Bruxist Activity Monitor System (BAMS): An instrumental approach tool in the assessment of Bruxism.

The magnitude of harmful effects on dental structures, periodontium, masticatory muscles, and the temporomandibular joint, derived from temporomandibular disorders, specifically from sleep Bruxism, generates evidence that needs to be objectively collected. This paper introduces a portable device aiming at extracting and analyzing parameters (like timestamp, duration, or latency) from recordings obtained from the monitoring of occlusal activity, throughout a complete sleep cycle. An electronic device embedded in a mid-density medical grade silicon occlusal splint detects the moment in which the subject exerts sustained force, and records the time and length of the event, keeping the device on hold until a new event arises. The electronic device, based on a microcontroller, identifies occlusive events from an array of two piezo-resistive sensors and has a storage capacity of up to 36 hours of continuous activity. The collected data is wirelessly transmitted to an external module that is connected via USB to a PC. In the PC, the data is decoded, processed, analyzed, displayed, and stored in ordered files for case subjects, updating every recorded test for a complete history review. The proposed Bruxist Activity Monitor System (BAMS) was tested in one subject for more than 40 hours (5 sessions in 7 days). Preliminary results show the oral appliance endure without any significant damage over its surface nor undermining its functionality.

Changes in Electrical Activity of the Masseter Muscle and Masticatory Force after the Use of the Masseter Nerve as Donor in Facial Reanimation Surgery.

Introduction The masseter nerve has been used as a donor nerve for facial reanimation procedures due to the multiple advantages it offers; it has been generally considered that sacrifice of the masseter nerve does not alter the masticatory apparatus; however, there are no objective studies to support this claim. Objective To evaluate the impact that the use of the masseter nerve in dynamic facial reconstruction has on the electrical activity of the masseter muscle and on bite force. Materials and Methods An observational and prospective longitudinal study was performed measuring bite force and electrical activity of the masseter muscles before and 3 months after dynamic facial reconstructive surgery using the masseter nerve. An occlusal analyzer and surface electromyography were employed for measurements. Results The study included 15 patients with unilateral facial paralysis, with a mean age of 24.06 ± 23.43. Seven patients were subjected to a masseter-buccal branch nerve transfer, whereas in eight patients, the masseter nerve was used as a donor nerve for gracilis free functional muscle transfer. Electrical activity of the masseter muscle was significantly reduced after surgery in both occlusal positions: from 140.86 ± 65.94 to 109.68 ± 68.04 ( p = 0.01) in maximum intercuspation and from 123.68 ± 75.64 to 82.64 ± 66.56 ( p = 0.01) in the rest position. However, bite force did not show any reduction, changing from 22.07 ± 15.66 to 15.56 ± 7.91 ( p = 0.1) after the procedure. Conclusion Masseter nerve transfer causes a reduction in electromyographic signals of the masseter muscle; however, bite force is preserved and comparable to preoperative status.

Electromyographic Changes in the Masseter and Temporalis Muscles Before and After Orthognathic Surgery in Patients With Mandibular Prognathism.

OBJECTIVE: Evaluate the electromyographic changes in the Masseter (MM) and Temporalis (TM) muscles during voluntary clenching of the teeth both before and after orthognathic surgery in patients aged 18 years and older and diagnosed with mandibular prognathism. METHODS: Eleven patients with prognathism were included in the study, in all of whom the initial phase of orthodontic treatment had been completed. The orthognathic procedure to reduce prognathism comprised intraoral oblique sliding (or subsigmoid) osteotomy, after which intermaxillary fixation with ligaments in the maxilla and mandible was undertaken in all patients for 6 weeks post-surgery. Electromyographic activity was recorded during the baseline maximum voluntary contraction of the teeth, with the same measurement taken 3 and then 6 months after orthognathic surgery. RESULTS: Significant differences were found in the mean amplitude (17.0 vs 14.7, P = 0.020) and peak-to-peak amplitude (left [761.6 vs 457.0, P = 0.003] and right [676.9 vs 357.4, P = 0.007]) for the MM between the baseline score and 6 months after surgery. Likewise, significant differences were found in the mean amplitude (18.2 vs 25.6, P = 0.009) and peak-to-peak amplitude (left [856.4 vs 1594.2, P = 0.004] and right [804.4 vs 1813.4, P = 0.004]) for the TM between the baseline score and that taken 6 months post-surgery. Only 18.2% (2/11) presented orthodontic appliances problem in the 3 months post-surgery. CONCLUSION: Electromyographic activity was restored 6 months after the orthognathic surgery. From a clinical perspective, the results obtained confirm that orthognathic surgery has not only an esthetic but also a functional objective in terms of achieving equilibrium and occlusal harmony.

