Oral function of implant-assisted removable partial dentures with magnetic attachments using short implants: A prospective study.

OBJECTIVES: This prospective study aimed to compare the oral functions of removable partial dentures (RPDs) with those of implant-assisted removable partial dentures (IARPDs) with short implants and magnetic attachments in patients with mandibular Kennedy class I and II. MATERIAL AND METHODS: Thirty participants with mandibular Kennedy class I or II and at least three distal missing teeth were recruited. Oral functions, including mixing ability, comminuting ability, maximum bite force, and occlusal contact area, were assessed for RPDs (stage 0), IARPDs with healing caps (stage 1), and IARPDs with magnetic attachments (stage 2). The implants were loaded with occlusal force in stages 1 and 2. Finally, the data of the 27 participants who completed the evaluation at stage 2 were analyzed. The Wilcoxon signed-rank test with Bonferroni correction was used to assess the differences in the oral functions among the different stages. RESULTS: The implant survival rate was 93.8%. There were significant differences in the comminuting ability and occlusal contact area between stages 0 and 2 (p < .001 and p = .036, respectively) and stages 1 and 2 (p = .003 and p = .015, respectively). Regarding the maximum bite force, there was a significant difference between stages 1 and 2 (p = .018). However, there was no significant difference in the mixing ability between the three stages. CONCLUSIONS: Within the limitations of this study, it was concluded that IARPDs in the mandible with short implants and magnetic attachments may improve oral functions.

Effect of Different Filler Contents and Printing Directions on the Mechanical Properties for Photopolymer Resins.

Photopolymer resins are widely used in the production of dental prostheses, but their mechanical properties require improvement. We evaluated the effects of different zirconia filler contents and printing directions on the mechanical properties of photopolymer resin. Three-dimensional (3D) printing was used to fabricate specimens using composite photopolymers with 0 (control), 3, 5, and 10 wt.% zirconia filler. Two printing directions for fabricating rectangular specimens (25 mm × 2 mm × 2 mm) and disk-shaped specimens (φ10 mm × 2 mm) were used, 0° and 90°. Three-point bending tests were performed to determine the flexural strengths and moduli of the specimens. The Vickers hardness test was performed to determine the hardness of the specimens. Tukey's multiple comparison tests were performed on the average values of the flexural strengths, elastic moduli, and Vickers hardness after one-way ANOVA (α = 0.05). The flexural strengths and elastic moduli at 0° from high to low were in the order of 0, 3, 10, and 5 wt.%, and those at 90° were in the order of 3, 0, 10, and 5 wt.% (p < 0.05). For 5 and 10 wt.%, no significant differences were observed in mechanical properties at 0° and 90° (p < 0.05). The Vickers hardness values at 0° and 90° from low to high were in the order of 0, 3, 5, and 10 wt.% (p < 0.05). Within the limits of this study, the optimal zirconia filler content in the photopolymer resin for 3D printing was 0 wt.% at 0° and 3 wt.% at 90°.

Trueness and precision of artificial teeth in CAD-CAM milled complete dentures from custom disks with a milled recess.

