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1.
J Dent ; 108: 103638, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33727079

RESUMO

OBJECTIVES: This systematic review aims to investigate the efficacy of denture adhesives (DAs) for complete dentures (CDs), and to provide clinical recommendations for prosthodontists and general practitioners. DATA/SOURCES: Electronic databases (Medline, Embase, CENTRAL) and gray literatures were searched (up to March 2020) for relevant randomized and non-randomized controlled clinical trials (RCTs and CCTs) evaluating the efficacy of DAs when applied to CDs. Primary outcomes were objectively assessed variables directly related to mastication (denture retention, maximum bite force and masticatory efficiency). Secondary outcomes included other objectively assessed variables and patient-reported outcomes. STUDY SELECTION: Of the 1729 records identified, 39 studies (43 articles) were included in the analysis. Among them, 23 were RCTs and 16 were CCTs, with two multicenter clinical trials (1 RCT and 1 CCT). Meta-analysis results indicated that DAs provided significantly higher retention (SMD 1.34, 95 % CI: 0.89-1.79, P < 0.001) for CDs. Bite force (SMD 0.98, 95 % CI: 0.50-1.47, P < 0.001) and masticatory performance (SMD 0.72, 95 % CI: 0.23-1.22, P = 0.004) of the CD wearers were also improved after using DAs, but the effect size was relatively smaller. CONCLUSION: Based on the results of this systematic review, it is concluded that DAs can improve denture retention, bite force and masticatory performance of CD wearers. CLINICAL SIGNIFICANCE: This study investigated the effects of all types of DAs for CDs in terms of their effects on denture retention, masticatory performance, oral health-related quality of life and oral microorganisms for CD wearers.


Assuntos
Prótese Total , Qualidade de Vida , Adesivos , Força de Mordida , Retenção de Dentadura , Humanos , Mastigação , Estudos Multicêntricos como Assunto
2.
Sensors (Basel) ; 21(4)2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33671506

RESUMO

Teeth clenching during exercise is important for sports performance and health. Recently, several mouth guard (MG)-type wearable devices for exercise were studied because they do not disrupt the exercise. In this study, we developed a wearable MG device with force sensors on both sides of the maxillary first molars to monitor teeth clenching. The force sensor output increased linearly up to 70 N. In four simple occlusion tests, the trends exhibited by the outputs of the MG sensor were consistent with those of an electromyogram (EMG), and the MG device featured sufficient temporal resolution to measure the timing of teeth clenching. When the jaw moved, the MG sensor outputs depended on the sensor position. The MG sensor output from the teeth-grinding test agreed with the video-motion analysis results. It was comparatively difficult to use the EMG because it contained a significant noise level. Finally, the usefulness of the MG sensor was confirmed through an exercise tolerance test. This study indicated that the developed wearable MG device is useful for monitoring clenching timing and duration, and the degree of clenching during exercise, which can contribute to explaining the relationship between teeth clenching and sports performance.


Assuntos
Bruxismo , Protetores Bucais , Dispositivos Eletrônicos Vestíveis , Força de Mordida , Eletromiografia , Humanos , Contração Muscular
3.
J Oral Facial Pain Headache ; 35(1): 7-16, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33730122

RESUMO

AIMS: To investigate whether localized sensitization of the sternocleidomastoid (SCM) muscle using nerve growth factor (NGF) would affect masseter and anterior temporalis muscle sensitivity and pain profiles. METHODS: A total of 28 healthy participants attended two sessions (T0 and T1). At T0, the maximum voluntary occlusal bite force (MVOBF), as well as pressure pain thresholds (PPT), mechanical sensitivity, and referred pain/sensations for the SCM, masseter, and temporalis muscles, were assessed. Participants also completed the Pain Catastrophizing Scale (PCS), the Pain Vigilance and Awareness Questionnaire (PVAQ), and the Neck Disability Index (NDI). After these assessments, 14 participants received an injection of NGF into the SCM, and 14 received an injection of isotonic saline solution. At T1 (48 hours postinjection), the participants were again submitted to the same evaluations. RESULTS: NGF caused significant mechanical sensitization in the SCM (P < .025), but not in the masseter or temporalis muscles (P > .208). It also caused significant increases in NDI score (P = .004). No statistically significant differences were found for MVOBF, frequency of referred pain/sensations, or questionnaire scores (P > .248). CONCLUSION: These results suggest that 48 hours after localized sensitization of the SCM, the primary response is impairment of neck function, but not jaw function.


