Electromyography of masticatory muscles after denture relining with soft and hard denture liners

We evaluated electromyograms of masticatory muscles after denture relining with soft and hard liners. In total, 44 patients with complete dentures were studied: 22 underwent chairside relining of mandibular dentures with a soft, silicone-based liner (Mucopren Soft); the other 22 underwent relining with a hard, acrylic resin-based liner (Kooliner). Electromyograms of the masseter and temporal muscles were obtained before (T0) and 90 days after (T90) relining. Participants performed a maximum voluntary contraction (static test), on which percentage-overlapping coefficient (%), mandibular displacement (%), and standardized electromyographic activity, i.e., impact, (µV ⁄ µVs %) were analyzed. Participants were also asked to chew a wafer, cereal bar, and peanuts (dynamic test) to determine symmetrical mastication index (SMI%), frequency (Hz), and impact. The data were analyzed using a generalized linear model (α= 0.05). On the static test, mandibular displacement was lower and impact was higher at T90, as compared with baseline. On the dynamic test, SMI and impact were higher after relining for all foods. Frequency at T90 was higher only during cereal and peanut mastication. There were no differences between groups except for greatest impact during wafer chewing in patients with hard liners. Relining with hard and soft materials increased electromyographic activity and improved masticatory function. There was little difference between groups.