Prevalence of erosive tooth wear and associated factors in a group of Mexican adolescents.

BACKGROUND: Erosive tooth wear is the irreversible loss of dental hard tissue as a result of chemical processes. When the surface of a tooth is attacked by acids, the resulting loss of structural integrity leaves a softened layer on the tooth's surface, which renders it vulnerable to abrasive forces. The authors' objective was to estimate the prevalence of erosive tooth wear and to identify associated factors in a sample of 14- to 19-year-old adolescents in Mexico. METHODS: The authors performed a cross-sectional study on a convenience sample (N = 417) of adolescents in a school in Mexico City, Mexico. The authors used a questionnaire and an oral examination performed according to the Lussi index. RESULTS: The prevalence of erosive tooth wear was 31.7% (10.8% with exposed dentin). The final logistic regression model included age (P < .01; odds ratio [OR], 1.64; 95% confidence interval [CI], 1.26-2.13), high intake of sweet carbonated drinks (P = .03; OR, 1.81; 95% CI, 1.06-3.07), and xerostomia (P = .04; OR, 2.31; 95% CI, 1.05-5.09). CONCLUSIONS: Erosive tooth wear, mainly on the mandibular first molars, was associated with age, high intake of sweet carbonated drinks, and xerostomia. PRACTICAL IMPLICATIONS: Knowledge regarding erosive tooth wear in adolescents with relatively few years of exposure to causal factors will increase the focus on effective preventive measures, the identification of people at high risk, and early treatment.

Diferente adaptación sensorio-motora a nuevas dentaduras, entre no portadores y portadores de dentaduras completas / Varied sensory-motor adaptation to new dentures among full denture wearers and non wearers

La pérdida de las piezas dentarias provoca cambios importantes en la actividad sensorio-motora de los pacientes que la sufren, cambios que a su vez pueden afectarse al colocar una dentadura completa (DC) y todos en conjunto pueden alterar el proceso de la masticación a tal grado que se afecten condiciones generales de salud como, por ejemplo, una adecuada alimentación, por lo que ha sido importante estudiar la respuesta de los músculos masticatorios ante la colocación de una DC y además comparar entre aquellos pacientes que previamente han usado DC y aquellos que la utilizan por vez primera, considerando que pudiera existir un estado funcional diferente. Para ello se hicieron registros electromiográficos (EMG) en los músculos maseteros de 29 pacientes, antes (1ª sesión), a los 8 y 30 días (2ª y 3ª sesión respectivamente) de la colocación de la DC. Formando dos grupos: el grupo 1 (G1) (n = 15; 12 ♀ , 5 ♂ , edad promedio 67.2 años) aquellos que previamente estaban usando ya una DC y el grupo 2 (G2) (n = 12; 8 ♀ , 4 ♂ , edad promedio 66.5 años) los que nunca antes la habían usado. Los resultados indican que existe una diferencia funcional entre los músculos de aquellos pacientes que previamente han usado una DC con respecto a la de los músculos de los pacientes que no han usado antes DC. Se registró menor amplitud EMG en la 1ª sesión en el G1 con respecto al G2 y una menor capacidad de generar los ciclos masticatorios, ello podría influir, también a largo plazo, en una disminución de la capacidad masticatoria y en la calidad de vida de los pacientes. Es necesario continuar este tipo de estudios tanto para corroborar los resultados reportados en el presente trabajo como para que, en su caso, se implementen medidas que coadyuven a una mejor adaptación a la DC.

