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.

Odontogenic Infection Pathway to the Parapharyngeal Space: CT Imaging Assessment.

Introduction: Parapharyngeal space infection may lead to severe and potentially life-threatening complications. The aim of this study was to assess the odontogenic infection pathway to the parapharyngeal space using CT imaging. Materials and Methods: Nineteen patients in mandibular odontogenic infections with abscess who underwent contrast-enhanced CT were evaluated in this study. We reviewed the location of abscess and spread of odontogenic infections to the different components of the buccal space, submandibular space, sublingual space, masticator space and parapharyngeal space using CT imaging. The location of abscess and spread of odontogenic infections were analyzed with the Pearson Chi-square test. Results: Regarding the odontogenic infection pathway to parapharyngeal space, the masticator space (100%) was the most frequent, followed by the buccal space (85.7%), submandibular space (85.7%) and sublingual space (57.1%), while those without parapharyngeal space, the submandibular space (83.3%) was the most frequent, followed by the buccal space (75.0%), masticator space (58.3%) and sublingual space (33.3%). The masticator space was significant space in patients with/without parapharyngeal space infection (P = 0.047). Conclusion: CT imaging could be an effective method in assessment of odontogenic infection pathway to the parapharyngeal space. The odontogenic infection in masticator space tends to display spread of parapharyngeal space.

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.

Basic research to propose a new design of laminated mouthguard-Effect of lamination order on thickness.

BACKGROUND/AIM: Mouthguard thickness influences the protection ability from orofacial trauma. The aim of this study was to propose a new design for mouthguards and to evaluate the effect of the lamination order on the thicknesses of mouthguards. MATERIALS AND METHODS: Mouthguard sheets of 2.0-mm and 4.0-mm ethylene vinyl acetate were used. The sheets were pressure formed using a pressure former. Two lamination conditions were examined: The condition 24P used the 2.0-mm sheet as the first layer and 4.0-mm sheet as the second layer. The condition 42P used the 4.0-mm sheet as the first layer and 2.0-mm sheet as the second layer. The first layer was trimmed to cover only the anterior region, and then the second layer was formed over the first layer. Mouthguard thickness was measured using a measuring device at the labial surface of the central incisor, plus the buccal and occlusal surfaces of the first molar. Differences in thickness by measurement region of mouthguards formed under different lamination conditions were analyzed by two-way analysis of variance. RESULTS: Mouthguard thickness differed among the regions at the central incisors and the first molars (p < .01). The thickness at the labial surface of the central incisor became statistically significantly larger with the 42P condition (3.38 mm) than with the 24P condition (3.30 mm) (p < .05). The thickness at the buccal and occlusal surfaces of the first molar became statistically significantly larger with the 24P condition (2.25 mm and 2.72 mm, respectively) than with the 42P condition (1.23 mm and 1.44 mm, respectively) (p < .01). CONCLUSIONS: The results suggest that the combination of the 2.0-mm and 4.0-mm sheets could obtain the necessary thickness for the prevention at the labial surface of the central incisor and buccal surface of the first molar.

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.

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.

Effectiveness of oral moisturizing gel and flavor on oral moisture and saliva volume: A clinical study.

