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In this study, the physical properties of a custom block manufactured using a self-polymerizing resin (Custom-block), the commercially available CAD/CAM PMMA disk (PMMA-disk), and a heat-polymerizing resin (Conventional PMMA) were evaluated via three different tests. The Custom-block was polymerized by pouring the self-polymerizing resin into a special tray, and Conventional PMMA was polymerized with a heat-curing method, according to the manufacturer's recommended procedure. The specimens of each group were subjected to three-point bending, water sorption and solubility, and staining tests. The results showed that the materials met the requirements of the ISO standards in all tests, except for the staining tests. The highest flexural strength was exhibited by the PMMA-disk, followed by the Custom-block and the Conventional PMMA, and a significant difference was observed in the flexural strengths of all the materials ( p < 0.001). The Custom-block showed a significantly higher flexural modulus and water solubility. The water sorption and discoloration of the Custom-block were significantly higher than those of the PMMA-disk, but not significantly different from those of the Conventional PMMA. In conclusion, the mechanical properties of the three materials differed depending on the manufacturing method, which considerably affected their flexural strength, flexural modulus, water sorption and solubility, and discoloration.

This study aims to simulate the stress distributions of oral mucosa under different soft denture liners using the smoothed particle hydrodynamics (SPH) method. The Young's modulus and viscosity of denture liners composed of silicone (Sofreliner Super Soft and Sofreliner Tough Medium, Tokuyama Dental), acrylic (Vertex Soft, Vertex Dental), and a tissue conditioner (Visco-gel, Dentsply Sirona) were measured using a creep meter. A numerical simulation model that represents the stress distribution of oral mucosa under soft denture liners was also developed using the SPH method. The oral mucosa was divided into four regions: A) buccal border, B) buccal shelf, C) crest of residual ridge, and D) lingual border. For each region, the von Mises stress (hereafter, referred to as "Mises stress") of the oral mucosa was calculated. Based on a creep test, Sofreliner Super Soft and Sofreliner Tough Medium silicone liners showed an elastic behavior, whereas Vertex Soft acrylic liner and Visco-gel tissue conditioner showed a viscoelastic behavior. In addition, Sofreliner Super Soft and Visco-gel exhibited a large strain. The numerical simulation revealed that the mean Mises stress was the highest in region A and lowest in region D. Vertex Soft acrylic liners resulted in a statistically lower Mises stress on the oral mucosa compared to the other three soft denture liners. Different soft denture liner materials lead to different stress distributions on the oral mucosa. The acrylic soft denture liners cause a lower Mises stress on the oral mucosa than the silicon soft denture liners. This suggests that acrylic soft denture liners would be more effective for manufacturing painless dentures than silicone soft denture liners., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In acute stroke patients, it is important to maintain tongue hygiene and tongue function for prognosis management. However, the direct relationship between these factors is unclear, since these are often assessed by multiple observables. In this study, we used structural equation modeling (SEM) analysis, a tool to analyze the relationship between concepts that cannot be measured directly, to analyze the relationship between tongue hygiene and tongue function. The subjects were 73 patients with acute stroke admitted to a university hospital who underwent dental intervention. Age, sex, nutritional intake method, clinical severity classification of dysphagia, number of current teeth, number of functional teeth, oral health, tongue movement, tongue coating, number of microorganisms on the tongue surface, tongue surface moisture level, and tongue pressure were measured at the first visit. SEM analysis showed that the relationship between tongue function and tongue hygiene was 0.05 between tongue function and swallowing function was 0.90, and that between tongue hygiene and swallowing function was 0.09. We found no statistical relationship between tongue function and tongue hygiene in acute stroke patients. However, it was reconfirmed that tongue function is strongly related to feeding and swallowing functions.

Statement of Problem: The appropriate postpolymerization of stereolithography (SLA) resins with the least effect on dimensional accuracy and with optimal polymerization is unclear., Purpose: The purpose of this in vitro study was to investigate the dimensional accuracy and degree of polymerization of a photopolymer resin for SLA with different postpolymerizing times and temperatures., Material and Methods: Sixty 1.5-mm-thick specimens were made from clear photopolymer resin with a 3D printer to simulate a maxillary complete denture. They were postpolymerized for different periods (15 and 30 minutes) at 3 different temperatures (40 °C, 60 °C, and 80 °C). Both prepolymerization and postpolymerization gap sizes for each specimen were measured at 5 different locations under a stereomicroscope. The tissue surface was scanned before and after polymerization, and the images were superimposed. The deviation was analyzed by using computer-aided design (CAD) software; root mean square estimates (RMSE) and color map data were obtained. Fourier transform infrared spectrometry was used to determine the degree of conversion (DC) of all specimens. The Kruskal-Wallis and Mann-Whitney tests were used to calculate the difference value of the gap sizes (α=.05). One-way ANOVA and the Tukey test were used for RMSE and DC (α=.05)., Results: The smallest average change in gap sizes was found at 15 minutes and 40 °C, and the largest change at 30 minutes and 80 °C. The lowest RMSE was obtained at 30 minutes and 40 °C (P<.05). On the color map, a uniform deposited layer was created at 15 minutes and 40 °C and 30 minutes and 40 °C. The highest DC was found at 30 minutes and 60 °C, which differed significantly from 15 minutes and 40 °C (P<.05). The lowest degree of polymerization was found at 30 minutes and 40 °C., Conclusions: The polymerizing temperature exerted a greater effect than polymerizing time, with lower temperatures leading to improved fit and tissue surface accuracy. The recommended parameters for SLA polymerization are 15 minutes and 40 °C. These conditions offered high dimensional accuracy, favorable surface tissue adaptation, and satisfactory DC., (Copyright © 2020 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objectives: This study aimed to assess and compare postoperative bleeding occurrence after dental extraction in medically compromised elderly patients under anticoagulant therapy., Materials and Methods: This retrospective study included medically compromised elderly patients aged ≥ 65 years who were taking apixaban, dabigatran, edoxaban, rivaroxaban, or warfarin and had undergone single or multiple dental extractions. The primary outcome measure was postoperative bleeding occurrence, which was defined as oozing or marked hemorrhage from 24 h to 7 days after dental extraction. Postoperative bleeding occurrence was calculated for each anticoagulant and compared using Fisher's exact test, followed by multiple comparisons., Results: Two hundred thirty-two patients met the inclusion criteria. The highest postoperative bleeding occurrence was recorded for rivaroxaban (12/37: 32.4%), followed by apixaban (8/44: 18.2%), warfarin (17/98: 17.3%), and edoxaban (2/35: 5.7%). Patients taking dabigatran did not present postoperative bleeding (0/18: 0%). Fisher's exact test, followed by multiple comparison tests, revealed a significant among-anticoagulant difference (p = 0.0095). Postoperative bleeding was significantly higher in patients taking rivaroxaban than in those taking edoxaban or dabigatran (p = 0.03088)., Conclusions: Within the limitations of this retrospective study design, these findings suggest that different anticoagulants may affect postoperative bleeding occurrence after dental extraction among medically compromised elderly patients., Clinical Relevance: Clinicians should carefully consider postoperative bleeding after dental extraction in patients taking anticoagulant therapy, especially rivaroxaban.

Objective: To evaluate cardiovascular response in patients on warfarin and hypertensive patients not on warfarin during dental extraction., Materials and Methods: This retrospective study included 53 patients who had undergone dental extraction while on warfarin (mean age 78.8 ± 6.3 years, 26 men) and 66 with hypertension who had undergone dental extraction but were not on warfarin (mean age 77.4 ± 6.8 years, 22 men). Vital signs were monitored in both groups during extraction., Results: The highest systolic blood pressure (SBP) values (mean 150.1 ± 21.1 mmHg) were observed in patients on warfarin before (9.0%) and after (10.3%) administration of local anesthesia (LA), during extraction (39.7%), and during (33.3%) and after (7.7%) suturing (n = 78; p < 0.01), and in hypertensive patients not receiving warfarin (160.6 ± 24.8 mmHg) before (19.2%) and after (27.3%) administration of LA, during extraction (29.3%), and during (18.2%) and after (6.1%) suturing (n = 99; p < 0.01). The highest SBP was linearly correlated with SBP before administration of LA in patients on warfarin (highest SBP = 0.9415 × SBP before LA + 23.243, R 2 = 0.75481) and in hypertensive patients not on warfarin (highest SBP = 1.0027 × SBP before LA + 15.789, R 2 = 0.60341)., Conclusions: The highest SBP was not distributed evenly between patients on warfarin and hypertensive patients not on warfarin during dental extraction and was strongly associated with SBP before LA regardless of anticoagulant status., Clinical Relevance: Thorough management of SBP is required in patients on warfarin to avoid thromboembolism and major hemorrhagic complications. Knowing the SBP value before dental treatment would help predict the risk of cardiovascular complications.

