BACKGROUND: Masticatory muscle training by chewing gum can be performed easily and improve masticatory muscle function and strength. However, increased masticatory muscle activity and function may alter the mandibular shape.
OBJECTIVE: We aimed to investigate the effects of gum chewing training on the occlusal force, masseter muscle thickness (MMT) and mandibular shape in healthy adults.
METHODS: We conducted a prospective randomised controlled trial from January 2020 to September 2020 at the Yonsei University College of Dentistry. Fifty-eight participants were randomly assigned to the training and control groups. The training group chewed gum three times a day for 6 months, while the control group received no training. Changes in the maximum occlusal force and MMT were evaluated at baseline and after 1, 3 and 6 months. Changes in the mandibular shape were evaluated at baseline and after 6 months.
RESULTS: The mean maximum occlusal force of the training group at 3 months was significantly higher than that at baseline, which was also significantly different from that in the control group (p < .001). As the maximum occlusal force increased, the occlusal contact area also increased (p = .020). There was no statistically significant difference in MMT or mandibular shape compared to the baseline.
CONCLUSIONS: Mastication training using gum increases maximum occlusal force due to an increase in occlusal contact area but has no effect on MMT or mandibular shape.

OBJECTIVE: This pilot study evaluated the relationships between appetite and oral function, and between appetite and the subjective symptoms of decreased oral function.
METHODS: Seventy-one adult dental clinic patients (22 males, 66.0 ± 14.0 years) participated in this study. A Council on Nutrition Appetite Questionnaire score of ≤28 indicated anorexia, and the Mini Nutritional Assessment Short-form, body mass index and skeletal muscle mass index were used to define subject characteristics. Seven oral function tests and seven subjective symptoms related to oral function were evaluated. The relationship between subject characteristics, oral function tests, subjective symptoms and anorexia was analysed using the chi-square test and univariate and multivariate logistic regression.
RESULTS: There were significant differences between the normal appetite group and the anorexia group for the 10-item Eating Assessment Tool (EAT-10) survey and the question \'Food remains in the oral cavity after eating\' (p < .05). Univariate logistic regression found significant differences in the items of masticatory function, the EAT-10 survey and the question \'Food remains in the oral cavity after eating\'. Multivariate logistic regression revealed significant differences in masticatory function (AOR 4.35; 95% CI: 1.03-18.35; p = .045) and EAT-10 (AOR 6.27; 95% CI: 1.40-24.02; p = .016).
CONCLUSIONS: This pilot study investigated the influence of factors related to oral function on appetite. Relationships were found among poor masticatory function, poor swallowing function and anorexia.

UNASSIGNED: In cases of missing posterior teeth, treatment modalities based on the shortened dental arch (SDA) concept may be a viable alternative. However, the association between oral health-related quality of life (OHRQoL) and patients\' treatment decisions remains unclear. This study aimed to investigate the association between OHRQoL and the decision to be treated with implant-supported fixed partial dentures (IFPDs) or take a wait-and-see approach in patients with an SDA missing a single second molar and to clarify the impact of IFPD treatment on the OHRQoL.
UNASSIGNED: The Oral Health Impact Profile (OHIP) questionnaire was administered twice (pre- and post-treatment) and once to 41 patients with a unilateral SDA missing a single second molar who chose IFPD treatment (IFPD group, n = 22) and the wait-and-see approach (no treatment group, n = 19), respectively. Logistic regression analysis was performed with IFPD treatment choice as the objective variable and the four OHIP dimension scores, age, and sex as covariates. The pre- and post-treatment values of the OHIP summary and four-dimension scores were compared using a paired t-test.
UNASSIGNED: The IFPD treatment choice was significantly associated with sex (male), higher Oral Function dimension scores, and lower Psychosocial Impact dimension scores (all P < 0.05). The OHIP summary and four-dimension scores were significantly lower following IFPD treatment (all P < 0.05).
UNASSIGNED: IFPD treatment for a single missing second molar may be clinically beneficial for improving the OHRQoL of patients with an SDA who experience a decline in masticatory function.