STATEMENT OF PROBLEM: Oral dryness leads to problems in the oral cavity and pharynx and problems with dental prostheses. Although some moisturizing agents relieve the symptoms of oral dryness, the influence of the flavor of the moisturizing agent on the symptoms of oral dryness has not been clarified. PURPOSE: The purpose of this clinical study was to examine the effectiveness of moisturizing gels with different flavors. MATERIAL AND METHODS: Participants in this study consisted of 36 healthy adults and 20 individuals with oral dryness. They were randomly divided into 6 groups, and moisturizing gels with 5 different flavors (tasteless and odorless, sweet taste, acid taste with citric acid, acid taste with Japanese apricot extract, and Japanese apricot scent) were tested in 5 of the groups with 1 group acting as the control (no gel administered). Oral moisture and saliva volume were measured before applying the moisturizing gel, just after applying the moisturizing gel, and 10, 20, and 30 minutes after applying the moisturizing gel. Differences in oral moisture and saliva volume according to the gel flavor and duration of contact were analyzed by using 2-way analysis of variance (α=.05). RESULTS: Oral moisture did not differ among the gel flavors and the duration of contact. Saliva volume in the control (no gel administered) reported no statistically significant differences among any of the contact durations in both healthy adults and participants with oral dryness. The saliva volume in healthy adults increased after using the sweet taste (P=.012), acid taste with Japanese apricot extract (P=.006), and Japanese apricot scent (P=.005) moisturizing gels. The saliva volume in participants with oral dryness increased rapidly just after using the acid taste with Japanese apricot extract gel (P=.008) and increased slowly after applying the tasteless and odorless (P=.046), sweet taste (P=.048), and acid taste with citric acid moisturizing gels (P=.010). CONCLUSIONS: The effectiveness of moisturizing gel for increasing saliva secretion differed according to the flavor of the moisturizing gel. This suggests that the moisturizing gel's effect on increasing saliva secretion is related to the flavor of the gel in addition to the moisturizing agent.

Diagnosis of root fractures using cone-beam computed tomography: difference of vertical and horizontal root fracture.

OBJECTIVES: The aim of this study was to investigate the occurrence of vertical and horizontal root fractures using cone-beam computed tomography (CBCT). METHODS: We reviewed the CBCT images of 51 patients who were examined by CBCT for the diagnosis of root fracture. The occurrences of vertical and horizontal root fractures were investigated concerning the pulpal vitality and the kind of tooth, and analyzed by cross-tabulation. The fracture direction of vertical root fracture and the fracture angle were also investigated, and analyzed by cross-tabulation and Kruskal-Wallis test, respectively. RESULTS: The occurrence of vertical and horizontal root fractures was statistically significantly different between vital tooth and non-vital tooth (p = 0.044). The occurrence of vertical and horizontal root fractures was also different among anterior, premolar, and molar teeth (p = 0.004). The kind of tooth on traumatized tooth was only anterior teeth and the number was larger on horizontal root fracture. The occurrence of vertical and horizontal root fractures on non-traumatized tooth was different among the kind of tooth (p = 0.007), and the number of vertical root fracture was larger than that of horizontal root fracture on premolar teeth. Fracture direction was not different, but the fracture angle was different among the kind of tooth on vertical root fracture (p = 0.027). CONCLUSIONS: The results suggested that the number of vertical root fracture was larger on non-vital tooth and that of horizontal root fracture was larger on vital tooth. The number of vertical root fracture was larger on premolar teeth.

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.

Salivary secretion and salivary stress hormone level changes induced by tongue rotation exercise.

PURPOSE: Prevention of xerostomia and stress is important to prolong healthy life expectancy and improve the quality of life. We aimed to investigate the effects of tongue rotation exercise for increasing salivary secretions and stabilizing salivary stress hormone levels. MATERIALS AND METHODS: Twenty four participants without subjective oral dryness were enrolled. The exercises comprised tongue rotation exercise and empty chewing. The salivary stress hormone level was measured using a Salivary Amylase Monitor. Unstimulated whole saliva volume and salivary amylase activity were measured before tongue rotation exercise or empty chewing and subsequently 5, 10, and 15 minutes after these exercises. Differences in the rates of change of unstimulated whole saliva volume and salivary amylase activity were analyzed by repeated measure analysis of variance. RESULTS: Statistically significant differences among the rates of change were not observed after empty chewing for unstimulated whole saliva volume and salivary amylase activity at the four measurement times. However, the rate of change of unstimulated whole saliva volume and salivary amylase activity were statistically significantly different among the four time points: before the tongue rotation exercise and 5, 10, and 15 minutes post-exercise (P< .05 and P<.01, respectively). CONCLUSION: Tongue rotation is effective in increasing saliva secretion, reducing stress, improving oral function, and extending healthy life expectancy.

Measurement of Oral Moisture on Oral Dryness Patients.