New lines of evidence suggest that the oral-systemic medical links and oral hypo-function are progressively transcending beyond the traditional clinical signs and symptoms of oral diseases. Research into the dysbiotic microbiome, host immune/inflammatory regulations and patho-physiologic changes and subsequent adaptations through the oral-systemic measures under ageism points to pathways leading to mastication deficiency, dysphagia, signature brain activities for (neuro)-cognition circuitries, dementia and certain cancers of the digestive system as well. Therefore, the coming era of oral health-linked systemic disorders will likely reshape the future of diagnostics in oral geriatrics, treatment modalities and professional therapies in clinical disciplines. In parallel to these highlights, a recent international symposium was jointly held by the International Association of Gerontology and Geriatrics (IAGG), Japanese Society of Gerodontology (JSG), the representative of USA and Taiwan Academy of Geriatric Dentistry (TAGD) on Oct 25th, 2019. Herein, specific notes are briefly addressed and updated for a summative prospective from this symposium and the recent literature., (© 2020 Association for Dental Sciences of the Republic of China. Publishing services by Elsevier B.V.)

The objective of this study was to assess the influence of alumina sandblasting on the flexural strength of the latest generation of highly translucent yttria partially stabilized dental zirconia (Y-PSZ). Fully-sintered zirconia disk-shaped specimens (14.5-mm diameter; 1.2-mm thickness) of four Y-PSZ zirconia grades (KATANA HT, KATANA STML, KATANA UTML, all Kuraray Noritake; and Zpex Smile, Tosoh) were sandblasted at 0.2 MPa with 50-μm alumina (Al 2 O 3 ) sand (Kulzer) or left as-sintered (control). For each zirconia grade, the yttria (Y 2 O 3 ) content was determined using X-ray fluorescence (XRF). Surface roughness was assessed using 3D confocal laser microscopy. Micro-Raman spectroscopy (μ-Raman) and X-ray diffraction (XRD) were used to assess potentially induced residual stresses. Biaxial flexural strength (n = 20) was statistically compared by Weibull analysis. Focused ion beam - scanning electron microscopy (FIB/SEM) was used to observe the subsurface microstructure. Fracture surfaces after biaxial flexural strength testing were observed by SEM. KATANA UTML had the highest Y 2 O 3 content (6 mol%), followed by KATANA STML and Zpex Smile (5 mol%), and KATANA HT (4 mol%). Al 2 O 3 -sandblasting significantly increased surface roughness of KATANA UTML and Zpex Smile. μRaman and XRD revealed the presence of residual compressive stress on all Al 2 O 3 -sandblasted surfaces. FIB/SEM revealed several sub-surface microcracks in the sandblasted specimens. Weibull analysis revealed that Al 2 O 3 -sandblasting increased the characteristic strength of KATANA HT, KATANA STML, whereas it decreased the strength of KATANA UTML. The strength enhancement after Al 2 O 3 -sandblasting of KATANA HT was the highest, followed by KATANA STML. For Zpex Smile, the influence was statistically insignificant. The impact of Al 2 O 3 -sandblasting on the Weibull modulus was controversial. The strength of zirconia after Al 2 O 3 -sandblasting is determined by the balance between microcrack formation (decreased strength) and surface compressive stress build-up (increased strength)., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Purpose: To assess the degree of conversion (DC) of dual-curing composite cements when cured through ceramic-veneered zirconia disks., Methods: Portions of mixed cement, either G-CEM LinkForce (GC), Panavia V5 (Kuraray Noritake) or ResiCEM (Shofu), were placed on the ATR crystal of a Fourier Transform Infrared Spectroscope (FTIR; iS50, Thermo Scientific) and squeezed to a 100-µm film thickness using a microscopy cover glass. DC (%) of the composite cements applied in self-curing mode was measured in the dark at 37°C. Following the dual-curing mode, the cements were light-cured directly (positive control) or through a ceramic-veneered zirconia disk (0.5-mm thick zirconia with a 1.0-mm thick veneering ceramic) for 40 sec using two light-curing units (G-Light Prima 2, GC; PenCure, Morita). Per experimental group, 5 tests were conducted to measure DC in self-cure and dual-cure mode (n=5). FTIR spectra of the composite cement films were acquired to determine DC every min up to 30 min. DC of the composite cements was statistically compared using two-way repeated-measures ANOVA (α=0.05)., Results: For all cements investigated, the self-curing mode resulted in significantly lower DC at 10, 20 and 30 min than the light-curing mode. When the composite cements were light-cured through the zirconia disk, DC at 30 min dropped significantly for ResiCem (Shofu), while not for Panavia V5 (Kuraray Noritake) and G-CEM LinkForce (GC)., Conclusions: Self-curing slows down polymerization but does not reach for all composite cements the highest (light-cured) DC. Ceramic-veneered zirconia-based restorations may affect DC of some composite cements.

Background: Metabolic syndrome (MetS), caused by the accumulation of visceral fat, is considered a major cause of cardiovascular disease. This randomized controlled trial aimed to clarify the effect of dental intervention, including prosthodontics and/or periodontal treatment, combined with dietary and exercise guidance on MetS., Methods: In total, 112 patients who met the Japanese waist circumference criteria of MetS were recruited. The intervention group (ITG) received dental intervention along with dietary and exercise guidance, while the control group (CTG) received dietary and exercise guidance alone. Three outcome measurements were obtained before intervention (BL), 1 month after intervention (1M), and 3 months after intervention (3M)., Results: Body water rate (p = 0.043) was significantly higher in ITG than in CTG at 1M. Simultaneously, fasting blood sugar level (p = 0.098) tended to be lower in ITG than in CTG. Lean mass (p = 0.037) and muscle mass (p = 0.035) were significantly higher and body weight (p = 0.044) significantly lower in ITG than in CTG at 3M. Body mass index (p = 0.052) tended to be lower in ITG than in CTG., Conclusions: Dental intervention combined with lifestyle guidance may improve anthropometric status and reduce the risk of MetS., Trial Registration: University Hospital Medical Information Network Center Unique UMIN000022753. https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr&#95;view.cgi?recptno=R000026176 .

Dietary habits of middle-aged and elderly individuals affected by periodontal disease (PD) differ from those who are unaffected by it, according to previous reports. However, in young adults, there are only a few reports that show a correlation between nutrient/food intake and PD. Moreover, no report till date has assessed the correlation between dietary habits and PD using a self-administered diet history questionnaire (DHQ). Therefore, we assessed this correlation using a DHQ in young adult women who are likely to develop PD. The participants were enrolled from 2 universities and included 120 female college students a mean age of 20.4 y. The participants were assessed for the presence of PD according to the community periodontal index and were divided into two groups, the PD group and the non-PD group. Their dietary habits were investigated using a DHQ and the level of difficulty in chewing food was assessed. The PD group had a significantly lower nutrient intake of minerals, fat-soluble vitamins, water-soluble vitamins, and dietary fiber than the non-PD group. In terms of food groups, the PD group consumed significantly lesser amounts of green and yellow vegetables (GYV) than the non-PD group. Multivariate analysis revealed that the PD group had significantly lower intakes of vitamin E and GYV than the non-PD group. The PD group consumed significantly lesser amounts of hard foods than the non-PD group. In conclusion, young adult women who were evaluated for PD by a screening test had a significantly lower nutrient/food intake than those without a PD.

