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OBJECTIVE@#To investigate the influence of chronic masseter hyperalgesia induced by 17β-estradiol (E2) and experimental occlusal interference (EOI) on underlying mechanism in hippocampus of ovariectomized (OVX) rats.@*METHODS@#In the study, 32 OVX rats were randomly divided into 4 groups (8 rats/group): The control group was OVX group, and 0 μg/d E2 (vehicle) injection was started 7 d after OVX without EOI; in the experimental group (1) OVX + E2 group, 80 μg/d E2 injection was started 7 d after OVX without EOI; in the experimental group (2) OVX + EOI group, vehicle injection was started 7 d after OVX and EOI was applied 17 d after OVX; in the experimental group (3) OVX + E2 + EOI group, 80 μg/d E2 injection was started 7 d after OVX and EOI was applied 17 d after OVX. Bilateral masseter muscle mechanical withdrawal thresholds were measured before OVX, 7 days after OVX (before E2 injection), 17 days after OVX (10 days after E2 injection and before EOI) and 24 days after OVX (7 days after EOI). Immunofluorescence staining was used to reveal phospho-extracellular signal regulated kinase 1/2 (p-ERK1/2)-positive neurons in CA3 of hippocampus. The protein expression of p-ERK1/2 in hippocampus was detected using Western Blot.@*RESULTS@#Compared with the control group [left side: (135.3±8.5) g, right side: (135.4±10.8) g], bilateral masseter muscle mechanical withdrawal thresholds of OVX+E2 group [left side: (113.3±5.6) g, right side: (112.5 ± 5.6) g] and OVX+EOI group [left side: (93.3±5.4) g, right side: 90.8±5.5) g] were decreased (P < 0.01). Bilateral masseter muscle mechanical withdrawal thresholds were significantly lower in OVX+E2+EOI group [left side: (81.2±6.2) g, right side: 79.8±7.7) g] than in the control, OVX+E2 and OVX+EOI groups (P < 0.05). The proportion of p-ERK1/2 positive neurons in the CA3 region of the hippocampus was increased in the control, OVX+E2, OVX+EOI and OVX+E2+EOI groups in turn, and the difference between the groups was statistically significant (P < 0.05). p-ERK1/2 protein expression was increased in the control, OVX+E2 and OVX+EOI groups in turn, but the difference was not statistically significant (P>0.05). p-ERK1/2 expression was significantly higher in OVX+E2+EOI group than in the other three groups (P < 0.05).@*CONCLUSION@#High concentration of E2 could exacerbated EOI-induced chronic masseter hyperalgesia in ovariectomized rats, and its central mechanism may be related to the upregulation of the phosphorylation of ERK1/2 in hippocampus.
Subject(s)
Animals , Female , Humans , Rats , Estradiol , Hippocampus , Hyperalgesia/chemically induced , Masseter Muscle , Ovariectomy , Rats, Sprague-DawleyABSTRACT
RESUMEN Introducción: Es muy importante reconocer los factores que pueden estar relacionados con maloclusión en una determinada población, para realizar medidas preventivas basadas en su realidad. Objetivo: determinar factores relacionados con maloclusiones en niños ecuatorianos de 3 a 9 años de edad. Métodos: Estudio epidemiológico transversal realizado a 400 niños de 3 a 9 años de edad, que estaban en tratamiento en las clínicas de Odontopediatría de la Facultad de Odontología de la Universidad Central del Ecuador. Los padres de los niños respondieron a preguntas realizadas por un único investigador experimentado sobre la salud, hábitos y nivel socioeconómico. Cada niño fue evaluado clínicamente extra e intraoralmente, siendo cada cara de las piezas dentales observadas en sentido vertical, transversal y sagital, además de la cara oclusal. Se verificó sí existían interferencias oclusales, mordida cruzada posterior o anterior y mordida abierta. Los datos se tabularon en Excel y se aplicó la prueba chi cuadrado (p< 0,05). Resultados: El 77 % de niños presentó maloclusión (p< 0,001). No se encontró una relación significativa de la presencia de maloclusión en los niños con sus familiares que presentaban maloclusión, bajo nivel socioeconómico y lactancia por menos de 1 año (p> 0,05). La mordida cruzada y las interferencias oclusales estuvieron asociadas (p< 0,001). No se encontró asociación entre la mordida abierta y la respiración bucal (p= 0,944). Conclusiones: Existe una cantidad significativa de maloclusión. La herencia familiar, tipo y tiempo de lactancia y nivel socioeconómico no tienen una relación significativa con la maloclusión. La mordida cruzada y las interferencias oclusales están asociadas. La respiración bucal puede no causar mordida abierta en los niños de 3 a 9 años.
