Discussion
OME usually occurs following eustachian tube dysfunction. Rather than solely relying on natural resolution, hastening the process of restoring normal tube function will lead to a better quality of life for OME patients. Several techniques have been proposed to improve the function of the eustachian tube; for example, the Toynbee and Valsalva maneuvers aim to force open the eustachian tubes.3,8,10 In this study, we investigated the use of gum-chewing as a way of opening the tubes.
Gum-chewing creates jaw movement and induces more frequent swallowing. Gum-chewing is particularly beneficial for senile patients, who tend to have less eustachian tube activity due to dental problems, a poor or lost appetite, being less talkative, and a reduced swallowing frequency.11,12 In an earlier experimental study measuring tensor veli palatini muscle activity before and after eustachian tube rehabilitation by using electromyography monitoring, it was found that swallowing increases the strength of the tensor veli palatini muscle.13 Given that chewing gum increases the frequency of swallowing, the eustachian tube function should therefore improve.
Regarding the results, only 23 out of 43 ears (53.49%) became free of OME during the 12-week study period. Even though there is no definite, documented, resolution rate for OME in adults, this proportion is lower than the usual resolution rates in children reported in the literature (75%–90%)1 In other words, the gum-chewing did not enhance the cure rate. The reason why the resolution rates for adults are lower than those for children is possibly due to the cause of the eustachian tube dysfunction. OME in children often follows an acute upper-respiratory infection, such as the common cold or acute sinusitis. The OME is temporary and easy to cure. In contrast, the causes of OME in adults tend to be more chronic, for example, allergic rhinitis, exposure to smoking, and hormonal changes, all of which affect mucociliary activity.14,15 The other explanation is that there are age-related, morphological changes to the eustachian tubes. With advancing age, there are alterations in the size and shape of the eustachian tube cartilage, as well as in the positions of the levator veli palatini and tensor veli palatini muscles. Consequently, chewing gum may not always be sufficient to solve these problems in adult or senile patients, even though the method is intended to promote the swallowing activity.16
Taking a closer look at the data, only 2 parameters—patient age and the initial average air-bone gap—affected the resolution rate and time to improvement. The patients who were 40–60 years of age demonstrated a higher OME resolution and a shorter time to improvement than the other age groups. The effect of the muscular opening function could be the reason. In another study that measured middle-ear pressure after chewing, mouth opening, and jaw movement, the muscular opening function was found to be stronger in adults than in children or senile patients.17
Initial, average, air-bone gaps of ≤ 20 dB yielded a better OME resolution rate than gaps of > 20 dB. This could be explained by middle-ear fluid viscosity. Previous research has suggested that there is a correlation between middle-ear fluid viscosity and audiometry. Highly viscous or thick middle-ear fluid was found to result in a poorer air-conduction threshold and a larger air-bone gap (p-value < 0.001) than thin middle-ear effusion.18Thus, lighter viscosities tend to lead to faster resolutions of OME.
There were some limitations of this study. Firstly, only a small number of patients was investigated. Moreover, confounding factors (such as intranasal corticosteroid use, oral antibiotic use, and underlying conditions) might have affected the eustachian tube function. Furthermore, we lacked an exact protocol for the gum-chewing (the number of gums, frequency, and duration of gum-chewing). As a result, the conclusion that chewing gum is ineffective for the management of OME is still inconclusive. A further study with a randomized controlled trial utilizing a larger population is suggested.
Overall, given its minor side effects and low cost, xylitol-gum chewing could prove to be an adjunctive treatment to complement watchful waiting for the management of OME in selected patients. Its primary benefit is that it may help to hasten the natural resolution of OME.