Maximum Occlusal Force Research Articles

A Case-Control Split-Mouth Study of Comparison of Maximum Occlusal Forces in Endodontically Treated Teeth and Vital Counterparts.

To compare the maximum occlusal force in endodontically treated teeth and their vital contralateral counterparts and to evaluate the intraoral factors affecting them. Thirty adult participants presented with an endodontically treated tooth and its vital contralateral counterpart were recruited, with 15 males and females in each group. Maximum occlusal forces were measured using a wireless sensor network occlusal force recorder, and the mean maximum occlusal force of endodontically treated teeth was compared with that of their vital contralateral counterparts. Multiple-factor ANOVA was used to examine the association between various clinical factors and maximum occlusal force. The mean maximum occlusal force for endodontically treated teeth was significantly higher than their vital counterparts (215.44 ± 74.11N and 202.40 ± 70.67N, respectively) (P < 0.001). Among the clinical factors, the maximum occlusal forces were significantly influenced by the location of teeth (P < 0.01) and the crown root ratio (P = 0.01). Upon further analysis of endodontically treated teeth and control groups, the location of teeth was identified as a sole factor associated with maximum occlusal force, with P < 0.05. The maximum occlusal forces for endodontically treated teeth were statistically significantly higher than those of their corresponding vital contralateral teeth.

Effects of gum chewing training on occlusal force, masseter muscle thickness and mandibular shape: A randomised controlled clinical trial.

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. We aimed to investigate the effects of gum chewing training on the occlusal force, masseter muscle thickness (MMT) and mandibular shape in healthy adults. 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. 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. 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.

Relationship between malnutrition according to the global leadership initiative on malnutrition criteria and oral health among community-dwelling elderly aged 85 years and older: a cross-sectional study

BackgroundA new diagnostic criterion for malnutrition, the Global Leadership Initiative on Malnutrition (GLIM) criteria, has been proposed. Despite a recognized link between malnutrition and oral health, further clarification is needed regarding this association when using the GLIM criteria. This study examined the association between malnutrition and oral health in community-dwelling older adults aged ≥ 85.MethodsThis study was conducted using data from the Tokyo Oldest Old Survey on Total Health study, and altogether 519 participants ≥ 85 years were enrolled. Malnutrition was assessed using the GLIM criteria. Oral health information, on the number of teeth, maximum occlusal force (MOF), saliva production, denture-related questions (dissatisfaction and frequency of use), dental visit history in the past year, whether participants enjoyed meals, and oral-related quality of life was assessed using the Geriatric Oral Health Assessment Index (GOHAI) were collected. MOF was assessed the average values of three measurements and lower tertile by sex as decline in MOF. For GOHAI, the score for each items (Q1-Q12) was also evaluated, and further, the decline in each item (score: 1–2 points on a 5-point scale) was assessed as a “problem with each items.” Oral health factors differing between those with and without malnutrition were analyzed. For differing items, malnutrition risk was evaluated using Cox regression.ResultsEighty-nine (17.1%) participants experienced malnutrition. Significant differences were observed in the decline in MOF, enjoyment of meals, individual scores for Q2, Q4, and Q6, and the problem with Q3, Q6, Q7, and Q11. Cox regression analysis showed that decline in MOF (odds ratio [OR]: 1.728, 95% confidence interval [CI]: 1.010–2.959), enjoyment of meals (OR: 0.502, 95% CI: 0.289–0.873), problem with Q3 (OR: 5.474, 95% CI: 1.301–23.028), Q6 (OR: 5.325, 95% CI: 1.026–27.636), and Q7 (OR: 2.867, 95% CI: 1.397–5.882) were associated with ORs of malnutrition.ConclusionDecline in MOF, enjoyment of meals, swallowing problem (problem with Q3), limit contact due to oral condition (problem with Q6), and esthetics problem (problem with Q7) were associated with malnutrition as assessed using the GLIM criteria.

Improvement of oral function and its impact on oral food intake in subacute stroke patients: A prospective study with dental intervention.