STATEMENT OF PROBLEM: Studies on the movement of artificial teeth during the manufacturing of computer-aided design and computer-aided manufacturing (CAD-CAM) complete dentures using the custom disk method with milled recesses and on whether the movement is within a clinically acceptable range are lacking. PURPOSE: The purpose of this in vitro study was to assess the trueness and precision of the artificial teeth on custom disks the recesses of which were manufactured using a milling machine and to compare the results with the recesses manufactured using a 3-dimensional (3D) printer. MATERIAL AND METHODS: Four types of artificial teeth (maxillary left central incisors [Max-L1], mandibular left central incisors [Man-L1], maxillary left first premolars [Max-L4], and maxillary left first molars [Max-L6]) were prepared. Milling data were created, and 3 of each type of tooth were attached to each disk made up of 3 concentric circles (large, medium, and small). Five each of the 3D-printed custom disks and custom disks with milled recesses were milled based on the milling data. Standard tessellation language data were obtained through cone beam computed tomography and superimposed by using a CAD software program. Mean absolute error (MAE) values were calculated to assess trueness and precision; MAE values of artificial teeth in custom disks with milled recesses and 3D-printed custom disks were statistically compared by using the 2-way analysis of variance test with 2 factors, 2 types of custom disks and 4 types of artificial teeth, and the Tukey post hoc comparison (α=.05). RESULTS: Regarding position trueness, the MAE value of Man-L1 on the milling custom disk was significantly lower than that of the 3D-printed custom disk (P<.001), whereas the MAE values of Max-L4 and Max-L6 on the milling custom disk were significantly higher than those on the 3D-printed custom disk (P<.001). No significant difference was found in the MAE value of the position trueness of Max-L1 between the milling and 3D-printed custom disks. Regarding position precision, the MAE values of Max-L1, Man-L1, and Max-L4 on the milling custom disk were significantly lower than those on the 3D-printed custom disks (P=.002, P<.001, P=.025, respectively). However, no significant difference was seen in the MAE value of position precision of Max-L6 between the milling and 3D-printed custom disks (P=.180) CONCLUSIONS: Movement of artificial teeth during the manufacture of dentures using the custom disk method and custom disks with milled recesses was within a clinically acceptable range.

Patient-reported outcome and cost-effectiveness analysis of milled and conventionally fabricated complete dentures in a university clinic: A retrospective study.

STATEMENT OF PROBLEM: The custom disk is a novel method of complete denture fabrication; however, patient-reported outcomes and fabrication costs are unknown. PURPOSE: The purpose of this retrospective study was to evaluate general patient satisfaction with complete dentures fabricated through the custom disk method. In addition, a comparative cost-effectiveness analysis was conducted for the custom disk method and conventional removable complete dentures. MATERIAL AND METHODS: Complete dentures were fabricated for 44 edentulous participants by using the custom disk method (n=20) or the conventional removable complete denture (n=24). General patient satisfaction was measured by using visual analog scales before and after denture fabrication and compared by using the Wilcoxon signed-rank test (α=.05); the fabrication cost for each method was investigated and compared by using the Mann-Whitney U test (α=.05). Cost-effectiveness was analyzed with the incremental cost-effectiveness ratio as incremental cost per change in general patient satisfaction for the custom disk method with respect to the conventional removable complete denture. RESULTS: The median general patient satisfaction with the custom disk method and conventional removable complete denture after the intervention was 84.0 mm and 91.0 mm, respectively. General patient satisfaction with the custom disk method was significantly higher after the intervention (P=.002). The median labor costs for the custom disk method and conventional removable complete denture were 24 516 and 36 583 Japanese yen, respectively, and the difference was statistically significant (P<.001). The median of the total cost of the custom disk method and the conventional removable complete denture was 41 104 and 45 276 Japanese yen, respectively, and the difference was statistically significant (P=.004). The incremental cost-effectiveness ratio was -251.4. CONCLUSIONS: The custom disk method improved general patient satisfaction. The labor and total costs of the custom disk method were significantly lower than those of the conventional removable complete denture. The incremental cost-effectiveness ratio demonstrated that the custom disk method was more cost-effective than the conventional removable complete denture.

Effect of dental intervention on improvements in metabolic syndrome patients: a randomized controlled clinical trial.

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_view.cgi?recptno=R000026176 .

Association between tongue and lip motor functions and mixing ability in complete denture wearers.

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.

Combined effects of new complete denture fabrication and simplified dietary advice on nutrient intake in edentulous elderly patients for 6 months.

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.

Influence of simplified dietary advice combined with new complete denture fabrication on masticatory function of complete denture wearers.

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.

Reliability and Validity of the MD Anderson Dysphagia Inventory Among Japanese Patients.