Assuntos
Músculo Masseter , Fator de Crescimento Neural , Força de Mordida , Eletromiografia , Humanos , Limiar da Dor , Músculo Temporal
4.
J Oral Rehabil ; 48(7): 774-784, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33780558

RESUMO

BACKGROUND: In children with juvenile idiopathic arthritis (JIA), the temporomandibular joint (TMJ) can be involved, resulting in dysfunction of the masticatory system. Bite force is one of the variables that reflects the function of the masticatory system. The aim of this study was to compare maximum bite force in children with JIA, with and without TMJ involvement and with healthy children. METHODS: Children with JIA and healthy children between the ages 6 and 18 were included in this cross-sectional study. The clinical examination consisted of measuring the anterior maximum voluntary bite force (AMVBF), assessment of the TMJ screening protocol items and TMJ, masseter and temporal muscle palpation pain. Unadjusted linear regression analyses were performed to evaluate the explanatory factors for AMVBF. Two adjusted models were constructed with corrections for age and gender differences: model 1 to compare children with JIA and healthy children and model 2 to compare children with JIA with and without TMJ involvement. RESULTS: In this cross-sectional study, 298 children with JIA and 169 healthy children participated. AMVBF was 24 Newton (N) lower in children with JIA, when compared with healthy children (95%CI: -35.5--12.4, p = .000). When children with JIA also had clinically established TMJ involvement, AMVBF was reduced 42 N (component JIA:-16.78, 95% CI -28.96--4.59, p = .007 and component TMJ involvement:-25.36, 95% CI -40.08--10.63, p = .001). Age and male gender increased AMVBF. CONCLUSION: Children with JIA had a reduction in the AMVBF compared with healthy children. In children with JIA and clinically established TMJ involvement, AMVBF was more reduced.


Assuntos
Artrite Juvenil , Transtornos da Articulação Temporomandibular , Adolescente , Força de Mordida , Criança , Estudos Transversais , Humanos , Imagem por Ressonância Magnética , Masculino , Articulação Temporomandibular
5.
Proc Biol Sci ; 288(1945): 20202809, 2021 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-33593183

RESUMO

Biomechanical modelling is a powerful tool for quantifying the evolution of functional performance in extinct animals to understand key anatomical innovations and selective pressures driving major evolutionary radiations. However, the fossil record is composed predominantly of hard parts, forcing palaeontologists to reconstruct soft tissue properties in such models. Rarely are these reconstruction approaches validated on extant animals, despite soft tissue properties being highly determinant of functional performance. The extent to which soft tissue reconstructions and biomechanical models accurately predict quantitative or even qualitative patterns in macroevolutionary studies is therefore unknown. Here, we modelled the masticatory system in extant rodents to objectively test the ability of current muscle reconstruction methods to correctly identify quantitative and qualitative differences between macroevolutionary morphotypes. Baseline models generated using measured soft tissue properties yielded differences in muscle proportions, bite force, and bone stress expected between extant sciuromorph, myomorph, and hystricomorph rodents. However, predictions from models generated using reconstruction methods typically used in fossil studies varied widely from high levels of quantitative accuracy to a failure to correctly capture even relative differences between macroevolutionary morphotypes. Our novel experiment emphasizes that correctly reconstructing even qualitative differences between taxa in a macroevolutionary radiation is challenging using current methods. Future studies of fossil taxa should incorporate systematic assessments of reconstruction error into their hypothesis testing and, moreover, seek to expand primary datasets on muscle properties in extant taxa to better inform soft tissue reconstructions in macroevolutionary studies.


Assuntos
Força de Mordida , Fósseis , Animais , Evolução Biológica , Fenômenos Biomecânicos , Biofísica
6.
Artigo em Inglês | MEDLINE | ID: mdl-33546493