Purpose: The incidence of dementia is rapidly increasing worldwide, especially in developed countries. Little is known regarding the effectiveness of dental intervention to prevent dementia or a decline in cognitive functions among community-dwelling older adults, but a few studies have reported a correlation between the lack of regular dental checkups and dementia. For that reason, this study aimed to investigate the effects of oral health intervention on cognitive functions in community-dwelling subjects with a mild cognitive decline via a randomized controlled trial., Patients and Methods: Fifty-five community-dwelling older adults with a Mini-Mental State Examination score of ≥21 to ≤26 who had not visited a dental clinic in the previous year were randomized to an intervention group (n = 28) or a control group (n = 29). The intervention group received monthly oral health intervention by dental hygienists for 8 months while the control group did not. Data on demographics, cognitive function and oral parameters were collected before and after the intervention., Results: Twenty-five subjects in the intervention group (mean age 77.0 years) and 25 in the control group (mean age 72.8 years) completed the study. Significant improvements were observed in the Trail Making Test (TMT)-A, TMT-B, bleeding on probing rate, oral diadochokinesis, tongue pressure and chewing ability in the intervention group (P < 0.05). There were also significant interactions between the TMT-A and TMT-B scores, oral diadochokinesis, tongue pressure and chewing ability (P < 0.05)., Conclusion: Oral health intervention by dental hygienists may be effective for improving the oral health and executive function of cognitive function assessed via TMT., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This study was aimed to evaluate the effect of a novel surface pre-reacted glass-ionomer (S-PRG) filler-containing cement for root caries. We prepared the cements using five different S-PRG filler amounts (0, 10, 20, 30, and 40 wt%). Compressive strength, ion release, acid buffering capacity, and microstructure of the as-prepared cements were evaluated. The compressive strength was statistically significant; it was highest for 0 wt% S-PRG cement. Ion release in 0 wt% S-PRG was highest for F - and Al, whereas in 40 wt% S-PRG it was highest for B. For 20, 30, and 40 wt% S-PRG cements, Na and Sr release was higher compared to the other ions. The acid buffering capacity was significantly higher in the 40 wt% S-PRG cement than in the others. In the microstructural analysis, no difference of surface structure was observed among each of the S-PRG filler contents (0-40 wt% S-PRG).

Background: Oral hygiene management of patients with acute stroke is important for preventing aspiration pneumonia and ensuring oral intake. The tongue coating score can be useful for evaluating the oral hygiene level since it reflects the microorganism number on the tongue surface in elderly patients. However, the relationship between the number of oral microorganisms and the tongue coating score in patients with acute stroke remains unclear., Objectives: We aimed to investigate the relationships between the microorganism number on the tongue surface and oral factors, including tongue coating score, tongue surface moisture level and tongue function., Methods: This cross-sectional study enrolled 73 patients with acute stroke who were hospitalised at an acute care hospital and underwent dental intervention. Potential explanatory factors, including sex, age, Glasgow Coma Scale score, tongue coating score, tongue surface moisture level, nutrition intake method, number of functional teeth and tongue function, were evaluated. Logistic regression analysis determined their association with the microorganism number on the tongue surface., Results: The tongue coating score (odds ratio: 1.31) and tongue surface moisture level (odds ratio: 1.10) were significantly associated with increased microorganism numbers on the tongue surface., Conclusion: The tongue coating score, which reflects the actual number of microorganisms on the tongue surface, could be an effective tool for evaluating oral hygiene level in patients with stroke. Moreover, reducing oral microorganisms in saliva through oral hygiene management, including removing the tongue coating, could contribute towards the prevention of aspiration pneumonia., (© 2020 John Wiley & Sons Ltd.)

Fabrication of complete dentures using a 3D printer is quicker and more economic than conventional methods. However, the photopolymer resins used in 3D printers has a lower flexural strength than heat-cured resin. Furthermore, photopolymer resins exhibit anisotropic properties depending on the printing direction, but no studies have evaluated their mechanical properties. The impact of stress distribution caused by changing the printing direction of the 3D printed denture has not been clarified. This study aimed to investigate the effect of different printing directions (0°, 45°, and 90°) of stereolithography (SLA) 3D printed dentures on stress distribution. Artificial mucosa was fabricated to fit a maxillary edentulous model, which was scanned to generate a standard tessellation language (STL) file. Subsequently, the upper denture was designed using computer-aided design (CAD) software, output as an STL file (master data), and set in three different printing directions (0°, 45°, and 90°). It was printed by the SLA 3D printer using photopolymer resin (n=6, in each printing direction). The stress distributions of the dentures were monitored using four rosette strain gauges, which were cemented to the midline of each denture as follows: above the labial frenum (A), at the incisive papilla (B), at the endpoint of the denture (D), and at the mid-point of B and D (C). A load was applied to the posterior region at a loading rate of 20 N/s from 0 N to 200 N using a universal testing machine. Changes in the applied load and strain at each point were recorded. The maximum principal strain (MPS) and the direction of the MPS (θ) were calculated. Each mean MPS was compared using Kruskal-Wallis and Steel-Dwass multiple comparison tests (p < 0.05). The stress distribution showed that the MPS for 45° printing was the lowest at each measurement point except for A under 200 N loading. The MPS at C for 0° was significantly different from that at C for 45° and 90°. The MPS at D in all the printing directions showed significant differences. The MPS at B for 45° was significantly different from that at B for 90°. The MPS at A in all printing directions showed no significant difference. Within the limitations of this study, differences in printing direction affected the stress distribution of SLA 3D printed dentures. The results showed that the stress distribution of the denture printed at 45° by the 3D printer system was the smallest compared with dentures printed at 0° and 90°. These results suggest that a printing direction of 45° is preferable when fabricating dentures using a 3D printer in clinical setting., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study compared the mechanical properties and molecular distribution of a polymethyl methacrylate (PMMA) block (Dry) with specimens that were fabricated by a conventional method and cured in a wet environment (Control). Two specimen types were fabricated with heat-curing denture base resin. Dry specimens were polymerized at high pressure and in a dry system, while Control specimens were polymerized with a heat-curing method, in accordance with the manufacturer's recommended procedures. Specimens from each group were evaluated for three-point bending, water sorption and solubility, and color change, and by gel permeation chromatography (GPC). Mean values for the flexural strengths and moduli of the Dry specimens were significantly higher than those of the Control specimens (P > 0.05). Water sorption and discoloration values of the Dry group were significantly lower than those of the Control group. Mean weight-average molecular weights of the Dry group were higher than those of the Control group. As compared with the conventional method, the present method of fabricating PMMA blocks under high pressure yields superior mechanical properties for the denture base.

This study aimed to identify factors associated with poor oral health status, as indicated by salivary occult blood (SOB) level, in community-dwelling older adults. A total of 592 community-dwelling participants aged 70 to 84 years with 20 to 28 teeth participated in the survey and SOB evaluation. Survey items included behaviors during dental visits, systemic diseases, smoking habit, cognitive function, and findings of intraoral examination. To identify factors associated with high SOB levels, binomial logistic regression analysis was performed after classifying participants as having high and low SOB on the basis of 75th-percentile SOB measurements. Presence of dental plaque (odds ratio [OR]: 2.26), poor subjective oral health (OR: 2.99) (for the age group 70 to 74 years), fewer remaining teeth (OR: 0.80), no dental visits during the previous year (OR: 2.80) (for the age group 75 to 79 years), and no dental visits during the previous year (OR: 3.93) (for the age group 80 to 84 years) were significantly associated with high SOB levels. The factors associated with high SOB, which indicates poor oral health status, differed by age group in community-dwelling older adults. Therefore, oral health management may improve oral health by providing different age groups with care that accounts for their physical and social functional abilities.

In this study, a cellulose acetate (CA) membrane is formed as an interference rejection membrane on a glucose sensor to measure glucose in saliva. Glucose in saliva is successfully measured in vivo without any pretreatment of human saliva. A mouthguard (MG) glucose sensor is developed to monitor salivary glucose, which is reported to be correlated with the blood glucose level. Salivary components of ascorbic acid (AA) and uric acid (UA) hinder the accurate measurement of the glucose concentration of human saliva. CA-coated electrodes are prepared to investigate the interference rejection membrane. To measure hydrogen peroxide, which is a reaction product of glucose oxidase, effects of AA and UA are examined. Characteristics of the fabricated biosensor are examined on the basis of artificial saliva. The as-developed MG sensor can quantify the glucose concentration in the range of 1.75-10 000 μmol/L, which includes a salivary sugar concentration of 20-200 μmol/L. For the measurement of saliva samples collected from healthy subjects, the output corresponding to the concentration is confirmed; this suggests the possibility of glucose measurement. This MG glucose sensor can provide a useful method for the unrestricted and noninvasive monitoring of saliva glucose for the management of diabetes patients.

