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1.
Prague Med Rep ; 121(2): 87-95, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32553092

RESUMO

Osteoarthrosis is a disorder of synovial joints, resulting from destruction of the cartilage and subchondral bone. The present study is aimed to investigate the molar bite force, thickness and efficiency of the masseter and temporalis muscles of subjects with osteoarthrosis. A total of forty-eight subjects participated in the study. They were distributed into two groups: with osteoarthrosis (n=24) and asymptomatic controls (n=24). Subjects were analyzed on the basis of maximal molar bite force (right and left side), thickness (mandibular rest and dental clenching in maximal voluntary contraction) and electromyographic activity of masticatory cycles through the linear envelope integral in habitual (raisins and peanuts) and non-habitual (Parafilm M) chewing of the masseter and temporalis muscles. All the data were analyzed statistically using t-test with a significance level of p≤0.05. There was no difference between groups in maximal molar bite force, muscle thickness and non-habitual chewing. Differences were found on the raisins (p=0.02) and peanuts (p=0.05) chewing for right temporal muscle, with reduced masticatory muscle efficiency in osteoarthrosis subjects. This study showed that osteoarthrosis induces negative changes in habitual chewing, highlighting the efficiency of the right temporalis muscles. The greater temporal muscle activity in subjects with osteoarthrosis may compromise chewing and consequently the nutritional status of adult subjects.


Assuntos
Força de Mordida , Osteoartrite , Adulto , Eletromiografia , Humanos , Dente Molar , Osteoartrite/fisiopatologia , Músculo Temporal
2.
J Prosthodont ; 29(6): 472-478, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32394526

RESUMO

PURPOSE: Oral function in Down Syndrome (DS) patients has been of interest to clinicians and researchers. This study aimed to evaluate the parameters of occlusal force and pattern of children with Down syndrome (DS) during mixed dentition when compared to age and gender-matched controls. MATERIALS AND METHODS: Thirty DS and 30 healthy children, aged 7 to 12 years, participated in the evaluation of the parameters of the occlusal pattern and occlusal force distribution analysis. Both groups underwent clinical examination, occlusal force and pattern measurements using a computerized occlusal analysis system (T-Scan 8 occlusal analysis, Tekscan, Inc., S. Boston, MA). Occlusion time, percentage of force distribution, force outliers, center of force target area, center of force trajectory and evaluation of closure arc were compared between the two groups using the Pearson's Chi Square test. RESULTS: Children with DS had more occlusal and vertical malocclusion compared to the control group (p < 0.001). The occlusion time for DS group (0.75 ± 0.7s) was significantly longer than the control group (0.015 ± 0.05s) (p < 0.001). The closure arc for DS group was mostly irregular (53%), while the control group showed ideal closure arc. In control group, the age had a significant influence on the occlusion time, while height, weight, and BMI had a significant influence on the mouth opening. None of these variables had such effect on children with DS. CONCLUSIONS: The results of this study showed high prevalence of orofacial dysfunction among DS population. The occlusal analysis showed that children with DS had longer occlusion time and a lack of ideal occlusion pattern compared to age matched controls.


Assuntos
Síndrome de Down , Má Oclusão , Força de Mordida , Criança , Oclusão Dentária , Dentição Mista , Humanos
3.
J Oral Rehabil ; 47(8): 989-997, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32428306

RESUMO

In 2016, the Japanese Society of Gerodontology (JSG) proposed the concept of "oral hypofunction (OHF)," and recommended two initial criteria for reduced occlusal force (ROF): <200 N of maximum occlusal force (MOF) and < 20 remaining teeth. However, the JSG stated that these criteria need to be reviewed by accumulating further evidence. To examine the validity and equivalence of the two criteria for ROF in the diagnostic criteria for OHF by using the incidence of functional disability as the outcome. This study enrolled 815 community-dwelling Japanese individuals ≥ 70 years. They underwent examinations for physical, mental and social functions; MOF; and number of teeth at baseline. The incidence of functional disability (a condition that requires at least partial assistance with daily activities) based on the first certification of long-term care insurance was followed up. The Cox proportional hazard model revealed that MOF < 200 N (hazard ratio [HR], 1.33; 95% confidence interval [CI], 1.04-1.72) and < 20 teeth (HR, 1.40; 95% CI, 1.07-1.84) were significantly associated with increased risk of functional disability. Receiver operating characteristic curve analyses revealed that the optimal cut-off values of MOF and number of teeth that best predicted incident functional disability were 264.6 N and 19 teeth, respectively. Twelve teeth were the optimal threshold that best predicted < 200 N of MOF. The two criteria for ROF in the diagnostic criteria for OHF had some degree of validity. However, further studies are needed to develop appropriate and reliable criteria for a decision of ROF.