RESUMO

(1) Background: This study aimed to investigate maximum bite force (MBF) in elderly patients with natural full dentition (FD), patients rehabilitated with Traditional Complete Dentures (CD), with overdentures (IRO) and edentulous patients (ED). We also tested whether MBF changes are associated with gender, age of the patients and body mass index (BMI) as result of altered food; (2) Methods: Three hundred and sixty-eight geriatric patients were included. We studied two types of prostheses: (a) IRO with telescopic attachments. (b) CD (heat polymerized polymethyl methacrylate resin). The MBF was measured using a digital dynamometer with a bite fork; (3) Results: We found that MBF is higher in males than females, regardless of teeth presence or absence (p < 0.01). In patients with CD or IRO, there are no differences between males and females; prostheses improve MBF compared to edentulous patients (p < 0.0001) and this effect is greater with IRO prostheses (p < 0.0001); the chewing force of FD subjects remains greater (p < 0.0001); there are no differences among chewing strength based on different BMI categories, although FD subjects have a reduced incidence of obesity; there is a significant negative correlation between MBF and age (p = 0.038; R = 0.145), and no correlation between MBF and BMI; (4) Conclusions: This study showed that MBF improves more in patients using IRO prostheses, although not reaching the MBF of FD subjects. MBF does not correlate with BMI, although we found increased percentages of obesity in edentulous subjects or those with prostheses. Thus, old people wearing prostheses require special attention by a nutritionist to avoid risk of malnutrition.


Assuntos
Força de Mordida , Boca Edêntula , Idoso , Dentição , Revestimento de Dentadura , Feminino , Humanos , Masculino , Mastigação
7.
J Am Dent Assoc ; 152(3): 187, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33632405
8.
J Am Dent Assoc ; 152(3): 187, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33632406
9.
J Oral Sci ; 63(2): 145-147, 2021 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-33597338

RESUMO

PURPOSE: This study aimed to clarify whether occlusal force and masticatory performance reduced in elderly adults and whether these parameters were affected by age. METHODS: Seventy-eight elderly adults (elderly group) and 76 young adults (control group) with natural dentition were asked to maximally clench for 3 s, and occlusal force was calculated. The amount of glucose extraction after chewing a gummy jelly was measured as the parameter for masticatory performance. Occlusal force and masticatory performance were compared between the elderly and control groups. The correlation between age and occlusal force and between age and masticatory performance was also investigated. RESULTS: Occlusal force was significantly smaller in the elderly group (P < 0.05). Masticatory performance was lower in the elderly group, but this difference was not statistically significant. No significant correlation was observed between age and occlusal force in the control group, but a negative correlation was found in the elderly group (P < 0.05). No significant correlation was found between age and masticatory performance in either group. CONCLUSION: Occlusal force was affected by age and reduced significantly, whereas masticatory performance was not affected by age and was maintained in elderly adults.


Assuntos
Força de Mordida , Boca Edêntula , Idoso , Dentição , Humanos , Mastigação , Adulto Jovem
10.
J Prosthodont ; 30(S1): 52-60, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33474770

RESUMO

PURPOSE: The purpose of this Best Evidence Consensus Statement was to search the literature to determine if there is a relationship between patient specific factors and occlusal force. MATERIALS AND METHODS: A literature review was conducted in the following databases: Evidence-Based Medicine Reviews (EBMR), Cochrane Database of Systematic Reviews, Embase, and Ovid MEDLINE(R) and Epub Ahead of Print. Articles on patient factors and occlusal force were compiled by using a combination of the key words: "bite force," "occlusal force," "partial and complete edentulism," "bruxism," and "orthognathic class." Inclusion criteria included meta-analyses, systematic reviews, randomized controlled trials, case series, and journal articles. Exclusion criteria were case reports, studies in children, animals, and bench studies. RESULTS: Of the 1502 articles that met the initial search criteria, 97 related to patient-specific factors affecting occlusal forces. These articles were evaluated, rated, and organized into appropriate categories addressing questions of foci. CONCLUSIONS: The range of occlusal force is highly variable among subjects correlated to patient specific factors such as age, gender, partial and complete edentulism, the presence of a maxillofacial defect, location of edentulous area, orthognathic profile, and magnitude of occlusal vertical dimension. Tooth replacement therapies targeted at increasing occlusal contact seem to have a positive effect on increasing occlusal force. Bruxism does not necessarily demonstrate higher occlusal powering but may have greater tooth contact time. Occlusal force is not clearly affected by the type of dental restoration or restorative material used. The clinical significance of the changes in occlusal forces is yet to be determined.