This study evaluated the effects of the differences in the printing directions of stereolithography (SLA) three-dimensional (3D)-printed dentures on accuracy (trueness and precision). The maxillary denture was designed using computer-aided design (CAD) software with an STL file (master data) as the output. Three different printing directions (0°, 45°, and 90°) were used. Photopolymer resin was 3D-printed (n = 6/group). After scanning all dentures, the scanning data were saved/output as STL files (experimental data). For trueness, the experimental data were superimposed on the master data sets. For precision, the experimental data were selected from six dentures with three different printing directions and superimposed. The root mean square error (RMSE) and color map data were obtained using a deviation analysis. The averages of the RMSE values of trueness and precision at 0°, 45°, and 90° were statistically compared. The RMSE of trueness and precision were lowest at 45°, followed by 90°; the highest occurred at 0°. The RMSE of trueness and precision were significantly different among all printing directions ( p < 0.05). The highest trueness and precision and the most favorable surface adaptation occurred when the printing direction was 45°; therefore, this may be the most effective direction for manufacturing SLA 3D-printed dentures.

Background: Denture use for recovery of major tooth loss can reduce the need for care, and thus, it is important for dentists to identify the types of patients who use removable dentures., Objective: To identify factors associated with removable denture use in independent older Japanese people., Methods: This cross-sectional study investigated the oral condition; demographics; lifestyle; dental visit behaviour; and higher-level functional capacity, as assessed using the Tokyo Metropolitan Institute of Gerontology index of competence (TMIG index), of independent older people aged 65-74 years. Participants were divided into four groups based on sex and condition of the posterior occluding pairs (POPs). Multivariate-adjusted logistic regression analyses were performed for each group, with denture use or non-use as the dependent variable and the other items as independent variables., Results: Denture use or non-use was significantly associated with only dental consultation behaviour (regular dental visits and time since the last dental visit) in all groups. Subsequent analyses excluding dental consultation behaviour demonstrated that denture use or non-use was significantly associated with educational background in female participants with decreased POPs, with the type of household in male participants with lost POPs and with the TMIG index (social role) in female participants with lost POPs., Conclusions: Denture use was associated with dental consultation behaviour. We revealed factors related to denture use or non-use in females with decreased POPs and both males and females with lost POPs., (© 2020 John Wiley & Sons Ltd.)

Background: An increase in the number of elderly edentulous patients likely leads to a greater demand for dentures and denture adhesives. As denture adhesives have both positive and negative features, dentists need to know the types of denture adhesive users to be able to provide instruction to denture wearers on how to use denture adhesives effectively. This study aims to examine the utilization of denture adhesives and associated factors., Methods: Seven closed-ended questionnaires were developed for a web-based survey. After that, Fisher's exact tests were performed to determine the difference in the denture adhesive usage rate by gender, type of denture, last dental visit, and smoking status. A multivariate-adjusted logistic regression analysis was performed with denture adhesive use or non-use as the dependent variable and the other items as independent variables. Next, Fisher's exact tests and a multivariate-adjusted logistic regression analysis were performed with the type of denture adhesives as the dependent variable in the same way. Statistical analyses were performed for all denture wearers, complete denture wearers, and partial denture wearers. The level of statistical significance was set at p = 0.05., Results: A total of 1470 denture wearers in Japan participated in this study. Of these, 318 used denture adhesives, while 212 (66.7%) used cream; 74 (23.3%) used home liner; 25 (7.9%) used powder; four (1.3%) used sheets; and three (0.9%) used several types. The Fisher's exact tests revealed that the ratios of using denture adhesives were significantly higher for complete denture wearers (p < 0.001), last dental visit over 1 year (p = 0.005), and smokers (p = 0.005). For partial denture wearers, the ratio was significantly higher in smokers (p = 0.262). The multivariate adjusted logistic regression revealed that denture adhesive use or non-use were significantly associated with the type of denture and smoking status in all denture wearers, and just smoking status in partial denture wearers. There were no significant results about the type of denture adhesive selection., Conclusions: From all denture wearers, complete denture wearers and smokers are more likely to use denture adhesives. In addition, smokers significantly use denture adhesives if they are partial denture wearers.

Purpose: The purpose of this study was to investigate the effect of denture adhesives on oral moisture in a 10-center parallel randomized clinical trial., Methods: Two hundred edentulous subjects wearing complete dentures were allocated into three groups: cream-type adhesive, powder-type adhesive and control groups. The adhesives (and saline solution in the control group) were applied to the mucosal surface of the dentures for 4 days, and baseline data and data after the intervention for eight meals over 4 days were obtained. For the main outcome, oral moisture was measured with a moisture checking device. Secondary outcomes were denture satisfaction, masticatory performance, denture retention, and occlusal force. In addition to between-group and within-group comparisons of oral moisture, investigations for secondary outcomes were undertaken in subgroups classified according to the degree of oral moisture at baseline (normal subgroup and dry mouth subgroup). Intention-to-treat analysis was also performed., Results: Between-group and within-group comparisons of oral moisture showed no significant differences. The cream-type and powder-type denture adhesives were significantly effective in the dry mouth group for denture satisfaction ratings of ability to masticate, stability, retention, and comfort of mandibular dentures (p<0.05). The masticatory performance and retentive force of the dry mouth denture adhesive using groups were significantly improved after intervention (p<0.05)., Conclusions: The oral moisture of complete denture wearers was not influenced by the use of denture adhesives. Our findings showed that denture adhesives improved subjective denture satisfaction, masticatory performance, and retention for complete denture patients with oral dryness., (Copyright © 2019. Published by Elsevier Ltd.)

Adequate oral status and functional assessments are important for dysphagia rehabilitation in acute care inpatient settings, especially to establish individualised oral intake. However, the association between food intake levels and oral function has not been elucidated in acute care inpatients. This cross-sectional study clarified the association between oral intake levels and the oral status/function of patients with dysphagia admitted to acute care settings. Admitted patients aged ≥40 years (n = 459; men: 288; mean age: 70.8 ± 12.0) examined at the Department of Dysphagia Rehabilitation at the Iwate Medical University Hospital from April 2007 to March 2014 were included. The oral health status was evaluated by the tongue coating, oral dryness severity, plaque control, posterior occlusal support and a repetitive saliva swallowing test (RSST). Dysphagia severity was determined from the Dysphagia Severity Scale. Oral intake levels were evaluated using the Functional Oral Intake Scale (FOIS) at the time of the initial dental examination (FOIS-I), and they were re-evaluated after the revision of levels according to the participants' general condition and oral health status (FOIS-R). Divergence between FOIS-I and FOIS-R was noted in >40% patients. Multiple regression analysis showed significant associations between FOIS-R and consciousness level, activities of daily living, tongue coating, RSST and posterior occlusal support. Patients with dysphagia in acute care settings require detailed assessments of their oral status and function, including swallowing, to determine the most suitable feeding methods and dental interventions to improve oral intake levels., (© 2020 John Wiley & Sons Ltd.)

Background: Although age-related changes in muscle quality influence muscle strength, the relationship between masseter muscle (MM) quality and maximum biting force (MBF) has never been studied., Objective: The aims of the study were to verify the relationship among MM quality, MBF, and the displacement of the MM while biting forcefully (MMD) and to clarify the age-related decline in MBF in healthy elderly persons., Methods: Seventy-four healthy community-dwelling individuals (mean age, >65 years) from Tokyo metropolis were recruited. The thickness (index of muscle quantity), echo intensity (index of muscle quality) and displacement of the MM while biting forcefully (MMT, MMEI and MMD, respectively) were measured by ultrasonography. MBF was measured using a pressure-sensitive sheet. Independent predictors of MBF and MMD were determined using multivariate linear regression analyses adjusted for age, sex and the number of present teeth., Results: MBF was significantly correlated with the number of teeth (β = 0.577, P < .001) and MMD (β = 0.302, P = .015), but not with MMT (β = 0.019, P = .868) or MMEI (β = 0.054 P = .703). MMD was significantly correlated with MMEI (β = -0.606, P < .001), but not with MMT (β = 0.048, P = .681) or the number of teeth (β = 0.065, P = .613)., Conclusions: MMEI was associated with MMD, an index of MBF, regardless of tooth number. The age-related quality change in the MM might cause a decrease in its contraction, resulting in age-related decline in MBF., (© 2019 John Wiley & Sons Ltd.)