ABSTRACT Introduction: Recognizing the factors potentially related to malocclusion in a given population is crucial to implement preventive actions based on that information. Objective: Determine the factors related to malocclusion in 3-9-year-old Ecuadorian children. Methods: A cross-sectional epidemiological study was conducted of 400 children aged 3-9 years attending pediatric dental clinics at the Central University of Ecuador School of Dentistry. The children's parents answered a number of questions about health, habits and socioeconomic level at the request of a single experienced researcher. Each child underwent extra- and intraoral clinical examination in which the sides of each tooth were observed on a vertical, transversal and sagittal plane, as well as the occlusal side. Verification was made of the presence of occlusal interference, posterior or anterior crossbite and open bite. The data obtained were tabulated onto Excel spreadsheets and the chi-square test was applied (p< 0.05). Results: Of the total children studied 77% had malocclusion (p< 0.001). The presence of malocclusion in children was not found to have a significant relationship to relatives with malocclusion, low socioeconomic level or breastfeeding for less than 1 year (p> 0.05). An association was found between crossbite and occlusal interference (p< 0.001). No association was observed between open bite and mouth breathing (p= 0.944). Conclusions: Malocclusion is significantly prevalent. Family inheritance, breastfeeding type and duration, and socioeconomic level do not have a significant relationship to malocclusion. Crossbite and occlusal interference are associated. Mouth breathing may not be the reason for open bite in 3-9-year-old children.
Subject(s)
Humans , Child, Preschool , Child , Malocclusion/prevention & control , Epidemiologic Studies , Cross-Sectional StudiesABSTRACT
OBJECTIVE@#To observe the effect of occlusal interference on the afferent pathway of the trigeminal nerve and neuronal excitability in the trigeminal subnucleus caudalis (SPVC) of rats by electrical stimulation of the trigeminal ganglion (TG) and extracellular recordings of SPVC activities.@*METHODS@#Twenty male Wistar rats were randomly divided into control group and model group (=10). In the model group, occlusal interference for 30 consecutive days was induced using light-cured flowable resin on the right maxillary molars. During occlusal interference, the pain sensitivity was scored with von Frey Fibers in the masseter. Simultaneous recordings of electrical activities from the SPVC, electrocardiogram, body temperature and electromyogram of the breath muscles of the anesthetized rats were performed, and the responses evoked by electrical stimulation of the TG were analyzed.@*RESULTS@#Compared with the control rats, the rats in the model group showed significantly increased pain sensitivity scores ( 0.05). Train stimulation (0.2 ms, 1 mA, 30 s, 100 Hz) of the TG significantly increased the discharge frequency of the SPVC only in the rats in the model group ( < 0.05).@*CONCLUSIONS@#The functional activities of the pain afferent pathway of the trigeminal nerve can be electrophysiologically monitored by electrical stimulation of the TG and extracellular recordings of SPVC activities in rats. Occlusal interference can increase the excitability of the neurons in the SPVC and enhance their sensitivities to TG afferent activation, suggesting the neural plasticity of the pain afferent pathway.
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The occlusal interference model in rats was established. In the masseter the level of MDA was increased, but both SOD and GPX were decreased in the presence of the occlusal interference, while the expression of UCP3 was higher than that in the control group (P ＜ 0. 05) .The findings indicate that the occlusal interference can induce the oxidative damage of masseter in rats, which has a correlation with UCP3.