Assuntos
Força de Mordida , Bruxismo , Animais , Criança , Consenso , Humanos
11.
Sensors (Basel) ; 21(2)2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33451097

RESUMO

The aim of this preliminary study was to evaluate the short-term changes of occlusal contacts and muscle activity after orthodontic treatment during the use of a multi-layer clear retainer. Evaluation was done with the T-scan and BioEMG systems. A total of 18 subjects were included, who were evaluated at three time intervals-T0 at debonding, T1 at one month after retainer delivery, and T2 at four months after retainer delivery. The T-scan and electromyography (EMG) data were recorded simultaneously. The T-scan system recorded the occlusion time, disclusion time and force distribution. The EMG waves were quantified by calculating the asymmetry index and activity index. The time variables changed but not significantly. Occlusal force decreased in the anterior dentition and increased in the posterior dentition during T0-T2. There was no clear evidence of a relationship between unbalanced occlusal forces and muscle activity. In most subjects, the temporalis anterior muscle was more dominant than the masseter muscle. From this preliminary computerized study, there were no significant changes in the state of the occlusion or muscle activity during the short-term retention period.


Assuntos
Músculo Masseter , Adolescente , Adulto , Força de Mordida , Eletromiografia , Feminino , Humanos , Masculino , Músculo Temporal , Dente , Adulto Jovem
12.
J Oral Rehabil ; 48(5): 592-600, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33481324

RESUMO

There is wide variation in chewing behaviours, even among healthy humans. Further, the way in which humans determine swallowing initiation when chewing solid foods remains unclear. The current study sought to investigate how the bolus properties change over time during chewing, and to clarify which factors affect chewing and swallowing behaviours, including swallowing initiation, in healthy humans. Twenty-four healthy volunteers were instructed to chew 8 g of steamed rice and spit it out at 50%, 100% and 150% of their own chewing duration, defined as the time of chewing from onset of the first chewing cycle to onset of the first swallow. Chewing and swallowing behaviours were monitored and determined by visual inspection of video recordings. The physical properties such as hardness, cohesiveness and adhesiveness as well as water content of the bolus were measured. In each subject, maximum bite force, tongue pressure and stimulated salivary flow rate were also measured. Hardness gradually decreased, and the cohesiveness and water content of the bolus did not change up to 50% of chewing duration, followed by a slight but significant increase. The adhesiveness of the bolus rapidly decreased at the beginning of chewing. Chewing duration was significantly related to stimulated salivary flow rate; greater salivary flow rate was associated with shorter chewing duration. Variation of chewing duration and swallowing initiation was not dependent on bolus properties during the chewing of steamed rice, but mainly depended on the surface lubrication of the bolus.


Assuntos
Deglutição , Língua , Força de Mordida , Alimentos , Humanos , Mastigação , Pressão
13.
J Oral Rehabil ; 48(6): 701-710, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33486815

RESUMO

Common impressions cannot accurately duplicate the dental occlusion under occlusal force due to tooth displacement and mandibular deformation. To establish new methods to construct virtual intercuspal occlusion and assess their construction accuracy. The intraoral occlusal contacts of posterior teeth of 15 subjects were recorded with 8 µm and 100 µm articulating paper, respectively, and the marked teeth and buccal bite data were scanned with an intraoral scanner. The virtual dental occlusions were separately determined by buccal bite registration (BBR) method, and 3 new methods, namely segmented tooth registration (STR), occlusal contact areas (marked by 8 µm articulating paper) registration (OCR) and mixing registration (MR) methods. With the intraoral contact areas marked by 100 µm articulating paper set as reference and contact areas of the 4 virtual occlusions as tests, sensitivity, positive predictive value (PPV) and the ratio of overlapping areas were calculated. Kruskal-Wallis test or 1-way ANOVA was used to analyse the difference among groups. The sensitivity ranged from 0.69 to 0.94 and the PPV from 0.67 to 0.90. Sensitivity of OCR group and PPV of STR and OCR groups were different from that of BBR group at overlapping threshold of 50% (P = .028, .028 and .006). There was statistical difference of the ratio of overlapping areas over reference areas, and the values of STR and OCR groups were higher than that of BBR group (P = .045 and .021). The ability of STR and OCR methods to construct virtual intercuspal occlusion was better than BBR method.


Assuntos
Oclusão Dentária , Dente , Força de Mordida , Humanos , Registro da Relação Maxilomandibular , Mandíbula/diagnóstico por imagem
14.
J Mech Behav Biomed Mater ; 115: 104296, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33465750

RESUMO

The bite force of the piranha (Serrasalmidae) has drawn considerable attention due to its ability to effectively capture and masticate prey. Herein, we analyze theoretical anterior bite forces using a lever approach and compare them to in-vivo maximum bite forces. We provide a mechanics analysis that explains the scaling allometry of the bite force (Foutput) with the length of the fish (l), Foutputαl2.