The aim of this study was to investigate the effects of framework materials manufactured by dental CAD/CAM systems on complete denture deformation. Four materials were used for the maxillary complete denture framework: fiber-reinforced composite (FRC), nano-zirconia (N-Zr), cobalt-chromium-molybdenum alloy (CCM), and polyether-ether-ketone (PEEK). The framework materials were prepared using CAD/CAM systems. Six dentures of each material were fabricated, using polymethyl-methacrylate (PMMA) as a control. The thickness of the palatal area was 1.0 mm for PMMA and PEEK and 0.5 mm for FRC, N-Zr, and CCM. The denture deformation during occlusal load was monitored using four rosette strain gauges placed on the midline of the denture. The maximum principal strain (MPS) of each gauge, except that at the labial frenum, increased proportionally with increasing applied load. The directions of MPS were predominantly perpendicular to the midline of the denture. When a 200-N load was applied, the MPS at the incisive papilla in N-Zr and CCM was half that of PMMA; there was no significant difference among MPSs of PEEK, PMMA and FRC. The MPS at the end point of the denture in FRC, N-Zr, and CCM was significantly smaller than that of PMMA. The MPSs of the complete denture decreased when the CAD/CAM fabricated framework was used. The effects of the CAD/CAM fabricated framework on complete denture deformation varied due to the material used; however, a CAD/CAM fabricated framework material is considered to be effective for reducing complete denture deformation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Mastication is a complicated task that involves the teeth and perioral muscles, such as the tongue and lip. Previous studies have shown correlations between masticatory performance and perioral muscle strength (eg tongue pressure) and between masticatory performance and occlusal forces., Objective: To investigate the relationships between masticatory performance and perioral muscle characteristics., Methods: Forty-nine healthy young subjects (men: 24 and women: 25) with Eichner classification group A were included in this cross-sectional study. Age, body weight, masticatory performance, masseter muscle thickness, masseter muscle echo intensity, cross-sectional area of geniohyoid muscle, geniohyoid muscle echo intensity, tongue thickness (TT) and tongue echo intensity were assessed. Masticatory performance was evaluated using a colour-changeable chewing gum. The thickness and echo intensity of the masseter muscle, geniohyoid muscle and tongue were observed using an ultrasonic diagnostic apparatus. Stepwise multiple regression analysis was conducted to examine relationships between perioral muscle characteristics and masticatory performance., Results: Tongue thickness (P < .01) was the sole significant explanatory variable for masticatory performance. The standard partial regression coefficient was 0.47. The multiple correlation coefficient (R) was .47, and the adjusted R 2 was .20; the variance inflation factor was 1.0. This study showed that TT was related to masticatory performance, whereas perioral muscle quality was not. Moreover, perioral muscle quantity was highly correlated with perioral muscle quality., Conclusions: Tongue thickness is a predictor of masticatory performance in healthy young subjects. An ultrasonic diagnostic apparatus is useful in the evaluation of perioral muscle characteristics., (© 2019 John Wiley & Sons Ltd.)

This study evaluated marginal bone loss and prosthetic complications associated with single implant-retained mandibular overdentures (1-IODs) with locator attachments. The 1-IOD was placed in the mandibular midline by using a conventional loading protocol in 22 patients with an edentulous mandible. Marginal bone loss at the start of loading and 12 months postoperatively was assessed by radiographic and crestal bone evaluation. The crestal bone was defined as the distance between the customized abutment shoulder and the top of the bone, as indicated by probing. In addition, implant stability quotient and prosthetic complications were recorded. The cumulative implant survival rate was 95.5%. Median implant stability quotient remained greater than 80, and median radiographic bone loss was 0.56 mm. Crestal measurement showed a median crestal bone loss of 0.16, 0.43, 0.39, and 0.52 mm on the buccal, right, lingual, and left sides, respectively. Both radiographic and crestal bone loss values significantly differed between the start of implant loading and 12 months postoperatively (except on the buccal and lingual sides; P < 0.05). The need to replace the nylon insert was the most common complication. Conventional loading of a 1-IOD with a locator attachment resulted in a high survival rate, good implant stability, and acceptable marginal bone loss.

Objectives: This study aimed to evaluate pulse pressure fluctuation on dental local anesthetic administration in diabetic patients with and without coronary heart disease undergoing tooth extraction., Materials and Methods: This retrospective study in diabetic patients undergoing tooth extraction included 33 patients with coronary heart disease (mean age 79.3 ± 7.4, 64% male) and 49 patients without coronary heart disease (mean age 78.6 ± 6.5, 29% male). The increase in pulse pressure before and after administration of local anesthetics was compared between diabetic patients with and without coronary heart disease., Results: Pulse pressure was increased in male diabetic patients with coronary heart disease compared with those without coronary heart disease following administration of 3% prilocaine hydrochloride with felypressin 0.03 IU/mL (prilocaine) (15.6 ± 15.4 mmHg in those with coronary heart disease (n = 11) versus 4.3 ± 10.9 mmHg in those without coronary heart disease (n = 13), p = 0.03)., Conclusions: Prilocaine administration increased pulse pressure in male diabetic patients with coronary heart disease compared with those without coronary heart disease. Further study is needed to reveal the mechanisms involved in the increase in pulse pressure., Clinical Relevance: This is the first study of pulse pressure fluctuation in diabetic patients with and without coronary heart disease following administration of local anesthetics. Our findings can help guide the choice of local anesthetics and serve as a predictor of coronary vascular condition in diabetic patients during dental treatment.

Background: Dietary advice combined with prosthetic treatment could improve dietary intake earlier than prosthetic treatment only. This early improvement might signify early adaptation to new prostheses. Therefore, dietary advice might affect functional adaptation to new prostheses., Objective: The aim was to clarify the influence of simple dietary advice on masticatory function of elderly individuals with new complete dentures., Methods: A randomised controlled trial was performed on 59 edentulous elderly individuals who had received new complete dentures. Participants were randomly divided into an intervention group (received simple dietary advice: 15 men and 15 women, mean age: 74.8 ± 8.0 years) or a control group (received denture care advice: 15 men and 14 women, mean age: 78.6 ± 6.8 years). Masticatory function was assessed using colour-changeable chewing gum for mixing ability and test gummy jelly for shearing ability. Mixing and shearing ability were assessed at pre-treatment, and 3 and 6 months post-treatment. At each assessment time, mixing ability was compared using Student's t test and shearing ability using Mann-Whitney's U test. Within-group differences in mixing ability were analysed using repeated-measures one-way analysis of variance and those in shearing ability were analysed using Wilcoxon signed-rank test with Bonferroni correction., Results: At each assessment time, there was no significant difference in mixing or shearing ability between groups. In the intervention group, mixing and shearing ability significantly increased at 3 and 6 months post-treatment. In the control group, mixing ability significantly increased at 6 months post-treatment., Conclusion: Simple dietary advice might lead to relatively early improvements in masticatory function., (© 2019 John Wiley & Sons Ltd.)

Background: Oral function deteriorates easily during the acute phase of cerebral stroke. Therefore, oral health care involving a transdisciplinary approach consisting of dental and medical professionals might be important, but has not been studied in detail., Objective: This study assessed the oral health status of patients with cerebral stroke in the acute phase, with the aim of elucidating the efficacy of collaborative, transdisciplinary oral health care involving dentists, dental hygienists, nurses and speech therapists., Methods: The participants were 115 consecutive acute cerebral stroke patients, who received oral health care while hospitalised at the university hospital. Their oral health status was assessed using the oral health assessment tool (OHAT) on admission and discharge., Results: Patients with acute cerebral stroke had high OHAT scores on admission, meaning poor oral health status. The collaborative oral health care resulted in significant decrease of OHAT scores at discharge, indicative of the improvement of oral health status. Multivariate analysis identified OHAT score for tongue, dentures and oral cleanliness on admission as the significant variables associated with poor oral health status at discharge., Conclusions: Thus, the oral health of cerebral stroke patients in the acute phase can be improved by implementing transdisciplinary collaboration of medical and dental professionals. Particularly, patients with problems pertaining to the tongue, dentures and oral cleanliness as revealed through OHAT on admission may require more intensive intervention., (© 2019 John Wiley & Sons Ltd.)

