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.

CAD-CAM milled complete dentures with custom disks and prefabricated artificial teeth: A dental technique.

A digital complete denture was manufactured from a disk customized for each patient. The custom disk was made of resin and contained prefabricated artificial teeth. Both the denture base and the artificial teeth in the custom disk were milled in this technique, resulting in dentures with a high bond strength between the artificial teeth and denture base, excellent esthetics because of the prefabricated artificial teeth, and accurate occlusion because of the custom occlusal surface.

Evaluation of trueness and precision of stereolithography-fabricated photopolymer-resin dentures under different postpolymerization conditions: An in vitro study.

STATEMENT OF PROBLEM: Stereolithography (SLA) additive manufacturing (AM) technologies have become popular for the fabrication of complete dentures; however, the trueness and precision of the dentures under different postpolymerization conditions remain unclear. PURPOSE: The purpose of this in vitro study was to investigate the effect of different postpolymerization times and temperatures on the trueness and precision of SLA dentures. MATERIAL AND METHODS: Specimens simulating maxillary complete dentures were fabricated by SLA 3D printing. They were polymerized for 15 minutes or 30 minutes at different temperatures (40 °C, 60 °C, and 80 °C). The intaglio surface trueness of the specimens was evaluated by superimposing the postpolymerization standard tessellation language (STL) file on the original STL file for each specimen via a best-fit method (n=10). The precision was measured across specimens by superimposing the postpolymerization STL file from each specimen group and using the combination formula (n=45). Subsequently, root-mean-square estimates (RMSEs) and color map data were obtained, and a normality test was conducted on the obtained data. The results indicated that the distributions were not normal; therefore, nonparametric Kruskal-Wallis and Mann-Whitney tests were used to analyze the data (α=.05). RESULTS: For trueness, the lowest RMSE corresponded to the postpolymerization time of 30 minutes and a temperature of 40 °C. This result was significantly different from specimens those of the 15-minute and 60 °C, 15-minute and 80 °C, and 30-minute and 80 °C specimens (P<.001). For precision, the median of the lowest RMSE corresponded to the 30-minute and 40 °C specimens. This median value was significantly different from those of other specimens (P<.001). The findings indicate that the postpolymerization condition of 30 minutes and 40 °C affords the highest trueness and precision and the most favorable intaglio surface adaptation of the denture. CONCLUSIONS: The postpolymerization conditions influenced the RMSE values of the trueness and precision of a clear photopolymer resin. The RMSE and color map data associated with the 30-minute and 40 °C condition corresponded to the greatest trueness and precision of all the SLA denture specimens considered.

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

STATEMENT OF PROBLEM: Insufficient information is available regarding the trueness and precision of artificial teeth in computer-aided design and computer-aided manufacturing (CAD-CAM) milled complete dentures fabricated from custom disks, including prefabricated teeth. PURPOSE: The purpose of this in vitro study was to determine the trueness and precision of the position of the artificial teeth arranged in CAD-CAM milled complete dentures manufactured by using a custom disk method and to compare the trueness and precision of different tooth types and the occlusal surface and entire surface of the teeth. MATERIAL AND METHODS: The milling data were designed by using a CAD software program. Four types of artificial teeth (maxillary-left central incisor, mandibular-left central incisor, maxillary-left first premolar, and maxillary-left first molar) were arranged concentrically in the disk with 3 corresponding teeth per disk. Five custom disks were milled based on the milling data. The sample size for maxillary-left central incisor, mandibular-left central incisor, maxillary-left first premolar, and maxillary-left first molar was 15. The standard tessellation language data were obtained by scanning the milled disks with cone beam computed tomography. The obtained data were superimposed by using a CAD software program to assess the trueness and precision of the tooth positions. For the occlusal surface, the data were superimposed after trimming to assess the trueness and precision of the tooth position with respect to the entire tooth surface. After data superimposition, the deviation was analyzed by using a 3-dimensional analysis software program to obtain the mean absolute error values and color maps. The data were analyzed by using 2-way ANOVA and the Games-Howell post hoc test (α=.05). RESULTS: Significant differences were found in the mean absolute error values of the position trueness of the entire surface between the different teeth, except for maxillary-left first premolar and maxillary-left first molar (P<.05). Moreover, significant differences in the mean absolute error values of the precision for the entire surface were observed between mandibular-left central incisor and maxillary-left first premolar, as well as between mandibular-left central incisor and maxillary-left first molar (P<.05). The mean absolute error values of the position trueness of the occlusal surface were significantly smaller than those for the entire tooth surface for mandibular-left central incisor, maxillary-left first premolar, and maxillary-left first molar (P<.05). Finally, the mean absolute error values of the position precision of the occlusal surface were significantly smaller than those for the entire tooth surface for mandibular-left central incisor and maxillary-left first premolar (P<.05). CONCLUSIONS: The trueness and precision of the posterior teeth were higher than that of anterior teeth. The trueness of the movement of the artificial teeth during the manufacturing of dentures by using the custom disk method was found to be 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.