Assuntos
Força de Mordida , Vida Independente , Idoso , Humanos , Incidência , Japão , Estudos Prospectivos
4.
J Oral Rehabil ; 47(7): 862-871, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32275327

RESUMO

BACKGROUND: Quantitative clinical assessment tests for oral function have become popular in patient assessment; however, their comparability remains unclear. OBJECTIVE: To assess the reliability and comparability of pairs of different instruments for measuring maximum tongue pressure (MTP), chewing function (CF) and maximum lip force (MLF), and to analyse the influence of subjects' characteristics on the applied instruments. METHODS: Each pair of instruments, as well as a single device measuring the maximum voluntary bite force (MBF), was assessed across 26 healthy volunteers. The respective pairs of devices were compared using Bland-Altman plots and linear regression analysis. Furthermore, the influence of age, occlusal support zones, number of functional occlusal units, MBF, MTP and MLF were investigated as predictors on CF using a generalised estimating equation model. RESULTS: Neither the two assessments of CF, nor of MLF were correlated to each other, but there was a significant correlation between the assessments of MTP. Hue-Check Gum was able to demonstrate a significantly higher CF in younger compared to older individuals (P = .004) and individuals with high numbers compared to low numbers of occlusal units (P < .001). Those differences could not be demonstrated with the Vivident chewing gum. CONCLUSION: The absolute values of MTP assessed by the two applied devices cannot directly be compared, although normalised values may be directly comparable. Moreover, our observations suggest that the Hue-Check Gum was able to discriminate the effects of age and the number of occlusal units on CF. Our observations suggest that the two gums cannot be used interchangeably.


Assuntos
Lábio , Língua , Força de Mordida , Goma de Mascar , Humanos , Mastigação , Pressão , Reprodutibilidade dos Testes
5.
J Oral Rehabil ; 47(6): 766-774, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32242981

RESUMO

To evaluate the changes in occlusal surface area (OSA) and occlusal force distribution (OFD) following the wear of Vacuum-formed (VFR), Hawley (HR) and Bonded (BR) retainers, using T-Scan III. A total of 60 subjects using three different maxillary and mandibular orthodontic retainers, VFR (n:20), HR (n:20) and BR (n:20), were included in this study. The changes in OSA and OFD were evaluated using the T-Scan III. The evaluations were made 2 hours after debonding orthodontic appliances (T0) and in the 3rd (T1) and 6th (T2) months of the retention phase. For left (LDA), right (RDA) and posterior dental arches (PDA), intragroup comparison of OSA showed significant increase in the VFR and HR groups at T1-T2 and T0-T2 time intervals and in the BR group at T0-T1 and T0-T2 time intervals. For the anterior dental arch (ADA), only the increase in the HR group at T0-T1 and T0-T2 time intervals was found significant. When compared between the groups, the changes between HR and BR groups detected at T1-T2 time interval for the RDA and at T0-T1 and T0-T2 time intervals for the ADA were found significant. Intragroup comparison of OFD displayed significant changes only in the BR group. At T0-T1 time interval, the decrease in the ADA and the increase in the PDA were found significant. Also, intergroup OFD comparison exhibited significant differences between HR and BR groups at T0-T1 time interval for ADA and PDA. Although no significant differences were found between the VFR group, the increase in OSA occurred faster in the PDA in the BR group, whereas in the ADA it was significant only in the HR group.