Purpose: To treat mandibular edentulous patients by fitting immediately loaded two-implant overdentures via guided flapless surgery and evaluate their masticatory performance., Materials and Methods: Nineteen patients who presented with edentulous mandibles (mean age: 69.8 years; range: 60 to 85 years) at the Dental Hospital, Tokyo Medical and Dental University, were enrolled in this study. A newly fabricated complete denture was used as a radiographic guide. Computer planning followed the design procedure, and surgical guides were fabricated for each patient. Flapless surgery was performed using this guide, and two implants were placed in the canine positions. On the day of surgery, a removable overdenture supported by two ball attachments was fitted. Masticatory function was evaluated on the basis of masticatory performance with a color-changeable chewing gum, maximum occlusal force with an occlusal force meter, and occlusal contact area with an occlusal diagnostic system., Results: The masticatory performance significantly improved from 48 months after surgery. The maximum occlusal force significantly increased 24 months after surgery. The occlusal contact area significantly increased from 6 months after surgery. This prospective study indicated that maximum occlusal force and occlusal contact area significantly improved at a comparatively earlier period after implant surgery and were maintained for up to 5 years with the immediate loading of two-implant overdentures with stud attachments. However, masticatory performance took more time to improve than maximum occlusal force and occlusal contact area., Conclusion: According to this 5-year prospective study, masticatory performance, maximum occlusal force, and occlusal contact area showed significant improvement after 4 to 5 years, 2 years, and 6 months postsurgery, espectively.

Purpose: The study aimed to compare the mixing ability (MA), comminuting ability (CA), and maximum bite force (MBF) of single-implant overdentures (IODs) and clinically acceptable complete dentures (CDs) through a randomized crossover control trial., Methods: New CDs were fabricated for 22 patients. One implant was inserted in the middle of the symphyseal region for each patient. The patients were randomly allocated into two groups: group IC received an IOD, whereas group CI received a CD, for 2 months; the treatments were interchanged for the next 2 months. The MA, CA, and MBF were evaluated with the old CDs, new CDs (at the end of CD treatment period), and IODs (at the end of IOD treatment period)., Results: The MA, CA, and MBF of the IODs were significantly higher than those of the old and new CDs (p < 0.01). New CDs only showed a significant improvement in MA (p < 0.05), while there were no significant differences in CA and MBF between the old and new CDs., Conclusions: Compared with the CD, IOD is more effective in restoring the MA, CA, and MBF of edentulous mandibles., (Copyright © 2019 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.)

We assessed the effect of 2% lidocaine with 1:80,000 adrenaline (L + AD) and 3% prilocaine with 0.03 IU/mL felypressin (P + FP) on blood pressure and heart rate in older adults with systemic diseases undergoing dental extraction. This double-blind, randomized crossover study included 22 elderly participants, aged over 65 years. The participants were administered L + AD for one dental extraction and P + FP for the other. Blood pressure and heart rate were recorded immediately, 5, and 10 minutes after local anesthetic administration and the data were analyzed. The systolic and diastolic blood pressures in the P + FP group increased at all measurement points ( p < .001). In the L + AD group, the diastolic blood pressure decreased at 5 and 10 minutes after local anesthetic administration ( p < .05), whereas the heart rate increased at all measured time points ( p < .001). There were statistically significant differences in systolic blood pressure at 5 and 10 minutes after local anesthetic administration and in diastolic blood pressure and heart rate at all time points between the 2 groups. In older adults, P + FP administration increased the systolic and diastolic blood pressures. L + AD administration increased the heart rate and decreased the diastolic blood pressure.

Background: Masticatory performance of elderly complete denture wearers is low, which may lead to restriction on intakes of several foods such as fresh fruit or raw vegetables., Aim: The aim of this study was to investigate the relationship between tongue motor function, lip motor function, and mixing ability in complete denture wearers., Materials and Methods: Participants comprised 54 complete denture wearers with a mean age of 77.1 years. Maximum tongue pressure and oral diadochokinesis were measured to evaluate tongue and lip motor functions. A color-changeable, chewing gum was used to evaluate mixing ability. The relationship between tongue and lip motor functions and mixing ability was assessed using stepwise multiple regression analysis., Results: The stepwise multiple regression analysis identified maximum tongue pressure, the number of repetitions of the syllable "ka", and gender as significant predictors for mixing ability among complete denture wearers., Discussion: The elderly edentulous individuals mainly used tongue motor function in oral motor functions for mixing color-changeable chewing gums, which might be ascribable to wearing complete dentures., Conclusions: Under the limited conditions of this study, factors relating to tongue motor function, tongue pressure and the number of repetitions of the syllable "/ka"/ significantly contributed to the mixing ability of complete denture wearers. It was suggested that tongue motor function had positive effect on the mixing ability of complete denture wearers.

Dysphagia is a common problem among older adults, causing aspiration pneumonia and malnutrition. It has been reported that calf circumference (CC), an index of nutritional status and physical activity, correlated with dysphagia in acute care hospitals, suggesting that CC can be a useful index for assessing dysphagia. We therefore aimed to explore the association between dysphagia and CC among community elderly people who require long-term care and determined the optimal CC cut-off value for patients with dysphagia. Our cross-sectional study, conducted at Tokyo Metropolis, included 154 participants (65 men) aged > 65 years (mean age: 80.1 ± 7.1) who required long-term care and were examined for dental disease and dysphagia during home visiting treatment. Age, body mass index (BMI), mini-nutritional assessment short-form (MNA-SF) score, Barthel index (BI), CC, functional oral intake scale (FOIS), and dysphagia severity scale (DSS) were evaluated. A DSS score < 5 was defined as dysphagia. To determine the association between CC and dysphagia, we performed logistic regression analysis and calculated the CC cut-off value for dysphagia. Thirty-seven participants (24.0%) were diagnosed with dysphagia. The logistic regression analysis showed that the presence of dysphagia was independently associated with CC after adjusting for age and sex. The CC cut-off value for the presence of dysphagia was 31.0 cm in men (sensitivity, 0.818; specificity, 0.868) and 29.3 cm in women (sensitivity, 0.760; specificity, 0.859). CC is a useful index for assessing dysphagia among community dwelling individuals who require long-term care.

Purpose: To investigate the relationship between oral health-related quality of life (OHRQoL) and usage period of complete dentures., Materials and Methods: Data were obtained from 432 edentulous patients who required complete dentures as part of an investigation registered in the University Hospital Medical Information Network (UMIN) Center (UMINCTR clinical trial, unique trial number: 000028711). Mandibular ridge form, denture quality, and usage period of the dentures were recorded and incorporated into a multiple linear regression analysis., Results: Multiple linear regression analysis in the 267 participants who completed the study demonstrated significant effects on OHRQoL of mandibular ridge form, mandibular denture stability and retention, accuracy of jaw relation recording, and usage period of dentures., Conclusion: A significant relationship between the usage period of dentures and OHRQoL in complete denture wearers was noted when the effects of mandibular ridge form and denture quality were controlled for.

Purpose: Providing appropriate dental prostheses and dietary interventions may improve food and nutrient intake in elderly edentulous patients, but evidence to support their use is scarce. In this trial, we aimed to clarify the combined effect, on the nutritional statuses of edentulous elderly patients, of dentists providing complete dentures with dietary advice., Methods: A randomized-controlled trial was performed on a healthy elderly population who required new complete dentures. All participants had new complete dentures fabricated and were randomly divided into an intervention or a control group. The intervention group received simple dietary advice through standardized patient information leaflets and the control group received advice on denture care only. Nutritional status was assessed using the Mini Nutritional Assessment short-form (MNA-SF) before and at 3 and 6months after treatment. At each assessment point, the MNA-SF scores were compared using the Mann-Whitney U test. The within-group differences in the MNA-SF scores were analyzed using the Wilcoxon signed-rank test with Bonferroni correction., Results: In total, 59 participants completed all trial steps. At 6months after treatment, the MNA-SF score in the intervention group was significantly higher than that in the control group (p=0.01). Comparing the within-group changes in the MNA-SF score revealed that the score increased significantly from 3 to 6months in the intervention group (p=0.001, Bonferroni correction)., Conclusions: Nutritional statuses of healthy edentulous elderly population might be improved by fabricating new complete dentures and providing simple dietary advice., (Copyright © 2019 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.)