This study aimed to validate the Japanese version of a dysphagia-specific quality of life questionnaire, the MD Anderson Dysphagia Inventory (MDADI-J), and to verify trends between MDADI-J and Functional Oral Intake Scale (FOIS) scores. The original 20 MDADI items were translated using a forward-backward method following accepted cultural adaptation guidelines. Seventy-two patients with a history of head and neck cancer treatment completed the MDADI-J between October 2015 and August 2016. Concurrent validity was determined by correlations with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Head and Neck 35 (EORTC QLQ-H&N35) instruments. Discriminant validity was examined using cancer stage grouping between stages I-II and III-IV. Additionally, trends between the FOIS and the MDADI-J total scores were analyzed using a trend test. The Cronbach's α coefficient of the MDADI-J total score was 0.92, indicating high internal consistency. The average inter-item correlation coefficients ranged from 0.39 to 0.49. ICC, an indicator of test-retest reliability, was 0.84 for the total score, and 0.58 to 0.81 for individual subscales. The total score and all subscales were significantly associated with the scores for each factor of the EORTC QLQ-C30 and EORTC QLQ-H&N35. The total score and all subscales were significantly different between clinical tumor stages I-II and III-IV. The total scores all increased with the progress of the FOIS. In conclusion, this study validated the Japanese version of the MDADI and showed that as FOIS scores deteriorate, MDADI-J scores tend to constantly decrease.

Prognoses of new complete dentures from the patient's denture assessment of existing dentures.

OBJECTIVES: The aim was to determine prognostic factors affecting frequent post-delivery adjustments of new complete dentures using patients' assessments of existing complete dentures. MATERIALS AND METHODS: A total of 125 edentulous participants (56 men, 69 women; mean age, 76.4 years) who required new complete dentures evaluated existing dentures using the patient's denture assessment (PDA), a questionnaire regarding the self-assessment of dentures composed of 22 question items and containing six subscales: "function," "lower denture," "upper denture," "expectation," "esthetics and speech," and "importance." Moreover, the numbers of post-delivery adjustments of new dentures were recorded. A multiple logistic regression analysis was performed to identify significant factors for frequent adjustments of new dentures with five subscales of the PDA (excluding "importance"), level of mandibular ridge resorption, and age as independent variables. RESULTS: The analysis showed that "function," "esthetics and speech," and level of mandibular ridge resorption were significant variables for a frequent number of post-delivery adjustments of new complete dentures. CONCLUSIONS: The results suggested that patients' assessments of existing dentures using the PDA might allow a prediction of prognosis for complete denture treatments. Additionally, low "function" scores and high "esthetics and speech" scores for existing dentures and high levels of mandibular ridge resorption were significant prognostic factors affecting frequent post-delivery adjustments of new complete dentures. CLINICAL RELEVANCE: It may be difficult for edentulous persons to adapt to new complete dentures, especially those who have complaints about mastication and swallowing with existing dentures and poor mandibular ridges, but are satisfied with esthetics and speech.

Reliability and validity of a questionnaire for self-assessment of complete dentures.

BACKGROUND: Demand for complete denture treatment is expected to rise over several decades. However, to date, no questionnaire on complete dentures, as evaluated by edentulous patients, has been shown to be reliable and valid. This study sought to assess the reliability and validity of Patient's Denture Assessment (PDA), which provides a multidimensional evaluation of dentures among edentulous patients. METHODS: Patients, who had new complete dentures fabricated at the University Hospital of Dentistry, Tokyo Medical and Dental University through 2009 to 2010, were enrolled. The reliability of the PDA was determined by examining internal consistency and test-retest reliability. Internal consistency for all of the question items and the six subscales was measured using Cronbach's α and average inter-item correlation coefficients among 93 participants. For 33 of these participants, test-retest reliability was determined at a 2 month-interval using the interclass correlation coefficients (ICCs) and 95% confidence interval for the summary scores and the six subscale scores. The PDA was validated in 93 participants by examining the difference in the summary score and the six subscale scores of the PDA before and after replacement with new dentures by the paired t-test. Ability to detect change was also tested in 93 patients using effect size. RESULTS: The Cronbach's α for the PDA ranged from 0.56 to 0.93. The average inter-item correlation coefficients ranged from 0.28 to 0.83. ICCs for the PDA ranged from 0.37 to 0.83. The paired t-test showed a significant difference between the summary score and the six subscale scores before and after replacement with new dentures (p < 0.05) and the effect size was 0.97. CONCLUSIONS: The PDA demonstrated good reliability by assessing internal consistency and test-retest reliability. In addition, the PDA demonstrated good validity by assessing discriminant validity. Thus, the PDA could help dentists obtain a detailed understanding of the patients' perceptions in using their dentures.