Assuntos
Força de Mordida , Desenho de Aparelho Ortodôntico , Humanos , Aparelhos Ortodônticos Fixos , Contenções Ortodônticas , Vácuo
6.
J Oral Rehabil ; 47(7): 851-861, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32270885

RESUMO

BACKGROUND: There is growing international interest in the prevention of decreased oral function for managing oral health in older people. OBJECTIVE: The aims of the present study were to identify factors related to decreases in masticatory performance and masticatory function until swallowing in subjects aged 20-79 years old. METHODS: A total of 152 subjects, ranging in age from 20 to 79 years, were divided into six groups according to their chronological age: 20-29, 30-39, 40-49, 50-59, 60-69 and 70-79 years. Grip strength, maximum occlusal force, maximum tongue pressure, masticatory performance and swallowing threshold were measured in all subjects. Masticatory performance and swallowing threshold were determined according to the concentration of dissolved glucose obtained from gummy jellies; decreased masticatory performance and decreased swallowing threshold were defined as glucose concentrations in the lowest 20th percentile. A multivariate binary logistic regression analysis was used to identify factors associated with decreased masticatory performance and decreased swallowing threshold. A self-administered lifestyle questionnaire was also completed. RESULTS: Logistic regression analyses revealed that factors related to decreased masticatory performance included use of more than one kind of medicine for treating chronic diseases and removable denture use, while factors related to decreased swallowing threshold included eating between meals once or more per day, poorer mental health and decreased saliva flow. CONCLUSIONS: Different factors are related to decreased masticatory performance and decreased swallowing threshold, although both of these phenomena are closely associated with general health status.


Assuntos
Deglutição , Mastigação , Força de Mordida , Pressão , Língua
7.
J Oral Rehabil ; 47(6): 750-756, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32232877

RESUMO

BACKGROUND: Maximum bite force (MBF) is a common and useful index of masticatory function; it correlates with physical strength in elderly people. Palpation of stiffness in the masseter muscle during forceful biting has been considered to be associated with MBF. However, this assessment method relies on subjective judgments; no study has verified the relationship between MBF and quantitative measurements of masseter muscle stiffness (MMS). OBJECTIVE: We aimed to verify the association between masseter muscle myotonometric assessment results and MBF. METHODS: In total, 117 community-dwelling >65-year-old individuals from the Tokyo metropolitan area were assessed. MMS on the dominant side during forceful biting was measured with a MyotonPRO device. Masseter muscle thickness (MMT) during rest and forceful biting was measured with an ultrasonic diagnostic apparatus, and the difference in MMT (DMMT) between the rest and forceful biting conditions was determined. MBF data were obtained with a pressure-sensitive sheet and an associated device. To determine the independent variables affecting MBF and MMS, multivariate linear regression analyses with adjustments for age, sex and number of teeth were performed. RESULTS: The multivariate analysis revealed that MBF correlated with the number of teeth (ß = .489, P < .001) and MMS (ß = .259, P = .003) (R2  = .433). MMS correlated with MBF (ß = .308, P = .003) and DMMT (ß = .430, P < .001) (R2  = .326). CONCLUSION: Masseter muscle stiffness possibly reflects a force generated by the masseter muscle during forceful biting. Therefore, MMS is effective to assess tooth loss as well as an index of masseter muscle strength when evaluating MBF.


Assuntos
Força de Mordida , Dente , Idoso , Humanos , Vida Independente , Músculo Masseter , Força Muscular
8.
J Appl Oral Sci ; 28: e20190409, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267378

RESUMO

BACKGROUND: Menopause induces oral bone loss, leading to various oral diseases. Mastication importantly affects bone metabolism in the jawbone. OBJECTIVE: To analyze the effect of enhanced masticatory force on osteoprotegerin (OPG), receptor activator of nuclear factor kappa B ligand (RANKL), and mechano-growth factor (MGF) in alveolar bone of ovariectomized rats and to study the mechanics mechanism of the alveolar bone of ovariectomized rats response to enhanced masticatory force. METHODOLOGY: Thirty Sprague Dawley rats were randomly divided into three groups: sham-operation group (fat around the removed ovary + normal hard diet), model group (ovariectomy + normal hard diet), and experimental group (ovariectomy + high hard diet). It was a 2-month experiment. Enzyme-linked immunosorbent assay (ELISA) detected serum estradiol (E2), osteocalcin (BGP) and alkaline phosphatase (ALP) in rats. Bone histomorphometric indices in the third molar region of maxilla were detected by micro-CT; protein expressions of OPG, RANKL, and MGF in the third molar region of maxilla was detected by Western blot; and gene expression of OPG, RANKL, and MGF in the third molar region of maxilla was detected by Quantitative Real-Time PCR. RESULTS: Comparing with model group, serum E2 in experimental group increased but not significantly, serum BGP and serum ALP in experimental group decreased but not significantly, OPG in experimental group in alveolar bone increased significantly, RANKL in experimental group in alveolar bone decreased significantly, RANKL/OPG ratio in experimental group decreased significantly, MGF in experimental group in alveolar bone increased significantly, bone volume to total volume fraction increased significantly in experimental group, trabecular thickness increased significantly in experimental group, and trabecular separation decreased significantly in experimental group. CONCLUSION: Enhanced masticatory force affected the expression of OPG, RANKL, and MGF in alveolar bone of ovariectomized rats, improved the quality of jaw bone of ovariectomized rats, and delayed oral bone loss by ovariectomy.


