 0.01). The mouthguard formed by the pressure-forming method showed smaller thickness on the central incisor (labial surface) than that formed by the vacuum-forming method (P < 0.01). The mouthguard formed by the vacuum-forming method showed smaller thickness on the first molar (buccal and occlusal surface) than that formed by the pressure-forming method (P < 0.05 or P < 0.01). The mouthguard fabricated by the pressure-forming method showed greater fit than that fabricated by the vacuum-forming method (P < 0.01). CONCLUSIONS: The results of this study suggest that the vacuum-forming method was easy to decrease the mouthguard thickness at the first molar, and the pressure-forming method was easy to decrease the mouthguard thickness at the central incisor but obtain better fit when using polyolefin sheet.

Highly producible method for determination of occlusal vertical dimension: relationship between measurement of lip contact position with the closed mouth and area of upper prolabium.

PURPOSE: A new method inducing the physiologic rest position of the mandible using the lip contact position with the closed mouth have compared with those obtained using conventional methods of placing the mandible in the physiologic rest position. METHODS: The lip contact position with the closed mouth as a method was investigated whether the technique was useful for determining the occlusal vertical dimension. The relationship between the space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth and the areas of the prolabia was also investigated. RESULTS: Median space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth was 1.53mm, a value intermediate between the value of 2.16mm in the resting mandibular position obtained by the conventional technique and that of 1.33mm in the swallowing position. The coefficient of variation of the space in the lip contact position with the closed mouth was significantly lower than those in the resting mandibular position and in the swallowing position. A significant positive correlation was recognized between the space in the lip contact position with the closed mouth and the area of the prolabium of the upper lip. CONCLUSIONS: 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.