Assuntos
Força de Mordida , Caraciformes , Animais , Fenômenos Biomecânicos , Comportamento Alimentar , Mastigação
15.
Braz. dent. sci ; 24(1): 1-9, 2021. tab, ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1145518

RESUMO

Objective: To determine the force decay and discoloration in Generation I and Generation II elastomeric chain on artificial saliva immersion. Material and methods: Generation I and Generation II elastomeric chains stretched on an acrylic board and immersed in artificial saliva for 1, 7, 14, 21, and 28 days according to the group of days. On each specified day, the force of each sample measured by an orthodontic force gauge and the magnitude of the force obtained is entered to the formula to find out the force decay in percentage, whereas discoloration of each sample analyzed by the color reader with CIE Lab analysis. Results: The force decay between Generation I and Generation II elastomeric chains showed a statistically significant difference in every group of days, in which Generation II is more effective in maintaining stretch force. Similar to force decay, the discoloration in Generation I elastomeric chains on the 14th day showed significant value and Generation II elastomeric chains were more stable in maintaining color compared to Generation I. Conclusions: over the entire research period time, Generation II elastomeric chains are more stable in maintaining stretch forces and color compared to Generation I elastomeric chains. (AU)


Objetivo: Determinar a queda de força e descoloração nos elásticos ortodônticos tipo corrente de Geração I e Geração II na imersão em saliva artificial. Material e métodos: Elásticos Geração I e Geração II foram esticados em placas de acrílico e imersas em saliva artificial por 1, 7, 14, 21 e 28 dias, de acordo com o grupo de dias. Em cada dia especificado, a força de cada amostra medida por um medidor de força ortodôntica e a magnitude da força obtida são inseridos na fórmula para descobrir sua queda em porcentagem, enquanto a descoloração de cada amostra foi analisada pelo leitor de cores "CIE Lab". Resultados: A queda da força entre os elásticos Geração I e Geração II apresentou diferença estatisticamente significativa em todos os grupos de dias, sendo que a de Geração II foi mais efetiva na manutenção da força de alongamento. Semelhante à queda de força, a descoloração nos elásticos da Geração I mostrou um valor significativo no 14º dia, e elásticos da Geração II foram mais estáveis na manutenção da cor em comparação com a Geração I. Conclusões: durante todo o período de pesquisa, os elásticos tipo corrente da Geração II foram mais estáveis na manutenção das forças de alongamento e da cor em comparação com os elásticos da Geração I (AU)


Assuntos
Saliva Artificial , Técnicas de Movimentação Dentária , Força de Mordida
16.
J Clin Pediatr Dent ; 44(6): 423-428, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33378468

RESUMO

OBJECTIVE: To determine the maximum occlusal bite force (MOBF) of the complete spectrum of dental caries in first permanent molars (FPMs) in children aged 7-9 years. STUDY DESIGN: A cross-sectional study was conducted on 123 children. The evaluation of the caries spectrum of FPMs was carried out using the Caries Assessment Spectrum and Treatment index (CAST). The MOBF was measured in the FPM region using the portable occlusal force gauze. Independent sample t-test and one-way analysis of variance test were performed to compare MOBF with CAST scores of FPMs. Based on the CAST scores, FPMs were categorized into three groups, group 1: healthy (score 0, 1, 2), group 2: premorbid (score 3), group 3: morbid (score 4, 5). RESULTS: A significantly lower MOBF was observed (167.56 N ± 49.77) in the morbid stage (group 3) than in the premorbid stage (group 2: 291.57 N ± 56.64), and healthy (group 1; 320.93 N ± 54.23). Intergroup comparison also revealed that FPMs in the healthy stage was associated with a higher bite force compared to those in the premorbid and morbid stages (p<0.001). CONCLUSIONS: The mean MOBF decreased with the progression of the caries spectrum of FPMs in early permanent dentition.