Assuntos
Processo Alveolar/fisiopatologia , Força de Mordida , Fator de Crescimento Insulin-Like I/análise , Osteoprotegerina/análise , Ovariectomia , Ligante RANK/análise , Fosfatase Alcalina/sangue , Animais , Western Blotting , ELISPOT , Estradiol/sangue , Feminino , Osteocalcina/sangue , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase em Tempo Real , Microtomografia por Raio-X
9.
J Appl Oral Sci ; 28: e20190544, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32348440

RESUMO

Objective To evaluate the influence of three levels of dental structure loss on stress distribution and bite load in root canal-treated young molar teeth that were filled with bulk-fill resin composite, using finite element analysis (FEA) to predict clinical failure. Methodology Three first mandibular molars with extensive caries lesions were selected in teenager patients. The habitual occlusion bite force was measured using gnathodynamometer before and after endodontic/restoration procedures. The recorded bite forces were used as input for patient-specific FEA models, generated from cone-beam computed tomographic (CT) scans of the teeth before and after treatment. Loads were simulated using the contact loading of the antagonist molars selected based on the CT scans and clinical evaluation. Pre and post treatment bite forces (N) in the 3 patients were 30.1/136.6, 34.3/133.4, and 47.9/124.1. Results Bite force increased 260% (from 36.7±11.6 to 131.9±17.8 N) after endodontic and direct restoration. Before endodontic intervention, the stress concentration was located in coronal tooth structure; after rehabilitation, the stresses were located in root dentin, regardless of the level of tooth structure loss. The bite force used on molar teeth after pulp removal during endodontic treatment resulted in high stress concentrations in weakened tooth areas and at the furcation. Conclusion Extensive caries negatively affected the bite force. After pulp removal and endodontic treatment, stress and strain concentrations were higher in the weakened dental structure. Root canal treatment associated with direct resin composite restorative procedure could restore the stress-strain conditions in permanent young molar teeth.


Assuntos
Força de Mordida , Resinas Compostas/química , Resinas Compostas/uso terapêutico , Restauração Dentária Permanente/métodos , Dente Molar , Dente não Vital/terapia , Criança , Força Compressiva , Tomografia Computadorizada de Feixe Cônico , Análise do Estresse Dentário , Módulo de Elasticidade , Análise de Elementos Finitos , Humanos , Modelagem Computacional Específica para o Paciente , Valores de Referência , Reprodutibilidade dos Testes , Resistência à Tração , Dente não Vital/diagnóstico por imagem , Resultado do Tratamento
10.
Arch Oral Biol ; 112: 104683, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32120053

RESUMO

OBJECTIVE: In the present study, we aimed at evaluating the steadiness of incisal bite force during isometric contractions of masticatory muscles. DESIGN: Two separate experiments were carried out in 11 healthy young women. A first experiment was performed to test the reliability of our protocol for measurement of incisal bite force steadiness. The second experiment aimed to evaluate the steadiness of incisal bite force at four submaximal (i.e., percentage of maximum voluntary contraction, MVC) levels (5 %MVC, 10 %MVC, 15 %MVC, and 20 %MVC), along with the bilateral myoelectric activity of two masticatory muscles (temporalis and masseter). RESULTS: The results from the first experiment showed that our protocol is substantially reliable (intraclass correlation coefficient, ICC > 0.80) for estimating force variability and moderate reliable (0.60 < ICC < 0.80) for estimating spectral properties of force signals. In the second experiment, we found that force standard deviation (SD) increased proportionally to the power of mean force, and coefficient of variation (CoV) was higher at low-intensity contractions and maintained at an approximately constant level for high-intensity contractions. The force-EMG relationships were linear for both muscles at the contraction intensities evaluated in the study (5 %MVC to 20 %MVC), and the median frequency did not change with contraction intensity. CONCLUSION: Therefore, we presented a reliable method to estimate the incisal bite force, along with additional data on force control and myoelectric activity of jaw elevator muscles during isometric steady contractions.


