Effect of acupuncture on the molar bite force in women with chronic neck pain / Efecto de la acupuntura sobre la fuerza de mordida en mujeres con cervicalgia crónico

Objetive: To investigate the maximum molar bite force in women with chronic neck pain after treatment with acupuncture. Materials and Methods: Twenty-three women with chronic neck pain participated. Dynamometer was used to measure the right and left maximum molar bite force. Dong Bang acupuncture needles - 0.25 mm x 30 mm was inserted into the integumentary tissue. Treatment was 10 sessions, each 30 minutes long and twice a week. Results: The right (p = 0.01) and left (p = 0.004) molar bite force was assessed after treatment with acupuncture, and showed increased occlusal strength. Conclusions: This study suggests a functional improvement in the stomatognathic system in women with chronic cervical pain after treatment with acupuncture. However, it is important to note that further research is needed to fully elucidate the long-term effects and potential clinical implications of these findings in the field of pain management and rehabilitation.

Objetivo: Investigar la fuerza masticatoria máxima en mujeres con dolor crónico de cuello después del tratamiento con acupuntura. Materiales y Métodos: Participaron veintitrés mujeres con dolor crónico de cuello. Se utilizó un dinamómetro para medir la fuerza máxima de mordida del molar derecho e izquierdo. Agujas de acupuntura Dong Bang se insertaron 0,25 mm x 30 mm en el tejido tegumentario. El tratamiento fue de 10 sesiones, cada una de 30 minutos de duración, dos veces por semana. Resultados: Se observó la fuerza de mordida del molar derecho (p=0.01) e izquierdo (p=0.004) después del tratamiento con acupuntura, que mostró un aumento de la fuerza oclusal. Conclusión: Este estudio sugiere una mejora funcional en el sistema estomatognático en mujeres con dolor cervical crónico después del tratamiento con acupuntura. Sin embargo, es importante señalar que se necesita más investigación para dilucidar por completo los efectos a largo plazo y las posibles implicaciones clínicas de estos hallazgos en el campo del tratamiento y la rehabilitación del dolor.

Effect of Photobiomodulation on Salivary Cortisol, Masticatory Muscle Strength, and Clinical Signs in Children with Sleep Bruxism: A Randomized Controlled Trial.

Background: The diagnosis of sleep bruxism (SB) in children is difficult due to the lack of a polysomnographic protocol for this population. Moreover, the gold standard treatment [occlusal splint (OS) therapy] has limitations, as adequate use depends on the child's cooperation. The etiology of SB may include stress factors. Salivary cortisol is a biomarker used as a noninvasive method to evaluate the response to stress. Besides physiological aspects, it is also important to investigate morphological aspects, such as masticatory muscle strength. The aim of the present study was to determine the occurrence of bite marks on the buccal mucosa in children as a complementary sign for the diagnosis of SB and investigate and the effectiveness of photobiomodulation as an alternative treatment for this condition. Methods: Seventy-six children 6-12 years of age were divided into four groups: G1-with SB and submitted to laser therapy over acupuncture points (λ = 786.94 nm, 20 sec per point, fluency = 33.5 Jcm2, energy = 1 J, number of points = 12); G2-with SB, use of OS, G3-with SB and submitted to sham laser therapy; and G4-control group without SB. Clinical signs (bite marks on buccal mucosa and headaches), bite force (BF), and salivary cortisol (biomarker of stress) were evaluated before and after treatment. Statistical analysis involved the Kolmogorov-Smirnov, Shapiro-Wilk, and analysis of variance (ANOVA) tests. Results: Bite marks on the buccal mucosa were significantly associated with SB (p < 0.001). A statistically significant difference was found between the frequency of children with headache before and after treatment in G1 (p = 0.0005) and G2 (p = 0.0001), with no significant differences between the two groups (G1 and G2). The children in G1 had lower BF on both sides compared to the other groups. In the intragroup analysis after treatment, all groups exhibited an increase in salivary cortisol levels. Conclusions: Bite marks on the buccal mucosa can be used as a complementary sign for the clinical diagnosis of SB. Children with SB responded well to photobiomodulation therapy, as evidenced by the reduction in BF and reports of headache.