Background: The tongue plays an important role during the oropharyngeal phase of swallowing. Each part of the tongue has a different function during swallowing. Ageing causes changes in muscle quantity and quality. Qualitative changes, such as an increase in intramuscular adipose tissue, can be determined by the echo intensity (EI) of the tongue on ultrasonography (US)., Objective: To clarify the relationship between EI and thickness and function of the tongue., Methods: Ninety-four healthy elderly individuals (30 male, 64 female) aged >65 years (mean 71.10 ± 4.13 years) were enrolled. Tongue thickness (TT) and EI were determined by US. Tongue function was evaluated by measurement of tongue pressure and oral diadochokinesis (OD). Multiple regression analysis was used to identify the factor with the strongest influence on EI of the tongue., Results: The mean thickness of the middle of the tongue was 40.42 ± 4.24 mm and that of the base was 23.35 ± 3.32 mm; the respective EI values were 46.54 ± 9.33 and 49.33 ± 9.83. The average OD rates for /ta/ and /ka/ were 5.73 ± 1.09 and 5.40 ± 1.00 times/s, respectively. Multiple regression analysis for EI showed that /ta/ (β = -2.518, P = 0.042) and thickness of the middle of the tongue (β = -1.278, P < 0.001) were significant independent variables. Similarly, the EI at the base of the tongue showed that /ka/ (β = -4.038, P = 0.021) and base of TT (β = -0.913, P = 0.004) were significant independent variables., Conclusion: EI may be an indicator of TT and OD in both the middle and base of the tongue. Ultrasound is beneficial for evaluating TT and function., (© 2019 John Wiley & Sons Ltd.)

Purpose: To examine the effect of mandibular ridge form and denture quality on oral health-related quality of life (OHRQoL) in complete denture wearers by using structural equation modeling (SEM) analysis of data before and after new complete denture insertion., Methods: Four hundred thirty-two edentulous patients who visited the Dental Hospital of Tokyo Medical and Dental University for new complete dentures were recruited. An intervention study design was conducted, including complete denture fabrication with SEM analysis. Mandibular ridge form, mandibular denture stability, accuracy of jaw relation record, and the Oral Health Impact Profile for edentulous subjects (OHIP-EDENT-J) total score before and after new complete denture insertion were used in the hypothesized model., Results: Two hundred and thirty-seven participants completed the research. SEM analysis demonstrated adequate model fit. Path coefficients of mandibular ridge form to OHIP-EDENT-J before and after insertion, and mandibular denture stability to OHIP-EDENT-J before insertion, were significant., Conclusions: This study demonstrated that mandibular denture stability and mandibular ridge form are important to ensure successful complete denture therapy., (Copyright © 2019 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.)

Objective: The aim was to evaluate the combined effects of a new complete denture fabrication and simple dietary advice (using unique pamphlets) by dentists on nutrient intake in edentulous elderly patients., Materials and Methods: A randomized controlled trial was performed on edentulous elderly patients who were randomly allocated to either an intervention or a control group. The intervention group received a new complete denture and simple dietary advice, whereas the control group received a new complete denture and denture care advice. The outcomes of this trial (nutrient intakes) were calculated using a brief-type self-administered diet history questionnaire (BDHQ) and assessed at three time points (pretreatment and 3 and 6 months post-treatment)., Results: At 3 months post-treatment, the intake of several nutrients such as proteins (p = 0.004), magnesium (p < 0.001), and vitamin B1 (p = 0.014) was significantly higher in the intervention group than the control group, whereas at 6 months post-treatment, plant protein (p = 0.028) intake was significantly higher in the intervention group than the control group. On the contrary, animal protein (p = 0.049) and vitamin B12 (p = 0.028) intakes were significantly higher in the control group., Conclusions: New complete denture fabrication with simple dietary advice might improve nutrient intake in elderly edentulous patients; however, the effect is probably short term., Clinical Significance: New complete denture fabrication along with simple dietary advice by dentists might improve nutrient intake in edentulous elderly patients. Therefore, regular use of these interventions in the dental setting might have long-term effects on nutrient intake in elderly edentulous patients., Trial Registration: UMIN-CTR Clinical Trial, unique trial number: UMIN000017879.

Aim: In recent years, the relationships of arm circumference and calf circumference with swallowing function have been reported. However, the efficacy of using the neck circumference, which is closer to the swallowing-related muscles, has never been verified. Jaw-opening force, an indicator of suprahyoid muscle strength, is known to be useful for screening for dysphagia. The aim of the present study was to identify the relationships between neck circumference and swallowing-related muscle strength, and to clarify the association between these variables in older individuals., Methods: A total of 104 healthy, independent older individuals, aged ≥65 years (36 men, 68 women, mean age 71.5 ± 4.5 years, range 65-83 years), participated in the study. Neck circumference, arm circumference, calf circumference, jaw-opening force and repetitive saliva swallowing test scores were measured. Multiple regression analysis was carried out to determine the relationship between neck circumference and jaw-opening force, between neck circumference and repetitive saliva swallowing test score, and to identify variables affecting jaw-opening force and neck circumference., Results: The participants' mean body mass index was 22.8 ± 2.9 (range 15.8-32.4). Sex and neck circumference, but not arm or calf circumference, were significant independent factors related to jaw-opening force. Independent factors affecting neck circumference were sex, body mass index, jaw-opening force and arm circumference, but not repetitive saliva swallowing test score., Conclusions: In healthy older individuals, neck circumference was more strongly related to jaw-opening force than were arm or calf circumference. This suggested that neck circumference could be useful for evaluating swallowing-related muscle strength non-invasively and easily. Geriatr Gerontol Int 2019; 19: 330-334., (© 2019 Japan Geriatrics Society.)

Objectives: To compare the effect of conventional complete dentures fabricated using two different impression methods on masticatory performance and factors relating to masticatory performance in a randomized controlled trial., Methods: A crossover randomized controlled trial was performed with edentulous patients requiring maxillomandibular complete dentures. Mandibular complete dentures were fabricated using two different methods. The conventional method (C) used a custom tray border molded with an impression compound and a silicone. The simplified method (S) used a stock tray and an alginate. Participants were randomly divided into the two groups. In the C-S group, the conventional method was used first, followed by the simplified method; the order was reversed in the SC group. Adjustments were performed four times. The wash out period was 1 month. Masticatory performance as assessed by the mixing of a color-changeable chewing gum (mixing ability). Maximum occlusal force, occlusal contact area, and perceived chewing ability were assessed for each group., Results: Twenty-seven patients underwent randomization and 24 participants completed the trial. With regard to occlusal contact area, the conventional method showed significantly larger occlusal contact area than the simplified method. No significant differences were observed between the two methods regarding mixing ability, maximum occlusal force, and perceived chewing ability., Conclusions: This study showed that complete dentures fabricated with the conventional method had a significantly larger occlusal contact area than those made using the simplified method., Clinical Significance: Complete dentures fabricated with the conventional method, comprising a preliminary impression using alginate in a stock tray followed by a final impression using silicone impression material in a border molded custom tray, resulted in fewer post-insertion adjustments than the simplified method, potentially contributing to earlier stability of new dentures., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Statement of Problem: Single-implant-retained mandibular overdentures (1-IODs) may be an alternative to 2-IOD for maladaptive denture patients giving comparable satisfaction, lower cost, and shorter treatment times. However, studies evaluating the effect of the number of implants on the strain exerted around the implants of IODs using strain-gauge analysis are lacking., Purpose: The purpose of this in vitro study was to evaluate the effect of the number of implants on the strain in an IOD under various loading and dislodging conditions., Material and Methods: A mandibular IOD with the Locator attachment system (pink nylon inserts) was fabricated on artificial mucosa. Three implant positions recorded the loading: 1-IOD (mid-anterior), 2-IOD (bilateral lateral incisor), and 3-IOD (mid-anterior and bilateral canine) were prepared. Strain gauges attached to the mid-anterior implant replica for the 1-IOD, the left lateral incisor replica for the 2-IOD, and the anterior and left canine replicas for the 3-IOD. Vertical loads of 50 N were applied to the experimental overdenture in the mid-anterior and right molar and left molar regions. Three dislodging tests were performed in 3 different areas: mid-anterior, posterior, and mid-anterior and bilateral molar. Six measurements were made under each loading and dislodging condition for each IOD (N=6). During the calibration test, the resultant strain measured by strain gauge was converted into a lateral force (F) value by using linear regression: F anterior-posterior (N)=1.08×strain (με), F posterior-anterior (N)=0.192×strain (με), F left-right (N)=0.590×strain (με), F right-left (N)=0.560×strain (με). Statistical analysis was performed by using 1-way ANOVA and the Tukey honestly significant difference test (α=.05)., Results: The 3-IOD demonstrated the significantly highest strain under loading and dislodging conditions (P<.05). The 1-IOD demonstrated the significantly highest strain during right-side loading (P<.05). Upon anterior and left-side loading, no significant difference was noted in strain between the 1-IOD and 2-IOD (P=.413, P=.272). Under dislodging conditions, the 1-IOD exhibited the significantly lowest strain (P<.05)., Conclusions: Within the limitations of this study, the 3-IOD demonstrated the highest lateral resistance force during load and dislodge testing, whereas the 1-IOD exhibited the lowest., (Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