Assuntos
Força de Mordida , Músculos da Mastigação/fisiologia , Adulto , Eletromiografia , Feminino , Humanos , Músculo Masseter , Contração Muscular , Reprodutibilidade dos Testes , Músculo Temporal
11.
J Oral Rehabil ; 47(6): 731-735, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32160328

RESUMO

Biting food too quickly might affect the control of jaw-closing muscles and the estimation of bite force. The objectives of this study were to compare the incisal bite forces used to cut food and the activity of masseter (MA) and anterior temporalis (AT) muscles between slow, habitual and fast biting speeds and also between small and large jaw openings. Twenty subjects were asked to use their incisors to cut through a 5 mm thick of chewing gum. In the first experiment, subjects bit at 10-mm incisal separation with slow, habitual and fast biting speeds, and in the second experiment, subjects bit with their habitual speed at 10- and 30-mm incisal separations. The activities in the MA and AT muscles were assessed with surface electromyography, and the bite force was recorded by a force sensor placed beneath the chewing gum. Peak bite forces and associated MA amplitudes were increased significantly as biting speed was increased (P's < .05). Anterior temporalis amplitude was significantly increased during fast biting compared to slow and habitual biting (P's < .001). At 30-mm incisal separation, both peak bite force and AT amplitude were significantly increased, whereas MA amplitude was significantly decreased, compared to those at 10-mm separation (P's < .05). Biting off food quickly with incisor teeth results in larger activities in both MA and AT muscles. In addition, biting a large piece of food resulted in increased activity of AT muscle. Both conditions could be injury stimulator for jaw muscles.


Assuntos
Músculo Masseter , Músculo Temporal , Força de Mordida , Eletromiografia , Incisivo , Arcada Osseodentária , Mastigação , Músculos da Mastigação
12.
J Am Dent Assoc ; 151(2): 118-126, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32000935

RESUMO

BACKGROUND: Decreased masticatory performance leads to deterioration of overall health among older adults. However, maintaining and improving masticatory performance in ways other than maintenance of natural teeth and appropriate prosthodontic treatment remains unclear. If the factors related to the mixing and shearing abilities for masticatory performance are clarified, it may be possible to maintain and improve the masticatory performance of older adults. We aimed to clarify the association among mixing ability, shearing ability, and masticatory performance-related factors. METHODS: Of the 707 community-dwelling older adults in Kusatsu Town, Japan, 344 who had been treated for any dental defects were enrolled in this study. Masticatory performance was evaluated on the basis of mixing ability and shearing ability. The number of natural teeth and artificial teeth, occlusal force, tongue pressure, and oral diadochokinesis /ta/ were measured as masticatory performance-related factors. Their relationship with mixing ability, shearing ability, and masticatory performance-related factors was examined by means of Spearman rank correlation coefficient and path analysis. RESULTS: Among masticatory performance-related factors, the number of natural teeth, occlusal force, and tongue pressure were directly associated with both mixing ability and shearing ability. Moreover, mixing ability was also directly associated with shearing ability. CONCLUSIONS: Tongue pressure, which can be improved by means of training, is a masticatory performance-related factor associated with both mixing and shearing abilities. PRACTICAL IMPLICATIONS: Training for tongue pressure after proper prosthetic treatment may provide an effective means of maintaining and improving masticatory performance in older adults.


Assuntos
Vida Independente , Mastigação , Força de Mordida , Estudos Transversais , Japão , Pressão , Língua
13.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 38(1): 30-36, 2020 Feb 01.
Artigo em Chinês | MEDLINE | ID: mdl-32037763