Assuntos
Força de Mordida , Cárie Dentária , Criança , Estudos Transversais , Dentição Permanente , Humanos , Dente Molar
17.
Av. odontoestomatol ; 36(4): 208-217, sept.-dic. 2020. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-198591

RESUMO

INTRODUCCIÓN: Para los trastornos temporomandibulares (TTM) el tratamiento de primera línea es el conservador, éste incluye a la terapia convencional, además se ha descrito el uso de la estimulación nerviosa eléctrica transcutánea (TENS). El objetivo de este estudio fue determinar la respuesta terapéutica del TENS como complemento a la terapia convencional comparado con pacientes que recibieron exclusivamente terapia convencional. MATERIAL Y MÉTODOS: Estudio retrospectivo caso-control en pacientes diagnosticados con TTM, tratados en la Clínica de Especialidades de la Escuela de Odontología de la Universidad de Valparaíso, entre los años 2009 y 2012. De los 231 pacientes, 63 cumplieron con los criterios de inclusión y fueron pareados en un grupo convencional y un grupo TENS. Se evaluó el dolor articular y muscular; aperturas mandibulares activa sin dolor, activa forzada y pasiva; y fuerza masticatoria. Se aplicaron test estadísticos de Kruskal-Wallis, Wilcoxon y Spearman. RESULTADOS: Para el grupo TENS, se encontraron respuestas significativas en dolor articular y muscular derecho e izquierdo, apertura mandibular activa sin dolor y fuerza masticatoria. Para el grupo convencional, se encontraron resultados similares a excepción de dolor articular derecho. También respuestas significativas para todas las variables que midieron dolor inmediatamente posterior a la aplicación de TENS. Finalmente se establecieron correlaciones entre la edad y las aperturas activa sin dolor, activa forzada y pasiva. DISCUSIÓN: La terapia convencional y la complementada con TENS demostraron similar respuesta terapéutica a largo plazo, sin embargo, la aplicación del TENS produce una respuesta inmediata que reduce el dolor en el corto plazo


INTRODUCTION: For temporomandibular disorders (TMD), conservative therapies, including conventional therapy, are the first line of treatment, and the use of transcutaneous electrical nerve stimulation (TENS) has also been reported. The aim of this study was to determine the therapeutic response to TENS as complement to conventional therapy compared with patients receiving conventional therapy exclusively. METHODOLOGY: A retrospective study was carried out with patients diagnosed with TMD, treated at the Clinic of Specialties of the Dental School of Universidad de Valparaíso, between 2009 and 2012. Of 231 patients, 63 met the inclusion criteria and were randomly allocated to a conventional therapy group (controls) and a coadjuvant TENS group (cases). Both were evaluated for pain in the temporomandibular joints (TMJ) and masseters, active opening without pain, forced active opening, passive opening, and occlusal force. Statistical analysis was performed with Kruskal-Wallis, Wilcoxon and Spearman tests. RESULTS: For TENS group, significant differences were found for pain in the right and left TMJ, pain in the right and left masseter, active opening without pain, and occlusal force. For the conventional group, the same results were obtained, except for pain in right TMJ. For the variables measured immediately after applying TENS, significant differences were found in all pain variables. Correlations were established with age, active opening without pain, forced active opening, and passive opening. DISCUSSION: Conventional therapy and TENS-complemented therapy showed good therapeutic response, concluding that TENS is a good complement to conventional therapy


Assuntos
Humanos , Masculino , Feminino , Adulto , Transtornos da Articulação Temporomandibular/terapia , Estimulação Elétrica Nervosa Transcutânea/métodos , Estudos de Casos e Controles , Estudos Retrospectivos , Artralgia/diagnóstico , Mialgia/diagnóstico , Força de Mordida
18.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 55(10): 743-749, 2020 Oct 09.
Artigo em Chinês | MEDLINE | ID: mdl-33045785

