Effect of rapid maxillary expansion on masticatory and swallowing functions in children with posterior crossbite

Abstract Objective: Investigate the influence of posterior crossbite on masticatory and swallowing functions by videofluoroscopy examination and to analyze the effects of Rapid Maxillary Expansion (RME) on the same functions. Methods: A prospective longitudinal study was conducted on 32 children, 21 of them with posterior crossbite (10 girls and 11 boys, mean age 9.2 years, study group) and 11 children with no occlusal changes (6 girls and 5 boys, mean age 9.3 years, control group). The children were evaluated by an orthodontist for diagnosis, group characterization and occlusal treatment, by the otorhinolaryngology team for the assessment of respiratory symptoms, and by a speech therapist for videofluoroscopic evaluation of masticatory and swallowing parameters. The children with posterior crossbite were treated orthodontic ally using the Haas disjunctor for approximately six months and re-evaluated 5-months after removal of the appliance. Data were analyzed statistically by the Studentt-test for independent samples for comparison of the crossbite and control groups before and after treatment. Results: There was no significant difference in oral preparatory and oral transit times, nor in cycles and masticatory frequency, between the pre and post orthodontic treatment groups and the control group. Conclusion: Rapid maxillary expansion did not influence the masticatory and swallowing variables studied by videofluoroscopy. However, the data require caution in interpretation.

Características anatómicas-funcionales que orientan la posición del cóndilo en la fosa mandibular en una relación céntrica: una descripción narrativa / Anatomical functional characteristics that guide the condylar position in mandibular fossa a centric relation: narrative description

RESUMEN: La Relación Céntrica (RC) es un concepto que busca definir la posición ideal del cóndilo de la mandíbula en la fosa mandibular, siendo esta posición muy discutida en la literatura y ha ido cambiado con los avances en conocimiento y tecnología. Tomándose en la actualidad en consideración elementos anatómicos esenciales que son utilizados como guía para el clínico. La importancia de poder reconocer esta posición radica en la correcta ejecución tanto de procedimientos diagnósticos como de tratamiento en diversas áreas de la odontología. Existen elementos anatómicos de la articulación temporomandibular (ATM) que nos ayudarían a comprender mejor el concepto de RC, entre estos destacan que la condensación ósea de las superficies articulares funcionales y su recubrimiento por fibrocartílago; la porción media del disco articular, desprovista de vasos y nervios; el techo de la fosa mandibular que puede llegar a ser extremadamente delgado por lo cual no se consideraría un área para soportar carga; la prolongación posterior del disco articular (DA) que es altamente vascularizada e inervada. El DA se encuentra íntimamente relacionado con estructuras como el ligamento temporomandibular o lateral y la cabeza superior del músculo pterigoideo lateral que permitirían junto a los elementos anteriormente mencionados el adecuado funcionamiento de la ATM. El correcto aprendizaje y utilización de estos conceptos contribuirá a lograr un mejor ejercicio del desarrollo profesional de estudiantes y profesionales del área de la odontología.

SUMMARY: The Central Relation (CR) is a concept that defines the ideal position of the mandibular condyle in the mandibular fossa. The position has been the subject of much discussion in the literature, noting changes as advancements in knowledge and technology are achieved. Thus, certain essential anatomical elements that are used as a guide for the clinician, are taken into account. The importance of being able to identify this position lies in the correct execution of both diagnostic and treatment procedures in various areas of dentistry. There are anatomical elements of the temporomandibular joint (TMJ) that improve understanding of the CR concept. These include: Bone condensation of the functional articular surfaces and their fibrocartilage coating; the middle portion of the joint disc, devoid of vessels and nerves. The roof of the mandibular fossa can become extremely thin, so it would not be considered an area to support load; the posterior prolongation of the articular disc (AD) Which is highly vascularized and innervated. The AD is also closely related to structures such as the temporomandibular or lateral ligament and the superior head of the lateral pterygoid muscle. Along with the previously described elements, this would allow proper functioning of the TMJ. The correct learning and use of these concepts contributes to a better exercise in the professional development of students and professionals in the area of dentistry.