The association between oral food intake and oral function during the subacute stage of stroke is not well known. To investigate (1) oral function changes in subacute stroke patients and (2) association between oral function and oral intake status at several time points. In a prospective study involving 324 stroke patients at a convalescent rehabilitation unit, four oral function parameters (maximum tongue pressure, MTP; lip-tongue motor function, LTMF; maximum occlusal force, MOF and oral health assessment tool, OHAT) were quantitatively measured upon admission (T0), at 1 month (T1) and 2 months (T2). Oral feeding status was assessed using the Functional Oral Intake Scale (FOIS) and divided based on the FOIS score into the dysphagic and regular diet groups. The changes in oral functions at the three time points were tested using generalized estimating equation analysis. The association between FOIS groups and oral functions at T1 and T2 was analysed by means of logistic regression analysis. All oral function parameters improved significantly over time during the hospital stay (mean differences: 4.9 for MTP, 0.6 for LTMF, 1.1 for MOF and -1.8 for OHAT). The FOIS groups were significantly associated with MTP (p < .05) and OHAT (p < .05) at both T1 and T2. Our findings suggest that oral function significantly improves in patients during subacute stroke rehabilitation and better oral health can be associated with better oral intake. Improved oral function through dental intervention and oral rehabilitation may contribute to gains in oral food intake.

Factors Related to Masticatory Rhythm in Patients with Oral Tumors.

Background: Older adults who have undergone surgery for oral tumors are at increased risk of impaired masticatory rhythm. This study investigated the correlations between masticatory rhythm, objective masticatory performance, and subjective masticatory performance as well as factors related to masticatory rhythm. Methods: The participants were 44 adults (24 men, 20 women; age range 42~90 years old) who had undergone maxillectomy, mandibulectomy, or glossectomy and were rehabilitated with a maxillofacial prosthesis. The number of functional contact teeth pairs was confirmed by intraoral examination. Chewing rate, cycle duration, coefficient of variation (CV) for cycle duration (reflecting the stability of masticatory rhythm), and mixing ability were measured simultaneously using a mastication movement rhythm tracking device during gum chewing. Maximum occlusal force was measured using the dental prescale system. Patients' perception of chewing ability was rated using a questionnaire. Results: The Spearman's rank correlation test revealed that mixing ability, patient-rated masticatory scores, cycle duration, CV for cycle duration, and maximum occlusal force showed significant correlations with chewing rate. Multiple linear regression analysis identified mixing ability and the CV for cycle duration as significant predictors of masticatory rhythm. Conclusions: Factors associated with a faster chewing rate were higher mixing ability and masticatory scores, greater maximum occlusal force, shorter cycle duration, and smaller CV for cycle duration. Stable masticatory rhythm and mixing ability are significant predictors of chewing rate. Poor masticatory performance and unstable masticatory rhythm can result in slower chewing and thus a higher risk of inadequate dietary intake.

The effectiveness of botulinum toxin for temporomandibular disorders: A systematic review and meta-analysis.

The current body of research on utilizing botulinum toxin (BTX) to manage temporomandibular disorders (TMDs) has not yet yielded definitive conclusions. The primary objective of this study was to determine the effectiveness of BTX in pain reduction for TMDs compared to placebo and other treatments. The secondary outcomes evaluated were adverse events, maximum mouth opening, bruxism events, and maximum occlusal force. A literature search was performed on PubMed, Dimension Publication, Scopus, and Google Scholar. The RoB 2 tool was used for quality assessment. The mean differences in pain scores were estimated to measure the effect of BTX on pain reduction. For adverse events, the risk ratio for the incidence of side effects was calculated. Two hundred and sixty non-duplicate articles were identified; however, only 14 RCTS were included in this review. The total study population included 395 patients. The overall risk of bias showed a low to moderate quality of evidence. Results from 6 studies were reported only narratively; four studies were used for meta-analysis on pain reduction, and five were used for meta-analysis on adverse events. The control used in the meta-analysis was placebo injections. Results of the meta-analysis for pain reduction were statistically insignificant for the BTX group with mean differences at MD = -1.71 (95% CI, -2.87 to -0.5) at one month, -1.53 (95% CI, -2.80 to -0.27) at three months, and -1.33 (95% CI, -2.74 to 0.77) at six months. This showed that BTX treatment was not significantly better than placebo for a reduction in pain scores at 1, 3, and 6 months. Regarding safety, the placebo group showed a relative risk of 1.34 (95%CI, 0.48-6.78) and 1.17 (95%CI, 0.54-3.88) at 1 and 3 months respectively. However, the risks were not statistically significant. There was also no difference in the effectiveness of BTX compared to placebo and other treatments for maximum mouth opening, bruxism events, and maximum occlusal force. BTX was not associated with better outcomes in terms of pain reduction, adverse events, maximum mouth opening, bruxism events, and maximum occlusal force. More high-quality RCTs are needed to better understand this topic.