Factores morfofuncionales de interés en prostodoncia que dependen de los biotipos craneofaciales / Morphofunctional factors of interest in prosthodontics depending on the craniofacial biotypes

El presente es un trabajo de investigación bibliográfica que busca establecer la posibilidad de utilizar las cefalometrías como elementos de diagnóstico pronóstico y elaboración de prótesis. Centra su objeto de estudio en encontrar y clasificar los factores morfológicos y funcionales que varían con los biotipos craneofaciales y que son de interés en la prostodoncia. La metodología empleada fue la revisión de la literatura histórica hasta la actualidad en la que se relacionan temas de prostodoncia a los biotipos craneofaciales. Si bien solo dos autores relacionaron la prostodoncia con los biotipos cráneo faciales, sí se encontraron varios temas de interés asociados directamente a la prostodoncia. Se clasificaron en temas de oclusión: Curva de Spee, plano de oclusión, movimientos mandibulares, dimensión vertical oclusiva y de especio libre interoclusal. Tema de maloclusiones. Tema de fuerza muscular. Tema variaciones morfológicas de procesos alveolares, corticales ósea y de la forma dentaría. Encontrándose para cada uno de ellos alguna correlación positiva con los distintos tipos faciales. De este estudio, se concluye que es necesario sistematizar el estudio de los conocimientos que puede aportar la cefalometría como una importante herramienta de diagnóstico al prostodoncista a partir de haberse encontrado variaciones muy importantes en los aspectos mencionados que hacen al interés de la rehabilitación prostodóncica (AU)

This Work is a bibliographic research that seeks to establish the use of cephalometries as elements of diagnosis prognostic and prosthesis elaboration. Its focus is to find and classify morphological and functional factors that vary with facial types which are of interest in prosthodontics. This was a review of the historical literature to date, in which prosthodontics are related to facial types. Although only two authors related prosthodontics to facial ypes, they did find several topics of interest directly associated with prosthodontics. They were classified into occlusion themes: Spee curve, occlusion plane, mandibular movements, occlusive vertical dimension and interocclusal free space. Malocclusion issue. Muscle strength theme. Morphological variations of alveolar processes, cortical bone and dental morphology. They found some positive correlation with the different facial types for each of them. From this study, it is concluded that it is necessary to systematize the study of cephalometries because they can provide to be an important diagnostic tool to the prosthodontist because there were found very important variations in the mentioned aspects that are of interest in prosthodontic rehabilitation (AU)

Intelligent Occlusion Stabilization Splint with Stress-Sensor System for Bruxism Diagnosis and Treatment.

Bruxism is a masticatory muscle activity characterized by high prevalence, widespread complications, and serious consequences but without specific guidelines for its diagnosis and treatment. Although occlusal force-based biofeedback therapy is proven to be safe, effective, and with few side effects in improving bruxism, its mechanism and key technologies remain unclear. The purpose of this study was to research a real-time, quantitative, intelligent, and precise force-based biofeedback detection device based on artificial intelligence (AI) algorithms for the diagnosis and treatment of bruxism. Stress sensors were integrated and embedded into a resin-based occlusion stabilization splint by using a layering technique (sandwich method). The sensor system mainly consisted of a pressure signal acquisition module, a main control module, and a server terminal. A machine learning algorithm was leveraged for occlusal force data processing and parameter configuration. This study implemented a sensor prototype system from scratch to fully evaluate each component of the intelligent splint. Experiment results showed reasonable parameter metrics for the sensors system and demonstrated the feasibility of the proposed scheme for bruxism treatment. The intelligent occlusion stabilization splint with a stress sensor system is a promising approach to bruxism diagnosis and treatment.

Associação entre os aspectos da avaliação clínica da língua realizada em crianças / Association between aspects of clinical assessment of the tongue accomplished in children

RESUMO Objetivo Pesquisar a existência de associação entre os aspectos da avaliação clínica da língua. Métodos Estudo transversal observacional, com 80 crianças brasileiras, saudáveis, faixa etária entre 8 e 12 anos, sendo 36 (45%) do gênero masculino e 44 (55%) do gênero feminino. Foram avaliados aspectos da língua relacionados à morfologia, frênulo, mobilidade, praxias e força. Foram obtidas as associações entre os aspectos da avaliação clínica, considerando nível de significância de 5%. Resultados Houve associação entre largura e altura; entre extensão do frênulo e as provas de sugar a língua no palato, vibrar, protrair/retrair e tocar comissuras direita e esquerda e lábios superior e inferior e entre a fixação do frênulo no assoalho da boca e as provas de sugar a língua no palato e vibrar. A prova de estalar ápice de língua apresentou associação com estalar o corpo. Estalar a língua (ápice ou corpo) apresentou associação com sugar a língua no palato, vibrar, protrair/retrair, tocar comissuras direita e esquerda e lábios superior e inferior e força. A prova de sugar a língua no palato apresentou associação com vibrar, protrair/retrair, tocar comissuras direita e esquerda e lábios superior e inferior e força de língua e a prova de vibrar a língua, com protrair e retrair e força de língua. Também houve associação entre protrair e retrair e tocar comissuras direita e esquerda e lábios superior e inferior. Conclusão Os aspectos da língua na avaliação clínica apresentaram associações entre si.