RESUMO

Objective: To quantitatively evaluate the change of the long axis angle and the relative displacement of the crown feature points of the posterior teeth under normal bite force utilizing an intraoral scanner, and to provide clinical reference. Methods: From May to December 2019, fifteen graduate volunteers (5 males and 10 females, aged from 22 to 30, with an average age of 25.7 years) from Peking University School and Hospital of Stomatology were recruited to participate in the study. The surface data (U1, L1) of the maxillary and mandibular posterior teeth were scanned by an intraoral scanner i500, and saved as original data. The volunteers were guided to bite in the intercuspal position with normal bite force. The buccal bite data of the posterior teeth were scanned as the basis for registration. The digital casts were imported into Geomagic studio 2013 software and the boundary lines along the gingival margin and mesial and distal contact area of posterior teeth of data (U1, L1) were determined. Long axis of the crown, crown centroid and mesial functional cusp vertex were establishd. The data (U1, L1) were segmented into single tooth. Single tooth was aligned to buccal bite data separately using best-fit alignment command based on the buccal common area of the crown and new casts data (U2, L2) were obtained as the data under bite force. The long axis angle and centroid distance between adjacent teeth (second premolar and first molar, second molar and first molar) were measured and the deviation between data obtained at mouth-open state and that at biting state was calculated. Negative value meant centroid distance became shorter under bite force. The first molar was set as the common area and registrate the U1, L1 to U2, L2. The angle of long axes, and displacement of centroid and of functional cusp vertex between second premolar of two casts were calculated, as well as between second molar of two casts. Wilcoxon signed rank test was used to analyze the differences of teeth displacement between second premolar and second molar, and between maxillary and mandibular jaws with SPSS 26.0 statistical software. Results: The result of second premolar and second molar in the same jaw had no statistical difference (P>0.05). The centroid distance deviation of mandibular second premolar-first molar [-0.022(0.046) mm] was larger than that of maxilla [-0.006 (0.040) mm] (P<0.05). The long axis angle of second premolar itself [0.913°(0.647°)] and centroid distance of second molar itself [0.102 (0.106) mm] on the mandibular jaw were different from that on the maxillary jaw, which were 0.590°(0.550°) and 0.074(0.060) mm respectively (P<0.05). Conclusions: Under bite force, displacement of the second premolar and second molar was present, including the displacement of centroids and deflection of long axes. The mandibular posterior teeth have larger displacement than the maxillary teeth.


Assuntos
Força de Mordida , Dente Molar , Adulto , Dente Pré-Molar , Oclusão Dentária , Feminino , Humanos , Masculino , Maxila , Dente Molar/diagnóstico por imagem
19.
Proc Biol Sci ; 287(1935): 20201818, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32993469

RESUMO

The acquisition of elongated, sabre-like canines in multiple vertebrate clades during the last 265 Myr represents a remarkable example for convergent evolution. Due to striking superficial similarities in the cranial skeleton, the same or similar skull and jaw functions have been inferred for sabre-toothed species and interpreted as an adaptation to subdue large-bodied prey. However, although some sabre-tooth lineages have been classified into different ecomorphs (dirk-tooths and scimitar-tooths) the functional diversity within and between groups and the evolutionary paths leading to these specializations are unknown. Here, we use a suite of biomechanical simulations to analyse key functional parameters (mandibular gape angle, bending strength, bite force) to compare the functional performance of different groups and to quantify evolutionary rates across sabre-tooth vertebrates. Our results demonstrate a remarkably high functional diversity between sabre-tooth lineages and that different cranial function and prey killing strategies evolved within clades. Moreover, different biomechanical adaptations in coexisting sabre-tooth species further suggest that this functional diversity was at least partially driven by niche partitioning.


Assuntos
Evolução Biológica , Carnívoros , Dente/anatomia & histologia , Animais , Fenômenos Biomecânicos , Força de Mordida , Fósseis , Mandíbula , Crânio/anatomia & histologia
20.
Proc Biol Sci ; 287(1935): 20201578, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32962547

RESUMO

The southern alligator lizard (Elgaria multicarinata) exhibits a courtship behaviour during which the male firmly grips the female's head in his jaws for many hours at a time. This extreme behaviour counters the conventional wisdom that reptilian muscle is incapable of powering high-endurance behaviours. We conducted in situ experiments in which the jaw-adductor muscles of lizards were stimulated directly while bite force was measured simultaneously. Fatigue tests were performed by stimulating the muscles with a series of tetanic trains. Our results show that a substantial sustained force gradually develops during the fatigue test. This sustained force persists after peak tetanic forces have declined to a fraction of their initial magnitude. The observed sustained force during in situ fatigue tests is consistent with the courtship behaviour of these lizards and probably reflects physiological specialization. The results of molecular analysis reveal that the jaw muscles contain masticatory and tonic myosin fibres. We propose that the presence of tonic fibres may explain the unusual sustained force properties during mate-holding behaviour. The characterization of muscle properties that facilitate extreme performance during specialized behaviours may reveal general mechanisms of muscle function, especially when done in light of convergently evolved systems exhibiting similar performance characteristics.


Assuntos
Arcada Osseodentária/anatomia & histologia , Lagartos/fisiologia , Músculos da Mastigação/anatomia & histologia , Comportamento Sexual Animal , Animais , Força de Mordida , Corte , Feminino , Masculino , Contração Muscular , Músculo Esquelético
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