RESUMO

OBJECTIVE: This study aims to investigate the occlusal and myoelectric characteristics of implant-supported fixed denture in the mandibular region and provide reference for the design of fixed restoration. METHODS: Sixty edentulous patients with implant-supported fixed denture were selected and divided into three groups: group A, 20 cases with implant-supported fixed restoration in the maxillary region; group B, 20 cases with natural dentition, and group C, 20 cases with removable partial denture. The T-scan 8.0 digital occlusion analysis system was used to evaluate the occlusal characteristics of patients in the three groups at intercuspal, protrusion, and left and right lateral positions. Electromyography was used to analyze the myoelectric amplitude and bilateral asymmetry index of the anterior temporalis and masseter of the three groups in different states such as resting and clenching. The relationship between occlusion and myoelectricity was also investigated. RESULTS: In the occlusion analysis by T-scan, the occlusion time, the balance of left and right bite force, the left and right asymmetry of the occlusion center, the trajectory of central occlusion force, and the disclusion time were higher in group C than in groups A and B (P<0.05). No significant differences were observed in the anterior and posterior asymmetry of the occlusion center and percentage of bite force at anterior region among the three groups. In the analysis of myoelectricity, the myoelectric amplitude at resting state and the asymmetry index of masticatory muscles in group C were higher than those in groups A and B (P<0.05). The myoelectric amplitude during clenching in groups A and B groups was higher than that in group C (P<0.05). CONCLUSIONS: In implant-supported fixed restoration at edentulous mandibular, when maxillary includes the removable partial denture, degree of occlusal instability and left and right asymmetry of occlusion center are greater than those with the natural dentition and implant-supported fixed denture at maxillary. The myoelectricity is closely related to occlusion. The removable partial denture can increase the myoelectric activity and reduce the potential of the masticatory muscle. The asymmetry of bilateral myoelectricity is related to the occlusion imbalance.


Assuntos
Implantes Dentários , Prótese Dentária Fixada por Implante , Força de Mordida , Humanos , Mandíbula , Músculos da Mastigação
14.
Comput Methods Biomech Biomed Engin ; 23(7): 261-270, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31965827

RESUMO

Computational models of the masticatory system can provide estimates of occlusal loading during (static) biting or (dynamic) chewing and therefore can be used to evaluate and optimize functional performance of prosthodontic devices and guide dental surgery planning. The modelling assumptions, however, need to be chosen carefully in order to obtain meaningful predictions. The objectives of this study were two-fold: (i) develop a computational model to calculate the stress response of the first molar during biting of a rubber sample and (ii) evaluate the influence of different occlusal load models on the stress response of dental structures. A three-dimensional finite element model was developed comprising the mandible, first molar, associated dental structures, and the articular fossa and discs. Simulations of a maximum force bite on a rubber sample were performed by applying muscle forces as boundary conditions on the mandible and computing the contact between the rubber and molars (GS case). The molar occlusal force was then modelled as a single point force (CF1 case), four point forces (CF2 case), and as a sphere compressing against the occlusal surface (SL case). The peak enamel stress for the GS case was 110 MPa and 677 MPa, 270 MPa and 305 MPa for the CF1, CF2 and SL cases, respectively. Peak dentin stress for the GS case was 44 MPa and 46 MPa, 50 MPa and 63 MPa for the CF1, CF2 and SL cases, respectively. Furthermore, the enamel stress distribution was also strongly correlated to the occlusal load model. The way in which occlusal load is modelled has a substantial influence on the stress response of enamel during biting, but has relatively little impact on the behavior of dentin. The use of point forces or sphere contact to model occlusal loading during mastication overestimates enamel stress magnitude and also influences enamel stress distribution.


Assuntos
Simulação por Computador , Oclusão Dentária , Análise do Estresse Dentário , Mastigação/fisiologia , Dente/patologia , Adulto , Fenômenos Biomecânicos , Força de Mordida , Análise de Elementos Finitos , Humanos , Masculino , Mandíbula/fisiologia , Estresse Mecânico
15.
J Oral Rehabil ; 47(3): 325-331, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31721269

RESUMO

BACKGROUND: Mastication is a complicated task that involves the teeth and perioral muscles, such as the tongue and lip. Previous studies have shown correlations between masticatory performance and perioral muscle strength (eg tongue pressure) and between masticatory performance and occlusal forces. OBJECTIVE: To investigate the relationships between masticatory performance and perioral muscle characteristics. METHODS: Forty-nine healthy young subjects (men: 24 and women: 25) with Eichner classification group A were included in this cross-sectional study. Age, body weight, masticatory performance, masseter muscle thickness, masseter muscle echo intensity, cross-sectional area of geniohyoid muscle, geniohyoid muscle echo intensity, tongue thickness (TT) and tongue echo intensity were assessed. Masticatory performance was evaluated using a colour-changeable chewing gum. The thickness and echo intensity of the masseter muscle, geniohyoid muscle and tongue were observed using an ultrasonic diagnostic apparatus. Stepwise multiple regression analysis was conducted to examine relationships between perioral muscle characteristics and masticatory performance. RESULTS: Tongue thickness (P < .01) was the sole significant explanatory variable for masticatory performance. The standard partial regression coefficient was 0.47. The multiple correlation coefficient (R) was .47, and the adjusted R2 was .20; the variance inflation factor was 1.0. This study showed that TT was related to masticatory performance, whereas perioral muscle quality was not. Moreover, perioral muscle quantity was highly correlated with perioral muscle quality. CONCLUSIONS: Tongue thickness is a predictor of masticatory performance in healthy young subjects. An ultrasonic diagnostic apparatus is useful in the evaluation of perioral muscle characteristics.