Proposal of surface electromyography signal acquisition protocols for masseter and temporalis muscles

Abstract Introduction The aim of this study was to propose a method of electrodes positioning on the superficial masseter and anterior temporalis muscles for surface electromyographic (sEMG) recordings in order to overcome some known methodological constraints. Methods Fifteen volunteers with normal occlusion participated in two experimental sessions within a 7 day-period. Surface electrodes were placed on two different locations that were based on palpable and individual anatomical references. Surface EMG signals (2000 Hz per channel; A/D: 16 bits; gain: 2000 X; band-pass filter: 20-500 Hz) were recorded under three conditions: mandibular rest position, 30% and 100% of maximum voluntary bite force. Three measurements of maximal bite force were taken by using a force transducer positioned over the lower right first molar region and the highest record was taken into account. The root mean square value was considered for analysis. Intraclass correlation coefficients (ICCs), paired t test, and the Bland-Altman method comprised the statistical analyses. The level of significance was set at 0.05. Results ICC records for right and left masseter and anterior temporalis muscles at T0 (first sEMG record) and T7 (second sEMG record) intervals were significantly different (p<0.05). The results showed satisfactory to excellent reproducibility of RMS values at rest, MVBF and 30% MVBF, as well as for MVBF in kgf. Conclusion The results showed reliable reproducibility for the sEMG signal recording in masseter and anterior temporalis muscles from the protocols presented and under the three conditions investigated.

Cambios en la vía aérea después de cirugía ortognática bimaxilar en pacientes con maloclusión clase III esquelética / Airway changes after bimaxillary orthognatic surgery in patients with skeletal class III malocclusion

Introducción: el objetivo fue determinar radiográficamente el porcentaje de estabilidad de la altura del reborde alveolar del maxilar superior e inferior en pacientes sometidos a cirugía preprotésica de aumento de reborde con implante de HA no reabsorbible. Métodos: el estudio se realizó en quince pacientes, en quienes se determinaron mediciones reproducibles. Para el maxilar superior: (A) desde espina nasal anterior; (B derecha-izquierda) desde el borde más inferior de las fosas nasales; (C derecha- izquierda) desde el borde más inferior de la órbita. Para el maxilar inferior: (E) desde el borde inferior de la mandíbula y pasando por la sínfisis; (F derecha-izquierda) pasando por el agujero mentoniano; (G derecha-izquierda) pasando 5 mm. atrás del agujero mentoniano; (H derecha-izquierda) pasando 10 mm posterior al agujero mentoniano. Todas las mediciones se realizaron en el prequirúrgico, en el posquirúrgico inmediato, y a los nueve meses. Resultados: se promediaron los diferentes puntos del maxilar superior (PPMXS) y se observó una pérdida de altura entre el 6,29 y un 33,6% con promedio del 17,36 %. En el maxilar inferior (PPMXI) se observó una variación desde ganancia del 6,31% hasta una disminución del 18,87%, con promedio del 2,54%. Conclusiones: el implante de HA permite restablecer adecuada altura del reborde alveolar. La altura del reborde alveolar obtenida inicialmente presenta un porcentaje de disminución de su altura en el maxilar superior del 17,36%, y en el maxilar inferior del 2,54 durante el seguimiento a nueve meses.

Introduction: the purpose of this study was to determine radiographically the percentage of stability of alveolar ridge height in the maxilla and the mandible in patients subjected to pre prosthetic surgery of ridge augmentation with non resorbable HA implants. Methods: the study was performed in 15 patients in whom reproducible measurements were taken. For the maxilla: (A) From Anterior Nasal Spine; (B right and left) from the lowest border of the nasal fossae; (C right and left) from the lowest border of the orbit. For the mandible: (E) from the lowest border of the mandible passing through symphysis; (F right and left) passing through the mental foramen; (G right and left) passing 5 mm posterior to the mental foramen; (H right and left) passing 10 mm posterior to mental foramen. All measurements were performed before surgery, immediately after and, nine months after surgery. Results: the different points of the maxilla were averaged (PPMXS) and a height loss between 6.29% and 33.6% was observed, with an average of 17.36%. For the mandible (PPMXL) variations ranging from 6.31% of augmentation to 18.8% loss were observed, with an average of 2.54%. Conclusions: HA implants allow reestablishment of adequate alveolar ridge height. The alveolar ridge height initially obtained presents a decrease percentage in height for the maxilla of 17.36% and 2.54% for the mandible after nine months follow up.