Evaluation of dimensional accuracy and degree of polymerization of stereolithography photopolymer resin under different postpolymerization conditions: An in vitro study.

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.

Replacing mandibular central incisors with a direct resin-bonded fixed dental prosthesis by using a bilayering composite resin injection technique with a digital workflow: A dental technique.

A straightforward technique is presented for an interim or short-term definitive esthetic replacement of missing anterior teeth requiring no tooth preparation. Composite resins are injected into transparent silicone indices fabricated from 3-dimensional-printed casts of a digital waxing. The dentin core is formed of a durable short fiber-reinforced injectable composite resin and veneered with an enamel-shade composite resin for enhanced esthetics. Besides being noninvasive, this technique is more straightforward than traditional options, reducing chair time while providing an accurate outcome.

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.

In vitro variation measurement of mandibular denture displacement resistance involving 1 to 3 implants.

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: Fanterior-posterior(N)=1.08×strain (µÎµ), Fposterior-anterior(N)=0.192×strain (µÎµ), Fleft-right(N)=0.590×strain (µÎµ), Fright-left(N)=0.560×strain (µÎµ). 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.

Measuring the retention of removable mandibular prostheses by a standardized model: A technical report.

Three cases of mandibular implant overdentures (IODs) were measured for retention by a developed model. A nylon thread was tied through a hole at the midline of the IOD and seated it in the patient's mouth properly. Briefly, a facebow was set on the patient, with its arms firmly held by an assistant. The other end of the thread was tied into a loop, and the thread was inserted through a hole at the Camper's line of the facebow and hooked onto a portable force gauge. The thread was then pulled in parallel with the arms of the facebow by the force gauge until the prosthesis dislodged while the patient opened his mouth. Denture retention was measured five times, and the mean was calculated. Appropriate analysis for validity and reliability of the model was performed, and statistical results showed that it was valid and reliable for measuring the retention of removable mandibular prostheses.

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.

Oral hypofunction in the older population: Position paper of the Japanese Society of Gerodontology in 2016.

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.

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.

Clinical guidelines and procedures for provision of mandibular overdentures on 4 mini-dental implants.

This article describes the flapless placement of mini-dental implants (MDI) to retain mandibular overdentures. Clinical inclusion/exclusion criteria and clinical protocols for the flapless placement of MDIs and for retrofitting the overdenture are presented. A minimum bone height of 13 mm and a minimal flap are recommended. After drilling, the 4 implants are placed with a self-tapping process. A minimum of 15 Ncm of resistance upon final insertion indicates that immediate loading can be performed. The metal housings with O-rings are incorporated into the prosthesis using autopolymerizing resin. The technique and protocol for immediately loaded 4-mini-implant mandibular overdentures is minimally invasive and cost effective.

Influence of implant number on the movement of mandibular implant overdentures.

STATEMENT OF PROBLEM: The rotational movement of an implant overdenture (IOD) has a negative effect on the perceived masticatory ability of the denture wearer. However, the influence of implant number on the movement of IODs has not been investigated. PURPOSE: The purpose of this in vitro study was to evaluate the denture movement of mandibular IODs anchored by different numbers of implants. MATERIAL AND METHODS: An edentulous mandibular test model with artificial mucosa and 5 experimental overdentures (N=5) was fabricated. The locator attachment system with blue nylon inserts was chosen for this study. Three implant positions were prepared: anterior midline (1-IOD), bilateral lateral incisor regions (2-IOD), and anterior midline and bilateral canine regions (3-IOD). Vertical loads of 50 N were applied to the mid-anterior region, the left canine region, the left premolar region, and the left first molar region. The vertical and horizontal displacements at the right distal edge and the vertical displacements at the loading point were measured. The displacement values were statistically analyzed using a 1-way analysis of variance and the post hoc Tukey honest significant difference test with the implant number as a factor. In addition, the values of the vertical and horizontal displacements at the distal edge of the overdenture were statistically compared using a paired t test, and the values of the vertical displacement at the distal edge of the overdenture were statistically analyzed by a repeated measures analysis of variance and the post hoc Tukey honest significance difference test with the loading point as a factor (a=.05). RESULTS: Upon anterior loading, the 2-IOD showed significantly larger vertical displacements at the right distal edge than the 1-IOD or 3-IOD (P<.01). The horizontal displacements at the right distal edge were small compared with the vertical displacements at the same point, although the displacement of the 2-IOD was significantly larger than that of the 1-IOD upon anterior loading (P=.03). The magnitude of the vertical displacement at the loading point of the 2-IOD was significantly larger than that of the 3-IOD upon anterior loading (P<.01). No statistically significant differences were shown under the other conditions for each loading (P>.05). CONCLUSIONS: Within the limitations of this in vitro study, the following conclusions were drawn: During mastication with the anterior teeth, the use of 2 implants for anchoring an IOD increased the rotation of the denture base more than the use of 1 or 3 implants. The horizontal movements of the IODs were small compared with the vertical movements. Denture movement under the occlusal force in the molar region was smaller than that in the anterior region.