Fernando Ángeles Medina

Differences in masseter activity in patients with and without self-reported rheumatoid arthritis using surface electromyography: A cross-sectional study

Introduction: Muscle weakness is frequent in patients with rheumatoid arthritis but electromyographic activity of masticatory muscles in these patients remains unclear. The aim of this study is to evaluate the differences of Root Mean Square activity in patients with and without rheumatoid arthritis during a 30 seconds period using a longitudinal approach. Material and methods: We performed a cross-sectional study and measured bilateral electromyographic activity (EMG) of masseter muscles for 30 seconds in maximum intercuspation. We measured EMG by using a digital electromyograph, developed by our group (Hardware and software) to determine μV every 0.001 seconds and root medium square (RMS) values were recorded. Patients were treated at the Department and Physiology Laboratory in the UNAM in 2017. We performed a descriptive, bivariate analysis and a random effects linear regression model for repeated measurements adjusted by confounders. Results: We analyzed the information of 60 patients. Mean age was 43.9 years (±15.9), and 33.3% of the participants were males. As result of the multivariate analysis we identified that in patients with rheumatoid arthritis the RMS increased by 52.3 μV (95%CI 11.7; 85.73, p= 0.012) compared to patients without rheumatoid arthritis, but over a 30 second period RMS mean activity decreased at a rate of -0.44 μV per second (95%CI -0.48; -0.38, p< 0.001). Conclusion: EMG in patients with rheumatoid arthritis had higher mean values of RMS but a decreased activity over the evaluated period. More research is needed to clarify the electromyographic activity in patients with rheumatoid arthritis. Correspondence to: Luis Pablo Cruz Hervert, Physiology department, DEPeI, Faculty of dentistry, National Autonomous University of Mexico, Mexico. Email: aeoorto@gmail.com

Development Proposal of a Masticatory Reflexmetry System Used in Monitoring the Treatment of People with Craniomandibular Dysfunctions

This paper describes the development of a masticatory refleximetry system to be used in clinic during the track of treatment to people with craniomandibular dysfunctions such as bruxism and temporomandibular joint disorders; proposing two alternative methods to evoke the masseter inhibitory reflex (MIR).

Diferente adaptación sensorio-motora a nuevas dentaduras, entre no portadores y portadores de dentaduras completas

Teeth loss elicits signifi cant changes in the sensory-motor activity of patients thus affl icted. 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 patients 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 fi rst 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.