Fabrication of sports mouthguards using a semi-digital workflow with 4D-printing technology.

Purpose This technical procedure report explains the fabrication protocol for a newly developed 4D-printed sports mouthguard (MG) based on 4D-printing technology.Methods An intraoral scanner was used to scan a maxillary arch model. A two-layer sports MG was designed based on the scanned model using computer-aided design software and output in a standard tessellation language file format. Two types of filament materials were used for the MG material: a thermoplastic shape memory polyurethane elastomer with a unique glass transition temperature for the external layer and a thermoplastic elastomer for the internal layer. Both MGs were printed using a fused deposition modeling 3D printer and assembled using adhesives after trimming the support material. To confirm the shape-memory performance of the fabricated 4D-printed MG, a deviation analysis was performed by superimposing the internal surface data of the fabricated MG and the MG whose shape was recovered. The distance between the data obtained by deviation analysis was calculated, and the root mean square error value (mm) was determined.Conclusions The 4D-printing technology simplifies the complex processes required with conventional methods. It also overcomes the issues of conventional and 3D-printed MGs, such as the reduced fitting accuracy caused by deformation, because this technology employs shape memory materials.

Effect of digital complete dentures manufactured using the custom disk method on masticatory function.

Statement of problem: The effect of using the custom disk method (CDM) for fabricating digital dentures on patients' masticatory function should be studied to support its use in clinical practice. Purpose: To investigate the effect of digital dentures fabricated using CDM on patients' masticatory function. Material and methods: This single-center prospective clinical study included 20 patients with edentulous maxillary and mandibular arches who used a complete denture. The digital impression and complete denture manufacturing procedures using CDM have already been reported by Kanazawa et al. (2018) [32] and Soeda et al. (2022) [18] Thedigital dentures fabricated with CDM were delivered to the participants, and periodic adjustments were made until the patient could use the denture without pain. A color-changeable chewing gum, two types of gummy jellies that can evaluate the masticatory function, and pressure-sensitive sheets were used to evaluate the participants' masticatory function at baseline, 1 month, and 6 months following adjustment of the new digital complete dentures fabricated with CDM. These masticatory function values had already been measured in the previous conventional dentures and were recorded as baseline values. Results: The study participants included 8 women and 12 men (mean age, 77.6 years). The color-changeable chewing gum analysis indicated that there was no significant improvement of masticatory function from baseline to 1 M (P = .083) and 6 M (P = .157).The gummy jelly analysis indicated no significant differences between the masticatory function baseline and 1 month (P = .387); however, a significant improvement was observed from baseline to 6 months (P = .020). Tests with Glucolum indicated a significant improvement from baseline to 1 month (P = .012) and 6 months (P = .003). The maximum bite force and occlusal contact area showed no significant difference at any time point. Conclusions: Significant improvement in masticatory function was observed upon evaluation with gummy jelly and Glucolum 6 months after delivering the new digital complete dentures. Under limited conditions, the digital denture fabricated using CDM resulted in good recovery of the masticatory function in elderly edentulous patients. The present results combined with the cost-effectiveness and patient satisfaction associated with CDM indicate its clinical utility.

Association between occlusal supports and nutritional status in older adults: A systematic review.

Background/purpose: Impaired masticatory performance results in nutritional deficiencies in older adults. This systematic review aims to investigate the following clinical question (CQ): Do occlusal supports impact nutritional intake or nutritional status in older individuals? Materials and methods: An extensive systematic literature search was performed to summarize the currently available knowledge to address the CQ. The cohort and intervention studies with participants of ≧60 years old or a mean age of 65 years performed before May 2021 were included. Studies were required to measure the parameters related to occluding tooth pairs/occlusal units and food/nutrient intake and/or nutritional status. Bias risk was assessed using the Risk of Bias Assessment Tool for Nonrandomized Studies. Results: After an independent screening of 1130 initial records, 24 reports from 22 studies were included. Participants (n = 8684) in the included studies were mainly residents of nursing homes or community-dwelling individuals. Following the assessment of bias risk, it is revealed that all studies had methodological weaknesses. Over half of the studies concluded that there was an association between occlusal support and nutritional intake or status. However, it was also revealed that various confounding factors are involved in the association between occlusal support and nutrition. Conclusion: This systematic review concludes that occlusal support might be associated with nutritional intake or nutritional status in the older population, although there are methodological limitations of each study. The evidence is still insufficient, and more well-designed studies are required.