ABSTRACT Purpose Investigate the possible association between myofunctional aspects of the tongue clinical evaluation. Methods Observational, cross-sectional study conducted with 80 healthy Brazilian schoolchildren aged 8-12 years: 36 (45%) males and 44 (55%) females. The following aspects of the tongue were assessed: morphology, frenulum, mobility, praxis, and force. Association between the aspects of clinical evaluation was obtained considering a statistical significance level of 5%. Results The following associations were observed: between tongue width and height; between frenulum length and the tasks of sucking the tongue on palate, tongue vibration, tongue protrusion/retraction, and touching right and left commissures and upper and lower lips; between frenulum attachment to the floor of the mouth and the tasks of sucking tongue on palate and tongue vibration. In the snap task, tongue apex snap was associated with tongue body snap. Tongue snap (apex or body) was associated with sucking the tongue on palate, tongue vibration, tongue protrusion/retraction, touching right and left commissures and upper and lower lips, and tongue force. Sucking tongue on palate was associated with tongue vibration, tongue protrusion/retraction, touching right and left commissures and upper and lower lips, and tongue force. Tongue vibration was associated with tongue protrusion/retraction and tongue force. Association was also observed between the tongue protrusion/retraction task and touching right and left commissures and upper and lower lips. Conclusion Association between tongue aspects was verified in the clinical evaluation.

A efetividade de dois tratamentos para disfunção temporomandibular muscular: estudo piloto / The effectiveness of two treatments for muscle temporomandibular dysfunction: pilot study

Objetivo: comparar a eficácia de dois protocolos de tratamento para disfunção temporomandibular (DTM) de origem muscular. Sujeitos e método: Estudantes da Faculdade Especializada na Área de Saúde do Rio Grande do Sul foram selecionados por meio de questionário, para avaliar a presença de sinais e sintomas de DTM e diagnóstico de DTM muscular pelos Critérios de Diagnóstico para Transtornos da Pesquisa Temporomandibular. Dez estudantes compuseram a amostra, divididos em dois grupos, de acordo com o protocolo de tratamento: G1 ­ hipertermia induzida, exercícios mandibulares e massagem; e G2 ­ agulhamento seco, hipertermia induzida, exercícios mandibulares e massagem. Os alunos foram instruídos a realizar o protocolo do tratamento G1 todos os dias em casa e na instituição de ensino por três sessões, que ocorreram a cada cinquenta dias. O agulhamento seco foi realizado no G2 apenas nas segunda e terceira sessões de tratamento. Para avaliar a efetividade dos dois tratamentos antes e após cada sessão, avaliaram-se: abertura bucal (AB), por meio de régua milimetrada; dor, pela escala visual analógica; força de mordida (FM), usando um medidor de força digital; e qualidade de vida, avaliada imediatamente antes do início do tratamento e depois do término do tratamento. Resultados: a dor mostrou diferença estatística significativa no G2 após a segunda sessão (p=0,020) e a terceira sessão (p=0,047). Os demais resultados mostram que não houve diferença estatisticamente significativa entre os grupos (p>0,05). Conclusão: considera-se que neste estudo piloto ambos os tratamentos foram eficazes para DTM muscular, uma vez que todos os pacientes apresentaram melhora dos sintomas. Não houve diferença estatisticamente significativa entre os tratamentos, exceto a dor pós-procedimento, causada pela técnica do agulhamento seco. (AU)

Objective: the present study aims to compare the efficacy of two treatment protocols for temporomandibular dysfunction (TMD) of muscular origin. Subjects and method: students of the Faculdade Especializada na área de Saúde do Rio Grande do Sul, that were selected through the questionnaire to evaluate the presence of TMD signs and symptoms and diagnosis of muscular TMD from the Diagnostic Criteria for Temporomandibular Research Disorders. Ten students composed the sample, divided into two groups according to the treatment protocol: hyperthermia induced by G1, mandibular exercises and massage; G2 ‒ dry needling, induced hyperthermia, mandibular and massage exercises. Students were instructed to complete the G1 treatment protocol every day at home and at the educational institution for three sessions that occurred every fifty days. Dry needling was performed in G2 only in the second and third treatment sessions. To evaluate the effectiveness of the two treatments before and after each session, we evaluated: mouth opening (AB), through a millimeter ruler; visual analogue scale; bite force (FM) using a digital force gauge and quality of life was assessed immediately prior to initiation of treatment and after termination of treatment. Results: pain obtained a statistically significant difference in G2 after the second session (p=0.020) and the third session (p=0.047). The other results show that there was no statistically significant difference between the groups (p>0.05). Conclusion: it is considered that in this pilot study both treatments were effective for muscular TMD, since all the patients presented improvement of the symptoms. There was no statistically significant difference between treatments, except for post- -procedure pain, caused by the dry needling technique. (AU)

Evaluation of integral electromyographic values and median power frequency values in women with myogenous temporomandibular disorder and asymptomatic controls.