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Objective@#To investigate the morphological changes in microglia and astroglia before and after the removal of occlusal interferences in rats and to further understand whether astroglia and microglia activation is involved in experimental occlusal interference-induced masticatory muscle pain.@*Methods@#Male Sprague-Dawley rats (200-220 g) were used. Crowns of two heights (0.2 mm and 0.4 mm) were bonded to the right maxillary first molars to establish experimental rat models of occlusal interference. The rats were randomly assigned to one of five groups of twelve rats each: sham-occlusal interference control group, 0.4 mm occlusal interference group, 6-day removal of 0.4 mm occlusal interference group, 0.2 mm occlusal interference group, and 6-day removal of 0.2 mm occlusal interference group. The rats were sacrificed by transcardiac perfusion after deep anesthetization on days 3, 5, 7, and 14. Brain stem sections were obtained and processed for immunofluorescence staining of GFAP and OX-42. Expression levels were semiquantitatively analyzed.@*Results@#① Based on the markers OX-42 and GFAP, trigeminal-spinal nucleus (Vsp) microglia and astroglia showed no activation in the sham-occlusal interference control group. ② In the 0.4 mm and 0.2 mm occlusal interference groups, Vsp microglia and astroglia showed mild to moderate activation after 3-7 days of occlusal interference. Vsp astroglia remained activated on day 14, but Vsp microglia did not. At the same time point, the 0.4 mm occlusal interference group had greater activation than the 0.2 mm occlusal interference group. ③ In the 6-day removal of 0.4 mm and 0.2 mm occlusal interference groups, microglia and astroglia activation decreased after removal of the occlusal interference. Vsp astroglia remained activated on day 14, but microglia showed no activation.@*Conclusion@#Microglia and astrocyte activation is induced in the Vsp after experimental occlusal interference. The astrocytes remained activated for longer than the microglia. The glia activation level is closely related to the intensity of occlusal interference.
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Objective@#To investigate the morphological changes in microglia and astroglia before and after the removal of occlusal interferences in rats and to further understand whether astroglia and microglia activation is involved in experimental occlusal interference-induced masticatory muscle pain.@*Methods@#Male Sprague-Dawley rats (200-220 g) were used. Crowns of two heights (0.2 mm and 0.4 mm) were bonded to the right maxillary first molars to establish experimental rat models of occlusal interference. The rats were randomly assigned to one of five groups of twelve rats each: sham-occlusal interference control group, 0.4 mm occlusal interference group, 6-day removal of 0.4 mm occlusal interference group, 0.2 mm occlusal interference group, and 6-day removal of 0.2 mm occlusal interference group. The rats were sacrificed by transcardiac perfusion after deep anesthetization on days 3, 5, 7, and 14. Brain stem sections were obtained and processed for immunofluorescence staining of GFAP and OX-42. Expression levels were semiquantitatively analyzed.@*Results@#① Based on the markers OX-42 and GFAP, trigeminal-spinal nucleus (Vsp) microglia and astroglia showed no activation in the sham-occlusal interference control group. ② In the 0.4 mm and 0.2 mm occlusal interference groups, Vsp microglia and astroglia showed mild to moderate activation after 3-7 days of occlusal interference. Vsp astroglia remained activated on day 14, but Vsp microglia did not. At the same time point, the 0.4 mm occlusal interference group had greater activation than the 0.2 mm occlusal interference group. ③ In the 6-day removal of 0.4 mm and 0.2 mm occlusal interference groups, microglia and astroglia activation decreased after removal of the occlusal interference. Vsp astroglia remained activated on day 14, but microglia showed no activation.@*Conclusion@#Microglia and astrocyte activation is induced in the Vsp after experimental occlusal interference. The astrocytes remained activated for longer than the microglia. The glia activation level is closely related to the intensity of occlusal interference.
