Yuriko Komagamine

Association between masticatory performance using a colour‐changeable chewing gum and jaw movement

The purpose of this study was to investigate the relationship between masticatory performance as determined using a colour-changeable chewing gum and mandibular movements. Subjects comprised 45 fully dentate adults (23 men, 22 women; mean age, 28·1 years). The gum was chewed for a specified number of chewing strokes (20, 40, 60, 80, 120 or 160 strokes) without any instructions as to chewing side. A colourimeter was used to measure L*, a* and b* values (CIE-L*a*b* colour system) for the chewed gum, then the difference between two colours in the CIE-L*a*b* colour space (ΔE) for each number of chewing strokes was calculated according to a formula. Index of masticatory performance (ΔE60) for each subject was obtained using ΔE for 20, 40, 60, 80, 120 and 160 strokes. Mandibular movements were recorded using an opto-electric system with six degrees of freedom. Twelve parameters of mandibular movements relating to amplitude, duration, velocity and angle were computed for each cycle, and mean values for 10 cycles (from cycle 11 to 20) were calculated separately. Stepwise multiple regression analysis identified maximum closing velocity and closing angle as predictors accounting for 18% of the variation in ΔE60. These results suggest that lower angles of approach to intercuspation and faster speed during closing duration are associated with colour changes in the colour-changeable chewing gum.

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

BackgroundDemand 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.MethodsPatients, 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.ResultsThe 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.ConclusionsThe 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.

Association between near occlusal contact areas and mixing ability

This study investigated the relationship between occlusal contact and near contact areas defined by clenching intensity using electromyograms (EMGs) and mixing ability assessed with colour-changeable chewing gum. Participants comprised 44 dentate adults (24 men, 20 women) with a mean age of 28·2 ± 6·8 years. Silicone material was used to measure the occlusal contact and near contact areas (the area of each type of tooth, the total area of the first molar and second molar, the second premolar to the second molar and the first premolar to the second molar) defined by clenching intensity at 10% maximum voluntary contraction (MVC). Colour-changeable chewing gum was used to assess mixing ability. A colorimeter was used to measure colour changes, and the calculated colour difference (ΔE) was used as a measure of mixing ability. Correlation analysis of ΔE and occlusal contact and near contact areas revealed a significant positive correlation of 0·47 at 0-160 μm thicknesses of the silicone registration material of the second molar (P < 0·01). The near contact area with a thickness up to 200 μm was correlated with mixing ability, with the correlation strengthening as the interocclusal distance increased up to 160 μm. Notably, occlusal contact and near contact areas of the second molar were strongly correlated with mixing ability in dentate adults.

The effect of new complete denture fabrication and simplified dietary advice on nutrient intake and masticatory function of edentulous elderly: A randomized-controlled trial

BACKGROUND & AIM Combination of new complete denture fabrication and tailored dietary counseling is necessary to improve nutrient intake of the edentulous elderly. However, there is no evidence on the effect of simple dietary advice combined with new complete denture fabrication on the nutrient intake of the edentulous elderly. The aim of this study was to clarify the combined effect of new complete denture fabrication and simple dietary advice, using a uniform pamphlet, on the nutrient intake and masticatory function of edentulous elderly. The null hypothesis was that there would be no difference in the nutrient intake and masticatory function between edentulous elderly patients provided with simple dietary advice and new complete dentures and those provided with new dentures alone. METHODS A double-blind, randomized-controlled, parallel clinical trial was performed on the healthy edentulous elderly who were required to fabricate a new pair of complete denture. The participants were randomly divided into two groups, and each group received different advice: the intervention group received simple dietary advice using a uniform pamphlet, whereas the control group received denture care advice. During the process of new complete denture fabrication, two 20-min one-on-one advice sessions were conducted by a dentist. The primary outcome of this trial was protein intake, which was calculated from the responses in the brief-type self-administered diet history questionnaire (BDHQ). Secondary outcome was masticatory function, which was measured with a color-changeable chewing gum and a test gummy jelly. Outcome assessment was conducted twice, at baseline and at 3 months post-treatment. RESULTS Among 70 participants who were randomized, 62 completed this trial. Protein intake in the intervention group significantly increased compared with that in the control group. Masticatory function was not significantly different between groups, but significantly increased at 3 months post-treatment compared with the baseline in both groups. CONCLUSION Simple dietary advice using a uniform pamphlet and a new complete denture fabrication increased nutrient intake and masticatory function of healthy edentulous elderly. CLINICAL TRIAL REGISTRATION NUMBER https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000020716 UMIN000017879.

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.