Teeth loss elicits significant changes in the sensory-motor activity of patients thus afflicted. These changes can in turn be affected upon placement of a full denture (FD). Overall changes can alter mastication processes, to the point of affecting the patient's general state of health, as would be the case when impinging on proper feeding. This shows the importance of studying masticatory muscles response to the placement of a full denture. It is as well opportune to compare patients who have previously worn dentures with new denture wearers, since it must be borne in mind they could present different functional states. To this end, electromyographic records (EMR) were conducted in masseter muscles of 29 patients before (1st session) at 8 and 30 days (2nd and 3rd session) of FD placement. Two groups were tailored: Group 1 (G1) (n = 15, 12 ♀, 5 ♂, average age 67.2 years) those who had previously worn a full denture, and group 2 (G2), (n =12, 8 ♀, 4 ♂, average age 66.5 years) comprising individuals who had never before worn a full denture. Results indicated there was functional difference among muscles of patients having previously worn FD when compared to muscles of patients who had never worn a FD. Lesser EMG amplitude was found in G1 when compared to G2 in the first session as well as lesser ability to generate masticatory cycles. In the long run, this could also bear upon masticatory ability decrease and patients quality of life. It is necessary to continue this type of studies to substantiate recorded results of the present study, as well as to implement measures geared at contributing to improved FD adaptation.

Reflejo inhibitorio masetérico en niños: Influencia de las etapas de la dentición y de las interferencias oclusales / Inhibitory masseteric reflex in children: Influence of the stages of the dentition and occlusal interferences

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.

[Effects of orthodontic treatment on the masseter muscle inhibitory reflex]. / Efectos del tratamiento de ortodoncia sobre el reflejo inhibitorio del músculo masetero.

OBJECTIVE: The aim of this study was to identify the effect of the orthodontic treatment on inhibitory masseteric reflex. METHODS: Twenty-three patients with any type of malocclusion and without any temporomandibular joint dysfunction were studied and treated under arch wire technique with Roth's brackets prescription (0.22" x 0.28"). Electromyographic record of the inhibitory masseteric reflex was obtained before and after orthodontic treatment. RESULTS: ANOVA test identified not reflex differences between molar relation types; using Student t test for paired data it was identified that with orthodontic treatment (14.65 +/- 2.40 months), the left reflex latency was increased from 6.17 +/- 9.29 ms to 37.00 +/- 66.33 ms (p < 0.05). However the left inhibition duration was decreased from 57.78 +/- 30.70 ms to 35.31 +/- 25.72 ms (p < 0.05), the right inhibition amplitude was decreased from 48.40 +/- 34.44 mV to 28.59 +/- 17.26 mV (p < 0.05) and the left inhibition amplitude was decreased from 40.72 +/- 29.75 mV to 18.73 +/- 17.68 mV (p < 0.05). CONCLUSIONS: Orthodontic treatment produced constraint of the masseter inhibitory capacity, which could be a transitory neuromuscular adaptation signal in the presence of sensorial scheme modifications. It is necessary to wait for a longer period of time before a new register to clarify the reflex morphology tendency.

Reflejo inhibitorio masetérico y condiciones clínicas estomatológicas en pacientes con parálisis cerebral / Inhibitory masseteric reflex and clinical stomatological conditions in cerebral palsy patients

Para contribuir al entendimiento de los mecanismos que acompañan las alteraciones masticatorias en pacientes con daño en el sistema nervioso central, se estudiaron en reflejo inhibitorio masetérico (RIM) y aspectos clínicos estomatológicos en 32 pacientes con diferentes tipos de parálisis cerebral (PC) en un rango de edad de 15 a 30 años. Se utilizó un modelo de regresión logística, la morfología refleja la distinción entre el tipo espástico y atetósico con una clasificación errónea de 31.35 por ciento (X2 =6.771, p=0.2382), con el conjunto de características cefalométricas, de la oclusión dental y de la articulación temporomandibular la distinción fue del 12.50 por ciento, (X2 =22.708, p=0.0453). A través del calculo de regresiones lineales, las condiciones estomatológicas y la edad explicaron las áreas inhibitorias faltantes (derecha e izquierda) y la razón de áreas (potenciación/inhibición) derecha con significancia estadística (p<0.05). Las variables clínicas con mayor poder de explicación respecto de los cambios reflejos fueron los contactos dentarios posteriores y anteriores (p<0.05). Se concluyó que los cambios en el tipo de PC no explican, por si mismos, los cambios del RIM y que estos últimos están asociados fundamentalmente con la disponibilidad de contactos dentarios. Se propone el registro del RIM con golpe al mentón para identificar la rapidez de la evolución de las secuelas masticatorias en pacientes con PC