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Considerada como una articulación glinglimoartrorial, la Articulación Témporo-mandibular (ATM) realiza todos los movimientos en el espacio, sin presentar ningún signo o síntoma en condiciones normales, sin embargo en presencia de anomalías manifiesta ruidos, partiendo de este enfoque nos centramos a analizar si estos ruidos articulares se encuentran relacionados con la oclusión dental, específicamente con la presencia de interferencias oclusales en el lado de no trabajo, en adultos de ambos sexos de entre 20 - 40 años de edad totalmente dentados. De esta forma 31 participantes que presentaron ruidos articulares en los diferentes movimientos mandibulares, fueron evaluados en cuanto a la clase de Angle, guías laterales, presencia de guía canina normal y presencia o ausencia de función de grupo. Analizando clínicamente la presencia de interferencias en el lado de no trabajo y comprobando estas interferencias en articulador semiajustable (ASA) tipo Bioart. Los datos obtenidos fueron analizados en el programa SPSS versión XX, revelando una relación entre los ruidos articulares y la presencia de interferencias oclusales en el lado de no trabajo, sin embargo, evidenciando cierta relación entre la presencia de interferencias oclusales con género, presente con mayor prevalencia en el género masculino que en femenino.
Considered as a glinglymoarthrodial articulation, the temporomandibular joint) (TMJ) is both a hinging and a sliding joint. In a healthy condition the joint doesn't show any particular sign or symptom, however if there is a dysfunction it will present noises during jaw movement. Starting from this principle, we analyzed if the TMJ dysfunction sounds are connected to dental malocclusion, focusing on occlusal interferences in the non-working side, in patients between 20 and 40 years of age. Thirty-one patients presented articular noises during jaw movement, so we proceeded to evaluate Angle class (molar relationship), lateral guidance, normal canine guidance and the presence or absence of group function. Clinically, we analyzed the presence of interferences in the non-working side and we studied them using a Semi-adjustable Articulator (ASA) (Bioart). The data, evaluated using the program SPSS Version XX, revealed a clear relation between articular noises and interferences in the non-working side, however the population of men showed a higher rate of occlusal interferences than that of women.
Subject(s)
Humans , Male , Adult , Female , Temporomandibular Joint/anatomy & histology , Dental Articulators , Mandibular Condyle , Skull Base/anatomy & histology , Dentistry , MalocclusionABSTRACT
The talon cusp or dens evaginatus of anterior teeth is a relatively rare dental developmental anomaly characterized by the presence of an accessory cusp like structure projecting from the cingulum area or cementoenamel junction. It commonly occurs in either maxilla or mandibular anterior teeth in both the primary and permanent dentition .This article reports three cases of talon cusp and its management.
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Introducción. El reflejo inhibitorio masetérico (RIM) se evoca mediante estimulación de diversos sitios intra o extrabucales y durante contracción voluntaria de los músculos elevadores de la mandíbula; el principal fenómeno observado es un período de silencio u onda inhibitoria en el electromiograma de los músculos mencionados, cuya función es proteger las estructuras bucales y controlar la fuerza de mordida, seguida por una onda potenciadora que, en sujetos adultos sanos, siempre es menor que la inhibitoria. Objetivo: identificar los cambios del RIM que se asocian con las etapas de dentición (primaria, mixta o permanente) y con las interferencias oclusales. Material y métodos. Se estudió el RIM en 28 niños, 17 con oclusión normal y 11 con interferencias oclusales, en las 3 etapas de dentición. El RIM se registró con técnicas electromiográficas, aplicando estímulo sobre el mentón para evocar el reflejo; se realizaron 20 réplicas que fueron promediadas obteniendo el reflexigrama en el que se midió latencia, duración y amplitud de las ondas inhibitorias y potenciadoras derechas e izquierdas. Resultados. Mediante análisis de conglomerados, se identificó la interacción del RIM con la dentición y las interferencias oclusales y se encontró diferencia estadística significativa respecto de las últimas (P =0.05). Conclusiones. Hubo influencia de las interferencias oclusales sobre el RIM, modificando su efecto fisiológico protector, situación no observada respecto de la dentición.