BACKGROUND: Surface electromyography (EMG) has been used as a reliable tool for the evaluation of electrical muscle activity. OBJECTIVE: The purpose of this study was to evaluate the EMG indices of the masticatory muscles (masseter, anterior temporalis and suprahyoid) in women with temporomandibular disorder (TMD) and asymptomatic controls in the time domain, by the integrated EMG signal (IEMG) and in the frequency domain, using the median power frequency (MPF). METHODS: An observational, cross-sectional study was conducted involving 30 asymptomatic women as the control (mean age: 25.85 ± 2.57 years) and 74 women with myogenous TMD (mean age: 26.54 ± 2.45 years) diagnosed using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Three EMG readings were taken during maximum voluntary clenching (MVC) of the molars on parafilm for five seconds with a three-minute rest interval between readings. The mixed-model analysis of variance test followed by the Bonferroni correction or the Student-t test was used for the analyses, with the level of significance set to 5% (p < 0.05). RESULTS: IEMG values were significantly higher in the masseter muscles than the anterior temporalis muscles in the control group (p < 0.01). IEMG values were significantly higher in the masseter muscles of the control group than the group with myogenous TMD (p < 0.05). MPF values of the suprahyoid muscles were significantly higher in the myogenous TMD group than the control group. CONCLUSIONS: These significant findings show that women with myogenous TMD have reduction of electrical activity of their masseter muscles and increased firing rate of the motor units of the suprahyoid muscles. These findings may help the treatment of myogenous TMD in women.

Effect of Phototherapy on Masseter and Anterior Temporal Muscles Before Induction of Fatigue: A Randomized, Sham-Controlled, Blind Clinical Trial.

OBJECTIVE: This is a randomized, sham-controlled, blind clinical trial that aimed to evaluate the effect of phototherapy on bite force, mandibular range of motion, sensitivity to palpation, and fatigue in the masseter and anterior temporal muscles of young patients when administered before the induction of fatigue. MATERIALS AND METHODS: Fifty-two healthy volunteers aged 18-23 years were randomly allocated to a laser group and sham group. Both groups were submitted to a clinical evaluation to record mandibular range of motion, bite force, muscle sensitivity to palpation, and muscle fatigue. The laser group was then submitted to phototherapy (780 nm, 25 J/cm2, 50 mW, 20 sec, and 1 J per point) on three points of the masseter and one point of the anterior temporal muscle on each side. The sham group was submitted to the same procedure, but with the device switched off. The volunteers were then instructed to chew two pieces of gum (one on each side) for 6 min, with the pace set by a metronome calibrated to 80 bpm, followed by the reevaluation of all variables. The results were submitted to t-test and Wilcoxon test. A significance level of 5% (p < 0.05) was considered in all analyses. RESULTS: No statistically significant intergroup or intragroup differences were found for the variables analyzed. CONCLUSIONS: With the proposed protocol, phototherapy administered before the induction of fatigue did not lead to any changes in bite force and mandibular range of motion, indicating that further studies are needed with different phototherapy dosimetric parameters.

Evaluation of the Effect of Phototherapy in Patients with Mandibular Fracture on Mandibular Dynamics, Pain, Edema, and Bite Force: A Pilot Study.

OBJECTIVE: The aim of this study was to evaluate the effect of phototherapy on bite force, facial swelling, mandibular movements, and pain in patients having undergone surgical treatment for mandibular fractures. BACKGROUND: These are among the predominant types of facial fractures, and treatment involving surgical fixation with titanium plates is one of the most common procedures in oral-maxillofacial surgery. Phototherapy has been used to accelerate the muscle healing process and significantly improves muscle regeneration by inducing the formation of new muscle fibers. METHODS: The patients were divided into two groups: Group 1-active phototherapy, and Group 2-sham phototherapy. Both groups underwent the surgical procedure by the same surgeon using the same surgical technique. Dosimetric parameters are wavelength, 660 nm; power, 108 mW; radiant energy, 21.6 J; fluency, 21.6 J/cm2; radiance, 38197 mW/cm2; exposure time, 200 sec per point, 10 points bilaterally. Photobiomodulation was performed in 15 sessions. RESULTS: The primary variable was bite force measured with a gnathodynamometer and the secondary variables were facial swelling, mandibular movements (measured with digital calipers), and pain. The Student's t-test was used to determine intergroup differences. CONCLUSIONS: The findings suggest improvements in the laser group in comparison with the sham group with regard to mandibular dynamics, a reduction in postoperative facial swelling, a reduction in pain, and an increase in bite force.

