Effect of Hard Gummy Candy Chewing on Masticatory Function.

Background Although various training methods have been reported for improving oral function such as occlusal force, there are few reports that show the training effect of eating hard food on the oral functions. Objective To examine the training effects of habitually ating hard gummy candies on oral functions. Methods Participants of this cohort study were recruited into a training (six women, eight men; mean age 27.6 +/- 3.5 years) and control group (two women, seven men; mean age 28.3 +/- 4.9 years). The training group ate nine custom-developed hard gummy candies three times per week for 3 months. Training effects were evaluated by measuring the maximal occlusal force, masticatory performance, maximal tongue pressure, number of chewing cycles until swallowing the candy, duration of chewing and cycle time before training, after 1, 2 and 3 months of training, and 1 month after stopping training. The iEMG/force, which evaluates masseter muscle hypertrophy with electromyograms (EMG), was calculated. Results Masticatory performance after 1 month (p = 0.01), maximal occlusal force after 2 months (p < 0.01) and maximal tongue pressure after 3 months of training were significantly increased (p = 0.02), and the cycle time after 2 months of training (p = 0.02) was significantly decreased compared to before the intervention. Except for masticatory performance, the other effects were maintained for 1 month after stopping training. Changes in iEMG/force were not significant, but a tendency for muscle hypertrophy was observed in the training group. Conclusion Habitual eating of hard gummy candies is a task-specific training that can improve overall masticatory function, including tongue pressure.