OBJECTIVE: Japanese children have been shown to exhibit decreased masticatory function; however, limited evidence is available regarding the efficacy of certain food items in improving this issue. Therefore, this study examined the effects of chewing hard gummy candy on the masticatory function of Japanese children aged 6-12 years.
METHODS: The study included 26 participants (10 boys and 16 girls; mean age ± standard error = 9.3 ± 0.3 years) who were asked to chew hard gummy candy twice daily for 4 weeks at home. The lip-closing force, occlusal force, and masticatory performance of the participants were recorded before commencement (T1), 4 weeks after commencement (T2), and 4 weeks after completion (T3) of the training. Statistical analyses were performed using the Wilcoxon rank-sum test or the Wilcoxon signed-rank test with Bonferroni correction.
RESULTS: No significant differences in masticatory function by gender and age groups (defined based on mean age at T1) were observed at T1. The lip-closing and right occlusal forces increased significantly after 4 weeks of exercise, and the effects persisted for another 4 weeks after completion. The masticatory performance also improved after training, although these effects did not persist and deteriorated substantially 4 weeks after completion of the training.
CONCLUSIONS: Habitual mastication training using hard gummy candy markedly enhances masticatory function (e.g., lip-closing force, occlusal force, and masticatory performance) in Japanese children.

OBJECTIVE: The purpose of this study was to analyze oral functions (MOF: maximum occlusal force; MTP: maximum tongue pressure; and MF: masticatory function) in Eichner A subjects aged from 20 to 49 years.
METHODS: The data of three oral functions in Eichner A patients aged from 20 to 49 years were extracted. The mean values, subjects with lower values than the thresholds, and the differences among ages, and between sexes were investigated retrospectively.
RESULTS: Although the mean values of these oral functions in 183 subjects were higher than the thresholds, the numbers of the subjects with lower values than the thresholds were 30 in MTP, 19 in MOF, and only three in MF. No significant effects of ages on all oral functions were identified and all functions in males were significantly higher than those in females. The subjects whose two functions were lower than the thresholds were nine females, eight of whom were associated with malalignment.
CONCLUSIONS: Although the mean values of oral functions were higher than the thresholds, some patients showed lower values, especially in MOF and MTP, even though they were unaware of any inconvenience. Patients with malalignment might be associated with declined oral functions.

BACKGROUND: The occurrence of cognitive impairment (CI) is expected to increase within an ageing population. CI is associated with tooth loss, which influences masticatory performance. A decrease in masticatory performance may cause functional and morphological changes in the brain. However, whether CI is associated with masticatory performance, demographics, and structural brain signatures has not been studied yet.
OBJECTIVE: To assess the associations between CI on the one hand, and masticatory performance, demographic factors, and structural brain signatures (i.e. cortical volume and thickness) on the other hand.
METHODS: In total, 18 older adults with CI (mean ± SD age = 72.2 ± 9.5 years) and 68 older adults without CI (65.7 ± 7.5 years) were included in this study. Masticatory performance was quantified using a colour-changeable chewing gum. A Magnetic Resonance Imaging (MRI) scan was used to map structural brain signatures. To study our aim, a multivariate binary logistic regression analysis with backward selection was performed.
RESULTS: The cortical volume of the right entorhinal cortex was negatively associated with CI (p < .01). However, demographic factors, masticatory performance, and the other structural brain signatures under investigation were not associated with CI.
CONCLUSIONS: A decrease in the volume of the right entorhinal cortex is associated with CI in older people.

OBJECTIVE: There is a scarcity of randomized clinical trials (RCT) that report medium- and long-term results and a lack of consensus in the literature on the predictability of immediately loaded unsplinted narrow diameter implants supporting mandibular overdentures. This RCT compared the performance of conventional (CL) and immediate loading (IL) of mandibular overdentures retained by two narrow-diameter implants for 3 years.
METHODS: Patients from an RCT treated with CL or IL were invited to attend to 2- and 3-year follow-ups. Clinical, radiographic, functional, and oral health-related quality of life parameters were evaluated. Prosthetic maintenance events, biological complications, and success and survival rates were also recorded. The data were tested by multilevel mixed-effects linear regression analysis and chi-squared tests.
RESULTS: The 1-year survival rates of 90% in the CL group and 85% in the IL group were maintained as no implants were lost between 1 and 3 years. The marginal bone loss (MBL) in the IL group was significantly lower after year 3 (-0.04; p < 0.01). Significant changes were found only for the intra-group comparisons in the third year of function: (i) CL and IL presented similar progression of implant stability, MBL, and posterior bone area resorption; (ii) while CL started deteriorating of masticatory function, IL still exhibited functional evolution and (iii) oral comfort domain in the CL and pain domain in the IL were improved.
CONCLUSIONS: Although IL experienced the lowest MBL after 3 years, the outcomes showed that both loading protocols result in predictable medium-term rehabilitation when monitored annually.
CONCLUSIONS: It can be expected that in the third year of function, patients with immediate loading may present more complaints related to general performance even with acceptable masticatory function and self-reported improvements in oral comfort.