Biomechanical analysis of alveolar bones with compromised quality supporting a 4-unit implant bridge; a possible association with implant-related sequestration (IRS).

This study aimed to investigate the strain in the bone surrounding dental implants supporting a 4-unit bridge and assess the role of excessive strain as a possible risk factor for implant related sequestration (IRS)or peri-implant medication-related osteonecrosis of the jaw (PI-MRONJ). A 3D-mandibular model was constructed using computed tomography and segmented it into cortical and cancellous bones. The 4-unit implant-supported bridges replacing the mandibular posteriors were constructed, and each featuring two, three, and four implants, respectively. The Young's modulus was assigned based on the quality of the bone. A maximum occlusal force of 200N was applied to each implant in the axial and in a 30-degree oblique direction. The maximum principal strain of the fatigue failure range (> 3000 µε) in the bone was analyzed. The volume fraction of fatigue failure was higher in poor-quality bone compared to normal bone and oblique load than in axial load. An increasing number of implants may dissipate excessive strain in poor-quality bones. Occlusal force applied to poor-quality bone can result in microdamage. Given that unrepaired microdamage may initiate medication-related osteonecrosis of the jaw, long-term occlusal force on fragile bones might be a risk factor. When planning implant treatment for patients with compromised bone status, clinical modifications such as strategic placement of implants and optimization of restoration morphology should be considered to reduce excessive strain which might be associated with IRS or PI-MRONJ.

Biological Properties of 3D-Printed Zirconia Implants with p-Cell Structures

Research on 3-dimensional (3D) printed porous zirconia-based dental implants is still in its infancy. This study aimed to evaluate the biological responses of novel zirconia implants with p-cell structures fabricated by 3D printing. The solid zirconia samples exhibited comparable density, 3-point flexural strength, and accelerated aging properties compared to specimens prepared previously by conventional methods. Cell-based experiments showed that the p-cell structure promoted cell proliferation, adhesion, and osteogenesis-related protein expression. Mechanical tests showed that both p-cell and control implants could withstand a torque of 35 Ncm without breaking. The mean maximum breaking loads of p-cell and control implants were 1,222.429 ± 115.591 N and 1,903.857 ± 250.673 N, respectively, which were much higher than the human physiological chewing force and human mean maximum occlusal force. An animal experiment showed that the bone trabeculae around the implants were significantly thicker, more numerous, and denser in the p-cell group than in the control group. This work could provide promising guidance for further exploring 3D printing techniques for porous zirconia bionic implants in dentistry.

Distribution of main occluding area and associated factors in adolescents.

This study was designed to investigate the distribution of the main occluding area in adolescents. Furthermore, the importance of the main occluding area was clarified by examining its interrelationship with oral function and craniofacial morphology. A total of 102 patients were included in this study. The main occluding area was identified using a previously described method. Maximum occlusal force, occlusal contact area, lip-closing force, tongue pressure, and masticatory efficiency were measured to evaluate oral function. Craniofacial morphology was assessed using lateral cephalography. In terms of the degree of consistency of the main occluding area, the proportion of cases in which two matches were obtained among three trials was the highest. The most common main occluding area was the first molar. Regarding the anteroposterior position of the hyoid bone, the anteroposterior distance between the hyoid bone and the menton (Me-H) was significantly shorter in the group where the first molar was used for occlusion, relative to the group in which second premolar was used. The main occluding area in adolescents was less stable than that in adults and older adults; however, first molars accounted for most of the main occlusion areas, suggesting that the position of the hyoid bone might play a role in establishing their location.

Long-term clinical performance of short 6-mm implants supporting single crowns in the posterior region: A 10-year cohort study.