Efficacy of botulinum toxin in treating myofascial pain and occlusal force characteristics of masticatory muscles in bruxism.

AIM AND OBJECTIVE: The present study was conducted in patients with bruxism to evaluate the effect of botulinum toxin type A (BTX-A) (Botox, Allergan, Inc., Irvine, CA, USA) in the treatment of myofascial pain and the occlusal force characteristics of masticatory muscles. MATERIALS AND METHODS: Twenty-four diagnosed with bruxism were randomly divided into three groups (n = 8) and treated by bilateral intramuscular injection of BTX-A and placebo-treated with saline placebo injections and control group where no injections were given. The clinical parameters such as pain at rest and during chewing were assessed and occlusal force analysis system to measure the distribution of occlusal force in bruxism patients. All the three groups were assessed at baseline time and at 1 week, 3 months, and 6 months follow-up appointments. Descriptive analysis showed that improvements in parameters such as pain at rest; pain during chewing clinical outcome variables were higher in the botox treated group than in the placebo-treated subjects. RESULTS: The pain at rest and at chewing decreased in the BTX-A group while remaining constant in the placebo group and control group. There was a significant change in maximum occlusal force in the BTX-A group compared with the other two groups (P < 0.05, post hoc Bonferroni test, no exact P value), and there was no significant difference between the placebo and control groups (post hoc Bonferroni test, no exact P value). CONCLUSION: Results from the present study supported the efficacy of BTX-A to reduce myofascial pain symptoms in bruxers, and effective in reducing the occlusal force.

Evaluation of muscle activity, bite force and salivary cortisol in children with bruxism before and after low level laser applied to acupoints: study protocol for a randomised controlled trial.

BACKGROUND: Bruxism is a repetitive activity that causes tooth wear, audible sounds, and discomfort. Preventive measures have been studied for conditions that can exert a negative influence on physiological development in children. Low-level laser therapy administered over acupoints is an effective, painless, low-cost treatment option that has achieved good results. Thus, the aim of the proposed study is to evaluate changes in muscle activity, bite force and salivary cortisol in children with bruxism after the application of low-level laser to accupoints. METHODS: The children will be randomly allocated to four groups of 19 individuals: G1 - low-level laser; G2 - occlusal splint; G3 - placebo laser; and G4 - control (without bruxism). The BTS TMJOINT electromyography will be used to determine muscle activity and a digital gnathodynamometer will be used to measure bite force. Salivary cortisol will be analysed at baseline as well as one and six months after treatment. Two-way ANOVA will be employed and complemented by Tukey's test. DISCUSSION: Bruxism is a repetitive activity of the masticatory muscles that can have negative consequences if not treated, such as tooth wear, noises, discomfort and anxiety. Thus, control and treatment measures should be taken. Although low-level laser therapy over acupoints has been indicated for children, the effects of this treatment modality have not yet been studied. TRIAL REGISTRATION: NCT02757261 on 8 April 2016. This study protocol received a grant from the Brazilian fostering agency São Paulo Research Foundation (FAPESP: #2015/24731-0).

Fine motor control of the jaw following alteration of orofacial afferent inputs.