Effect of support structures on the trueness and precision of 3D printing dentures: An in vitro study.

Purpose Additive manufacturing has revolutionized the fabrication of complete dentures. However, this process involves support structure, which is a construction part that holds the specimen during printing, and may prove to be disadvantageous. Therefore, this in vitro study compared the effect of support structure reduction on various volume and area distributions of a 3D-printed denture base to determine optimal parameters based on accuracy.Methods A complete maxillary denture base construction file was used as reference. Twenty denture bases were 3D printed under four conditions (total n=80): no support structure reduction (control), palatal support structure reduction (Condition P), border support structure reduction (Condition B), and palatal and border support structure reduction (Condition PB). Printing time and resin consumption were also recorded. The intaglio surface trueness and precision of all acquired data were exported to a 3D analysis software, and the dimensional changes to the denture base were analyzed using the root-mean-square estimate (RMSE) to assess geometric accuracy and generate color map patterns. Nonparametric Kruskal-Wallis and Steel-Dwass tests (α=0.05) analyzed the accumulated data.Results Control had the lowest RMSE values for trueness and precision. Nevertheless, it demonstrated a significantly lower RMSE than that of Condition B (P=0.02) in precision. Owing to negative deviation at the palatal region, Conditions P and PB had higher retention than Control and Condition B regarding the color map pattern.Conclusions Within the limitations of this study, the reduction of palatal and border support structures showed optimal accuracy with resource and cost savings.

Accuracy of newly developed color determination application for masticatory performance: Evaluating color-changeable chewing gum.

PURPOSE: Color-changeable chewing gums are used to evaluate masticatory performance, as measured by a colorimeter or visually based on a color scale. Although anyone can use a color scale, the evaluation accuracy depends on the evaluator. We develop an application that can determine the degree of color change in chewing gum using smartphone images, making color evaluation accurate and easy to measure. METHODS: For the application, 60 chewed gum samples were prepared. Two shots were captured using two smartphone models. To create the application algorithm, a formula was developed to approximately map the color value from the smartphone images to the true value using a colorimeter. A basic validation was performed on 60 new samples covering a range of colors, followed by a field validation on 100 healthy dentate participants aged 20-39 years. RESULTS: The intraclass correlation coefficient for two repeated shots had a high value ≥ 0.97 in the basic and field validations, confirming reliability. No significant differences were observed in the paired t-test and Wilcoxon signed-rank test, and a significant and strong correlation (correlation coefficient ≥ 0.92) was observed between the evaluation values using the colorimeter and the basic and field validations. Bland-Altman plots further confirmed the validity of the application. CONCLUSIONS: A software application was developed to enable easy, quick, and accurate determination of the masticatory performance of a chewing gum from images taken using a smartphone with highly reliable and validated results.

Effect of gum-chewing exercise on maintaining and improving oral function in older adults: A pilot randomized controlled trial.

Background/purpose: Gum chewing has been found to improve oral function. Nevertheless, few randomized controlled trials have investigated the effects of gum-chewing exercises on oral function in older adults. This study aimed to examine the effect of gum-chewing exercises on oral function in older adults. Materials and methods: This was a single-blind, randomized controlled trial, conducted from November 2021 to January 2022. A total of 130 participants were divided randomly into the intervention and control groups. The intervention group was told to chew experimental gums for one month, while the control group was instructed to chew experimental tablets for one month. Maximum bite force, occlusal contact areas, oral dryness, tongue pressure, tongue and lip functions (number of times each of the following syllables is pronounced per second:/pa/,/ta/, and/ka/), masticatory function, subjective masticatory function, and gum-chewing time were measured at baseline and one month following intervention to assess outcomes. Results: One month following the intervention, tongue pressure was significantly higher in the intervention group than in the control group (P = 0.027). In the within-group comparisons, maximum bite force (P < 0.001), unstimulated saliva flow (P < 0.001), tongue and lip functions (/pa/: P < 0.001;/ta/: P < 0.001;/ka/: P < 0.001), color scale value (P = 0.019), and ΔE value (P = 0.024) were significantly increased in the intervention group. Conclusion: The results suggest that gum-chewing exercises can improve oral functions in older adults, although additional increases in masticatory load may be necessary to establish a more effective oral function training method using gum-chewing exercises in older adults.