Long-term clinical success of non-splinted, posterior, and short implants still is unclear. This prospective cohort study reports the 10-year follow-up of 6-mm implants supporting single crowns in the posterior region, and patient-reported outcomes. Baseline sample comprised 20 patients treated with 46 screw-retained crowns supported by 6-mm implants with moderately rough implant surface. Participants were recalled for a 10-year clinical follow-up to assess survival rates, biologic and mechanic conditions, quality of life (OHIP-14), and treatment satisfaction. Data were collected with clinical-radiographic exams and analyzed using descriptive and inferential statistics. Fourteen patients with 35 implant-crown units were examined after 127.6 ± 11.8 months. For the entire cohort period, 7/46 implants were lost (survival estimate: 77.7% at 133 months), and mechanic complications occurred in 14/46 units (survival estimate: 66.4% at 116 months). In the Cox models, "maximum occlusal force" had a significant effect for implant loss (p = 0.038) and for prosthetic screw loosening (p = 0.038); "arch" and "bruxism" were not significant. Peri-implant bone loss was 0.4 ± 0.6 mm at 10 years. For peri-implant bone level, "crown-to-implant ratio" (p < 0.001) and "time" (p = 0.001) were significant. Bone levels differed from baseline to 12, 48, and 120 months. Satisfaction VAS was 94.0 ± 7.9 mm and OHIP-14 was 2.3 ± 2.2. Single screw-retained crowns supported by 6-mm implants have an acceptable long-term clinical performance, with stable peri-implant bone levels after 10 years of function.

Impact of gender and physical differences on the development of oral functions in children aged 6–17 years: A cross-sectional study

ObjectiveThis study aimed to establish the age at which oral function development completes in males and females, and to determine if obesity contributes to underdevelopment of oral function. Materials and MethodsThe study included 241 participants, including 121 males and 120 females aged 6 to 17 years. Following anthropometry and oral examination, maximum occlusal force, lip-closing strength, maximum tongue pressure, and masticatory performance were measured in all participants. The Rohrer Index and body mass index (BMI) were calculated using height and weight measurements, and these scores were grouped into underweight/severely underweight, normal weight, and overweight/obese categories. ResultsIn males, maximum occlusal force, lip-closing strength, maximum tongue pressure, and masticatory performance increased with age. In females, maximum occlusal force, maximum tongue pressure, and masticatory performance peaked during the teenage years. Masticatory performance in the overweight/obese male group was significantly lower than in the normal weight group (p < 0.05). In females, maximum occlusal force in the underweight/severely underweight group and maximum tongue pressure in the overweight/obese group were significantly lower than in the normal weight group (both, p < 0.05). ConclusionGrowth patterns of each oral function differ considerably between males and females. Oral functions in females typically reached their peak earlier than in males, with most functions peaking during the teenage years. Overweight/obesity contribute to the underdevelopment of oral functions in both genders. Underweight may also hinder oral function development in females.

일부 성인의 일반적·저작계 특성에 따른 최대교합력 분석

Objectives: The purpose of this study is to confirm the relationship of maximum occlusal force and physical and oral features.&#x0D; Methods: A self-reported questionnaire was filled by 50 adults and oral examination was conducted by dental hygienist in Gyeongnam from March to June, 2023. The occlusal force was measured by Innobyte for 2 times. All presented results were analysed by SPSS ver 21.0.&#x0D; Results: The maximum occlusal force of males is higher than females(p&lt;0.05). Those who had no bruxism, subjective malocclusion showed the greater occlusal force than candidates with bruxism, subjective malocclusion(p&lt;0.05).&#x0D; Conclusions: The gender, bruxism and subjective malocclusion are associated with the occlusal force.

Comprehensive Analyses of Masticatory Function in Maxillectomy Patients with Functioning Removable Prostheses: A Retrospective Cross-Sectional Study.

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.

Relationships of physical constitution with occlusal force and masticatory performance in adults with natural dentition.