OBJECTIVE: The study was designed to investigate if alteration of different orofacial afferent inputs would have different effects on oral fine motor control and to test the hypothesis that reduced afferent inputs will increase the variability of bite force values and jaw muscle activity, and repeated training with splitting of food morsel in conditions with reduced afferent inputs would decrease the variability and lead to optimization of bite force values and jaw muscle activity. MATERIAL METHODS: Forty-five healthy volunteers participated in a single experimental session and were equally divided into incisal, mucosal, and block anesthesia groups. The participants performed six series (with ten trials) of a standardized hold and split task after the intervention with local anesthesia was made in the respective groups. The hold and split forces along with the corresponding jaw muscle activity were recorded and compared to a reference group. RESULTS: The hold force and the electromyographic (EMG) activity of the masseter muscles during the hold phase were significantly higher in the incisal and block anesthesia group, as compared to the reference group (P < 0.001). However, there was no significant effect of groups on the split force (P = 0.975) but a significant decrease in the EMG activity of right masseter in mucosal anesthesia group as compared to the reference group (P = 0.006). The results also revealed that there was no significant effect of local anesthesia on the variability of the hold and split force (P < 0.677). However, there was a significant decrease in the variability of EMG activity of the jaw closing muscles in the block anesthesia group as compared to the reference group (P < 0.041), during the hold phase and a significant increase in the variability of EMG activity of right masseter in the mucosal anesthesia group (P = 0.021) along with a significant increase in the EMG activity of anterior temporalis muscle in the incisal anesthesia group, compared to the reference group (P = 0.018), during the split phase. CONCLUSIONS: The results of the present study indicated that altering different orofacial afferent inputs may have different effects on some aspects of oral fine motor control. Further, inhibition of afferent inputs from the orofacial or periodontal mechanoreceptors did not increase the variability of bite force values and jaw muscle activity; indicating that the relative precision of the oral fine motor task was not compromised inspite of the anesthesia. The results also suggest the propensity of optimization of bite force values and jaw muscle activity due to repeated splitting of the food morsels, inspite of alteration of sensory inputs. CLINICAL RELEVANCE: Skill acquisition following a change in oral sensory environment is crucial for understanding how humans learn and re-learn oral motor behaviors and the kind of adaptation that takes place after successful oral rehabilitation procedures.

Periodontal tactile input activates the prefrontal cortex.

The prefrontal cortex (PFC) plays a role in complex cognitive behavioural planning, decision-making, and social behaviours. However, the effects of sensory integration during motor tasks on PFC activation have not been studied to date. Therefore, we investigated the effect of peripheral sensory information and external information on PFC activation using functional near-infrared spectroscopy (fNIRS). Cerebral blood flow (CBF) was increased around bilateral Brodmann areas 46 and 10 during visual and auditory information integration during an occlusal force (biting) task. After local anesthesia, CBF values were significantly decreased, but occlusal force was similar. In conclusion, the effects of peripheral sensory information from the periodontal ligament and external information have minimal impacts on occlusal force maintenance but are important for PFC activation.

Accelerated Fatigue Resistance of Thick CAD/CAM Composite Resin Overlays Bonded with Light- and Dual-polymerizing Luting Resins.

PURPOSE: To evaluate the accelerated fatigue resistance of thick CAD/CAM composite resin overlays luted with three different bonding methods. MATERIALS AND METHODS: Forty-five sound human second mandibular molars were organized and distributed into three experimental groups. All teeth were restored with a 5-mm-thick CAD/CAM composite resin overlay. Group A: immediate dentin sealing (IDS) with Optibond FL and luted with light-polymerizing composite (Herculite XRV). Group B: IDS with Optibond FL and luted with dual-polymerizing composite (Nexus 3). Group C: direct luting with Optibond FL and dual-polymerizing composite (Nexus 3). Masticatory forces at a frequency of 5 Hz were simulated using closed-loop servo-hydraulics and forces starting with a load of 200 N for 5000 cycles, followed by steps of 400, 600, 800, 1000, 1200 and 1400 N for a maximum of 30,000 cycles. Each step was applied through a flat steel cylinder at a 45-degree angle under submerged conditions. RESULTS: The fatigue test generated one failure in group A, three failures in group B, and no failures in group C. The survival table analysis for the fatigue test did not demonstrate any significant difference between the groups (p = 0.154). The specimens that survived the fatigue test were set up for the load-to-failure test with a limit of 4600 N. The survival table analysis for the load-to-failure test demonstrates an average failure load of 3495.20 N with survival of four specimens in group A, an average failure load of 4103.60 N with survival of six specimens in group B, and an average failure load of 4075.33 N with survival of nine specimens in group C. Pairwise comparisons revealed no significant differences (p < 0.016 after Bonferroni correction). CONCLUSION: Within the limitations of this in vitro study, it can be concluded that although the dual-polymerizing luting material seems to provide better results under extreme conditions, light-polymerizing luting composites in combination with IDS are not contraindicated with thick restorations.

Novel stress increases hypothalamic-pituitary-adrenal activity in mice with a raised bite.