Assuntos
Força de Mordida , Língua , Músculos Faciais , Feminino , Humanos , Masculino , Músculo Masseter , Mastigação , Músculos da Mastigação , Pressão
16.
J Oral Rehabil ; 47(3): 319-324, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31729769

RESUMO

BACKGROUND: The articular eminence of the temporomandibular joint is an anatomical structure exposed to functional loads resulting from masticatory forces. Tooth loss may change the biomechanics of the masticator system, and the articular eminence can be affected by this change. OBJECTIVE: The aim of this study is to examine the relationship between the edentulousness and the articular eminence inclination of the temporomandibular joint. METHODS: The articular eminence inclination was measured in panoramic radiographs in the right and left temporomandibular joint on a total of 100 patients (50 dentate and 50 edentulous). The articular eminence inclination of dentate and edentulous patients was compared, as well as the influence of gender and duration of edentulousness. RESULTS: The mean articular eminence inclination value in the dentate group (42.6 ± 4.30 ) was higher than that of the edentulous group (35.1 ± 4.70 , P < .001). Although there was no significant difference between males and females in the dentate group with regard to articular eminence inclination (42.0 ± 4.70 and 42.9 ± 4.10 , respectively, P = .373), in the edentulous group, males had higher values as compared to females (37.1 ± 4.70 and 34.2 ± 4.50 , respectively, P = .003). Finally, the duration of edentulousness and the degrees of articular eminence inclination values did not show positive correlations (P = .782). CONCLUSION: According to the results of this study, we found that edentulous patients had lower articular eminence inclination than dentate patients, and it was more prominent in female than male patients.


Assuntos
Boca Edêntula , Perda de Dente , Força de Mordida , Feminino , Humanos , Masculino , Radiografia Panorâmica , Articulação Temporomandibular
17.
Oral Maxillofac Surg ; 24(1): 19-24, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31713697

RESUMO

PURPOSE: This study was to assess the efficiency of using a combination of one microplate and one miniplate for management of patients with parasymphyseal mandibular fractures versus two miniplates through measurement of the biting force. PATIENTS AND METHODS: The study sample consisted of sixteen patients with an isolated mandibular fracture and randomly divided into two groups; group I was managed using two miniplates, while group II was managed using a combination of one microplate at subapical region and one miniplate at the inferior border of the mandible. The biting force was measured at 1 week, 1 month, and 3 months follow-up visits. A control group consisted of 40 healthy adult volunteers was selected to measure the normal biting force. RESULTS: The mean of the normal biting force of the control group was 435 N ± 219, 103.2 N ± 4.8, and 390.6 N ± 195.4 at right molar, incisor, and left molar regions respectively. There was a statistically non-significant difference regarding the bite force of both study groups, with a progressive increase through the different follow-up visits and a period of 3 months is sufficient for recovery of patients to regain their normal biting force. CONCLUSION: Consequently a combination of one microplate and one miniplate is efficient for the management of isolated parasymphyseal mandibular fracture in the same way as two miniplates.


Assuntos
Placas Ósseas , Fixação Interna de Fraturas , Fraturas Mandibulares , Adulto , Força de Mordida , Humanos , Mandíbula
18.
J Prosthodont Res ; 64(2): 175-181, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31685341