Effect of New Complete Dentures and Simple Dietary Advice on Cognitive Screening Test among Edentulous Older Adults: A Randomized Controlled Trial.

Mild cognitive impairment (MCI), including memory loss, has been attracting attention in Japan. This study assessed the effect of new complete dentures provision alone and with dietary intervention on cognitive functions assessed using the Japanese version of the Montreal Cognitive Assessment (MoCA-J). A randomized controlled trial was conducted with 70 older adults who required new complete dentures. The participants had new complete dentures fabricated and were randomly classified into the intervention or control group. The intervention group received simple dietary advice, and the control group only received denture care advice. Cognitive function was assessed using the MoCA-J before and at 3 and 6 months after treatment. The between-group comparison and within-group comparison were analyzed. No significant differences were reported for comparisons between the intervention and control groups. A significant increase was revealed in the within-group comparisons for the total scores between the 3- and 6-month assessments (p = 0.002) and between the baseline and 6-month assessments (p = 0.012) in the intervention group. In the control group, a significant increase in the total scores was not revealed between any of evaluation period. Complete denture replacement combined with simple dietary intervention may help improve MoCA-J scores in edentulous older adults.

Prediction accuracy of incisal points in determining occlusal plane of digital complete dentures.

PURPOSE: This study aimed to predict the positional coordinates of incisor points from the scan data of conventional complete dentures and verify their accuracy. MATERIALS AND METHODS: The standard triangulated language (STL) data of the scanned 100 pairs of complete upper and lower dentures were imported into the computer-aided design software from which the position coordinates of the points corresponding to each landmark of the jaw were obtained. The x, y, and z coordinates of the incisor point (XP, YP, and ZP) were obtained from the maxillary and mandibular landmark coordinates using regression or calculation formulas, and the accuracy was verified to determine the deviation between the measured and predicted coordinate values. YP was obtained in two ways using the hamular-incisive-papilla plane (HIP) and facial measurements. Multiple regression analysis was used to predict ZP. The root mean squared error (RMSE) values were used to verify the accuracy of the XP and YP. The RMSE value was obtained after cross-validation using the remaining 30 cases of denture STL data to verify the accuracy of ZP. RESULTS: The RMSE was 2.22 for predicting XP. When predicting YP, the RMSE of the method using the HIP plane and facial measurements was 3.18 and 0.73, respectively. Cross-validation revealed the RMSE to be 1.53. CONCLUSION: YP and ZP could be predicted from anatomical landmarks of the maxillary and mandibular edentulous jaw, suggesting that YP could be predicted with better accuracy with the addition of the position of the lower border of the upper lip.

Fabrication of milled removable partial dentures using a custom plate with prefabricated artificial teeth.

PURPOSE: Although digital removable partial dentures have been previously described, there have been no reports on how to fabricate them in one piece. This study proposes a new method for fabricating patient-specific digital removable partial dentures using a custom plate. METHODS: First, a gypsum model was scanned using a laboratory scanner and a removable partial denture was designed using computer-aided design (CAD) software based on standard tessellation language data. The metal clasp was fabricated from Ti-6Al-4V using a 3D printer. For custom plate fabrication, a resin plate frame was designed using computer-aided design (CAD) software and fabricated using a 3D printer. An artificial tooth and metal clasp were fixed on the base surface of the frame, an auto-polymerizing resin was poured into the frame for the denture base, and the artificial tooth and metal clasp were packed to form a custom plate. The plate was cut using a milling machine. Subsequently, the support attached to the denture was removed and polished for complete fabrication of the denture. CONCLUSIONS: Our novel removable partial denture fabrication method is more efficient than the conventional method. The obtained removable partial dentures demonstrated satisfactory accuracy.