BACKGROUND AND OBJECTIVE: In humans, occlusal disharmony may cause various physical complaints, including head and neck ache, stiffness in the shoulder and neck, and arthrosis of the temporomandibular joints. Occlusal disharmony induced by raising the bite in rodents, increases plasma corticosterone levels, which leads to morphologic changes in the hippocampus and altered hippocampus-related behavior. The paraventricular nucleus (PVN) of the hypothalamus regulates the hypothalamic-pituitary-adrenal system. Chronically stressed animals exposed to a novel stress exhibit higher adrenocorticotropic hormone levels than naive control animals. We hypothesized that there would be different response of the corticotrophin releasing hormone (CRH) and arginine vasopressin (AVP) to a novel acute stress with occlusal disharmony. DESIGN: In order to investigate how exposure of mice with occlusal disharmony to a novel acute stress (restraint stress) affects the PVN, we induced occlusal disharmony by raising the vertical dimension of the bite (bite-raised condition) and examined the expression of corticotrophin releasing hormone (CRH) mRNA and arginine vasopressin (AVP) mRNA in mouse PVN. RESULTS: CRH mRNA expression was increased in the PVN of the bite-raised group 90min after the bite-raising procedure, but the expression was recovered to the control level at 14days. AVP mRNA expression in the PVN was normal at 90min, and increased significantly 14days after the bite-raising procedure. Exposure to restraint stress in the bite-raised mice induced a significant increase in CRH mRNA expression in the PVN. CONCLUSIONS: The bite-raising procedure induced a rapid CRH mRNA response and a slower AVP mRNA response in the parvocellular PVN of the hypothalamus. Exposure to a novel stress following the bite-raising procedure further reinforced the CRH stress response. Thus, occlusal disharmony, such as that induced by raising the bite, may be a risk factor for hypersensitivity to a novel stress.

Fracture Strength of Endodontically Treated Teeth Restored with Composite Overlays with and without Glass-fiber Reinforcement.

PURPOSE: To evaluate the fracture strength and the failure mode of endodontically treated teeth restored with composite resin overlays with and without glass-fiber reinforcement. MATERIALS AND METHODS: A total of 32 extracted molars were divided into four equal groups. In the NFR-NFRC (no foundation restoration, no fiber-reinforced composite) and NFR-FRC (no foundation restoration, fiber-reinforced composite) groups, only a 5-mm-thick composite resin layer sealed the pulp chamber floors, whereas in the FR-NFRC (foundation restoration, no fiber-reinforced composite) and FR-FRC (foundation restoration, fiber-reinforced composite) groups, a 3.0-mm foundation restoration was used. NFR-NFRC and FR-NFRC groups were restored with composite resin overlays, whereas NFR-FRC and FR-FRC groups were restored with fiber-reinforced composite resin overlays. All specimens were subjected to mechanical loading in a computer-controlled masticator and then the fracture resistance was evaluated. Differences in means were compared using two-way ANOVA and Tukey's test. The level of significance was set at ɑ = 0.05. RESULTS: All specimens successfully completed the fatigue test. The least fracture-resistant group was NFR-FRC, exceeded by FR-NFRC, NFR-NFRC, and FR-FRC, in that order, with FR-FRC being the most fracture-resistant group. Statistically significant differences were detected between the pairs NFR-NFRC/FR-FRC (p = 0.001), NFR-FRC/FR-FRC (p = 0.001), and FR-NFRC/FR-FRC (p = 0.001). Eight vertical root fractures occurred in group FR-NFRC, six in group NFR-NFRC, four in group NFR-FRC, and none occurred in group FR-FRC. CONCLUSIONS: Within the limitations of this in vitro study, the incorporation of glass fibers and the presence of a foundation restoration were found to increase the fracture resistance and can favorably influence the fracture mode.

Evaluation of low-level laser therapy in the treatment of masticatory muscles spasticity in children with cerebral palsy.

Spasticity is a motor disorder frequently present in individuals with cerebral palsy (CP). This study aimed to evaluate the effect of low-level laser therapy (LLLT) on the spasticity of the masseter and anterior temporal muscle fibers in children with CP over three weeks of intermittent laser exposures. The bite force (BF) of the masticatory muscles and the amplitude of mouth opening were evaluated before and after laser irradiation in 30 children with CP. Both sides of the masseter and temporalis muscles were irradiated with low-intensity diode laser pulses of 808-nm wavelength six times over three consecutive weeks. During the subsequent three weeks of postlaser exposures, although no laser treatment was applied, the evaluation parameters were measured and recorded. A significant improvement in the amplitude of mouth opening and a decrease in the BF were observed in the weeks following LLLT (P<0.05 ). However, by the sixth week post-LLLT, the BF and the amplitude of mouth opening reverted to values equivalent to those obtained before the first application of LLLT. Our investigation revealed low-level energy exposures from a 808-nm diode laser to be an effective short-term therapeutic tool. This method increased the amplitude of mouth opening and decreased the muscle tonus of children with spastic CP over a time course of three weeks of intermittent laser applications.