Introduction. The inhibitory masseteric reflex (IMR) evoked by means of stimulation of diverse intra or extra oral sites and during voluntary contraction of elevators muscles of the jaw; the main observed phenomenon is a period of silence or inhibitory wave in electromyogram of the mentioned muscles, whose function is to protect the oral structures and to control the bite force, followed by a potentiation wave that, in healthy adult subjects, is always minor that the inhibitory one. Material and methods. Twenty eight children were studied with temporary, mixed and permanent dentition, 17 without dental malocclusion and 11 with occlusal interferences. The IMR was registered by electromyography techniques, applying stimulus on the chin. Twenty stimuli were applied and averaged to obtain a reflexigram in which was measured: latency, duration and amplitude of the inhibitory wave and potentiation wave on both sides. Results. Clusters analysis identified interaction between IMR with dentition and occlusal interferences with statistically significative differences regarding occlusal interferences (P =0.05). Conclusions. It was observed influence of oclusal interferences on IMR, modifying its physiological protector effect, it was not observed regarding the dentition stages.
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Objective:To investigate the oral-maxillofacial pain and t he surface electromyographic (EMG) activity of masseter muscles and anterior and posterior portions of temporalis muscles after experimental interference. Methods:A cast onlay of 0.5 mm in height was placed on the right low er first molar and remained for three days in 10 adult volunteers with normal oc clusion and without any symptom of TMD. The oral-maxillofacial pain was continu ously scored on a visual analogue scale(VAS)by the subjects before and after t he placement of the onlay. At the same time, the integral data of surface EMG we re recorded, and then the asymmetry index of the activity of bilateral muscles w as calculated. Results:Three days after the placement of the occ lusal highspot, all the subjects complained oral-maxillofacial pain. 8 of them had headache in right temporal region with VAS value of 1~4; the activity of tem poralis anterior at rest position of mandible was increased significantly (P
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The occlusal interference during adolescent period makes some effects on growth and development and morphological changes. And so, if we could predict the timing and results of orthodontic treatment who have occlusal interference during adolescent period, it may be helpful for diagnosis and treatment planning of orthodontic treatment. For about those, the purpose of this study was to evaluate the effects of the posterolateral displacement by the metal casting crown with inclined pathway on the mandibular condyle and morphologic changes of mandible in the rat. The experimental animals were thirty six Sprague-Dawley male rats of 8 weeks old. Eight of them was used as control group, and experimental group I (continuous appliance wearing group) was composed of sixteen and experimental group 2 (appliance removal group after worn the appliances during 3 months ) was composed of remaining twelve. The animals of experimental group 1 were sacrificed after 1, 2, 3, 6 months from beginning of the experiment and experimental group 2 were sacrificed 1, 2, 3 months after removal of the appliance from worn the appliance during 3 months. Both of mandible and temporomandibular joint were observed histologically and radiologically. The results were as follows: 1. In experimental group 1, the mandibular length and lower posterior height were decreased with experimental period, while the lower anterior height was increased, and the curvature of lower incisors and lingual inclination of anterior alveolar bone were profound as compared with control group. 2. In experimental group 1, both of the thickness of the condylar cartilage were thinned in the posterosuperior region, and this phenomenon was more prominent on right than left in 3-Mo experimental period and both sides were marked thinned in 6-Mo experimental period. 3. In experimental group 2, the lower anterior height was low and lower posterior height was high as compared with experimental group 1, and the curvature of lower incisors and lingual inclination of anterior alveolar bone were recovered to control group. 4. In experimental group 2, both of the thickness of the condylar cartilage were thickened in the posterosuperior region, and this phenomenon was more prominent with experimental period. 5. In experimental group 2, the mandibular length was short, lower anterior height was hight, the curvature of lower incisors were profound, and in histologically, both of the thickness of the condylar cartilage were thickened in the posterosuperior region as compared with control group. As shown above, the occlusal interfernce affected the condylar cartilage, curvature of lower incisor, inclination of anterior alveolar bone, mandibular length, and anterior and posterior height. When the interference was removed, significant recover was found in condylar cartilage, mandibular length, and posterior height. Although no significance was found, other items of measurement showed trends for recovery.