Many elderly patients have oral dryness; thus, it is necessary to evaluate the oral moisture in a clinical setting. The aim of this study was to clarify the importance of controlling the measuring pressure of the oral moisture-checking device. The influence of the measuring pressure of the oral moisture-checking device was examined using agar under 10 measuring pressure conditions (Kruskal-Wallis test). Fifty-five oral dryness patients were examined the lingual moisture using the device with and without a tongue depressor. The tongue depressor was placed underneath the tongue to support it during the measurement. The mean value and the coefficient of variation of five measurements was evaluated (paired t-test or Wilcoxon signed-ranks test). The agar moisture values changed according to the measuring pressure (p < 0.05). The lingual moisture value with the tongue depressor was higher than that without the tongue depressor (p < 0.05). The coefficient of variation with the tongue depressor was smaller than that without the tongue depressor (p < 0.01). The results of this study indicated that the measuring pressure of oral moisture-checking device influenced the measurement value, and it is necessary to support the tongue for the measurement of lingual mucosal moisture in a uniform manner.

Forming temperature of ethylene vinyl acetate sheets for fabrication of vacuum-formed mouthguards.

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.

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

BACKGROUND/AIMS: The appropriate heating conditions for polyolefin sheets have not yet been determined and polyolefin sheets are usually formed in the same manner as ethylene vinyl acetate sheets. The aim of this study was to examine the appropriate heating conditions for polyolefin sheets when fabricating vacuum-formed mouthguards. MATERIALS AND METHODS: Mouthguard sheets of 3.0 mm polyolefin were vacuum 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 by two-way analysis of variance. RESULTS: Mouthguard thickness varied among the measured regions of the central incisors and first molars (P < .01). The smallest thickness was found at the labial surface of the central incisor in mouthguards fabricated at 90°C (P < .01). The smallest thickness was found at the buccal and occlusal surface of the first molar in mouthguards fabricated at 120°C (P < .01). The worst fit was obtained with the heating temperature of 90°C (P < .01). CONCLUSIONS: The appropriate heating temperature for polyolefin sheets was 105°C to maintain mouthguard thickness and to obtain proper fit.

Relationships between the upper central incisor crown forms and degree of labial inclination, overbite, and overjet in Japanese young adults.

PURPOSE: The present study aimed to investigate the relationships between the crown form of the upper central incisor and their labial inclination, overbite, and overjet. MATERIALS AND METHODS: Maxillary and mandibular casts of 169 healthy dentitions were subjected to 3D dental scanning, and analyzed using CAD software. The crown forms were divided into tapered, square, and ovoid based on the mesiodistal dimensions at 20% of the crown height to that at 40%. The degree of labial inclination of the upper central incisor was defined as the angle between the occlusal plane and the line connecting the incisal edge and tooth cervix. The incisal edges of the right upper and lower central incisor that in contact with lines parallel to the occlusal plane were used to determine the overbite and overjet. One-way ANOVA was performed to compare the labial inclination, overbite, and overjet among the crown forms. RESULTS: The crown forms were classified into three types; crown forms with a 20%/40% dimension ratio of 1.00±0.01 were defined as square, >1.01 as tapered, and <0.99 as ovoid. The labial inclination degree was the greatest in tapered and the least in square. Both overbite and overjet in tapered and ovoid were higher than those in square. CONCLUSION: Upper central incisor crown forms were related to their labial inclination, overbite, and overjet. It was suggested that the labial inclination, overbite, and overjet should be taken into consideration for the prosthetic treatment or restoring the front teeth crowns.

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.

Difference in pressure-formed mouthguard thickness according to the laminate procedure.