This study aimed to clarify whether physical constitution affects masticatory function. A total of 251 healthy adults with completely natural dentition participated in this study. Height, weight, and body mass index (BMI) were used as parameters representing physical constitution, and the amount of glucose eluted from chewed gummy jelly and maximum occlusal force was used as parameter representing masticatory function. Handgrip strength was also measured. After comparing each parameter between male and female participants, the relationship between physical constitution and masticatory function was investigated in the combined (male and female) group, the male group, and the female group. The relationship between handgrip strength and masticatory function was also investigated. Stepwise multiple linear regression analysis was performed with masticatory function as the dependent variable and physical constitution as independent variable. The mean values of each parameter were significantly greater in the male group than in the female group. Regarding the relationship between physical constitution and occlusal force, the occlusal force tended to increase as the parameter value representing physical constitution increased, and a significant correlation was observed for all parameters. For masticatory performance, a significant correlation was observed in all parameters in the combined group, but no significant correlations were observed in the male group and in the female group. Multiple linear regression analysis showed that weight was significantly associated with occlusal force. Though occlusal force may be affected by physical constitution, masticatory performance is not easily affected by physical constitution.

Common eating habit patterns are associated with a high maximum occlusal force and pre-eating cardiac vagal tone.

Masticatory function is associated with nervous function, including autonomic nervous function, and both functions are influenced by human habits. In a previous preliminary study of 53 young women, we found that eating habit patterns were associated with occlusal force as an indicator of masticatory function. Therefore, we hypothesized that relationships exist between occlusal force, the autonomic nervous system, and eating habit patterns. To test our hypothesis, we analyzed the relationship between heart rate variability measured before and after lunch in 53 young women, and measured and surveyed maximum occlusal force and eating habit patterns, respectively, in these participants. High occlusal force was associated with an increased high-frequency (HF) component (vagal tone index) of the heart rate variability index immediately before lunch (standardized regression coefficient (β)=0.417, P=0.002). Each of the eating habit items surveyed in a questionnaire showed a similar tendency for the HF component immediately before lunch and maximum occlusal force; in particular, "Habit of eating breakfast" and "Number of meals per day" were significantly associated with both variables. Additionally, total eating habit scores related to higher maximum occlusal force were associated with an increase in the HF component immediately before lunch (β=0.514, P<0.001). The maximum occlusal force and the pre-eating HF component values were stratified by total eating habit scores (into low, medium, high categories), and the high scores were significantly higher than the medium or low scores. Occlusal force and the pre-eating cardiac vagal response of individuals were characterized by their common eating habit patterns, indicating that eating habits may be simultaneously associated with the development of masticatory function, nervous system development, and cardiovascular rhythm. Although further research is needed to investigate these relationships in detail, our findings provide insights that will inform the study of physical functions, neurodevelopment, habitual behaviors, and health in humans.

Association of low occlusal force as an oral hypofunction with the prevalence of irritable bowel syndrome in Japanese adults.

We investigated whether oral-dental conditions may be associated with the prevalence of irritable bowel syndrome (IBS) in a cross-sectional study in Japan. Information on lifestyle and abdominal symptoms was collected, and oral-dental examinations were performed from 2013 to 2017. To investigate the association between oral-dental conditions and IBS, this study used logistic regression analyses adjusted for relevant confounding factors, such as age, sex, BMI, stress, and eating between meals. The prevalence of IBS was 484 (13.4%) among 3626 participants. The mean maximum occlusal force in the IBS group was significantly lower than that in the non-IBS group (0.306±0.192 kN vs. 0.329±0.205 kN, p =0.014). The maximum occlusal force of the constipation-type IBS was significantly lower than that of other types of IBS without constipation type (0.269±0.164 kN vs. 0.317±0.198 kN, p =0.010). Compared with those who had high values of maximum occlusal force (≧0.265 kN), those with a low value of maximum occlusal force (<0.265 kN) had a significantly greater risk for IBS (OR, 1.426; 95%CI, 1.135-1.792; p=0.002), by multivariate analyses, across different categories of oral-dental condition in women, not in men. Women who had lowest third occlusal force (<0.206 kN) had approximately 35% significanlty greater odds of having IBS compared with those who had highest third occlusal force (≧0.386 kN). Results suggest that a reduction in the maximum occlusal force increases the risk of IBS in Japanese women.