RESUMO

PURPOSE: Dementia is a growing health problem for countries with aging populations, but few effective dementia treatments are available. However, there is increasing interest in oral health as a modifiable risk factor in interventions to prevent cognitive decline. This study aimed to investigate the impact of oral health on the decline of cognitive function over 3 years among Japanese people aged 70 and 80 years. METHODS: Participants (n = 860) were community-dwelling older adults who participated in baseline and follow-up surveys (at baseline: 69-71 years n = 423; 79-81 years, n = 437). Registered dentists examined the number of teeth, number of functional teeth, number of periodontal teeth, and occlusal force. The Japanese version of the Montreal Cognitive Assessment was used to evaluate cognitive function. We also evaluated socioeconomic factors, medical history, drinking and smoking habits, physical performance, genetic factors, and C-reactive protein concentration in blood. A generalized estimating equation (GEE) was used to examine how oral health at baseline influenced cognitive decline over 3 years. RESULTS: The GEE showed that the number of teeth (non-standardized coefficient: B = 0.031, p = 0.022) and occlusal force (B = 0.103, p = 0.004) at baseline were associated with cognitive function at follow-up, even after adjusting for other risk factors. Furthermore, maintaining more teeth (B = 0.009, p = 0.004) and a stronger occlusal force (B = 0.020, p = 0.040) buffered cognitive decline. CONCLUSIONS: Number of teeth and occlusal force predict cognitive decline over 3 subsequent years in Japanese older adults aged 70 and 80 years.


Assuntos
Força de Mordida , Disfunção Cognitiva , Idoso , Idoso de 80 Anos ou mais , Humanos , Vida Independente , Japão , Estudos Prospectivos
19.
Support Care Cancer ; 28(3): 1491-1501, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31273502

RESUMO

PURPOSE: The purpose of this study was to observe the impact of oral oncological treatment, including the recovery of several tongue functions (force, mobility, and sensory functions), and to determine the influence of these functions on masticatory performance. MATERIALS AND METHODS: Masticatory performance and tongue force, mobility, and sensory functions were determined in 123 patients with oral cavity cancer. The assessments were performed 4 weeks before treatment and 4 to 6 weeks, 6 months, 1 year, and 5 years after treatment. Generalized estimation equations and mixed model analyses were performed, correcting for previously identified factors in the same population. RESULTS: A significant deterioration in tongue mobility and sensory function was observed in patients with mandible and tongue and/or floor-of-mouth tumors. Better tongue force and sensory function (thermal and tactile) positively influenced masticatory performance, and this effect was stronger where fewer occlusal units were present. The effect of both the tongue force and maximum bite force was weaker in dentate patients in comparison with patients with full dentures. A web-based application was developed to enable readers to explore our results and provide insight into the coherence between the found factors in the mixed model. CONCLUSIONS: Tongue function deteriorates after oral oncological treatment, without statistically significant recovery. Adequate bite and tongue forces are especially important for patients with a poor prosthetic state. Patients with sensory tongue function deficits especially benefit from the presence of more occluding pairs.


Assuntos
Mastigação/fisiologia , Neoplasias Bucais/patologia , Língua/fisiologia , Idoso , Força de Mordida , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Bucais/terapia , Estudos Prospectivos
20.
J Prosthodont ; 29(1): 19-25, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31270888

RESUMO

PURPOSE: To determine the reliability of T-scan and 3D intraoral scan techniques for assessing the occlusal contact area (OCA), compared to occlusal registration and also to assess the validity of the techniques. MATERIALS AND METHODS: Thirty-one dentate adults participated in this cross-sectional study. T-scan records were used to measure the OCA at maximum bite force and at 50% of maximum force using the software's bite force selection tool. A second method measured the OCA between 2 virtual models scanned intraorally using a 3D surface scan and considering the occlusal contact at 2 interocclusal distances (0-100 and 0-200 µm). The third method measured OCA using occlusal registration at moderate and maximum occlusal force, and considering contact at the 2 interocclusal distances (0-100 and 0-200 µm). Images obtained using the 3 methods were analyzed using ImageJ software. Test-retest reliability was assessed by the intraclass correlation coefficient (ICC) and validity by Pearson correlations. RESULTS: ICCs ranged from 0.56 to 0.79 (p < 0.001) for the T-scan; 0.37 to 0.61 (p < 0.05) for 3D surface scan; and 0.92 to 0.95 (p < 0.0005) for occlusal registration. The highest OCA values were obtained using the T-scan, and the lowest using the 3D surface scan. Occlusal registration measurements had the highest correlations with those of the other techniques. CONCLUSIONS: T-scan is a reliable method for measuring the OCA, but the 3D surface scan is not. Occlusal registration showed a high validity.


Assuntos
Oclusão Dentária , Imageamento Tridimensional , Adulto , Força de Mordida , Estudos Transversais , Humanos , Registro da Relação Maxilomandibular , Reprodutibilidade dos Testes
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