AIM: Mouthguard thickness influences the preventive effects against dental and oral injury. The aim of this study was to examine the difference in pressure-formed mouthguard thickness according to the laminate procedure used. MATERIALS AND METHODS: The materials used were mouthguard sheets of 2.0-mm and 3.0-mm ethylene vinyl acetate, and pressure formed using a pressure former. Two forming conditions for laminated mouthguards were examined: the condition 23P used the 2.0-mm sheet as the first layer and 3.0-mm sheet as the second layer. The condition 32P used the 3.0-mm sheet as the first layer and 2.0-mm sheet as the second layer. The first layer was trimmed to cover only the anterior region; then, the second layer was formed over the first layer. Mouthguard thickness was measured at the labial surface of the central incisor, buccal surface of the first molar, and occlusal surface of the first molar. Statistical analysis was performed by two-way analysis of variance and Bonferroni method to analyze the differences in thickness by measurement region of mouthguards and forming conditions. RESULTS: Mouthguard thickness differed in different regions of the central incisors and the first molars (P < .01). The thickness at the labial surface of the central incisor became statistically significantly larger on the 32P condition than that on the 23P condition (P < .01). The thickness at the buccal surface and the occlusal surface of the first molar became statistically significantly larger on the 23P condition than that on the 32P condition (P < .01). CONCLUSIONS: The thicknesses of the labial surface of the central incisor became larger when the sheet thickness of the first layer was larger.

Vacuum-formed mouthguard fabrication to obtain proper fit using notched sheet.

BACKGROUND/AIM: Mouthguards should be provided with appropriate thickness and proper fit to exert their effects. However, mouthguard thickness becomes thinner after forming. The aim of this study was to examine the effect of using a notched mouthguard sheet and forming as the heated surface of the sheet contacts the surface of the working model. MATERIALS AND METHODS: The material used was a 3.8-mm-thick Sports Mouthguard. Notches with a length of 90 and 80 mm were cut into an ethylene vinyl acetate sheet 20 mm from the anterior and posterior margins and 15 mm from the right and left margins, respectively, and the sheet was compared with the original. The sheets were then formed using a vacuum former. Original and notched sheets were heated until the temperature of the sheet reached 80°C, and the non-heated surface of the sheet was sucked down over the model. Both sheets were also heated at first until the sheet temperature reached 80°C, then turned upside down, and the heated surface of the sheet was sucked down over the model. The thickness and fit of the mouthguard were measured at the central incisor and first molar. Differences in thickness and fit according to the measurement parts and the sheet conditions were analyzed by two-way ANOVA. RESULTS: The thickness of the mouthguard significantly differed by the measurement parts and the sheet conditions (P < 0.01), and the notched sheet maintained the required thickness. Fit differed between the measurement parts and the sheet conditions (P < 0.01), and the sheets formed as the heated surface contacted the working model showed better fit. CONCLUSIONS: These results suggest that the ideal mouthguard with appropriate thickness and proper fit can be fabricated by notching a sheet and contacting the heated surface of the sheet to the working model.

Mouthguard sheet temperature after heating under pressure former.

BACKGROUND/AIM: Ethylene vinyl acetate and polyolefin sheets have been used commonly for fabricating mouthguards. However, the change of the sheet temperature during heating of the polyolefin has not been clarified. The aim of this study was to examine the effects of changing the sheet temperature during heating, and to examine whether there were any differences between the sheet materials. MATERIALS AND METHODS: The mouthguard materials used were 4.0 mm sheets of ethylene vinyl acetate and polyolefin. The sheet temperature of the two materials was measured when the center of the sheet was displaced by 10, 15, and 20 mm from the baseline after heating. The sheets were pressure-formed when the heating temperatures reached 100°C. Mouthguard thickness and fit were measured at the central incisor and the first molar. Differences in the sheet temperature and the thickness between the sheet materials were analyzed by two-way analysis of variance. RESULTS: The sheet temperature of ethylene vinyl acetate and polyolefin sheets became higher as the hanging distance became larger (P < 0.01), and there were statistically significant differences between ethylene vinyl acetate and polyolefin sheets at the hanging distance of 10 and 15 mm (P < 0.01). The thicknesses of the pressure-formed mouthguard at the central incisor and the first molar were greater in the mouthguards formed by ethylene vinyl acetate sheets than those with polyolefin sheets (P < 0.01 and P < 0.05, respectively). The fit of the mouthguard was not different between mouthguards formed by ethylene vinyl acetate sheets and those formed by polyolefin sheets. CONCLUSIONS: The change of mouthguard sheet temperature during heating was different between ethylene vinyl acetate and polyolefin sheets. The ethylene vinyl acetate sheets maintained the mouthguard thickness in comparison with the polyolefin sheets at the same heating temperature.