Impact on Dietary Intake of Removable Partial Dentures Replacing a Small Number of Teeth.

The aim of this study was to clarify the impact of wearing removable partial dentures (RPDs) replacing a small number of teeth on dietary intake. Participants had at least 20 teeth and were classified as Eichner B1 or B2. The participants underwent dental and oral examinations, and their dietary intake was assessed. Analysis of covariance showed that RPD wearers consumed more vegetables, n-3 fatty acids, calcium, vitamin A, and dietary fiber than nonwearers after adjusting for possible confounding factors. It is concluded that RPDs are effective for improving dietary intake even in participants who have lost a small number of teeth.

Feeding biomechanics of the cownose ray, Rhinoptera bonasus, over ontogeny.

Growth affects the performance of structure, so the pattern of growth must influence the role of a structure and an organism. Because animal performance is linked to morphological specialization, ontogenetic change in size may influence an organism's biological role. High bite force generation is presumably selected for in durophagous taxa. Therefore, these animals provide an excellent study system for investigating biomechanical consequences of growth on performance. An ontogenetic series of 27 cownose rays (Rhinoptera bonasus) were dissected in order to develop a biomechanical model of the feeding mechanism, which was then compared with bite forces measured from live rays. Mechanical advantage of the feeding apparatus was generally conserved throughout ontogeny, while an increase in the mass and cross-sectional area of the jaw adductors resulted in allometric gains in bite force generation. Of primary importance to forceful biting in this taxon is the use of a fibrocartilaginous tendon associated with the insertion of the primary jaw adductor division. This tendon may serve to redirect muscle forces anteriorly, transmitting them within the plane of biting. Measured bite forces obtained through electrostimulation of the jaw adductors in live rays were higher than predicted, possibly due to differences in specific tension of actual batoid muscle and that used in the model. Mass-specific bite forces in these rays are the highest recorded for elasmobranchs. Cownose rays exemplify a species that, through allometric growth of bite performance and morphological novelties, have expanded their ecological performance over ontogeny.

Dental arch size, biting force, bizygomatic width and face height in three Colombian ethnic groups / Tamaño del arco dental, fuerza de mordida, anchura bizigomatica y altura facial en tres grupos étnicos colombianos

The objective of this study was to describe transversal dimensions of the dental arches, bite force and facial index in three ethnic groups representative of Colombia. The sample size included 197 adolescents, 12 to 14 year old, 33% mestizo, 35% of African ancestry and 32% Amazon Indian; 50.3% male and 49.7% female. The comparative analysis to determine differences between ethnic groups was made by the Kruskal Wallis test and then the Principal Component Analysis was used to establish the pattern of measurements identifying ethnic characteristics. All measurements showed statistically significant differences among ethnic groups except facial height (p=0.157). It was evidenced that Amazon indian have a higher bite force (p <0.05) than the other twoethnic groups. Regarding dental arch transversal dimensions, Amazon Indian have a higher arch transversal width with a length average of 44.1 mm. This length was greater than mestizo adolescents (M=36.7 mm) and Afroamerican (M=38.3 mm). In conclusion, the amazon Ticuna Indian ethnia has a significantly higher bite force, higher dental arch transversal width and higher bizygomatic width than the other two ethnic groups considered.

El objetivo fue describir las dimensiones transversales de los arcos dentales, la fuerza de mordida y el índice facial en tres grupos étnicos de Colombia. El tamaño de la muestra fue de 197 adolescentes, de 12 a 14 años; 33% mestizos, 35% de ascendencia africana y 32% indio amazónico; 50,3% hombres y 49,7% mujeres. El análisis comparativo para determinar las diferencias entre los grupos étnicos se hizo mediante la prueba de Kruskal Wallis y luego el Componente Principal de Análisis se utilizó para establecer el patrón de las mediciones para identificar las características étnicas. Todas las mediciones mostraron diferencias estadísticamente significativas entre los grupos étnicos, excepto la altura facial (p=0,157). Se evidencia que el indio amazónico tiene una mayor fuerza de mordida (p<0,05) que los otros dos grupos étnicos. En cuanto a las dimensiones transversales del arco dental, el indio amazónico se caracterizó por tener un mayor ancho, con una longitud media de 44,1 mm. Esta longitud es mayor que en los adolescentes mestizos (M=36,7 mm) y afroamericanos (M=38,3 mm). En conclusión, la etnia india amazónica Ticuna tiene una fuerza de mordida significativamente mayor, así como mayor ancho del arco dental transversal y ancho bicigomático que los otros dos grupos étnicos considerados.