Measurement of Maximum Occlusal Force Using Digital Occlusal Force Measurement Device: A Scoping Review

The aim of this review was to provide an update on the current status of digital occlusal force measurement devices, as well as clinical and research applications in complete arch maximum occlusal force measurement. SCOPUS, ScienceDirect, and PubMed databases were used to conduct a literature search from January 2001 to January 2021. Identification and screening of literature were done independently according to published guidelines and selection criteria. The electronic searches turned up 394 articles, 16 of which met the inclusion and exclusion criteria and were selected for study analysis. All of these studies used T-scan and Dental Prescale digital occlusal analysis system with pressure-sensitive foils as occlusal force measurement devices. The devices showed a promising potential for identifying and comprehending maximum occlusal forces objectively. According to the current review, maximum occlusal force measured with digital occlusal force devices can be used as a prosthodontic adjunct to address issues that arise during the treatment of occlusal disorders, temporomandibular disorders, and complete dentures. It is also useful in predicting cognitive and functional decline in the elderly.

Relationship between occlusal force and psychological frailty in Japanese community-dwelling older adults: The Septuagenarians, Octogenarians, Nonagenarians Investigation with Centenarians study.

Frailty increases the risk of negative health-related events, such as falls, disability, hospitalizations, and death. Although the association between oral health and physical frailty is well established, the relationship between oral health and psychological frailty has not yet been investigated. Therefore, we conducted a cross-sectional study to examine the association between maximal occlusal force and psychological frailty in Japanese community-dwelling older adults. Psychological frailty was defined as a World Health Organization-5 scale (WHO-5) score of <13, cognitive and functional status was defined as a Japanese version of the Montreal Cognitive Assessment (MoCA-J) score of <23, and psychological robustness was defined as a WHO-5 score of ≥13 and a MoCA-J score of ≥23. We used a cross-sectional study design to measure maximal occlusal force in 1810 participants, and examined the following factors relevant to psychological frailty: educational level, financial status, living situation, history of chronic diseases, handgrip strength, and instrumental activities of daily living. We used propensity score matching to match the psychological frailty and psychological robustness groups according to demographic and confounding factors. This process, resulted in 344 participants, of whom 172 were in the psychological frailty group and 172 were in the psychological robustness group. In the matched cohort, differences between groups with and without psychological frailty were compared using generalized estimating equations for maximal occlusal force after adjusting for the number of teeth. After controlling for potential confounding factors of frailty, the psychological frailty group showed lower maximal occlusal force compared with the psychological robustness group (unstandardized regression coefficients=-72.7, 95% confidence interval: -126.3 to -19.1). Maximal occlusal force was associated with a reduced prevalence of psychological frailty among Japanese community-dwelling older adults participating in our study.

Evaluation of automatic cleaning in analysis of occlusal force.

This study aimed to clarify the usefulness of automatic cleaning in analysis of occlusal force. The maximum occlusal force was calculated in 151 healthy adults before cleaning (B), after manual cleaning (M), and after automatic cleaning (A) and compared among the three conditions. The absolute value of the error rate of A, based on M, was calculated. The occlusal forces in M and A were similar and significantly smaller than the occlusal force in B. The absolute error rate of A was 2.4%. These results suggest that automatic cleaning has a similar effect to manual cleaning and can be applied clinically.

The relationship between morphological changes and oral function before and after slow palate expansion

ABSTRACT Purpose Recent reports indicate that Japanese children have narrow dental arches with weakening oral functions. Therefore, this study investigated the relationship between palatal morphology and oral function after expansion treatment with a slow, removable expansion appliance. Materials and Methods We evaluated changes in the deep, middle, and shallow palatal widths of 22 children with narrow dental arches who visited our hospital. We also assessed the tongue raising force, maximum occlusal force, lip closure force, and masticatory movement patterns, representing the oral function. Changes in the hyoid and resting tongue position before and after treatment were also evaluated using lateral cephalometric radiographs. Finally, the patients were divided into two groups based on the expansion frequency (once every two weeks or once per week) for measurement comparisons. Results We found that the amount of expansion at the deep width of the palate was half that at the shallow width. Furthermore, the maximum occlusal force and tongue raising forces improved after the treatment. Additionally, multiple regression analysis indicated that the resting tongue position and maximum occlusal force before the expansion treatment were significantly associated with the amount of palate expansion. Conclusions Slow plate expand can expansion the basal palate. Moreover, oral function improves after expansion therapy.