With rapid aging of the world's population, the demand for research, for a better understanding of aging and aging-related disorders, is increasing. Ideally, such research should be conducted on human subjects. However, due to ethical considerations, animals such as rodents and monkeys are used as alternatives. Among these alternative models, non-human primates are preferred because of their similarities with humans. The small South American common marmoset (Callithrix jacchus) may offer several advantages over other non-human primates in terms of its smaller size, shorter life-span, and dental anatomy identical to humans. The purpose of this study was to determine the viability of using the marmoset as a human oral disease model. We collected saliva samples from eight marmosets and eight human subjects. Prokaryotic DNA was extracted from the saliva samples, and 16S bacterial rRNA gene sequencing was performed on each of the samples. Our results indicated that the types of oral microbiomes detected among human and marmoset samples were nearly indistinguishable. In contrast, the oral microbiomes of our human and marmoset subjects were distinctly different from those reported for rats and dogs, which are currently popular research animals. The oral microbiomes of marmosets showed greater diversity than those of humans. However, the oral microbiota of marmosets exhibited less variation than those of humans, which may be attributed to the fact that the marmoset subjects were kept in a controlled environment with identical lifestyles. The characteristics of its oral microbiota, combined with other technical advantages, suggest that the marmoset may provide the best animal model thus far for the study of oral health. This study characterized the oral microbes of the marmoset, thereby providing information to support future application of the marmoset as a model for age-related oral disease., Competing Interests: The following authors are affiliated with CLEA Japan, Inc.: KK and KF. The commercial affiliation with CLEA Japan, Inc. does not alter our adherence to PLOS ONE policies on sharing data and materials.

Background: Two-implant overdentures (2-IODs) is an expected treatment option to improve the masticatory performance (MP) of edentulous individuals., Purpose: The purpose of the current study was to compare MPs between immediately loaded and conventionally loaded mandibular 2-IODs retained by magnet attachments., Materials and Methods: Nineteen participants with edentulous mandibles were randomly assigned to an immediately loaded group or a conventionally loaded group. Each participant received two implants. The immediate group was loaded on the same day as implant insertion, whereas the conventional group was loaded 3 months after implant insertion. Both MP, measured by a color-changeable chewing gum and a gummy jelly, and maximum occlusal force were assessed at baseline and at 1, 3, 6, 12, 24, and 36 months after implant insertion., Results: A significantly higher MP, measured by gummy jelly, was observed at the 6-month time-point in the immediate group (P = .034). No significant differences in MP, measured by chewing gum, or maximum occlusal force were observed between the two groups at any time-point., Conclusions: Within the limitations of the present study, immediate loading of 2-IODs could improve MP at an earlier time-point than conventional loading of 2-IODs., (© 2018 Wiley Periodicals, Inc.)

Background: The tongue is responsible for compressing food against the palate and squeezing it into the pharynx during the oral preparatory phase of swallowing. Tongue pressure (TP), an indicator of tongue muscle strength, has been observed to decline with age; maximum occlusal force (MOF), an indicator of chewing ability, is correlated with TP. However, no study has investigated the relationship between TP and MOF., Objective: To investigate the correlation between TP and MOF according to age in healthy individuals., Methods: We retrospectively collected handgrip strength (HGS), body mass index (BMI), TP, MOF and tooth loss data for 785 healthy participants (305 men, 480 women). All subjects had either unilateral or bilateral occlusal support, regardless of the presence of dentures or natural teeth. The participants were divided into two groups: an adult (20s-50s, n = 497) group and an elderly (60s-80s, n = 288) group. Multivariate linear regression analysis was performed to determine significant independent variables associated with TP in both groups., Results: Multivariate analysis revealed that TP was significantly associated with age (β = -0.153), BMI (β = 0.205), HGS (β = 0.298) and MOF (β = 0.239) in the adult group (all P < 0.001) and with age (β = -0.266, P < 0.001), BMI (β = 0.160, P = 0.005), MOF (β = 0.217, P = 0.001) and tooth loss (β = 0.156, P = 0.011) in the elderly group., Conclusions: As age and MOF are each associated with TP in both elderly and adult patients, age-related TP decline can be prevented with routine lingual exercises, even before the onset of old age. Additionally, MOF deterioration may indicate a decline in TP for elderly., (© 2018 John Wiley & Sons Ltd.)

Background and Aims: Systemic muscle wasting during perioperative periods has a major impact on postoperative morbidity. However, data on oropharyngeal muscle weakness after surgery are scarce. We examined whether maximum tongue pressure (MTP) and hand grip strength (HGS) diminished during the perioperative period without and with oral feeding in patients receiving cancer surgery., Methods: A total of 258 patients undergoing cancer surgery who had visited a hospital dental clinic were prospectively recruited between October 2015 and February 2016. MTP and HGS were measured on the day before and 4 days after surgery. Data on age, sex, tumor location, surgical procedure, and oral feeding status were obtained from patient medical records. We analyzed for differences in the perioperative changes of MTP and HGS according to surgical procedure, oral feeding, and tumor location using ANOVA., Results: Neither MTP nor HGS differed significantly among tumor locations before surgery. The proportion of patients with an oral diet at 4 days after surgery was 36.7% and 34.5% for upper GI and colorectum groups versus 89.2% and 86.4% for genitourinary and lung groups, respectively. During the perioperative period, MTP decreased more significantly in patients without oral feeding than in those with oral feeding at 4 days after surgery (P < 0.01). HGS was not affected by postoperative oral feeding status. Both MTP and HGS decreased more significantly in the upper gastrointestinal group than in the genitourinary and lung groups (P < 0.05), except for MTP between upper GI and genitourinary groups (P = 0.10)., Conclusions: MTP, but not HGS, diminishes significantly during the perioperative period without oral feeding. As tongue muscle disuse after surgery may adversely impact postoperative oropharyngeal muscle decline, perioperative tongue muscle strengthening exercises may assist in maintaining muscle strength and good oral feeding., (Copyright © 2018 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.)

We report a case of difficult nasal intubation utilizing a Pentax-Airway scope ® AWS-100. A 4-month-old female with a rapidly growing melanotic neuroectodermal tumor was scheduled for resection under general anesthesia. The tumor was a large rubbery mass located in the middle of the mandible. For nasal intubation using the AWS, guidance of the tube toward the glottis was attempted using pediatric Magill forceps. Although we could hold the tube with the Magill forceps, it was difficult to insert the tube into the trachea due to the limited space in her hypopharynx. We then used a standard laryngoscope with a Miller straight blade for direct visual laryngoscopy and successfully intubated the patient with the aid of the pediatric Magill forceps. We often experience difficulty navigating a nasal endotracheal tube toward the glottis even when a clear glottic view is obtained with video laryngoscopes, especially in children with a small oropharyngeal space. However, some reports have been shown that video laryngoscopes are useful for intubation of the difficult airway and causes less stress to the upper airway than direct visual laryngoscopy. Video laryngoscopy can be an excellent way to provide nasal intubation in some but not all children.

Background: There is growing international interest in identifying the effects of ageing on oral health and on appropriate strategies for managing oral disorders. The Japanese Society of Gerodontology (JSG), as the official representative of researchers and clinicians interested in geriatric dentistry in Japan, makes several recommendations on the concept of "oral hypofunction.", Aims: This study proposes diagnostic criteria and management strategies to reduce the risk of oral hypofunction among older people., Conceptual Framework: We define oral hypofunction as a presentation of 7 oral signs or symptoms: oral uncleanness; oral dryness; decline in occlusal force; decline in motor function of tongue and lips; decline in tongue pressure; decline in chewing function; and decline in swallowing function. The criteria of each symptom were determined based on the data of previous studies, and oral hypofunction was diagnosed if the criteria for 3 or more signs or symptoms were met., Conclusions: We recommend that more evidence should be gathered from clinical studies and trials to clarify our diagnostic criteria and management strategies., (© 2018 The Authors Gerodontology published by Gerodontology Association and John Wiley & Sons Ltd.)