The aim of this retrospective cross-sectional study was to comprehensively assess masticatory function in maxillectomy patients with functioning removable prostheses. Their general and oral profiles, the measurement values of their oral functions, including masticatory function, and the history of tumor therapy were extracted from medical charts. The correlations of masticatory function with numerical data and the effects of tumor therapy-related factors on masticatory function were evaluated. In addition, a stepwise conditional logistic regression analysis was performed to identify the potential predictive factors comprehensively. The data from 55 maxillectomy patients revealed that the median value of masticatory function (138.0 mg/dL) was higher than the threshold (100.0 mg/dL) based on the concept of oral hypofunction. Moderate correlations of masticatory function with the number of remaining teeth, the number of functioning occlusal supports, and maximum occlusal force were found, as well as a weak correlation with maximum tongue pressure. These variables also showed statistically significant coefficients (p < 0.01). No significant effect of each tumor therapy-related factor on masticatory function was detected. A logistic regression analysis identified the number of functioning occlusal supports as a significant predictive factor. These results implied the crucial interactions of masticatory function with various factors and the specificities of maxillectomy patients.

This parallel cross-sectional study compared masticatory function and patient-centered outcomes among 3 removable treatment strategies for mandibular edentulism.
Thirty-six edentulous participants rehabilitated using 3 removable treatment strategies for mandibular edentulism were allocated to one of the three groups (n=12): CCD (control), 2-IMO, and 3-IMO. Narrow diameter implants were installed using single-stage surgery and conventionally loaded with stud abutments. After 3 months of usage, the quality of life, maximum bite force, and masticatory function were evaluated. Data were analyzed with the Kruskal-Wallis test and post hoc pairwise Mann-Whitney tests with Bonferroni correction (α=0.05).
The 2-IMO and 3-IMO wearers did not show significant differences in any outcome, except for the 2 domains of 3-IMO wearers quality of life that obtained better Pain and General Performance scores. Both IMO groups presented significantly higher maximum bite force than CCD wearers. The 2-IMO wearers showed superior outcomes to the CCD group in all outcomes of the masticatory performance test and the X50, B and ME5.6 outcomes of the swallowing threshold test (p = 0.01), while 3-IMO participants only showed superior masticatory performance in terms of lower X50 values (19.86%, p = 0.02) and higher ME 2.8 (141.15%, p = 0.04) than CCD wearers.
Compared to 2-IMO wearers, 3-IMO wearers report superior impact of treatment on daily living activities in the Pain and General Performance domains. 2-IMO and 3-IMO wearers showed no significant differences between them for all evaluated bite force and masticatory function parameters.
Although overdentures retained by 3 implants (3-IMO) provide biomechanical advantages over those retained by 2 implants (2-IMO), superior clinical and functional effectiveness is not yet proven.

OBJECTIVE: Masticatory function, including masticatory muscle activity and occlusal function, can be affected by craniofacial morphology. This study aimed to investigate the relationship between craniofacial morphology and masticatory function in participants who had completed orthodontic treatment at least two years before and had stable occlusion.
METHODS: Fourty-two healthy participants were prospectively enrolled and divided into three vertical cephalometric groups according to the mandibular plane angle. Masticatory muscle activity (MMA) in the masseter and anterior temporalis muscles was assessed using surface electromyography. The occlusal contact area (OCA) and occlusal force (OF), defined as occlusal function in this study, were evaluated using occlusal pressure mapping system. Masticatory muscle efficiency (MME) was calculated by dividing MMA by OF. The craniofacial morphology was analyzed using a lateral cephalogram. The masticatory function was compared using one-way analysis of variance. Pearson correlations were used to assess relationships between craniofacial morphology and masticatory function.
RESULTS: The hypodivergent group had the lowest MMAand the highest MME in the masseter (167.32 ± 74.92 µV and 0.14 ± 0.06 µV/N, respectively) and anterior temporalis muscles (0.18 ± 0.08 µV/N, p < 0.05). MMA in the masseter showed a positive relationship with mandibular plane angle (r = 0.358), whereas OCA (r = -0.422) and OF (r = -0.383) demonstrated a negative relationship (p < 0.05). The anterior temporalis muscle activity negatively correlated with ramus height (r = -0.364, p < 0.05).
CONCLUSIONS: Vertical craniofacial morphology was related to masticatory function. Hypodivergent individuals may have low MMA and high occlusal function, resulting in good masticatory muscle efficiency.
CONCLUSIONS: Hypodivergent individuals require careful consideration in orthodontic diagnosis and prosthetic treatment planning.